فهرست مطالب

مهندسی عمران مدرس - سال شانزدهم شماره 2 (تابستان 1395)
  • سال شانزدهم شماره 2 (تابستان 1395)
  • تاریخ انتشار: 1395/04/22
  • تعداد عناوین: 22
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  • علیرضا ابراهیمی رلویز*، حسن امینی راد صفحات 1-7
    در این پژوهش تاثیر واکنش های بیولوژیکی در حذف مواد آلی فاضلاب موجود در شبکه های جمع آوری نوین بررسی شد. برای این منظور شبکه های جمع آوری فاضلاب از جنس PVC تحت جریان ثقلی در مقیاس آزمایشگاهی طراحی و ساخته شد. از چسباندن توری پلاستیکی به عنوان واسطه به سطوح داخلی لوله، برای رشد و الحاق میکروارگانیسم ها، استفاده شد. جهت افزایش غلظت میکروبی و همچنین سرعت بخشیدن به تشکیل بایوفیلم، از لجن فعال تصفیه خانه شهرک یثرب استفاده گردید. فاضلاب مصنوعی با آلودگی مشابه با فاضلاب خانگی در این مطالعه استفاده گردید. در این مطالعه تجربی پارامترهایی مانند BOD، COD، TN، NH3-N ، NO3-N ، TSS، مقادیرDO و ضخامت بیوفیلم در شرایط آزمایشگاهی اندازه گیری شد.
    نتایج نشان می دهد بایوفیلم ایجاد شده بر روی سطح یکنواخت نبود و ضخامت آن بین 7/4-3 میلی متر و چگالی سطحی بایوفیلم بین 1/33-3/22 گرم بایومس بر متر مربع بدست آمد. نرخ مصرف اکسیژن تقریبا به 21/0 میلی گرم بر لیتر بر دقیقه بود. غلظت مواد معلق با کاهش 82 درصدی از 105 به 19 میلی گرم بر لیتر رسید. بیشترین راندمان حذف مواد آلی در شبکه، در بار گذاری های مختلف بهره برداری برای BOD ، COD به ترتیب به 59 و54 درصد رسید. با افزایش بار آلی 70% به شبکه فاضلاب، میزان راندمان حذف COD فقط 9% کاهش یافت . در هر دو حالت بارگذاری آلی شبکه، با توجه به غلظت بالایCOD پساب خروجی، شرایط رشد باکتری های نیترات ساز ویا فرآیند نیتریفیکاسیون شکل نگرفت و تغییرات غلظت ترکیبات نیتروژنی ناچیز بود.
    کلیدواژگان: واکنش های بیولوژیکی، شبکه جمع آوری، فاضلاب، بایوفیلم
  • محمد دلنواز *، غلامرضا اسدالله فردی، امیر خواجویی صفحات 9-20
    پراکنش آلاینده های هوا در واحدهای صنعتی یکی از مواردی است که همواره محیط زیست و اکوسیستم منطقه های مجاور را تحت تاثیر قرار می دهد و می تواند در دراز مدت زندگی افراد ساکن در مجاورت این گونه واحدها را با مشکلات جدی مواجه سازد. مدل های انتشار آلودگی ابزار مفیدی جهت شناخت رفتار آلاینده پس از خروج از منبع بوده و اندازه گیری های زیاد و پر هزینه را غیر ضروری می نماید. در این تحقیق دی اکسید گوگرد (SO2) که یکی از آلاینده های خطرناک ناشی از سوزاندن ترکیبات گازی مختلف در خروجی مشعل ها می باشد به عنوان مدل آلاینده و مجتمع نفت و گاز ابوذر که شامل 3 سکوی بهره برداری و 10 سکوی سرچاهی می باشد و فرایند اشتعال مشعل ها به عنوان اصلی ترین چالش زیست محیطی این مجتمع محسوب می گردد به عنوان منطقه مورد مطالعه در نظر گرفته شده است. جهت مدلسازی فرایند انتشار آلاینده، ابتدا اطلاعات هواشناسی با نرم افزار View Rammet پردازش شد و ارتفاع شعله با توجه به سرعت باد و گرمای خالص آزاد شده در مشعل محاسبه گردید. سپس غلظت SO2 خروجی از مشعل، از طریق شبیه سازی کامپیوتری به وسیله نرم افزار AERMOD View، در محدوده ی 150 کیلومترمربعی، محاسبه گردید. خروجی نرم افزار که همان گراف حاوی زون های اصلی تمرکز آلاینده می باشد، نشان داد که در حالات در نظر گرفته شده غلظت SO2 در تمامی سکوهای بهره برداری و سرچاهی اطراف مشعل از مقادیر استاندارد جهت 8 ساعت کار مداوم و همچنین استاندارد های سازمان حفاظت محیط زیست آمریکا، تجاوز می نماید.
    کلیدواژگان: دی اکسید گوگرد، سکوی ابوذر، آلودگی هوا، مشعل، مدل AERMOD
  • رضا آقایاری*، ابوالفضل عرب زاده، کیانا زنگنه زاده صفحات 21-30
    در این مقاله رفتار تیرهای عمیق بتن مسلح با مقاومت بالا به صورت آزمایشگاهی بررسی شد. بدین منظور 5 نمونه تیر عمیق بتن مسلح با مقاومت فشاری 60 مگاپاسکال تحت اثر بار گسترده مورد آزمایش قرار گرفت. تیرهای آزمایشگاهی در دو انتها دارای تکیه گاه ساده و با آرماتورهای برشی قائم به فواصل مساوی تقویت شده بودند. آرایش آرماتورهای برشی نمونه ها یکسان ولی قطر آنها متفاوت بود. در طول آزمایش رفتار کلی نمونه های آزمایشگاهی مورد بررسی قرار گرفت. مشاهدات آزمایشگاهی شامل تغییر شکل وسط دهانه، وضعیت شکست، حالت های گسیختگی و مقاومت فشاری نظیر ترک خوردگی اولیه و شکست نهایی نمونه تیر عمیق بود. گسیختگی هر 5 نمونه به صورت شکست ترد برشی بود. بر اساس نتایج حاصله، آرماتورهای قائم جان بر ظرفیت برشی تیرهای عمیق تاثیرگذار بوده و نمونه ها تحت بار گسترده عموما مقاومت برشی بالاتری در مقایسه موارد مشابه تحت بار متمرکز از خود نشان می دهند. نتایج آزمایشگاهی با نتایج به دست آمده از روش Strut-and-tie (مدل خرپایی) مقایسه گردید. نتایج حاصله از مقایسه حاکی از انطباق رضایت بخش مدل STM ارائه شده برای تیرهای عمیق بتن مسلح تحت بار گسترده با نتایج آزمایشگاهی می باشد .
    کلیدواژگان: تیر عمیق، مدل خرپایی، مقاومت برشی، آرماتور برشی، بارگذاری گسترده
  • محمد شاکرخطیبی*، زهرا اکبری، محمد مسافری، سیاوش درفشی، میرمحمد چاوشباشی، اسماعیل فاتحی فر، علی بهنامی صفحات 31-40
    این مطالعه به منظور ارزیابی عملکرد سیستم تصفیه پساب واحد تولید رزین اکریلونیتریل بوتادین استایرن (ABS) انجام شده است. سیستم تصفیه شامل 3 آشغالگیر ریز، یک حوض دانه گیر، یک حوض متعادل ساز، سیستم شناورسازی با هوای محلول (DAF)، یک واحد بیولوژیکی لجن فعال و واحد زلال ساز می-باشد. این سیستم پیش تصفیه به منظور کاهش مواد جامد معلق و COD پساب واحد ABS قبل از ورود به واحد تصفیه مرکزی شرکت پتروشیمی طراحی شده است. نمونه های ترکیبی متناسب با دبی در 4 نوبت در طی 6 ماه برداشته شده و پارامترهای BOD5، COD ،TSS، اکریلونیتریل، اکریلامید، اکریلیک اسید، سیانید و آمونیاک مطابق با روش های استاندارد اندازه گیری شده اند. ساختار جمعیت میکروبی سیستم لجن فعال نیز مورد بررسی قرار گرفته است. تحت بار سطحی m3/m2.h 76/2 اعمال شده به سیستم DAF، راندمان حذف COD و SS به ترتیب 24 و 43 درصد به دست آمد. در مقادیر بار آلی kg COD/m3.d 06/0±79/0اعمال شده به سیستم لجن فعال، راندمان حذف COD و BOD5 به ترتیب 59 و 68 درصد بوده است. در مجموع، راندمان حذف COD، BOD5 و TSS در کل سیستم پیش تصفیه به ترتیب 90،80 و88 بوده است. به علاوه، راندمان حذف اکریلونیتریل در سیستم 91 درصد بوده که 26 درصد حذف در واحد بیولوژیکی رخ داده است. در میان باکتری های جداسازی شده از لجن فعال، جنس های Alcaligenes، Pseudomonas، Bacillus و Moraxella به عنوان باکتری های نیتریفایر هتروترف شناسایی شده اند.
    کلیدواژگان: ارزیابی عملکرد، فاضلاب صنعتی، ABS، لجن فعال
  • ارسلان بذرافشان، ناصر خاجی* صفحات 41-52
    جداسازی لرزه ای یکی از مناسب ترین ابزارهای مهندسی زلزله در زمینه کنترل غیرفعال می باشد. اگرچه این روش در ابتدا برای سازه های کوتاه مرتبه با رفتار روسازه نسبتا صلب توسعه یافت، با این حال، کاربرد آن در سازه های متوسط و بلند رو به افزایش است. کمترین نتیجه ای که جداسازی لرزه ای در سازه های بلند به همراه دارد، کاهش تغییرمکان نسبی جانبی (دریفت) طبقات به علت تغییرشکل مود نخست، به علاوه تامین یک مکانیزم استهلاک انرژی مناسب در کف ساختمان می باشد. برای حفظ کارآیی جداسازی، زمان تناوب سیستم جداساز باید به اندازه کافی بزرگ درنظر گرفته شود. چنین سازه ای ممکن است در برابر زلزله های پریودبلند آسیب پذیر باشد. در این مقاله، عملکرد لرزه ای سه مدل ساختمان برشی 8، 14 و 20 طبقه جداسازی شده، توسط دو نوع جداساز سربی-لاستیکی و آونگ اصطکاکی، تحت اثر زلزله های پریود بلند، مورد مطالعه قرار می گیرد. نتایج نشان می دهد که با افزایش ارتفاع، میزان اثرپذیری سازه از زلزله های پریود بلند بیشتر می شود و این حرکات قادرند نیاز جابجایی بالایی را به جداساز تحمیل کنند.
    کلیدواژگان: ساختمان برشی، جداسازی لرزه ای، ساختمان های بلند، زلزله های پریودبلند
  • جعفر بلوری بزاز *، حدیث جلیلیان مشهود صفحات 53-65
    ریزشمع، یک شمع جایگزینی حفاری و تزریق شده با قطر کمتر از 300 میلی متر است که عموما مسلح بوده و برای اجرای آن ابتدا چاه شمع حفاری شده و مسلح کننده در داخل آن قرار می گیرد و سپس ملات به داخل چاه تزریق می شود. از این تکنولوژی برای بهبود ظرفیت باربری پی های موجود نیز استفاده می شود. تحقیق حاضر به بررسی میزان تاثیر ریزشمع در بهبود ظرفیت باربری پی تحت اثر بارگذاری استاتیکی قائم می پردازد. تعدادی آزمایش بارگذاری بر روی مدل آزمایشگاهی کوچک مقیاس از پی مسلح شده با ریزشمع که بر روی ماسه شل قرار گرفته انجام گردید. برای مسلح نمودن پی صلب دایره ای با قطر 10 سانتی متر، از ریزشمع های فولادی آج دار به قطر 6 میلی متر و طول 20 سانتی متر استفاده شد. با تغییر زاویه نصب و تعداد ریزشمع ها، تاثیر نحوه چیدمان ریزشمع ها بر رفتار ژئوتکنیکی پی مطالعه شد. برای سنجش کمی میزان افزایش ظرفیت باربری پی مسلح شده با ریزشمع، ضریب شبکه ای(R) تعریف می شود که عبارتست از نسبت ظرفیت باربری پی مسلح شده با ریزشمع به مجموع ظرفیت باربری پی و ریزشمع ها به صورت مجزا. نتایج آزمایش-ها نشان می دهد که مقدار ضریب شبکه ای با افزایش تعداد ریزشمع ها بالا می رود. همچنین در صورت کاربرد 6 یا 8 ریزشمع، با افزایش زاویه نصب ریزشمع نسبت به امتداد قائم، از مقدار R کاسته می شود. در حالت استفاده از تعداد زیادی ریزشمع های دارای زاویه نصب کوچک ، ظرفیت باربری به مقدار قابل توجهی افزایش می یابد. مقدار ضریب شبکه ای در صورت کاربرد 8 ریزشمع با زاویه نصب 15 درجه، برابر 997/1 می باشد.
