نشریه مهندسی عمران مدرس
سال هفدهم شماره 5 (آذر و دی 1396)

Clayey soils usually have low bearing capacity, high compressibility, shrinkage and swell characteristics. Several methods have been adopted to improve the geotechnical properties of such soils. Soil stabilizing by chemical materials is one of the most common methods for treating fine grained soils. Lime has been used to improve some mechanical and plastic properties of fine grained soils since many years ego. In recent years some studies has been also carried out to investigate the influence of adding pozzolany materials on the geotechnical properties of lime – treated clayey soils. Geotechnical behavior of clayey soils depends on chemistry of pore fluid. When drinking water is used to provide the needed moisture of soil in the laboratory, it will be lead to incorrect interpretation in engineering properties of soil where specific water such as sea water is utilized. Therefore, if the undrinkable water has been used to provide soil moisture, it is necessary to examine the behavior characteristics of the materials by the same water. For example, presence of some sulphates in the soil stabilized with lime leads to problems such as reduction of strength and increase of swelling in clay. In this laboratory study, effect of sea water on strength of stabilized kaolinite has been investigated by conducting several unconfined compression tests. The specimens were prepared at fore percentage of lime and pozzolan (i. e. 0%, 1%, 3%, 5%) by weight of dry soil and distilled water and three saline water which were taken from Caspian Sea, Persian Gulf and Urmia Lake. for every combination, weight of each material was determined exactly based on the optimum moisture content and maximum dry density which is obtained from the standard proctor compaction test. Clay and lime and pozzolan were mixed in dry condition properly and then water was added gradually. Afterwards, the mixtures were kept in plastic bags for 24 hours. Weight of each specimen was determined in accordance with given specific volume and obtained maximum dry density from compaction test. This weight was divided into four portion and each portion was compacted in 20 mm layer in a PVC mold. The specimens were cured in a oven having a temperature about 35 C for 3, 7 and 14 days. After each curing time a extruder was used to remove the specimens from the molds with constant rate vertically to avoid bending and formation of tensile cracks. Then the specimens were immediately tested under strain controlled at constant loading rate of 1. 0 mm per minute, according to requirements of ASTM D 2166. For each combination, three specimens were examined to assure repeatability of results. The results of conducted experiments indicate that unconfined strength of samples without additives (lime and pozzolan) prepared by sea water are higher than specimens containing distilled water. For the samples containing Urmia lake water, the unconfined strength were higher than the other samples. Also, for the specimens in which additive has been used, the strength of the samples containing Caspian Sea and Persian Gulf water were more than that with distilled water and the strength of samples containing Urmia lake water was less because of differences in the concentration of salts existed in the water. Finally, the results show that water minerals are higher in Urmia lake water, Persian Gulf and Caspian Sea, respectively.

Temporary soil improvement techniques are considered among the most important geotechnical topics. Artificial ground freezing is considered to be eco-friendly, economic, safe and applicable for all types of homogeneous, loose and soft soils. By lowering the soil temperature below zero, the pore water of the soil freezes which leads to improved mechanical properties of soil; it increases the shear and compressive strength of soil, without entering any chemicals into the soil environment. In practice, artificial ground freezing consists of two parts; (i) formation of frozen body before construction or test (active step) and (ii) maintenance of the frozen body during the construction and test procedure (passive step). There are two methods for using artificial ground freezing; (i) open method and (ii) closed method. In the open method, liquid nitrogen is used for cooling. With the evaporation of the liquid nitrogen, the soil freezes and the nitrogen gas is released to the atmosphere. In the closed method, a brine is used which is connected to a refrigeration plant. The brine is circulated until the formation of frozen body. The brine used can be ethylene glycol or calcium chloride. One of the difficulties of studying frozen soils is the absence of triaxial compression apparatus for frozen soils in the national and international markets, because it is an unconventional test apparatus. In this research, a triaxial compresion apparatus was developed for testing of frozen soils in the geotechnical laboratory of the University of Tabriz. This apparatus was placed in a cold and insulated room with minimum heat transfer. The temperature of the room was monitored continuously. This triaxial apparatus for frozen soils was developed using a closed system that is connected to a refrigeration plant.