    کلیدواژگان: پی، ریزشمع، زاویه نصب، تعداد، ضریب شبکه ای
  • رضا پیشگر، سیدعلی ایوب زاده*، مجتبی صانعی، مسعود قدسیان صفحات 67-80
    رسوبگذاری مخازن موجب بوجود آوردن مشکلاتی مانند کاهش حجم و عمر مفید مخازن، کاهش حجم کنترل سیلاب، گرفتگی آبگیرها، تونل ها و توربین ها و دیگر مسائل مرتبط می شود. علی رغم توسعه چندین روش برای حل این مسئله، نرخ رسوبگذاری مخازن سدهای دنیا بیانگر وجود داشتن این مشکل می باشد. در دهه گذشته روش های جدیدی ارائه شد که از بین آن ها روش هیدروساکشن لوله مکش دفن شونده بیشتر مورد توجه گرفته است. هدف از این تحقیق، بررسی آزمایشگاهی اثر فاصله بین روزنه های تحتانی و چگالی قسمت انحناء لوله مکش بر کارایی روش هیدروساکشن لوله مکش دفن شونده می باشد. در این تحقیق روزنه ها به سمت بالادست و پایین دست انحناء امتداد یافته اند. به منظور یافتن ارتباط بین کارایی روش با فاصله بین روزنه های تحتانی و چگالی قسمت انحناء لوله مکش، آزمایش های متعددی بر لوله مکش با قطر داخلی 61 میلیمتر، نسبت قطر روزنه ی تحتانی به قطر لوله مکش برابر 25/0 و فاصله نسبی 5/0، 75/0 و 1 بین روزنه های تحتانی انجام شد. نتایج نشان داد، اثر افزایش چگالی قسمت انحناء لوله مکش بر کارایی ابتدا افزایشی و سپس کاهشی است. بطوریکه با افزایش چگالی از 77/1 به 16/2 کارایی صعودی است و سپس با بیشتر شدن چگالی کارایی نزولی می شود. همچنین، کاهش فاصله بین روزنه ها موجب افزایش کارایی روش هیدروساکش می گردد و در فاصله نسبی 2 ، بیشترین غلظت متوسط خروجی با مقدار 58/1 درصد مشاهده شد. بعلاوه نتایج نشان داد، روش هیدروساکشن قادر است تا 5 برابر حجم رسوباتی که در محل قرارگیری لوله مکش ته نشین شده اند را تخلیه نماید.
    کلیدواژگان: رسوبگذاری مخازن، تخلیه رسوب، هیدروساکشن، لوله مکش، کارایی
  • سید حامی حجتی، سید هانی حجتی، سید علی اکبر صالحی نیشابوری* صفحات 81-90
    عمده ضوابط طراحی هیدرولیکی جام های پرتابی متکی بر روش های تحلیلی و تجربی بدست آمده از مدل های هیدرولیکی می باشد. با توجه اهمیت سرریزها در ایمنی سدها، این سازه ها بایستی سازه ای قوی، مطمئن و با راندمان بالا انتخاب شوند. زاویه جام مثلثی یکی از پارامتر های اساسی در طراحی جام محسوب می شود؛ چرا که میزان فشار دینامیکی بر روی جام، طول جت خروجی از جام، میزان استهلاک انرژی و عمق آبشستگی و غیره متاثر از این پارامتر می باشند. در تحقیق حاضر به منظور افزایش راندمان سرریز، با به کارگیری روش بهینه سازی ژنتیک سعی در طراحی بهینه زاویه انحراف جام مثلثی و عرض سرریز تنداب شده است. برای دست یابی به اهداف مذکور ابتدا ، روابطی که توسط حجتی در سال 1392 برای ارتفاع معادل فشار دینامیکی بر روی جام، طول جت خروجی از جام و عمق آبشستگی معرفی شده است، به عنوان پارامتر های تابع هدف مورد استفاده قرار گرفته اند. سپس وزن های مربوط به پارامتر های تابع هدف با استفاده از اطلاعات مربوط به سرریز سد کارون 3 کالیبره شده و درنهایت زاویه جام مثلثی و عرض سرریز شوت به کمک الگوریتم بهینه سازی ژنتیک طراحی شده است. با در نظر گرفتن پارامتر های طراحی سرریز سد کارون 3، میزان عرض سرریز تنداب و زاویه جام مثلثی طراحی شده به کمک الگوریتم ژنتیک بترتیب 4/17 متر و 30 درجه و اختلاف آن ها با سرریز تنداب و زاویه جام مثلثی سرریز سد کارون 3 بترتیب 16% و 0% بدست آمده است که نشان می دهد الگوریتم ژنتیک پتانسیل بالایی برای طراحی پارامتر های ذکر شده دارد.
    کلیدواژگان: جام پرتابی مثلثی، عرض سرریز تنداب، پرش اسکی، الگوریتم ژنتیک
  • مجید پورامینیان *، محمود حسینی، ارژنگ صادقی صفحات 91-102
    امروزه برای آنالیز سازه های مختلف اغلب، ابزارهای قدرتمندی نظیر نرم افزارهای اجزای محدود سه بعدی مورد استفاده قرار می گیرد. اما بکارگیری این نرم افزارها برای ارزیابی ایمنی لرزه ای ، آنالیز و ارایه طرح بهسازی سازه های تاریخی با مشکلاتی همراه است. هندسه پیچیده سازه، نبود اطلاعات دقیق از خصوصیات فیزیکی مصالح و عدم دسترسی به قسمت های داخلی احجام تشکیل دهنده بدنه سازه و آگاهی از خصوصیات مکانیکی آنها ، ممنوع بودن انجام آزمایش های مخرب روی اینگونه از سازه ها، توالی و تسلسل در ساخت و طولانی بودن زمان آنالیز و هزینه بر بودن آن از جمله مشکلات پیش روی محققین و مهندسانی است که در زمینه مدلسازی و آنالیز بناهای تاریخی بصورت تخصصی فعالیت می نمایند. آنالیز حدی جنبشی ساده شده، روشی قدرتمند برای آنالیز بناهای تاریخی است که در نشریه O.P.C.M.3431کشور ایتالیا استفاده از آن برای ارایه طرح بهسازی ساختمان های بنایی مجاز دانسته شده است. روابط مورد استفاده در این روش بر مبنای اصل کار مجازی بدست آمده اند. اطلاعات مورد نیاز در این روش، جهت مدلسازی و ارزیابی ایمنی لرزه ای سازه ها بسیار کمتر و قابل دسترس تر می باشد. در این مقاله تحقیقی در رابطه با قابلیت های این روش برای ارزیابی ایمنی لرزه ای بنای تاریخی ارگ علیشاه تبریز صورت گرفته است و صحت سنجی نتایج بدست آمده از این روش با نتایج آنالیز عددی نرم افزار ANSYS.V10 مقایسه شده است . نتایج نشان داد که سازه در برابر بارهای لرزه ای مستعد منطقه ایمنی لازم را ندارد. شتاب مبنای طرح ساختگاه ارگ g 35/0 ( احتمال وقوع 10% در 50 سال) می باشد.
    کلیدواژگان: ایمنی لرزه ای، بناهای تاریخی، آنالیز حدی جنبشی ساده شده، آنالیز اجزای محدود، ارگ علیشاه تبریز
  • شهرزاد داورپناه جزی، عبدالرضا کبیری سامانی*، حسین افضلی مهر صفحات 103-115
    پوشش گیاهی با ایجاد زبری در دیواره کانال ها و دشت های سیلابی رودخانه ها بر شکل هندسی، هیدرولیک و مقاومت جریان تاثیر گذاشته و مکانیزم انتقال رسوب را تغییر می دهد. با توجه به اهمیت شکل های بستر نظیر تلماسه ها در کنترل میزان انتقال رسوب، تولید آشفتگی و ایجاد مقاومت جریان، مطالعه اثرات شکل های بستر شنی و پوشش گیاهی بر ساختار جریان ضروری به نظر می رسد. هدف از پژوهش حاضر مطالعه ساختار جریان بر روی تلماسه های شنی با تاج مسطح به همراه پوشش گیاهی در دیواره است. برای دست یابی به این هدف تعداد هفت تلماسه مصنوعی با تاج مسطح در طول یک کانال آزمایشگاهی مورد بررسی قرار گرفته اند. اندازه گیری داده های سرعت و آشفتگی با استفاده از سرعت سنج صوتی انجام شد. نتایج نشان داد که در تلماسه های با تاج مسطح بر خلاف تلماسه های با تاج تیز، در هر دو حالت وجود و عدم وجود پوشش گیاهی، پارامتر سرعت بعد از تاج مسطح مقادیر منفی به خود نمی گیرد. تنش های رینولدز در حالت وجود نسبت به حالت عدم وجود پوشش گیاهی بیشتر هستند که این موضوع را می توان به افزایش مقاومت جریان در حضور پوشش گیاهی نسبت داد.
    کلیدواژگان: تلماسه شنی، پوشش گیاهی، تنش رینولدز، جریان آشفته
  • صادق دردایی، حامد باقری* صفحات 117-124
    امروزه استفاده از مصالح پلیمری در صنعت ساختمان رشد روز افزونی داشته است. بر این اساس از مصالح پلیمری در ساخت بتن، جهت اصلاح مشخصات آن استفاده می شود. سه نوع اصلی مصالح مرکب بتن پلیمری شامل پلیمر تزریقی، پلیمری و بتن پلیمر– سیمان در صنعت ساختمان شناخته شده می باشد. استفاده از انواع پلیمرها و نحوه ساخت نمونه جدید، می تواند مشخصات مکانیکی متفاوتی در رفتار بتن را باعث گردد. در این تحقیق اثرات مربوط به تغییرات میزان درصد وزنی رزین پلی استر در ساخت بتن و اثرات پخت تکمیلی بعد از ساخت در بتنهای پلیمر- سیمان بررسی می شود. بر این اساس نمونه های استوانه ای بتن با سیمان پرتلند بدون پلیمر، نمونه هایی که ده، بیست و سی درصد وزنی سیمان، پلیمر در ساخت آن جایگزین شده، مورد ارزیابی قرار می گیرند. همچنین اثرات مربوط به پخت تکمیلی در ساخت نمونه های بتن های پلیمر – سیمان (PPCC) مورد ارزیابی قرار می گیرد. بر اساس نتایج به دست آمده اثرات استفاده از پلیمر در ساخت بتن بر مشخصات مکانیکی از جمله مقاومت فشاری و مقاومت کششی و همچنین اثرات پخت تکمیلی بر ساخت این نمونه ها قابل توجه می باشد.
    کلیدواژگان: مشخصات مکانیکی، بتن، رزین پلی استر، پخت تکمیلی، بتن پلیمر، سیمان
  • سید مصطفی سیادت موسوی، امیررضا حمیدی* صفحات 125-134
    آب شستگی پیرامون پایه های پل در معرض جریان امری اجتناب ناپذیر است. برآورد عمق آب شستگی و فهم الگوی جریان اطراف پایه می تواند کمک زیادی به طراحی ایمن پایه کند. در این مطالعه از مدل عددی SSIIM به عنوان یک مدل دینامیک محاسباتی سیالات (CFD) برای مدل سازی همزمان جریان و رسوب در اطراف گروه شمع در معرض جریان استفاده شده است. از داده ها و نتایج آزمایشگاهی مربوط به دو پایه ی کنار یکدیگر به عنوان یک حالت خاص گروه شمع برای واسنجی و شناخت بهتر این مدل استفاده شده است. در این مدل معادلات سه بعدی ناویر-استوکس برای جریان به همراه مدل های آشفتگی k-ε و k-ω حل شده و از خروجی های محاسبات جریان برای حل معادلات انتقال رسوب استفاده شده است. با بررسی الگوی آب شستگی دو پایه و مقایسه ی آن با مقادبر آزمایشگاهی مشخص شد که مدل عددی SSIIM، محاسبات جریان رو به پایین در جلوی پایه ها را با دقت قابل قبولی انجام می دهد اما اثر گردابه های دنباله ای در پشت پایه ها و اثر تداخل گردابه های نعل اسبی بین پایه ها را بیش از واقعیت در نظر گرفته و مقادیر عمق های آب شستگی در این نواحی بیش از مقادیر واقعی است. الگوی آب شستگی حاصل از به کارگیری مدل آشفتگی k-ε دقت بسیار بهتری نسبت به الگوی آب شستگی حاصل از به کارگیری مدل k-ω در پیرامون دو پایه دارد. البته لازم به ذکر است به دلیل پیچیدگی محاسبات جریان و رسوب و ساده سازی های انجام شده برای مدل سازی، نتایج بدون اشکال نیست.
    کلیدواژگان: آب شستگی، مدل سازی، SSIIM، دو پایه
  • علی جلایی فر *، اسماء سیستانی، بهروز عسگریان صفحات 135-145
    زلزله های حوزه نزدیک منجر به ایجاد خرابی های قابل توجه در سازه های گوناگون در دهه های اخیر شده اند و در نتیجه ضوابط آیین نامه های طراحی لرزه ای در رابطه با این مسئله تغییرات عمده ای یافته است. در این میان آیین نامه ی طراحی لرزه ای کشور ایران (استاندارد 2800) ضوابط ویژه ای برای زلزله های حوزه نزدیک پیش بینی ننموده است. در این مقاله رفتار لرزه ای قاب های مهاربندی شده فولادی که بر اساس آیین نامه های طراحی لرزه ای مختلف، شامل ویرایش های اول، دوم و سوم آیین نامه طرح لرزه ای ایران (استاندارد 2800)، ضوابط طراحی لرزه ای UBC-97 و الزامات طراحی لرزه ای آیین نامه AISC-ASD89 طراحی شده اند، به صورت مقایسه ای مورد مطالعه قرار گرفته است. قاب های با ارتفاع و نوع مهاربندی متفاوت با استفاده از تحلیل دینامیکی افزایشی تحت زلزله های حوزه نزدیک آنالیز شده اند. تحلیل دینامیکی افزایشی (IDA) یک روش جدید و نوظهور در تحلیل سازه ها است که با استفاده از رکوردهای متعدد زلزله مقیاس شده و یک سری تحلیل های دینامیکی غیرخطی منجر به تخمین و ارزیابی ظرفیت لرزه ای، حدود پایداری و تقاضای لرزه ای سازه ها می گردد. نتایج حاصل از این تحقیق بیانگر آن است که قاب های طراحی شده بر اساس ضوابط لرزه ای حوزه نزدیک UBC-97 عملکرد بهتری تحت زلزله های حوزه نزدیک در مقایسه با دیگر قاب ها دارند و ضوابط ویرایش سوم استاندارد 2800 برای تامین ایمنی سازه ها، بخصوص سازه های بلند متربه تر، در برابر زلزله های حوزه نزدیک نیازمند بازنگری می باشد.
    کلیدواژگان: تحلیل دینامیکی افزایشی، سطح عملکرد، بهره برداری بی وقفه (IO)، آستانه فروریزش(CP)
  • حمزه شکیب *، وحید جهانگیری صفحات 147-159
    بررسی هم بستگی بین پارمترهای نیاز مهندسی و معیارهای شدت مختلف دارای اهمیت زیادی در مهندسی زلزله عملکردی برای تخمین نیاز لرزه ای سازه می باشد. در این تحقیق نیاز لرز های خطوط لوله فولادی مدفون پیوسته با توجه به روشی مبتنی بر عملکرد مورد بررسی قرار گرفته است. تحلیل دینامیکی فزاینده بر روی دو لوله فولادی مدفون با قطر به ضخامت (D/t) ، عمق دفن به قطر (H/D) و فشار داخلی متفاوت و نیز مشخصات خاک مختلف با استفاده از مجموعه ای از رکوردهای زمین لرزه حوزه دور انجام گرفته است. مدل سازی با استفاده از روش اجزاء محدود انجام شده که در طی آن از المانی مبتنی بر تئوری تیر تیموشنکو جهت مدل سازی لوله استفاده گردیده و برای مدلسازی خاک از فنرها و میراگرهای معادل استفاده شده است. کرنش فشاری محوری پیک در بحرانی ترین مقطع لوله به عنوان پارامترنیاز مهندسی برای لوله فولادی مدفون پیوسته انتخاب شده و سپس معیارهای شدت زمین لرزه مختلفی برای بررسی همبستگی آنها با پارامتر نیاز مهندسی مورد استفاده قرار گرفته اند. با استفاده از تحلیل رگرسیون کارایی و کفایت این معیارهای شدت در برآورد پاسخ لرزه ای خطوط لوله فولادی پیوسته مدفون بررسی شده است و مشخص گردید که مقادیر پاسخ حداکثر (مثل PGA، PGV، PGD و ) و نیز معیارهای شدت طیفی در زمان تناوب اصلی خط لوله (یعنی ، و ) معیارهای شدت ناکارایی هستند. در نهایت مشخص شد که جذر میانگین مربعات جابه جایی(RMSd معیار شدت بهینه برای خطوط لوله فولادی مدفون پیوسته می باشد.
    کلیدواژگان: خط لوله مدفون پیوسته، معیار شدت، کارایی، کفایت، مهندسی زلزله عملکردی
  • افسانه شهبازی *، شیرین زاهدی نیا، سید حسین هاشمی صفحات 161-172
    در مطالعه حاضر کارایی خاک اره صنوبر به عنوان یکی از ضایعات چوبی (بدون تغییرات شیمیایی) در حذف متیلن بلو از پساب، مورد بررسی قرار گرفته است. ایزوترم ها (با استفاده از مدل های ایزوترم لانگمیر و فروندلیچ) و سینتیک های جذب (با استفاده از مدل های شبه مرتبه اول، شبه مرتبه دوم، الوویچ و نیز مدل نفوذ درون ذره ای) مورد مطالعه قرار گرفت و مشاهده شد که رفتار فرآیند مورد نظر از مدل ایزوترمی لانگمیر (996/0=R2) تبعیت کرده و سینتیک آن بر واکنش شبه مرتبه دوم (999/0=R2) منطبق می گردد و این مکانیسم به وسیله جذب سطحی و نفوذ درون ذره ای کنترل شده است. همچنین پارامترهای ترمودینامیکی سیستم جذب از قبیل تغییر در آنتالپی (ΔH°)، آنتروپی (°ΔS) و انرژی آزاد گیبس (°ΔG) اندازه گیری و ارزیابی شد. حداکثر ظرفیت جذب خاک اره صنوبر در جذب رنگ کاتیونی متیلن بلو در شرایط بهینه برابر mg/g 85/26 بوده است. نتایج نشان داد که خاک اره صنوبر، جاذب طبیعی مناسبی در جذب رنگ متیلن بلو از پساب محسوب می شود که در شرایط بهینه درصد جذبی برابر 68/84% را دارا می باشد.
    کلیدواژگان: جذب متیلن بلو، خاک اره صنوبر، سینتیک، ایزوترم، ترمودینامیک
  • احسان الله ضیغمی، فرشید جندقی علایی*، منصور جامعی، مسعود سلطانی محمدی صفحات 173-186
    ماتریس های پایه سیمانی دارای مقاومت کششی و شکل پذیری ناچیز می باشند. افزودن الیاف به این ماتریس ها سبب بهبود مشخصات مکانیکی آنها می شود. مقاومت کششی پس از ترک خوردگی مواد مرکب سیمانی مسلح شده با الیاف فولادی به صورت مستقیم با تعداد الیاف عبور کننده از عرض ترک و رفتار بیرون کشیده شدن هرکدام از الیاف مرتبط می باشد. بنابراین شناخت دقیق رفتار بیرون کشیدگی الیاف منفرد، به منظور فهم رفتار کششی تک محوره و رفتار خمشی بتن های الیافی مسلح با الیاف فولادی ضروری بنظر می رسد. از آنجایی که الیاف فولادی قلابدار یکی از کاراترین نوع الیاف مورد استفاده برای کاربردهای سازه ای هستند، لذا بررسی و شناخت دقیق رفتار بیرون کشیدگی این نوع از الیاف از اهمیت بسیار بالایی برخوردار می باشد. در این مقاله یک مطالعه تجربی بر روی رفتار بیرون کشیدگی الیاف فولادی قلابدار در حالت هایی که الیاف عمود بر عرض ترک و یا به صورت مایل قرار می گیرند انجام گردیده و با بررسی رفتار بیرون کشیدگی الیاف فولادی قلابدار در زوایای تمایل 0، 15، 30، 45 و 60 و در طول مدفون های 10، 15، 20 و 25 میلی متر تاثیر زاویه تمایل الیاف نسبت به امتداد بارگذاری و طول مدفون الیاف، بر روی پاسخ بیرون کشیدگی شامل؛ بیشینه نیروی بیرون کشیدگی، لغزش مربوط به نقطه بیشینه نیرو، انرژی بیرون کشیدگی، میزان موثر بودن الیاف و همچنین کنده شدگی ماتریس در هر حالت مورد مطالعه قرار گرفته است.
    کلیدواژگان: الیاف فولادی قلابدار، رفتار بیرون کشیدگی، ماتریس پایه سیمانی
  • اصغر عزیزیان، علیرضا شکوهی* صفحات 187-201
    مدلهای رقومی ارتفاعی (DEMs) به عنوان یکی از ورودی های مهم بیشتر مدلهای بارش- رواناب به شما می آیند. در حال حاضر منابع مختلفی همچون: DEMهای SRTM و ASTER وجود دارند که با توجه به سهولت دسترسی و رایگان بودن از جایگاهی ارزشمند در مدلسازی های هیدرولوژیکی و استخراج خصوصیات ژئومورفولوژیکی حوضه ها برخوردار می باشند. در تحقیق حاضر به بررسی اثر منابع مختلف تهیه DEM بر شاخص توپوگرافی و نیز نتایج حاصل از مدل نیمه توزیعی TOPMODEL پرداخته شده است. نتایج حاکی از آن است که اختلاف بین متوسط شاخص توپوگرافی بدست آمده از DEMهای SRTM و نقشه های 1:50000 زمینی همواره بیشتر از مقادیر متناظر بدست آمده از DEMهای ASTER و نقشه های 1:50000 زمینی می باشد. بررسی نتایج حاصل از خروجی TOPMODEL نیز نشان می دهد که متوسط دبی روزانه، متوسط کمبود اشباع حوضه و متوسط فاصله تا تراز سطح ایستابی حوضه در منابع مختلف اختلاف چندان معنی داری با یکدیگر ندارند. اما شاخص کارائی بدست آمده بر مبنای DEMهای SRTM همواره از نتایج بدست آمده از نقشه های زمینی و DEMهای ASTER کمتر می باشد. در دبی های روزانه، شاخص کارائی مدل بر اساس DEMهای ASTER تا محدوده ابعاد سلولی 500 متر با نتایج بدست آمده از نقشه های زمینی تطابق مناسبی داشته و این در حالیست که در جریان های ساعتی (سیلاب) نتایج حاصل از دو منبع فوق در تمامی ابعاد سلولی تقریبا یکسان ارزیابی می شود.
    کلیدواژگان: مدلهای رقومی ارتفاعی، DEMهای SRTM و ASTER، مدل نیمه توزیعی TOPMODEL، شاخص توپوگرافی
  • نبی الله غریب زاده، اسماعیل فاتحی فر *، رضا علیزاده، امیرناصر حق لسان، میرمحمد چاوش باشی صفحات 203-213
    در این تحقیق، از فرایند شبه فنتون برای حذف تولوئن از محلول های آبی با غلظت اولیه ppm100 استفاده شد. نانوذرات اکسید آهن با قطر حدود nm 18، از کاتالیست های مستعمل پتروشیمی تبریز با استفاده از آسیاب گلوله ای تهیه شد. کاتالیست های مستعمل و نانوذرات تهیه شده، توسط آنالیزهای BET، XRF، XRD و FE-SEM تعیین مشخصات شدند. برای تعیین غلظت تولوئن، از دستگاه کروماتوگرافی گازی (GC) استفاده شد. به منظور بررسی بر هم کنش پارامترهای تاثیرگذار [H2O2]/[Catalyst]، ]غلظت آلاینده [H2O2]/[و زمان واکنش (دقیقه) بر درصد حذف تولوئن و یافتن شرایط بهینه، طراحی آزمایش به روش RSM صورت گرفت و مقادیر بهینه برای این پارامترها به ترتیب 460/0، 928/4 و 7/105 بدست آمد. معادله درجه دوم با ضریب همبستگی بسیار بالایی برای پیش بینی حذف تولوئن برازش شد که مقادیر R2 و R2(adj) مدل پیش بینی شده، به ترتیب برابر با %14/99 و %37/98 توسط نرم افزار minitab حاصل شد. بر اساس آزمایش های انجام شده، در شرایط بهینه پارامترهای تاثیرگذار، حذف کامل تولوئن از محلول های آبی حاصل شد. نتایج حاصل از این پژوهش نشان داد که روش RSM ابزار مناسبی جهت مدلسازی و بهینه سازی فرایند شبه فنتون برای حذف تولوئن می باشد. همچنین نتایج نشان داد که نانوذرات اکسید آهن تهیه شده از کاتالیست های مستعمل پتروشیمی تبریز، قابلیت بسیار خوبی برای استفاده در فرایند شبه فنتون جهت حذف تولوئن از محلول های آبی دارند.
    کلیدواژگان: تولوئن، شبه فنتون، نانوذرات اکسید آهن، محلول های آبی، بهینه سازی
  • سعید غفاری، افشین اقبال زاده *، میترا جوان صفحات 215-228
    سرریزهای جانبی دارای کاربرد گسترده ای در مهندسی هیدرولیک هستند، که به علت حساسیت موضوع نیاز به طراحی و بررسی دقیق دارند. در مقاله ی حاضر جریان عبوری از سرریز جانبی مستطیلی لبه تیز در کانال باز مستطیلی با استفاده از نرم افزار FLOW-3D و بکارگیری مدل آشفتگیRNG k- و روش VOF شبیه سازی شده است. در تحقیق حاضر پس از صحت سنجی نتایج مدل عددی با داده های آزمایشگاهی، به بررسی اثرات عدد فرود بالادست بر الگو و مشخصات جریان در امتداد سرریز جانبی پرداخته می شود. نتایج در این مطالعه نشان می دهد، با کاهش عدد فرود، ماکزیمم و مینیمم سرعت طولی در طول سرریز جانبی به ترتیب افزایش و کاهش می یابد. با کاهش عدد فرود، ماکزیمم سرعت جانبی در طول سرریز جانبی افزایش می یابد، که بیانگر افزایش دبی عبوری از سرریز جانبی می باشد. همچنین توزیع مولفه های مختلف سرعت در برابر تغییرات ارتفاع جریان در روی وسط تاج سرریز برای عدد فرود های متفاوت نشان می دهد، با کاهش عدد فرود بالادست، توزیع سرعت طولی در نزدیک تاج سرریز غیر یکنواخت تر می شود. برای اعداد فرود متفاوت، سرعت جانبی تا ارتفاع معینی از روی تاج سرریز افزایش می یابد و سپس با نزدیک شدن به سطح آزاد جریان مقدارآن کاهش می یابد. ماکزیمم سرعت قائم برای عدد-فرود های متفاوت، در نزدیکی تاج سرریز رخ می دهد و با افزایش ارتفاع و نزدیک شدن به سطح آزاد جریان مقدار آن به تدریج کاهش می یابد. با کاهش عدد-فرود، سرعت قائم در نزدیکی سطح آزاد جریان منفی می باشد. در خصوص سطح آزاد جریان در مجاورت سرریز جانبی، با افزایش عدد فرود بالادست، عمق سطح آب در انتهای سرریز دچار تغییرات شدیدی می شود.