In this study, void ratio, ice saturation and texture of soil were considered as constant parameters and temperature, confining pressure and strain rate were considered as variable parameters. The soil samples were remolded in the laboratory to represent the in situ soil in the line 2, station H of Tabriz Subway. The in situ soil was poorly graded sand and fully saturated. A special type of mold was designed for this research, that was composed of aluminum material with high heat transfer. The mold was insulated from top and bottom and it was rigid in radial direction. A series of unconsolidated undrained triaxial tests were conducted on samples of the frozen soil using the developed triaxial compression apparatus. The results show that, at constant confining pressure and strain rate, decreasing temperature leads to increase in the shear strength and modulus of elasticity of the soil. Decreasing temperature also results in the yield point of frozen soil occurring at higher strains. Also, at constant temperature and strain rate, increasing the confining pressure increases the shear strength and modulus of elasticity of the soil. At constant temperature and confining pressure, increasing the strain rate leads to a moderate increase in the modulus of elasticity and a significant increase in shear strength of frozen sandy soil. Furthermore, the results show that the poorly graded frozen sandy soil samples tested in this research program show softening behavior. All the stress-strain curves show a peak and a residual state.

Geological and site investigations in the world indicates that there are too many fields with soft soil. The existence of such soils in construction sites of buildings may create numerous problems for the foundations, for example the circumstances of roads, foundations and etc. Symmetrical and unsymmetrical settlement of foundations in soft soil areas may destroy even best constructions.
Three dimensional geosynthetics could significantly improve the performance of soil and reduce the costs compared with conventional methods. In this article the behavior of this system has been investigated under vertical load in granular soil for the gap between the applications and the design theories of reinforced base with geocell. Although the geocll system behavior and the effects of adjacent cells on central cell is one of the cases that has not been studied sufficiently.
In this article, the results of the plate loading tests on geocell reinforced sand bases have been studied, and the behavior of three dimensional cellular unit and the effects of adjacent cells have been considered as well. The effective parameters include the diameter and the number of cells. The test sample was a wooden box with 90 cm length and width and 60 cm height filled with poorly graded granular sand. In this study, geocells have been created by sewing the non-woven geotextile in a symmetrical pattern and dimension, and cells diameter were 12, 15, 17.5 and 22.5 cm. The strain gages were attached in order to eliminate measurement errors. The loading processes were carried out by a steel loading plate with 15 cm diameter.
In this investigation besides the considering the geocell behavior, the optional design parameter of this system has been considered with the purpose of decreasing the settlement. Also, the non-woven geotextiles has been sewed in a symmetrical arranged pattern and the behavior of one-cell and multi-cell geocell has been compared. In order to evaluate the failure mechanism of geocell, the novel method of strain gage installation in nonwoven geotextile has been used.
The results include the bearing capacity, the soil surface and cells deformations under a vertical loading. The results indicate that the cells which have a diameter equal to the loading plate have better performance than the others. Also it has been clarified that the existence of adjacent cells with the diameter of 0.8 times the diameter of loading plate, are more suitable for eliminating the settlement. It is also observed that the cells which are smaller than the loading plate, encountered more deformation than the bigger ones.
Also it has been proved that one-cell geocell with the diameter equal to the diameter of loading plate, improve the bearing capacity and base stiffness more than one- cell and nine-cell with diameter equal to 0.8 and 1.7 times of the loading plate diameter. It can be concluded that if the loading position was fixed, one-cell geocell wih diameter equal to foundation diameter is recommended. For moving loads (car load on road), geocell with diameter less than diameter of loading plate should be used.