    کلیدواژگان: سرریز جانبی، نرم افزار FLOW، 3D، عدد فرود، الگوی جریان، توزیع سرعت
  • امیررضا گودرزی*، متین میرمومن صفحات 229-241
    در پژوهش حاضر تاثیر مشخصات مایع منفذی و اثر زمان بر بازده روش الکتروکینتیک، ارزیابی شد. به این منظور، ابتدا رس کائولینیت با محلولهای حاوی نیترات روی و سرب بطور مجزا آلوده و با گرادیان ولتاژ V/cm 2 در زمانهای 3 الی 48 روز، در مقیاس آزمایشگاهی مورد آزمایش الکتروکینتیک قرار گرفت. از اسید نیتریک نیز به عنوان محلول کاتولیت، با هدف امکان شدتبخشی فرآیند پالایش خاک استفاده شد. نتایج بدست آمده نشان میدهد پاسخ خاک به اصلاح الکتروکینتیک تابعی از مشخصات ماده آلاینده، pH سیستم خاک-الکترولیت و زمان انجام آزمایش است. بر این اساس در شرایط یکسان بخصوص در زمانهای کم، بازده استخراج آلودگی از نمونه حاوی سرب به دلیل تمایل بیشتر این فلز به جذب سطحی و همچنین تشکیل رسوب، تقریبا 70 درصد نمونه آلوده به روی اندازه گیری شد. با توجه به طیفهای اشعه ایکس و تصاویر SEM، تقویت جبهه اسیدی محیط پیرامون کاتد با افزایش غلظت یون H+ درون توده خاک، سبب تغییر ساختار، افزایش تحرکپذیری فلز سنگین و در نهایت تشدید قابلیت رفع آلودگی از خاک میشود. مشخص شد میزان اصلاح خاک به ویژه در قطعات نزدیک به آند ابتدا با گذشت زمان، به شدت بهبود یافته اگرچه افزایش بیشتر زمان خصوصا در نمونه های با غلظت زیاد فلز روی، تاثیر محدودی بر نتایج دارد. این یافته بیانگر وجود یک زمان بهینه متناسب با نوع و غلظت آلاینده در فرآیند پاکسازی فلزات سنگین از خاک به روش الکتروکینتیک بوده بنحویکه کاهش pH محیط تاثیر بسزایی در کاهش این زمان و افزایش راندمان استخراج دارد.
    کلیدواژگان: الکتروکینتیک، فلزات سنگین، مشخصات مایع منفذی، زمان، ریزساختار
  • مجتبی مهرآیین*، مسعود قدسیان، مجتبی خسروی مشیزی صفحات 243-257
    در تحقیق حاضر میدان جریان اطراف آبشکن T شکل مستقر در قوس o90 با مطالعه پارامترهای آماری بررسی شد. برای این منظور از دو آبشکن با درصد استغراق %5 و %50 استفاده شد. آبشکنها در زاویه o45 نسبت به ابتدای قوس قرار گرفتند و آزمایشات در شرایط کف صلب (بدون حرکت رسوبات) انجام شد. در این تحقیق میدان جریان اطراف آبشکن مستغرق بررسی و احتمال ایجاد پدیده های چهارگانه آشفتگی، زاویه های اعمال پدیده ها، تبدیل پدیده های آشفتگی به یکدیگر و تنشهای رینولدز در جهتهای طولی و عرضی مورد بررسی قرار گرفت. نتایج این تحقیق نشان دهنده تشکیل دو جریان ثانویه در امتداد عرض کانال می باشد که بر مکانیزم انتقال رسوب بسمت ساحل داخلی و آبشستگی ایجاد شده در ترازهای بالایی جریان درساحل خارجی تاثیر گذار می باشد. در نزدیک نوک بالادست آبشکن تنشهای رینولدز برشی بزرگتری در آبشکن با %5 استغراق مشاهده شد که نشان دهنده قدرت بیشتر گردابه نعل اسبی در این ناحیه بدلیل جریان روبه پایین قوی تر در این ناحیه می باشد. توسعه حفره آبشستگی بسمت پایین دست در امتداد لایه برشی می تواند بدلیل احتمال بیشتر پدیده های آشفتگی بیرون رانی و جاروبی، ناپایداری بیشتر پدیده های اندرکنشی، کاهش زاویه های اعمال پدیده های بیرون رانی و جاروبی و افزایش تنشهای رینولدز برشی در این ناحیه باشد. تنشهای رینولدز برشی نیز در نزدیک کف در لایه برشی اطراف آبشکن با %5 استغراق بیشتر از آبشکن با %50 استغراق می باشد و عامل توسعه بیشتر حفره آبشستگی بسمت پایین دست در آبشکن با درصد استغراق کمتر می باشد.
    کلیدواژگان: آبشکن مستغرق، جریان آشفته، پارامترهای آماری، پدیده های چهارگانه
  • ابراهیم نعیمی فر *، شهاب الدین یثربی، علی فاخر صفحات 257-271
    احتمال خرابی و آسیب به سازه های مجاور محدوده گودبرداری همواره بعنوان یک مسئله چالش برانگیز در طول پایدارسازی دیوار گودبرداری های عمیق با روش «میخکوبی» مطرح بوده است. منشا این خرابی ها عمدتا جابجایی های ایجاد شده در دیوارهای گود با پیشرفت گودبرداری است. با این وجود تا کنون ارتباط منطقی بین میزان جابجایی های پیش گفته و میزان خرابی قابل انتظار در سازه های مجاور ارائه نشده است.
    در این پژوهش سعی گردیده است با تکیه بر10مطالعه موردی و90 تحلیل عددی سه بعدی کالیبره شده و بهره گیری از آنالیزهای احتمالاتی، به ارائه حدود مجاز جابجایی دیوار میخکوبی شده با توجه به احتمال آسیب به سازه های مصالح بنایی واقع در مجاورت گود پرداخته گردد. نتایج این پژوهش ارائه دهنده سطوح خرابی سازه های مجاور گود تحت مقادیر مختلف جابجایی می باشد. سطوح خرابی پیشنهادی دراین مقاله، نشان دهنده «میزان خرابی» محتمل درسازه های مجاور دیوارهای میخکوبی شده، باتوجه به «فاصله سازه» از دیوار گود و حداکثر مقادیر «جابجایی افقی» دیواره گود و با در نظر گرفتن اثرات عمق گود و نوع خاک می باشد.
    کلیدواژگان: گودبرداری، میخکوبی، حدود مجاز جابجایی، سطوح خرابی
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  • Alireza Ebrahimi*, Hasan Aninirad Pages 1-7
    The composition of wastwwater in sewer lines are changing due to their nature. Wastewater contains large amount of organic materials, therfore it is suseptible to biological disintegritaion. Normally the conditions of sewers dicctate and promote the type of growth of bacteria being either aerobic or anaerobic. Previous studies have shown that large number of concrete sewer lines were found to beeffected by anaerobic bacteria activites. In this experimental investigation the aerobic biological transformation of organic matter in small diameter gravity slope wastewater collection system is evaluated. In this study a sewer network reactor at pilot scale was designed and built. The reactor consists of 15 meters length of PVC with 0.1 m diameter, two storage tanks and re circulating pump. The whole system was set up on a platform with adjustable slope. To ease the Formation of attached growth of micro organism a plastic net was attached on the inner surface of PVC pipe, thus a rough surface for attachment of microorganisms was formed. Due to the variation of hydraulic mean diameter, contact area with flowing wastewater was ranged from 1.88 to 3.77 m2 (half or full). Synthetic wastewater with characteristic municipal wastewater was used. A settled activated sludge fromYasreb wastewater treatment plant in Qaemshahr city was used to start and accelerate the biofilm growth in the reactor. In order to study bio-film attachment rate two P.V.C square plates in dimensions of 10*10 cm were placed perpendicular on the direction flow of wastewater. The reactor was conducted under aerobic conditions in a hydraulic retention time of 7 hours under constant temperature changed about 20 ±3 C. In this study parameter such as BOD, COD, TN and NH3-N and NO3-N were measured on daily basis. The thickness of biofilm increased and formed as irregular with thickness of 3-4.7 mm. Biofilm characteristics analysis showed that density and surface density were respectively 55 mg Ts/cm-3 and between 22.3 and 33.1 m-2. The concentration of suspended biomass was varied from10-15 mgl-1 at optimum COD removal. Oxygen consumption rate was estimated from decreasing rate of soluble oxygen concentration which reached to 0.21 mg l-1 min-1 after 3 weeks of operation. The highest reduction in COD and biological oxygen demand (BOD) concentration were 59% and 54% respectively . By increasing the chemichal oxygen demand (COD) loading by 70 %, removal rate of COD reduced by only 9%. Due to high COD concentration of wastewater effuluent, the nitrification process was limited. In order to nitrify the waste water, a longer hydraulic retention time(HRT) or higher recirculation is required. From the results and analysis it can seen be seen that proposed innovative method is applicable in many fields such as mountainous area, area with water stress ratio, water scarce area and ... which normally an application of conventional wastewater treatment either are costly or impractical.
    And also with regard to publicized incentives for using waste water reclaimation as a source of water for agricultral irrigation, thus with more precision in desigin and operation, an effluent of these new configuration of PVC pipes can be used in agri-industry
    Keywords: reaction, collection networks, wastewater, microorganism, Biofilm
  • G. Asadollahfardi, A. Khajooe, Mohammad Delnavaz* Pages 9-20
    Aboozar oil field is located around 75 km south west of Kharg Island, in Bushehr state, southern part of Iran. Aboozar oil and gas complex contains 3 production platforms: Aboozar-A (AA), Aboozar-B (AB) and Aboozar-C (AC). Each of them includes some oil and gas wells which feed the process facilities and in addition each one comprises separate flare system in which separated gas is flared over there. Aboozar field offshore process is limited to oil and gas separation, and the produced gas from the separators is disposed in a common flare system in which more than 36 million standard cubic feet gas mixture are daily being flared. Flaring is the common practice of burning off unwanted, flammable gases via combustion in an open-atmosphere, non-premixed flame. This gas may be deemed uneconomic to process (i.e. if it is far from a gas pipeline or if it is ‘sour’ and contains trace amounts of toxic H2S) or it may occur due to leakages, purges, or an emergency release of gas in a facility. The flaring process can produce different pollutants such as SO2 as an index pollutant which has a substantial role in the environment and human health. SO2 is one the most major pollutants emitted from production platform flares due to gas mixture combustion.This pollutant concentration depends on the composition of gas sent to the flare combustion chamber and also flare combustion efficiency. To specify prevention and mitigation measures, it is needed to know about air pollutants concentration. In highly polluted places, to monitor amount of each pollutant all over the region, we should always measure concentration of pollutant by pollutant emission modeling from the source not to need costly routinely measurement by some special devices. Nowadays, air pollution models are routinely used in environmental impact assessments, risk analysis and emergency planning, and source apportionment studies. A dispersion model is essentially a computational procedure for predicting concentrations downwind of a pollutant source, based on knowledge of the emissions characteristics. These models is based on mathematical calculation and used to estimate pollutants concentration. As the project target, flare modeling as a point source to investigate its concentration around the platforms to understand whether the concentration of pollutant is more than the standard limit value or not was considered. In this project, we have simulated SO2 emission by means of an advanced model based upon the Gaussian model, and we tried to find out SO2 dispersion pathway after flame. In this study, Aboozar production platform flare SO2 dispersion has been simulated by means of AERMOD View software and its concentration was determined. Flare flame length and height was determined, using flare flame net heat release value, to achieve flare effective height. In addition, meteorological data was pre-processed in Rammet View Software to input in main software. Final results showed that SO2 estimated concentration is being exceeded from threshold limit value all over the complex in all living quarters and production and wellhead platforms based upon the American Conference of Governmental Industrial Hygienists standard.
    Keywords: SO2, Aboozar Platform, Air pollution, Flare, AERMOD model
  • Abolfazl Arabzaeh, Kiana Zanganeh Zadeh, Reza Aghayari* Pages 21-30
    Reinforced concrete deep beams have useful applications in many structures, such as tall buildings, foundations, offshore structures, and several others. The reinforced concrete deep as important structural elements having small span-to-depth ratio. The investigation of their behavior is a subject of considerable interest in RC structures researches and some studies on the shear strength of reinforced concrete deep beams have been carried out over the last fifty years. In deep beams, according to shear span-to-depth ratio and web reinforcement the ultimate strength is generally controlled by shear rather than flexure, if the sufficient amount of longitudinal reinforcement is used. Several different failure modes have been identified from experimental studies, due to variability in failure, the determination of their shear strength and identification of failure mechanism are very complicated. In this paper the influence of effective parameters on the behavior of high-strength RC deep beams was investigated. For this purpose, an experimental-analytical investigation was conducted; a total of five reinforced concrete deep beams with compressive strength in range of 60 MPa were tested under uniform contributed top loading. The tested specimens were simply supported and reinforced by vertical steel bars in various spacing. The general behavior of tested beams was investigated. Observations were made on mid-span vertical deflections, cracks form, failure modes and shear strengths. All the beam specimens showed a same response up to failure. The test results indicated that vertical web reinforcement are efficient in shear capacity of deep beams, all the specimens were failed at abrupt shear mode. According to the test results, the shear capacity is affected by amount of web reinforcement and the test specimens are stronger in comparison with those were tested under two-point loading. Elastic solutions of reinforced concrete deep beams provide a good description of the behavior before cracking, but after cracking, a major redistribution of stresses occurs and hence the beam capacity must be predicted by inelastic analysis. Due to their geometric proportions, the capacity of reinforced concrete deep beams is governed mainly by shear strength. Deep beams behave differently from shallow beams and have been identified as discontinuity regions where the strain distribution is significantly nonlinear and specific strut-and-tie models need to be developed, whereas shallow beams are characterized by linear strain distribution and most of the applied load is transferred through a fairly uniform diagonal compression field. Strut-and-tie method is one of the most simple and applicable methods which can be used to simplify analysis and design of deep beams. Strut-and-tie modeling is the most rational and simple method for designing no flexural members currently available. At least, the experimental strength of specimens was compared with predicted results of strut-and-tie method (STM). The performed comparison indicates that the STM to provide acceptable estimates of shear capacity of deep beam loaded under uniform loading.
    Keywords: deep beams, strut, and, tie, shear strength, shear reinforcement, contributed top loading
  • Mohammad Shakerkhatibi* Pages 31-40
    The treatment of wastewater generated from acrylonitrile butadiene styrene (ABS) resin manufacturing industry have a great importance due to its high chemical oxygen demand (COD) and some other toxic substances. Activated carbon adsorption, chemical oxidation and biodegradation are the most conventional methods to the treatment of ABS effluents. Among them, the biological treatment as an environmentally friendly technology is highly regarded in the bio treatment and biotransformation of the toxic compounds of ABS wastewater to the intermediate and final compounds such as CO2 and water. This study was conducted to evaluate the performance of an activated sludge system for pretreating ABS manufacturing effluents. The wastewater pretreatment plant is consisted of 3 fine screens, a grit chamber, an equalization basin, dissolved air floatation (DAF) system, an activated sludge reactor and a final clarifier. This system was operated to reduce the TSS and COD values in the effluent in order to obtain to interior discharge permits to the central wastewater treatment utility operated by Tabriz petrochemical complex. Four runs weighed average sampling was conducted during 6 months according to the standard methods of the examination of water and wastewater. The parameters including COD, BOD5, TSS, TDS, sulfate, total kjeldahl nitrogen (TKN), ammonia-N, nitrate-N, alkalinity, cyanide, phosphate and pH were measured in wastewater samples according to the standard methods. The concentrations of acrylonitrile, acrylamide and acrylic acid in wastewater samples were determined using gas chromatography (GC) equipped with flame ionization detector (FID) with capillary column. Microbial structure of activated sludge was also evaluated using R2A, PCA and Nutrient Agar culture media as well the biochemical standard tests. According to the results, at surface loading rate of 2.76 m3/m2.h applied to DAF, the COD and TSS removal efficiencies of 24 and 43% were obtained, respectively. The ratio of BOD5/COD in the influent was 0.57 indicated the moderate biodegradability of ABS wastewater. In addition, the COD and BOD5 removal efficiencies in biological reactor were 59 and 68% respectively, at the organic loading rates (OLR) of 0.79 ± 0.06 kgCOD/m3.d. Totally, the COD, BOD5 and TSS removal efficiencies in the pretreatment system were 80, 90 and 88%, respectively. In addition, at the acrylonitrile loading rates of 0.067 ± 0.008 kg ACN/ m3.d, the removal efficiency of acrylonitrile was 91% which 26% of that has occurred in the biological reactor. Also, the removal efficiency of cyanide was 97% which only 4% of that has occurred in the biological reactor. Twenty bacterial strains were isolated and identified from the activated sludge samples. Among the isolated bacterial strains, four strains include Alcaligenes sp. Pseudomonas sp. Bacillus sp. and Moraxella sp. were identified as heterotrophic nitrifiers. Based on the results, the nitrifier bacteria have played an important role in the degradation of acrylonitrile in the biological activated sludge system. The results of parameters analysis, performance evaluation and microbial assessment revealed the satisfactory performance of COD removal as well nitrification. However, it seems that a significant portion of the volatile organic compounds (VOCs) are removed from the influent wastewater by stripping.
    Keywords: Performance Evaluation, Industrial effluent, ABS, Activated sludge
  • Naser Khaji* Pages 41-52
    Base isolation systems may be considered as one of the most powerful tools of earthquake engineering pertaining to the passive structural vibration control technologies. It may enable a building or non-building structure to survive a potentially devastating seismic impact. Generally, it is thought that application of seismic isolation is limited to low- and medium-rise structures, and the use of isolation for high-rise buildings considered as impractical or unfeasible. However, existing examples of isolated high-rise buildings in Japan, also in Iran, suggest that these viewpoints clearly disagrees with the real state-of-practice that exists there. Since the 1995 Kobe earthquake, just fewer than 200 isolated high-rise buildings, ranging from 60 to 180 meters height, have been constructed in Japan. However, this strategy is still uncommon in most countries of the world. Implementation of base isolation can greatly decrease inter-story drifts and floor accelerations, which results in protection of building’s contents. As a result, high-rise buildings can be kept fully operational during the earthquake and also immediately occupiable just after the event. In other words, isolation can be adopted for the improved performance of high-rise buildings. To maintain the efficiency, the period of isolation system has to be considered between 4 and 7 seconds. Clearly, structures like this will be vulnerable to long period ground motions. Therefore, it is necessary to study the behavior of these structures under such earthquakes. Long-period ground motions can be divided into far-source and near-fault classes. Most far-source long-period ground motions were generated by large earthquakes and effective propagation paths. Therefore, far-source long-period ground motions are generally associated with offshore earthquakes in subduction zones. Near-fault long-period ground motions are generated mainly by rupture directivity effects in the vicinity of earthquake source faults,. They consist primarily of rupture directivity pulses, which can be damaging, especially when combined with site effects and basin edge effects. In this paper, three base isolated models of 8-, 14-, and 20-story shear buildings using isolator type of lead-rubber bearing (LRB) and friction pendulum system (FPS), under long-period ground motions are studied. A set of 14 long-period ground motions – 5 far-source long-period motions and 9 near-fault long-period motions – as well as 14 short-period ground motions were selected. Total earthquake input energy per unit mas was used as a measure to distinguish long-period motions so that those which had a significant input energy over the periods of 2 seconds were considered as long-period motions. For each model two isolators – LRB and FPS – were designed so that the design displacement and the period of systems were exactly the same. The isolators were designed carefully and all dimensions and parameters were checked to insure practicality of the design. Then nonlinear dynamic analysis was implemented to evaluate the response of the structures. Results show that in the cases that input motions are short-period, increasing the height of the structure doesn’t significantly affect the structure response and the isolation displacement are nearly the same. On the other hand, as the height of the structure is increased, its response due to the long-period ground motions becomes more significant, and these motions impose a great displacement demand in the isolation system.
    Keywords: Shear Buildings, Seismic Isolation, High, Rise Buildings, Long, Period Ground Motions
  • Jafar Bolouri Bazaz*, Hadis Jalilian Mashhoud Pages 53-65
    Improvement of bearing capacity of existing foundations is of great significance. There exist many methods for practical purposes. Micropile is one of the most promising methods. Micropile is a replacement pile of small diameter (usually less than 300 millimeter) which is frequently reinforced using steel elements. To construct a micropile, steel reinforcement is placed in the borehole after drilling the borehole and subsequently the grout is injected into it. Micropiles transfer the structural loads to the deeper and stronger layers of the ground and confine settlement (similar to conventional pile foundations). They also improve the mechanical properties of soil layer such as density, bearing capacity, permeability and compressibility. Owing to their advantages, micropiles are widely used as foundations of new structures construction and also for reinforcing the foundation of existing structures.
    This research aims at experimental investigation of bearing capacity of foundations reinforced with micropiles under the condition of static loading. A small-scale physical model of a foundation reinforced with micropiles was developed and a series of static loading tests were carried out on.
    The model micropile-foundation was located on loose sand. Density of the underlying soil was kept almost uniform throughout the tests. The foundation model was circular and 100 mm and 5o mm in diameter and thickness, respectively. It was made from polyamide and considered to act as a rigid foundation during the loading owing to its material and thickness.
    This foundation was reinforced with a group of micropiles with 6 mm and 200 mm in diameter and length, respectively. These model micropiles were made from threaded steel bars. In order to mobilize friction, sand grains were glued to the surface of the micropiles. Various arrangements of micropiles including the number and inclination angle of micropiles were tested. From the comparative examination of the observed behavior of micropile foundations, the influence of micropiles’ arrangement on the mechanism and improvement of bearing capacity of foundation was investigated. Number of micropiles used in the group varied from 2 to 8. Micropiles were inclined at different angles (0°, 15°, 13°, 45° and 60°) to study its influence on the behavior of foundation reinforced with these elements. In order to quantitatively assess the degree of improvement in the bearing capacity of surface foundations reinforced with micropiles, an index R called “Network Index” was introduced in this study. The index R of unity means that the bearing capacity of foundations reinforced with micropiles is simply equal to the summation of the individual value of the surface foundation and that of the micropile group. There is an upward trend in the rate of index R when the number of micropiles is increased. On the other hand, in high numbers of micropiles used to reinforce the foundation, index R declines with increasing of inclination angle. In the case of micropiles with low-inclination-angle being implemented, bearing capacity is improved remarkably; an index R of 1.997 is achieved in this study where 8 micropiles inclined at an angle of 15° were used to reinforce the foundation.
    Keywords: Foundation, Micropile, Inclination Angle, Number, Network Index
  • Reza Pishgar, Ali Aubzade* Pages 67-80
    The purpose of constructing and using a dam reservoir is storage and conservation of water. Sedimentation declines this object and can arise many problems such as reduction in capacity for flow regulation, reservoir lifetime and flood control volume, blocking intakes in reservoirs and damage of tunnels and turbines, and many other types of sediment-related problems can occur both upstream and downstream of dams. Several techniques have been proposed to prevent entrance of sediment to the reservoirs and removing deposited sediment from reservoirs. However, actual observations of world reservoirs sedimentation rates have revealed that the problem still remains. The “burrowing-type sediment removal suction pipe method” is widely considered among the new methods introduced in the last decade. This study investigated the suction pipe geometrical and mechanical characteristics on the efficiency of the burrowing-type sediment removal suction pipe method. The the suction pipe geometrical and mechanical characteristics of this experimental study includes the bottom holes spacing ratio and suction pipe bends part’s density. The suction pipe with different density at its bend part, used as a new technique conserving distance between bottom holes and sediment. The average concentration of suction flow during the experiment time known as the efficiency of the Hydrosuction sediment removal method. In this research, A series of experiments are carried out to reveal the effect of the bottom holes spacing and density of suction pipe bend part of the Hydrosuction method efficiency. The suction pipe used in this research is a flexible PVC pipe with an internal diameter of 61 mm. The ratio of bottom hole diameter to pipe diameter is 0.25, and the spacing ratio between bottom holes varies from 0.5 to 1. This study, also, used a layout of holes that the bottom holes extended both the upstream and downstream of the pipe bend part. This research also investigates the time series of suction flow concentration and suction cone volume. The results showed that the decrease of the bottom holes spacing ratio from 1 to 0.5 increases the efficiency of the method and the suction flow has its maximum average concentration (efficiency) at spacing ratio 2, with an amount of 1.58 %. Also, the density of pipe bend part has a remarkable effect on Hydrosuction method efficiency. Examination of pipe bend part density showed tha, with the increase of density of bend part from 1.77 to 2.16, the efficiency increases and it decreases just the pipe bend part density’s dimensionless parameter have greater value than 2.16. Suction flow concentration showed that, mostly, the maximum concentration occurs at the beginning of the test and then the concentration curve has an ascending branch, a maximum point and descending branch, respectively. After commencing the test, the suction flow concentration has a rapidly increasing trend untill the pipe reaches to the level of reservoir bottom, then the concentration decreases gradually. Volume ratio of flushing cone to sediment filled under suction pipe location has its maximum value at holes spacing ratio of 2 that its value, in this research, reaches to 5.