Tall buildings, due to their significant flexibility in horizontal direction, exhibit very limited inherent damping. As such, their resonance or near-resonance excitations induced by wind loads may result in lateral structural response values that exceed the serviceability limit states of the structure. A mass damper when attached on a tall building can significantly mitigate the near-resonance lateral response of the structure. Tuned liquid column dampers (TLCDs) which consist of one or more U-shaped vessels with partially-filled water are known as a common type of mass dampers. In the conventional type of these dampers, an orifice is located at the horizontal portion of the vessel to dissipate the energy of the oscillating liquid within the damper. In the new type of these dampers, the orifice is replaced by a coated steel ball that is immersed in water at the horizontal portion of the vessel to dissipate the oscillating energy of the liquid within the damper. The latter damper is termed as tuned liquid column ball damper (TLCBD). In this paper the performance of a set of different TLCDs and TLCBDs in response mitigation of a tall building (of 75-stories) under harmonic wind loads have been investigated. A large set of time history analysis runs have been performed to study the role of different damper design parameters on the lateral response of the tall building. The design parameters investigated in this paper include geometrical and mass properties of the liquid dampers, inherent damping of structure, and the frequency of input excitation. The outcome of analysis runs has been compared to highlight the cons and pros of TLCDs and TLCBDs in wind-response mitigation of the building. Results of this study indicate that both damper-types are effective in response mitigation of the original structure. The peak roof displacement is decreased by 50% to 88% as a result of using the liquid dampers in the structure. Given the mass and geometrical properties of dampers, the performance of TLCBDs will be superior to that of TLCDs in response mitigation of tall buildings. Based on the analyses conducted in this paper the attenuation of building deformations in a system equipped by a TLCBD is 5% to 25% larger than the case where the same system is equipped by a TLCD. However, the performance of TLCBDs is more sensitive to the frequency of input excitations. An increase in the mass of the damper, in both TLCD and TLCBD systems, results in an increased response mitigation. For instance, when the mass ratio of damper is increased from 1% to 5%, the peak lateral displacement of structure, depending on the type and geometry of damper, is further decreased by 30% to 50%. The length of the horizontal portion of the U-shaped vessel of the damper was found also to be significantly influencing the response mitigation efficiency of damper in both TLCD and TLCBD systems. When the length of the horizontal portion of the damper is increased from 0.5 to 0.9, the roof displacements experience approximately 30% to 40% further reduction.

Numerical Investigation of the number of baffles effect on the efficiency of primary sedimentation tank in true dimensions.
Settling tanks of wastewater treatment plants are the most important components so that about one-third of the cost of a wastewater treatment plant construction is concerned to these tanks. In addition, the regulations referred to design of settling tanks are not enough. According to these, the adverse factors in settling tanks is very important to design and improve their performance. These factors in primary sedimentation tanks are including circulation zones, the phenomenon of short circuiting and non-uniform flow. One of the most important ways to improve flow conditions and increase the efficiency of settling tanks, is modifying the geometry of the tank through the installation of baffles. In this investigation, the effect of baffle structures on the hydraulic efficiency of primary sedimentation tanks has been investigated by three-dimensional numerical modeling in Flow-3D software. In this study, the optimum number of baffles is studied to increase hydraulic efficiency. Settling tank in true size and simplified model primary settling tank treatment plant south of Tehran. The geometry Specifications of tank include of length tank (L) from the main inlet to the overflow output of 60 m, a width of tank (W) 12.9 m, water depth in normal mode (H) 3 m. the input flow rate to the tank 650 l/s. Model geometry using AutoCAD software and three-dimensional shape is drawn. In this study, from three mesh blocks to mesh geometry model is used. All three of these blocks in all directions are fully in touch with and the type of are linked blocks. Intended for three blocks, the size of the mesh is selected respectively, 5, 7 and 10 cm monotonically in each direction. In numerical modeling, the turbulence model used to solve turbulent flow and to solve pressure the GMRES method is used. In addition, the VOF technique to show the behavior of fluid on free surface flow and FAVOR technique have been used to simulate surfaces and geometric boundaries. Verification of numerical simulation results with former experimental data properly acknowledges the numerical results. It is already known the optimal location of the first baffle.