    Keywords: Reservoirs sedimentation, sediment removal, hydrosuction, suction pipe, efficiency
  • Seyed Hami Hojjati, Seyed Hani Hojjati, Seyed Ali Akbar Salehi Neyshabouri* Pages 81-90
    The criteria for hydraulic design of flip buckets are based on the analytical and experimental methods obtained from physical models. Due to the importance of spillways in the safety of dams, these structures should be secure and highly efficient. In the present study, in order to increase the efficiency of the spillway, it has been attempted to optimally design wide- triangular flip bucket angle and chute spillway by applying genetic optimization method. To achieve the aforementioned objectives, firstly, the equations derived for dynamic pressure head on the flip bucket, the exit jet length, and scour depth have been used as the parameters of objective function (Hojjati, 1392). Thereafter, the weights of objective function parameters have been calibrated using data related to the spillway of Karoon 3 dam, and eventually triangular flip bucket angle and chute spillway have been designed with the help of genetic optimization algorithm. Taking into consideration the design parameters of Karoon 3 spillway, the spillway length and angle of triangular flip bucket were obtain as 17.4 meters and 30 degrees, respectively by means of genetic algorithm. However, their difference with , the spillway length and angle of triangular flip bucket of Karoon 3 dam has been obtained as 16% and 0%, respectively wich indicates that the genetic algorithm enjoys high potential for designing the aforementioned parameters. The width of downstream and deflector angle have been obtained 3.6 meters and 30 degrees, respectively with 70% decrease of discharge, 45.4% increase of Froude number, and consistency of the weights of objective function and flip bucket height. Also by assuming the weight constant, increasing Froude number and decreasing the width of spillway, the flow rate increases and results in the increase of the parameters used in the objective function. With the design parameters of Karoon 3 dam remaining constant and the significant increase of weights associated with the parameters of pressure and scour depth independently of each other; spillway width was designed very largely which is not cost-effective. As well, with the design parameters of Karoon 3 dam remaining constant and the decrease of weights associated with the exit jet length in a way that all the three parameters can be viewed equally effective in minimizing the objective function, maximum dynamic pressure and scour depth have been reduced as much as 7% and 16%, respectively; however, the jet length has undergone a reduction of 12% and its width has undergone an increase of 38% which is not fully desirable. As a result, the weight reduction of jet length is not cost effective due to the slight change of scour depth and the maximum increase of pressure on the flip bucket and also the big increase of spillway width. Therefore, it seems preferable that the effect of jet range parameter outweigh the other two parameters because increasing the jet range results in the further depreciation of flow energy which is the main focus of the ski jump dissipator construction.
    Keywords: triangular flip bucket, chute spillway, ski jump, Genetic algorithm
  • Majid Pouraminian*, Mahmoud Hosseini Pages 91-102
    Iran with more than 11000 historical & monuments constructions is introduced one of the oldest civilizations in the word. Moreover, most of major earthquake in the world is referred to Iran , that is a serious threat for historical building that because during these constructions usually seismic loads are not considered, therefore it is necessary to identify these buildings behaviour in front of this natural hazard (earthquake), and doing necessary actions to strengthening the buildings and even reconstruct them in some cases. One of these splendid constructions is historical Tabriz citadel or Arge- Alisha Tabriz.
    Remained Citadel Alisha is a U shape plan with average 33 meters height, 51.2 meters width, 21.1 meters length. Arge Tabriz is situated in a city that is a high earthquake prone area. Thus because of different faults in this area and Arge- Alisha’s historical & cultural significance, this safety assessment of this building is unavoidable.
    Historical masonry structures have complex geometry that because of erosion, humidity and their materials mechanical properties has changed a lot. Usually, there is not enough exact information about compose materials of internal parts of the walls. On the other hand, because these constructions are cultural monuments of a country doing destructive tests for recognizing materials mechanicals properties is against international laws. Therefore producing a numerical model for construction analysis seems difficult, and if applicable solving it by software using FEA programs is time consuming. Simplified Kinematic Limit Analyses (SKLA) is a powerful method for historical building safety assessment analysis and its usage for retrofitting purpose that is permissible by O.P.C.M. 3431 Italian ordinance in both of the linear and nonlinear. In this research linear analysis is used for SKLA analysis. Because of masonry buildings have a rigid box behaviour, often local collapse mechanism (part of structure) is more important than its global collapse mechanism .this method assume that is collapse local, and large part of the structures are collapsed during earthquake. To identify probable collapse mechanism, we can use collapse of similar structure in the past earthquakes events.
    In this paper a research has been about this method (SKLA) capabilities for Tabriz Alisha Citadel seismic safety analysis. The results show that it doesn’t have enough safety against earthquake prone loads in the site. The analysis of both methods is more or less similar. Non linear time history response analysis results includes: displacement, stresses, wall’s collapse time, while SKLA only used for seismic safety assessment in different mechanisms. This method advantages such as, no need to exact information about materials mechanical properties and any destructive and non destructive test cause this method to be a powerful tool for evaluating seismic safety of historical buildings especially for huge and complex geometry structures. If we choose behaviour factor of structure 2 based on Italian ordinance, 3 mechanisms will not be active, although capacity and demand of the structure in three mechanisms have close value that indicates getting close to mechanism formation threshold.
    Keywords: Simplified Kinematic Limit Analysis, Finite Element Analysis, Earthquake Safety, Historical building, Tabriz Alisha citadel
  • Ar Kabirisamani* Pages 103-115
    Rivers have been always the main source of water for human kind and the basic element of population development. Study of the interaction between flow structure and bedforms is one way to understand the behavior of the rivers. Moreover,vegetation in natural rivers increases roughness of the main channel and flood plains which affects the geometry of channels, flow structure, bed resistance and consequently the pattern of sediment transport. Considering the role of bedforms on sediment transport, turbulence production and flow resistance, investigations on details of flow-bedforms interaction, vegetated banks and flow structure seem to be essential.
    In this study, the influence of straight crested gravel bedforms and vegetation of the banks of channels on flow turbulent characteristics are investigated based on model experimentation. For this purpose, seven fixed artificial 2-D straight crested bedforms were built inside a rectangular flume of 8 m long, 0.4 m wide and 0.6 m deep. The graded gravel particles used to create the bedforms had an average diameter of d50 = 10 mm. Johnson grasses with a diameter of 2.8 mm were used to simulate vegetation cover on the flume side-walls. Since, the fully developed flow was just observed after the fifth dune, experimental measurements were performed over the fifth and sixth dunes. Overall, three runs were performed over the dunes with a wave length, height, angle of repose and flow depth of 0.96 m, 0.04 m, 28 degrees and 0.28 m, respectively. In the first case 17 velocity profiles and in the second and the third cases 21 velocity profiles were measured. All the tests were performed with a constant discharge of 0.024 m3/s. The instantaneous three-dimensional velocity components were measured using a down-looking Acoustic Doppler Velocimeter ADV. Velocities were recorded for each point with a sampling rate of 200 Hz and the sampling volume of 5 mm. The sampling duration was at least 120 seconds. Overall, about 45400000 velocity data were collected, filtered by WinADV software. Results indicated no negative velocities for both cases of with and without vegetation cover. For no vegetation case, the least value of velocity was zero at a small region on the lee side of the dune. Whereas, for the case of vegetating the side-walls, the zero value of velocity was located at the dune's trough. Negative vertical velocity value in both cases of with and without vegetation along a dune confirmed that separation is not dominant for the case of straight crested dunes compared to the corresponding sharp-crested bedforms. The Reynolds stresses increase for the case of vegetating the side-walls compared to the case of without vegetation cover. This is in part due to the increase of flow resistance, while the side-walls are vegetated.
    Rivers have been always the main source of water for human kind and the basic element of population development. Study of the interaction between flow structure and bedforms is one way to understand the behavior of the rivers. Moreover,vegetation in natural rivers increases roughness of the main channel and flood plains which affects the geometry of channels, flow structure, bed resistance and consequently the pattern of sediment transport. Considering the role of bedforms on sediment transport, turbulence production and flow resistance, investigations on details of flow-bedforms interaction, vegetated banks and flow structure seem to be essential.
    Keywords: Gravel bedform, Vegetated wall, Reynolds stress, Turbulent Flow
  • Hamed Bagheri* Pages 117-124
    It is well known that general concrete alone lacks excellent mechanical properties especially in tension, hence there is need for modification by polymers. Research on polymer concrete began in the 1950s and it has been actively used since the 1970s. The use of Polymer cement concrete is in rapid increase as it possesses improved qualities over conventional concrete. Adequate design of polymer concrete members requires appropriate understanding of its mechanical behavior.There are three kind of polymer concrete: A) polymer concrete (PC): this kind of polymer concrete is formed by polymerization a mixture of a monomer of a thermoset polymer and aggregate, B) latex-modified concrete (LMC): this kind of polymer concrete is named polymer Portland cement concrete. In this way Conventional concrete is replaced with part of mixing water with latex and C) polymer-impregnated concrete (PIC): it is produced by impregnating or infiltrating a hardened concrete with a monomer then polymerization is done.
    There are many polymers that used in polymer concrete same as polyester, epoxy, styrene monomer and methyl methacrylate (MMA). Polyester concretes are viscoelastic and will fail under a sustained compressive loading at stress levels greater than 50 percent of the ultimate strength. Sustained loadings at a stress level of 25 percent did not reduce ultimate strength capacity for a loading period of 1000 hr.
    The main purpose of this paper is to investigate the effect of post curing effects on the mechanical properties of polymer cement concrete. Polyester was introduced to the mix as cement replacement by weight. A suitable concrete mix was designed and produced, using three different ratios of Polyester as cement replacement varying between conventional concrete for 0% Polyester to 30% Polyester. Two types of samples were cast, compacted and then cured for 28 days. The polymer concrete samples include two types, one has post cured and the other was without post curing. The cylinder specimens were tested in compression and split tension to determine the compressive and the tensile strength. The variation of compressive strength, tensile strength were determined and assessed for samples especially for samples with and without post curing. Based on the experimental program post curing has Significant effects compressive and tensile strength of concrete samples. The effect of weight percentage of polyester resin and post curing condition were investigated in relation to the mechanical properties of polymer concrete. The results indicate that an increase of polyester content in polymer concrete enhances the mechanical properties same as the tensile and compressive strength of the composite. Also, post curing increases mechanical properties, especially in the lower weight percent polyester. It seems that post curing causes increased degree of cross-linking in resin and increased the effect of polyester in the composite in lower percentage. It can be seen that post curing increased the mechanical strength for lower weight percentage of polyester more than the higher ones. In other words, lower weight percentage of polyester is more effective than the higher. This result comes from the effect of cross-linked density of polyester in polymer concrete composite because cross-linked density is very low when the weight percentage of polyester is low. Post curing can increase the cross-link density of polyester therefore increasing the mechanical properties of polymer concrete.
    Keywords: Polymer Cement Concrete, post curing, Mechanical properties, Polyester
  • Seyed Mostafa Siadatmousavi, Amirreza Hamidi* Pages 125-134
    Scour around pier in the flow is an Inevitable issue. Estimation of scour depth and understanding the flow field around pier would help us to design with safer factor. The most important factor of scour around pier is changing of streamelines that leads to a system so called local scour. It consist of two vortices: horseshoe vortices and wake vortex. The obstacle creates downflow jet in front of pier that collide with bed sediments and carry them to the downstream, making the horseshoe vortice. The wake vortex is caused by splitting the streamelines and formation of low pressure flow field region and absorption of flow in rear of pier and pick up the bsd sdiments in this district.
    In this study we used the numerical model SSIIM as a CFD model to simulate flow and scour pattern Simultaneously around a group piers. This model can be used in hydraulic and environment engineering and has the ability of sediment transport calculation in bed transient movement with temporal dependent as the most important advantage in compare with the other CFD models. The verification of this model was implemented by data and results reported for side by side piers examinations as one ofe the group categorize. In this model we considered the k-ε and k-ω seperately as a turbulence model to solve the eddy viscousity of 3D Navier-Stokes flow equations and use their outputs as inputs of sediment transition equations, we used Power-Law scheme as one of the descritization method of First-Order upstreame scheme to solve the flow and sediment equations on the grids. The pressure term of Navier-Stokes equations in cells was calculated by SIMPLE algorithm which is the First-Order upstreame scheme too. Also by changing the G⁄D distant ratio on the other simulation runs, we generated the diagrams with comparative situation with experimental diagrams.
    Results in the last time of simulation showed there is much more value of horizontal and vertical velocity between the piers than the other sides. It was 57% of final maximum scour depth in first hour of calculation. Similarly to velocity, The final scour patterns showed there is more scour depth counters between the piers. In details it was deriven that the scour depth pattern was symmetric in early time of calculation, but with time passing it appeared more in the region of between the piers. Although Numerical results show the SSIIM model have calculated the erosion depth in front of piers with high accuracy resulted from good calculation of downflow, comparisons between model results and data show the scour depth pattern that the model calculated the wake vortices behind the piers and Interference the horseshoe vortex between the piers with overestimate value and there are deeper countors of scour depth than experiment diagram. Also the RMS index of scour depth has been calculated in the grid and it represented the values of 0.0353 for k-ε model and 0.0899 for k-ω model. Therefore, the k-ε turbulence model resulted better scour depth pattern calculated in compare with k-ω turbulece model.
    Keywords: Scour, simulation, SSIIM numerical model, Side by side piers
  • Ali Jalaeefar*, Asma Sistani, Behrouz Asgarian Pages 135-145
    In last decades, most of the famous seismic design codes, had concentrated mainly on far field earthquakes. Generally no special requirements were introduced to minimize near fault earthquake effects. Near field ground motions have caused several structural damages in recent decades, causing seismic codes to be updated with related requirements. As a result, it seems necessary to evaluate domestic seismic design codes and their requirements to see their effectiveness in designing safe structures against near fault earthquakes. In this paper seismic behavior of concentrically braced frames (CBFs) designed based on different seismic design codes is comparatively studied. Various Frames of different heights, (5, 8 and 12 stories), and bracing types (X-bracing and inverted V bracing) are designed based on the Iranian seismic code (standard no.2800) and also taking into account the near fault requirements of AISC-ASD 89 and UBC-97. These frames are analyzed using a nonlinear time history analysis method, namely “Incremental Dynamic Analysis” (IDA) under near field ground motions. IDA is an emerging method in analysis of structures which allows estimating seismic capacity, limit states and demand via series of nonlinear dynamic analyses using multiple scaled ground motion records. A total of 15 near filed time histories are selected according to special characteristics namely: fault distance to site (less than 10 km), fault direction, earthquake moment magnitude, time history frequency content, time history velocity content, shear wave velocity in the site soil and near fault wave’s pulse nature.
    The 15 selected earthquake time histories were scaled in several steps. To achieve a more accurate point for yielding point of the frames, 0.1g steps were used in the initial elastic region.
    On other important step was to select proper intensity measure and damage measure. According to FEMA-350 requirements, the maximum inter story drift was selected as damage measure. For selecting a proper intensity measure, four intensity measures were selected and compared together, namely: first mode spectral acceleration , first mode spectral velocity , peak ground acceleration PGA and the equivalent first n modes spectral acceleration. Among them, first mode spectral acceleration showed the least dispersion in the analysis results.
    Finally, all the 20 frames designed were analyzed using the 15 time histories selected in multiple steps and IDA curves were extracted. Using FEMA requirements the points corresponding to 2 performance levels namely IO and CP were defined on summarized IDA curves using which it was possible to compare the performance of the frames.
    The results of this paper imply that frames designed based on the near field seismic design criteria of UBC-97 have better performance under near-field earthquakes comparing to others. It can be concluded that the requirements of the Iranian seismic code should be updated according to the effects of near fault earthquakes. Besides, frames with X-bracing system showed better performance in comparison with chevron ones. Also the deficiencies in the seismic requirements of the domestic codes are more obvious while designing taller frames and moving from 5 story frames to 12 story ones, their seismic performance obviously deteriorate.
    Keywords: IDA, Performance Level, Immediate Occupancy (IO), Collapse Prevention (CP)
  • Hamze Shakib*, Vahid Jahangiri Pages 147-159
    Investigation of the correlation between engineering demand parameter (EDP) and intensity measures (IMs) has received substantial attention in performance-based earthquake engineering for prediction of seismic demand of structures.In this study the seismic demands of buried steel pipelines are investigated in a performance-based context. Several nonlinear dynamic analyses of two buried steel pipe models with different D/t, H/D ratios and different soil properties and different pressures, performed under a suite of far-field earthquake ground motion records were scaled to several intensity levels to investigate the behavior of buried pipeline from elastic response to failure. Several scalar ground motion intensity measures (IMs) are used to investigate their correlation with engineering demand parameter (EDP) which is measured in terms of peak axial compressive strain in critical section. Using the regression analysis the efficiency and sufficiency of candidates IMs is investigated.
    To investigate the effects of different material and geometrical properties, two buried pipeline of API 5L Grade X65 models with different pipe and soil properties are considered. To simulate soil effects on pipe in axial, transverse and vertical directions bilinear force displacement curves (elastic-perfectly plastic) representation of soil are employed based on suggestions of the American Lifeline Alliance. The FEM was used in the analyses. The buried pipeline and the surrounding soil are modeled using shell, spring and damper elements. Each node of the model was connected to three spring-dashpots.
    Before deciding which ground motion IMs correlate well with seismic demand on buried pipes the first question to be answered is: how is the seismic demand measured? Usual failure modes of continuous buried pipelines are tensile ruptures or buckling because of compressive strains. Compressive straines that result in bukcling are smaller than strains induce tensile failure. Therefore, the peak axial compression strain at the critical section would seem the obvious candidate to use for EDP of buried pipe. It is necessary to examine a wide range of potential IMs for determining the best IM for evaluating the buried pipe response. Therefore a total of 16 different IMs are considered.
    Using an efficient IM results in smaller variability in the structural response for any given IM. Chosing an efficient IM causes the number of analyses and earthquake records needed to evaluate the probability of exceedance of each value of EDP given the value of IM to be reduced. In this paper, a one-parameter log-log linear regression of peak axial compressive strain on IM is utilized in evaluating the efficiency of each alternative IM. A sufficient IM results in EDP conditionally independent, for a given IM, of earthquake magnitude M and the source to site distance R. Using a sufficient IM, yields ignoring the effects of magnitude and distance in accurately predicting of EDP. Quantifying the sufficiency of IM is done by using the one-parameter regression of peak axial compressive strain on M or R for a given IM. Among the models investigated in this study it was seen that RMSd is the optimal IM for buried steel pipelines based on efficincy and sufficiency conceptions.
    Keywords: Continues Buried Pipeline, Intensity measure, efficiency, Sufficiency, Performance, based earthquake engineering
  • Afsaneh Shahbazi*, Shirin Zahedinia, Seyedhossein Hashemi Pages 161-172
    Abstract-Environmental pollution, in general, and water pollution, in particular, are of concern to the scientific community worldwide. Color removal from wastewater has been a matter of concern, both in the aesthetic sense and health point of view. Color removal from textile effluents on a continuous industrial scale has been given much attention in the last few years, not only because of its potential toxicity, but also mainly due to its visibility problem. Methylene Blue (MB) is cationic dye, used in several industries such as paper and pulp, leather, cotton, pulp, cosmetics, wool etc., for coloring their final products. The effluents of these industries containing huge amount of dyes, discharged into waters bodies, cause severe damage to the environment. Acute exposure to methylene blue will cause increased heart rate, vomiting, shock, cyanosis, jaundice and tissue necrosis in humans. Several methods have been used for the removal of dyes from the aquatic environment, including physical, chemical, and biological processes. These methods inevitably add to the cost of the overall process and some present the complication associated with the possible toxicity of degradation products. Among the methods, removal of dyes by adsorption is regarded as one of the competitive methods because of high efficiency, economic feasibility and simplicity of design/operation. Biosorption based on binding capacities of different low-cost adsorbents includes natural, agricultural, and industrial by-product wastes. They are attractive because of their abundant availability at low or no cost, their good performance in removing dyes from aqueous solutions as well as minimum volume of sludge to be disposed. Sawdust, among the low cost adsorbents, is one of the most promising adsorbent for removing dyes, and some other unwanted materials from waste water. Not only is sawdust abundant, but also it is actually an efficient adsorbent that is effective to many types of pollutants, such as, dyes, oil, salts, heavy metals, etc. If it was possible to use sawdust as adsorbent of contaminants from industrial waste water, it would solve simultaneously two problems, both waste disposal and purifying waste water of contaminants to desired limits. In the present study have been investigated the efficacy of Populus nigra sawdust as a wood waste (without chemical changes) in the removal of methylene blue from wastewater. Isotherms (using langmuir and freundlich isotherm models) and absorption kinetics (using pseudo first-order, pseudo-second order, elovich and intraparticle diffusion models) has been studied and was observed that the process treatment followed from langmuir isotherm model (R2 = 0.996) and its kinetic is consistent with pseudo-second order reaction (R2 = 0.999) and the mechanism was controlled by surface adsorption and intraparticle diffusion. The thermodynamic parameters such as change in enthalpy (ΔH°), entropy (ΔS°) and Gibb’s free energy (ΔG°) of adsorption systems were also determined and evaluated. This adsorbent had high absorption capacity equal 26.85 mg/g to the absorption of cationic dye methylene blue. The results showed that Populus nigra sawdust, natural sorbent is good to absorb methylene blue color of the water water which has removal percentage equal 84.68% in the optimal conditions.
    Keywords: Absorption of methylene blue, Populus nigra sawdust, Kinetic, Isotherm, Thermodynamic
  • Ehsan Zeighami, Farshid Jandaghi Alaee*, Mansour Jamee, Masoud Soltani Mohammadi Pages 173-186
    This paper presents the pull-out characteristics of inclined hooked steel fiber from cementitious matrix. The effect of fiber embedded length and angle of inclination are evaluated together with the interaction of these parameters. The experimental program involved single fiber pull-out test of five inclination angle and four embedded length. The studied inclination angles were 0, 15, 30, 45 and 60 degrees. The embedded lengths were 10, 15, 20 and 25 mm. Compressive strength of matrix was 40 Mpa. The length and diameter of hooked steel fibers were 50 mm and 1mm, respectively and their tensile strength was 800 Mpa.
    At least five specimens were prepared and tested for each combination of inclination angle and embedded length. A special mold supplemented by a cross shaped device was designed to hold the fiber in desired angle and embedded length. X-ray radiography was used to verify the inclination angle and embedded length of fiber. All the specimens were tested at 28-day age. Pull-out test performed under displacement control condition in order to record descending branch of pull-out curves. A load cell and a displacement transducer were used to acquire pull-out load and slip during pull-out test. Pull-out load versus slip were recorded and parameters such as maximum pull-out force and its associated slip, pull-out energy, fiber efficiency and matrix spalling were drawn for comparison purpose.
    Based on the experimental results, the pull-out response of hooked steel fibers is predominately influenced by fiber embedded length and inclination angle. The results indicate that the peak pull-out load is maximized at approximately 30 degrees, although at greater inclination angle, the peak pull-out load decreases. The fracture load also decreases as fiber inclination angle increases. The additional shear stress imposed on inclined fibers; provide mechanisms favoring slip between the crystals in the steel. This causes a reduction in both yield and ultimate strength of the finer, resulting in a reduced fracture load. The results indicate that providing the hook is fully mobilized, the peak pull-out load is almost independent of embedded length of fiber. The results indicate that fracture of fiber is more presumable at greater inclination angle.
    Slip associated with peak pull-out load increases as the inclination angle increases. This can be attributed to matrix spalling. Matrix spalling also causes the drop of pull-out load in pull-out curves. The load drop is directly related to the size of crushed matrix. Matrix starts to spall at 30 degrees inclination angle. The results indicate that increase in embedded length and inclination angle result in increase of pull-out energy. An inclined fiber with respect to the loading direction absorbs a greater amount of energy at a given slip than an aligned one, with maximum pull-out energy occurring around 30 degrees. Fiber efficiency increases as the embedded length of fiber increases. Maximum fiber efficiency occurs at 30 to 45 degrees and decreases at greater inclination angle. The effect of elastic deformation of fiber during pull-out test was taken into account by calculation of elastic deformation and subtracting from slip, although, its effect was negligible.
    Keywords: Hooked Steel Fiber, Pull, out Behavior, Cement, based Matrix
  • Alireza Shokoohi* Pages 187-201
    Digital Elevation Models (DEMs) are one of the most important inputs in most rainfall -Runoff models and also in deriving watersheds geomorphological characteristics. One of the most important issues that should be taken into account when using DEMs in rainfall runoff modeling is the effects of DEM source on the results of the models. At present time, radar based DEMs are attracting a considerable attention in many earth related fields. Currently, there are several sources such as: Shuttle Radar Topography Mission (SRTM) data and the advanced space thermal emission radiometer (ASTER) that due to ease of access and free of charge, have an important role in hydrological modeling and the extraction of geomorphological parameters of catchments. This paper addressed the effects of different DEM sources: ASTER, SRTM, and 1:50000 topographic based DEM on the topographic index and performance of a semi- distributed model, called TOPMODEL. The obtained results indicated that by increasing DEM cell size, disregarding its source, the topographic index inceased. Also, it was illustrated that for all cell sizes other that 30 m there was no difference between the results of ASTER and SRTM DEM. Such a coincidence was observed for TOPO DEM for cell sizes larger than 100 m, as well. Results showed that the effect of data resolution on the average daily discharge, average saturation deficit of basin and the average distance to water table level is not meaningful. In daily discharge simulation, the performance of TOPMODEL when using the TOPO DEM ,based on the NASH- SUTCLIFFE efficiency index, was the highest and for the SRTM DEM was the lowest. In flood simulation, upto 200 m resolution, TOPMODEL efficiency was constant disregarding the DEM source, while its efficiency reduced for cell sizes greater than 200 m in all conditions. It was illustrated that by increasing the cell size, surface runoff contribution to total runoff, in contrast to subsurface flow, increased. Furthermore, For all of the sources, increasing the DEM cell size, incresesd the surface runoff contribution and decreased subsurface flow. The percent of surface flow simulated by the model when implementing the DEM of SRTM is the highest. According to achieved results, the percentage of simulated surface runoff from SRTM DEM was higher than the other two sources. It was observed that the number of cells of low slope in SRTM DEM is greater than the other sources, which was concluded as the main reason for this issue. Reducing the slope of a cell could reduce its potential to carry subsurface flow, which in turn could increase the cell potential to be saturated. It was concluded that DEM different sources effects on average saturation deficit and water table is negligible, and these ouputs of TOPMODEL is mainly affected by DEMs cell size. Finally, this important conclusion was drawn from the present research that the information content of ASTER DEM is nearly similar to TOPO DEM and higher than SRTM DEM; therefore, between satellite based DEMs, it is more convenient to use ASTER DEM for rainfall runoff modeling.