The results show that baffle causes the uniformity flow and increase removal efficiency of the primary sedimentation tanks. To determine the optimum number of baffles, the comparison results between no baffle tank and optimized cases with one, two and three baffle done. Using more baffles, in ideal conditions, causes suppression of the jet flow and more chances the suspended particles deposition. The addition of new baffles in suitable locations reduces the maximum velocity amount, the size of the circulation zones and kinetic energy and create uniform velocity vectors inside the settling zone. Volume circulation zones by using one, two and three baffles compared to non-baffle decreased 4.18, 4.44 and 4.56% of the total tank volume, respectively. Finally, the results of the FTC method for several cases indicated that using number of baffles lead to increasing the performance of the sedimentation tanks.

HPFRCC is the materials including cement mortar, aggregate, and fibers which represent strain hardening within tensile load. The HPFRCC can be used in numerous cases such as seismic rehabilitation of structural members. One of the structural members is the existed coupling beam in coupling shear walls which is applied as shear fuse. Using the materials in the members can enhance ductility and energy absorption and also delays failure. This paper investigates a study on the effect of existence of diagonal reinforcements and spirals of diagonal reinforcements of the coupling beam. For this purpose, three prototypes of coupling shear walls with coupling beam were designed by HPFRCC with length-to-depth ratio of 2 and 1/2 scales. The first prototype is considered as reference and we use concrete with reinforcement design based on ACI 318-08 code. The other prototypes are built by HPFRCC with PPS fibers. But in one of them the spiral of diagonal reinforcements and in the other both spirals and diagonal reinforcements are omitted. In order to simulate the test set-up with real behavior, two strong walls were considered and cast at both sides of coupling beams. The rotation of these walls should be prevented, so in the experimental set-up, vertical small steel column in addition two strong steel roller were considered during tests. The several strain gauges were installed on longitudinal and diagonal and vertical bars to measure the strains during tests and particularly showing the displacement and load of yielding points of reinforcement. LVDTs were installed to measure the maximum displacement of the tip of beam and also to measure probable rotation. The drift if the ratio of the tip displacement of the specimen to the beam length and the ductility is the ratio of ultimate displacement to the yielding displacement and finally the energy absorption is the area under load-displacement cure for each separate cycle.
Results are indicating of appropriate effect of HPFRCC concrete in enhancing ductility and energy absorption capabilities and it can also reduce diagonal reinforcements. In addition improved crack pattern and shrinkage of cracks represent an appropriate participation of fiber in increasing the shear capacity. Comparing these prototypes, it is found the one in which spirals were omitted load capacity¡ ductility factor¡ energy absorption and failure displacement capabilities have been increased 15%, 36%, 69%, 35%. And the prototype in which diagonal reinforcements were omitted, has decreased load capacity down to 36% and ductility factor and failure displacement have been increased up to 13%, 35% and finally energy absorption has no changes. The pinching loops of load-displacement hysteresis curves of specimens were compared and the results indicated that the pinching of HPFRCC specimen was reduce comparing to reference specimen even in case of omitting the spiral. The stiffness slope of each specimen was calculated and results showed that the HPFRCC specimen with diagonal bars had more 8 percentage but the stiffness of HPFRCC specimen without diagonal bars was reduced up to 60% comparing to reference regular concrete specimen. Elastic experimental shear capacity of specimens was about 5 times of elastic Design code (ACI) shear capacity because the shear capacity calculated by ACI is conservatively only based of diagonal bar shear capacity.

Full factorial investigation is necessary in the study of the hydraulic phenomena which are function of different variables with different levels. It is logical to use the full factorial method when the number of variables and their levels are low. However, sometimes due to lack of time and shortage of financial restrictions, using the full factorial method is not possible. The Taguchi method, which is used for design of experiments, uses the fractional factorial instead of full factorial. This method not only decrease the number of studies but also guaranties the correlated comparison of all variables. In this paper the Taguchi method is used for finding the optimized hydraulic parameters like length and location of spur dike in different Froude Numbers in 90 degree bend. Furthermore, the comparison between the Taguchi method and full factorial is done for the number of investigations, finding the optimized level for each parameter and the time needed for study. In order to get the results, the parameters of length, location of spur dike in 90 degree bend, and the Froude Number are considered with three different levels. The SSIIM numerical model is applied to simulate the studies designed by Taguchi and full factorial methods. The results show that the Taguchi method, could predict the optimum parameters only with 9 studies whereas with full factorial method 27 studies was necessary. Also, using Taguchi method leads to more than 66% decrease in the total running time. For studies designed by Taguchi method, the optimum value of length of spur dike is the as one designed by Full factorial method. Also, the length of spur dike is the most effective parameter on flow pattern around spur dike and the position of spur dike and Froude Number are next in rank, respectively. These results are the same for two methods used to design of studies. Using 9 studies designed by Taguchi method, investigation of the effect of other parameter such as the angle of the spur dike is possible without changing the number of studies, whereas 81 studies should be done by full factorial method.
Full factorial investigation is necessary in the study of the hydraulic phenomena which are function of different variables with different levels. It is logical to use the full factorial method when the number of variables and their levels are low. However, sometimes due to lack of time and shortage of financial restrictions, using the full factorial method is not possible. The Taguchi method, which is used for design of experiments, uses the fractional factorial instead of full factorial. This method not only decrease the number of studies but also guaranties the correlated comparison of all variables. In this paper the Taguchi method is used for finding the optimized hydraulic parameters like length and location of spur dike in different Froude Numbers in 90 degree bend. Furthermore, the comparison between the Taguchi method and full factorial is done for the number of investigations, finding the optimized level for each parameter and the time needed for study. In order to get the results, the parameters of length, location of spur dike in 90 degree bend, and the Froude Number are considered with three different levels. The SSIIM numerical model is applied to simulate the studies designed by Taguchi and full factorial methods. The results show that the Taguchi method, could predict the optimum parameters only with 9 studies whereas with full factorial method 27 studies was necessary. Also, using Taguchi method leads to more than 66% decrease in the total running time. For studies designed by Taguchi method, the optimum value of length of spur dike is the as one designed by Full factorial method. Also, the length of spur dike is the most effective parameter on flow pattern around spur dike and the position of spur dike and Froude Number are next in rank, respectively. These results are the same for two methods used to design of studies. Using 9 studies designed by Taguchi method, investigation of the effect of other parameter such as the angle of the spur dike is possible without changing the number of studies, whereas 81 studies should be done by full factorial method.

Due to lightweight, high resistance, structural performance, and appropriate installation, sandwich system is used as structural load-bearing and non-load-bearing walls. To conduct this study and investigate on panel samples, finite element software was used. This research was conducted based a behavioral comparison between sandwich prefabricated structural components, particularly panel wall, in independent and dependent mode with opening.
In doing this research, the considered models that had large sizes with real scale were modeled including 320 320 with opening and box models with and without roof.Totally, 6 models have been proposed.Separate wall model was analyzed to investigate the behavior of the independent mode of panel components and other models were analyzed and studies to determine the effect on system on wall behavior.
Cases that were investigated included capacity of curve, chargeability capacity, displacement, plasticity and energy absorption of wall in various models, and behavior coefficient was calculated and compared in all models. Type and location fractures and the failure propagation procedure, and failure mechanism of samples were investigated. To consider the sandwich panel system, the impact of other elements connecting to it must be ignored so that actual and optimal behavior of it to be obtained.
With regard to appropriate structural and installations performance of sandwich panel systems, these walls are used load bearing and non-load bearing walls. Due to the lack of engineering parameters at the time of introduction of this system, the need for accurate and complete understanding of the structural behavior of the system is essential. In Figure 1, the details of forming the sandwich panel is shown. These panels consist of wire in sizes of 2.5 to 3.5 made of various steels and coppers (this is located at the exteror surface as steel grid known as mesh), an insulated enriched expanded polystyrene layer, polystyrene foam with thickness of mesh plates, with wired vaults. The connection of these vaults is the same type of panel grid, so that these three layers are interconnected by lateral wires.