    Keywords: Digital Elevation Models, SRTM, ASTER DEMs, Semi, Distributed model (TOPMODEL), Topographic Index
  • Nabi Allah Gharibzadeh, Esmaeil Fatehifar*, Reza Alizadeh, Amirnaser Haghlesan, Mirmohammad Chavoshbashi Pages 203-213
    Toluene is a dangerous pollutant in aqueous solutions that should be removed completely. In this paper iron oxide nanoparticles were employed for removing of toluene from aqueous solutions with initial concentration of 100 ppm by Fenton-Like process. Iron oxide nanoparticles synthesised from spent catalysts of Tabriz Petrochemical Styrene Unit using a ball mill. these nanoparticles were characterized by BET, XRD, XRF and FE-SEM analysis. The milling of spent catalysts was performed in dry ball mill. Dry ball milling of spent catalysts was carried out in presence of argon as an inert gas. Iron oxide nanoparticles with diameter about 18 nm were obtained after 4 hours by dry ball milling of spent catalysts using 15 balls with a diameter of 20 mm. The milling was performed at a rotation speed of 400 rpm.The results of BET analysis showed that specific surface of catalysts has increased more than 9 times with the milling of spent catalysts. XRD patterns showed that during dry milling, some of Fe3O4 has converted to Fe2O3. Due to the higher rate of reaction of Fe2O3 compared to the Fe3O4 in Fenton process, this conversion causes higher rate of toluene elimination from aqueous solutions. The crystal size of spent catalysts and synthesized iron oxide nanoparticles was calculated by Scherrer equation. The crystal size of spent catalysts and synthesized iron oxide nanoparticles were obtained 56.6 nm and 33.9 nm respectively which confirmed the results of BET analysis. The concentration of toluene in aqueous solutions was measured by Gas Chromatography (GC-Agilent 7890A) equipped with FID detector and HP-Plot Q column (30m × 0.530 mm× 40.0 μm) using liquid-liquid extraction by hexane. Hexane and samples were mixed with volume ratio of 1/10. Samples were injected to GC in volume of 1 micro liter by a syringe (Agilent). Experiments were performed at pH=3 and room temperature (25◦C) in a batch reactor in volume of 500 ml with a mechanical stirrer. Due to study of interaction between the parameters and determining the optimal conditions, experimental design was performed by RSM method. [H2O2]/[Catalyst], [H2O2]/[concentration of pollution] and time (min) were considered as efficient parameters on removing of toluene. Quadratic equation with high correlation coefficient fitted using RSM method. R2 and R2(adj) values of predicted model for removing of toluene in Fenton-Like process were obtained 99.14% and 98.37% respectively. The results showed that [H2O2]/[Catalyst] and [H2O2]/[concentration of pollution] have optimum ranges. The optimum ranges for [H2O2]/[Catalyst] and [H2O2]/[concentration of pollution] were obtained 0.36-0.5 and 4-5.5 respectively . Optimal values for [H2O2]/[Catalyst], [H2O2]/[concentration of pollution] and time (min) for removing of toluene in Fenton-Like process were obtained 0.460, 4.928 and 105.7 respectively. In optimum conditions for efficient parameters, complete removal of toluene by Minitab software was predicted. Experiments in the optimum conditions also confirmed the results of Minitab software. The results showed that spent catalysts of Tabriz Petrochemical which are considered as waste, have a good ability for activation of H2O2 and removing of toluene from aqueous solutions.
    Keywords: Toluene, Aqueous solution, Fenton, Like, Iron oxide nanoparticles, Optimization
  • Afshin Eghbalzadeh* Pages 215-228
    Diversion structures in side wall of open channel are to be used in order to divert flow from main channel. Side weirs, side orifices and side sluice gates are diversion structures which have wide application in dams, irrigation, drainage systems and combined sewer systems. Side weirs are one of the most important and applicable hydraulic structures for water controlling and directing systems that requires careful review and accurate designing due to their critical importance .In this paper, the flow over a sharp-crested rectangular side weir in open channel was simulated by FLOW-3D software. RNG turbulence model was used to apply the Navier-Stokes equations and the VOF method was used to model the free surface profile changes. In the present study, at first, results related to the distribution of the different components of velocity and angle of the outlet jet adjacent to the crest of the rectangular sharp crest side weir at various heights of the weir crest are validated with experimental data from Bagheri and Heidarpour (2012) research. Then the effects of upstream Froude number on flow pattern and free surface around the side weir were investigated. The results of this study indicated that with decreasing Froude number, maximum and minimum longitudinal velocity along the side weir increases and decreases, respectively. The maximum lateral velocity along the side weir increased with decreasing Froude number. That is why the discharge through the side weir increased with decreasing Froude number. The maximum vertical velocity along the side weir increased with decreasing the upstream Froude numbers because more flow is diverted to the side weir with decreasing the upstream Froude numbers. Distribution of the different components of velocity in the direction of flow height in the middle of the weir crest indicated that by reducing the upstream Froude number, longitudinal velocity distribution in the depth direction became more non uniform, especially near the weir crest. For different Froude numbers, lateral velocity would increased up to a certain elevation from the weir crest and then decreased toward the free surface. By increasing Froude number, the maximum lateral velocity occurs at greater heights above the side weir crest. The maximum vertical velocity for different Froude numbers occurred near the weir crest. Vertical velocity gradually decreased toward the free surface. By reducing the upstream Froude number, the vertical velocity near the free surface of flow is negative due to flow motion to downward. Free surface of the flow experienced extreme changes at the end of the side weir when upstream Froude number was increasing. By increasing the Froude number, the angle of inclination of the outlet jet along the side weir increases. Also by increasing the Froude number, the separation zone around the side weir in near the main channel bed, especially in the channel cross-section decreases.
    Keywords: Side weir, FLOW, 3D, Froude number, Flow pattern, Velocity distribution
  • Amir Reza Goodarzi*, Matin Mirmomen Pages 229-241
    The electrokinetic (EK) approach is one of the popular choices for the extraction of inorganic contaminants (e.g. heavy metals) from a soil matrix. On the other hand, many factors can affect the performance of EK contaminant remediation. Therefore, in the present study a series of macro and micro level tests including electrokinetic experiments, pH and electrical conductivity (EC), adsorption and desorption, X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses were performed to investigate the effects of time and pore fluid characteristics on the efficiency of EK remediation. For this purpose, the kaolinite clay was separately infected with different solutions containing zinc nitrate and lead nitrate in concentrations of 20 and 40 cmol/kg and then electrokinetic experiments on a laboratory scale were conducted at 2 V/cm voltage gradient in time periods of 3, 6, 12, 24 and 48 days. Nitric acid was also used as a catholyte solution to enhance the soil remediation process. The results obtained show that the soil response to the EK remediation is a function of the contaminant characteristics, the pH of soil-electrolyte system and the time of testing. In EK contaminant remediation from a soil matrix, it is significant to pay particular attention to the effect of the concentration and type of contaminant on the applicability and efficiency of this method. The results reveal that under the same conditions, especially in the low times, extraction efficiency from samples containing lead was measured approximately 70 percent of the samples containing zinc. This is because the lead tends to more adsorbe on the clay surface and has a greater tendency to form precipitate. In addition to the type of contaminants, it was found that the increase in concentration of contaminants in the soil through a series of physical-chemical reactions accelerates clean up capabilities, particularly in the initial time period of the EK experiments. Catholyte conditioning with acidic solution enhanced the removal of heavy metals, which is mainly due to microstructural changes and an increase in the mobility of pollutants. In fact, based on the X-ray diffraction and scanning electron microscope analyses, the microstructural characteristics and the arrangement of the clay particles have an important role in the process of electrokinetic soil remediation. The formation of flocculated structure decreases the retention capacity of the clay particles and also increases the flow path, which enhance the efficiency of pollutant extraction. It was found that the soil remediation, especially in the parts close to the anode, greatly enhanced with increase the time of EK test; however, the further increase in time had a limited impact on results, especially in the samples containing high concentrations of zinc. This indicates that there is an optimum time in the process of cleaning up heavy metals from the soil by EK method, which depends on the type and concentration of contaminant. Moreover, it was seen that the extent of contaminant removal from anode side towards the cathode side is considerable when catholyte conditioning with acidic solution is used. In other words, reducing the pH of soil-electrolyte system has a significant impact in increasing the efficiency of pollutant extraction.
    Keywords: Electrokinetic, Heavy metals, Pore fluid characteristics, time, Microstructure
  • Mojtaba Mehraein* Pages 243-257
    In this research the statistical parameter of the flow around T shaped spur dike located in a 90 bend was investigated. the experiments were conducted in a 90 bend at tarbiat modares university. the velocity was measured using ADV apparatuse. the frequency of the ADV set to 50 HZ this frequency was used by many previouse researchers. Two different submerged spur dike with submergence ratio equal to 5% and 50% were used. The submergence ratio is the ratio of the flow depth on crest of the spur dike to spure dike height. The spur dikes were located in 45 degree respect to the beginning of the bend and the experiments were done in freeze bed condition. The flow around the spur dike were investigated using parameters such as: Probability of the events (the ratio of the number of the events to the total of the events during the velocity measurment), variation of the events during the velocity measurments, shear Reynolds stresses in streamwise and lateral direction and angle of the events (the ratio of the vertical velocity fluctuation to the streamwise velocity fluctuation). The results showed that two secondary flow formed in lateral direction of the channel and the secondary flow affect on the upstream of the bend. These flow affect on sediment transport mechanism in lateral direction. In the upstream toe of the spur dike the Reynolds stresses in 5% submergence spur dike is greater compared to the 50% submergence spur dike since stronger horse shoe vortex due to the stronger downflow. The scour hole propagation along the shear layer in longitudinal direction may be due to the increasing the probability of the sweep and ejection events and variation of the interaction events, decreasing the angle of the events and increasing the Reynolds stresses. The Reynolds stresses along the shear layers located in 5% spur dike is greater that the 50% spure dike and larger scour process may be expected in this region. the stability of the events are more pronounced compared to the instability of the events. the angle of the sweep and ejection were minimum near the bed surface and maximum in the middle of the flow depth. Two different zone with maximum angle of sweep and ejection were observed that showed the fluid parcels deviate to the downstream recirculating zone. The angle of the events has different value near the over topping flow that passed from the crest of the spur dike. the flow measurments and analysis of the statistical parameters confirmes the previous researchers conclusions about larger scour hole around the spur dikes with lesser submergence. This may related to the difference of the flow structures around the submerged sour dikes especially near the upstram toe of the spur dike and sround the shear layer.
    Keywords: Submerged spur dike, Turbulent Flow, statistical parameter, four quadrant events
  • Ibrahim Naeimifar*, Shahab Yasrobi, Ali Fakher Pages 257-271
    Damage probability of structures caused by excavation wall movement is an important design aspect of support system in urban areas. This will be more important, if the adjacent structure be old or have low strength parameters. Frame distortion and crack generation are signs of building damage to excavation-induced ground movements which is a challenge in projects involving deep excavations. These highlight the importance of evaluation of building response in excavation projects. The aim of estimation and evaluation of building response is to establish limiting criterion for excavation support system design to certify the structure safety against undesirable damage. Thus, limiting criterion prepares a framework to determine the damage level of building based on excavation induced ground movements. Mentioned limiting criterion also is named Damage criterion or Damage model. Damage models are too practical before design progress of nailing wall. Based on uncertainty in data from excavation project and variability of the many factors that contribute to the response of nearby structures, existing Damage models are rare and generally need special instrumentation of excavation wall and nearby structures, so they cannot prepare a simple framework to use in practical situation.
    This paper describes a study of building response to excavation-related ground movements and provides procedure for damage assessment of building near excavation projects. This study uses field data based on 10 case studies and 90 calibrated 3D FEM models in addition to probabilistic analysis to establish new simple damage criterion for design consideration of excavation supported by soil nail wall technique. Presented Damage model simply relates the damage level of structure to maximum displacement of excavation wall.To create this paper following stages are used:1.Case studies:31 deep excavation (16.7-31 meters) from expert companies are studied in first stage.2.First filtering of the collected data: part of collected data (14 projects of 27 projects) is eliminated from data base because of inaccuracy in the results of monitoring, unfavorable results in displacement caused by nearby galleries or underground facilities, inappropriate execution and etc. 3.Evaluation of the structures in the excavation-affected zone (EAZ). 4.Second filtering of database: part of first-filtered data is eliminated from data base because of non-deductible conditions of structure in EAZ, mismatch between damage level and results of monitoring and etc. At the end of this stage only ten masonry structures (TMS) were selected to continue case studies. 5.Creating and calibrating FE models: at this stage, FE models are included excavation wall and adjacent structure were extended for each of TMS and were calibrated based on field results. 6.Idealization of calibrated TMS’s FE model (ICTM): each of calibrated TMS’s FE models were modified and idealized by removing water table, modification of excavation condition, simplification of structure frames and etc.7.Development of damage levels: in the last stage, DPI calculated from ICTM for each frame of structure and then compared with the value of excavation wall deflections. Finally, damage levels developed based on resulted database.
    Keywords: Excavation, Nailing, alloable limit of displacement, Damage level