In the panel pilot project in Shanghai, China in 1997 that was one of the key projects conducted in Shanghai, sandwich panels was investigated by Zhang and Shi. In this study, a six-floor building was examined that tested basic accelerations were limited to 0.65g (Shi Weixing, and Zhang Lixin. 1997). Regarding shotcrete concrete used in great and leader sandwich panel, they conducted some studies (Kabir, M. Z., Rezaifar, O. and Rahbar, M. R. 2005). The final resistance of the system under axial load was studied by Benayoun in 2005 (Benayoune, A., Aziz, A., Samad, A., Trikha, D. N., Abang, Ali, A. A. and Ashrabov, A. A 2005). Gara et al (Fabrizio Gara, Laura Ragni, Davide Roia, Luigino Dezi 2012) studied the bending tests on the roof of the sandwich panel. In this experiment, the effect of polystyrene foam and ending beams in tolerating the bending loads was very important. Mashal et al studied the behavior coefficient and plasticity of structure made of sandwich panels of a class (M. Mashal, A. Filiatrault 2012). In a numerical study in 2004 conducted by Kabir and Rezaei Far, dynamic parameters of system were evaluated by analyzing finite elements in non-linear area (Kabir, M. Z. and Rahbar, M. R. 2005), followed by general behavior of shear and bending of system proposed by the Great (Kabir, M. Z. 2005). Holmberg and Pelm also analyzed the bending behavior of the system (Holmberg, A. and Pelm, E. 1986). Report of committee of prefabricated concrete panels provides comprehensive view of the system along with design example (PCI Committee on Precast Concrete Sandwich Wall Panels 1997). According to what was said, this issue is essential in determining the correct behavior of this type of system that most of parametric studies are done in this regard. In this study, the parameters affecting the behavior of sandwich panels system and determining the behavior coefficient and plasticity will be discussed.

Unexpected events always occur without any alert about where or when they will happen. According to history of earthquake in Tehran, Iran, the probability of a huge earthquake occurrence (about 7 Richter) is high. The Unpredictable human behavior in disasters can affect the performance of the transportation networks. Considering the specific effects of an earthquake on the travel demand (i.e. the influx of travel demand in a short period and chaotic behavior of the users of the transport network), the issue of post-earthquake travel demand needs to be investigated. Since people travel behavior would be quite different from the ordinary situation, this research proposes a method to estimate the demand based upon the interview survey. The goal of this study is to determine the trip purposes immediately after the earthquake and the factors affecting the individual's decisions on their trip purposes. In most previous literatures, the majority of policies which have been modeled are based on unrealistic assumed demand. Many previous studies have acknowledged that more trip purposes in response to earthquake exist but few, if any, have examined it in-depth. For example, Since an earthquake cannot be predicted, in a study conducted by Chang et al. to estimate the post-earthquake travel demand, it is assumed that people will evacuate directly from their current locations immediately after earthquakes because under the no-notice earthquake scenarios, there is no time or considerably less time for people to return home or go to other places to pick up their relatives or friends [Chang et al. 2012] while most people will return to home to rescue their family [Hara, 2013]. This research developed discrete choice (Multinomial Logit) model to represent effective factors on travel demand behavior after 2 earthquake scenarios (Strong & weak) in a workday, with 4 trip purposes (rescue and Inquiry on Safety, return-to-home, evacuation and no-action). This study investigated on travel behavior after an earthquake, based on a statistical analysis on stated preference (SP) questionnaires which were answered by 364 interviews in Tehran. The survey data indicated that, 90% of people may prefer to make trips in order to return to home or to rescue survivals after a powerful day earthquake The collected data expressed that although, it is not expected to have a problem in transportation network after a weak earthquake, the statistics from this study represented that about 35% of people will travel with different purposes because of their fear and it should be considered that despite a moderate earthquake will not destroy transport infrastructures, heavy traffic congestion will cause an emergency situation in transportation network. The goodness of fit (ρ2 statistic) of the model was obtained 0.425 that is a fairly good indicator for the discrete choice models. The model has also predicted the trip purposes in 67% of the observations correctly. The results of the model show that the most effective factors on destination choice behavior are gender, age, travel time, magnitude of earthquake, house ownership and family number. Also unrelated education to the earthquake is not effective on people travel behavior. Informing people about probable open routs after earthquake in advance would help planners for disaster management.

From a statistical perspective, internal erosion and piping are from the main causes of failure in earth-rockfill dams. If these dams were located in a narrow valley, the steep slopes of the valley walls can cause increasing in stress transfer in the core. Therefore, the occurrence of hydraulic fracturing phenomenon in this kind of dams is more probable. Bidvaz dam is an earth-rockfill dam with a thin inclined clay core. The dam is located in the Northeast of Iran with a distance of twenty kilometers from the Esfrayen city. It has a height of 66 meters from the foundation and constructed in a narrow valley with a width of 40 meters on river bed and a wall slope of more than 60 degrees relative to horizontal direction. After about seven and a half years of starting first filling, a subsidence was observed at the upstream slope surface of this dam. The initial assessments, based on the data recorded in instruments which were installed inside the body and dam foundation, show at the lower level of the core and adjacent to left abutment, pore water pressure gradually has been increasing and finally reached to the reservoir water pressure, and at the same time effective stress with abnormal rate reduced to zero. These observations confirm the occurrence of internal erosion in the lower levels of the core adjacent to the left abutment. Due to the steep valley walls and noticeable difference of compressibility properties between the core and shell materials, it is expected occurring significant stress transfer in the core especially adjacent to the valley walls. Therefore, the hydraulic fracturing can be considered as a main cause initiating the process of internal erosion in this dam. The main objective of this paper is to assess the validity of this hypothesis. To achieve this purpose, this paper used a three-dimensional numerical model to simulate the behavior of the dam during construction and reservoir filling. This model has improved in the environment of a finite difference software, called FLAC3D. In the formulation of numerical model, the flow and mechanical equations have been solved simultaneously. The 3D model has been calibrated based on the recorded data from the instruments. With using a number valid suggested theoretical and empirical relationships, hydraulic fracturing potential have been calculated and the contour distribution of fracturing pressure at upstream side of the core has been presented. Also, the contour distributions of factor of safety against occurrence hydraulic fracturing phenomenon were determined for all of the suggested relationships at the upstream side of the core. The findings show that, as expected, the steep slopes of valley walls and the difference of the compressibility properties of the core and the shell materials caused significant stress transfer at lower parts of the core and adjacent to the valley walls. Moreover, the values of factors of safety against occurrence hydraulic fracturing phenomenon in upstream side of the core are less than unity near the walls. So, the hydraulic fracturing phenomenon is the one of the main causes initiating the process of internal erosion in the core.

Soil mixtures such as clayey sands, silty sands, or clayey silts are among the categories of common natural soils observed in liquefied sites. The substantial amount of liquefactions discussed in previous contributions appeared to occur in sands containing plastic fines. In saturated soils, a notable amount of experimental studies were performed in past to examine the influence of fine content on the liquefaction potential of sands. In spite to the occurrence of liquefaction in unsaturated zones due to ground motions observed in past, there are few amount of experimental data that relate the potential of liquefaction with degree of saturation, Sr, specifically for soils with high degrees of saturations. In this article, the results of a series of careful laboratory test program is represented to determine the liquefaction behaviour of a sand mixed with a range of kaolinite including zero to 30 perect at elevated saturation conditions. This is experimentally achieved using a double-walled suction controlled triaxial cell specifically developed to conduct cyclic triaxial tests at high degree of saturations that were 80, 85, 90, 95 and 100 percent. The stress-strain behaviour of the soil is represented and compared with respect to the amount existing data available in the literature. The variation of excess pore water pressure during the cyclic loading indicate that, in saturated pure sand, the generation of excess pore water pressure was mainly occurred at higher cycle of loads while, in saturated specimens with 30% clay content, it is observed from the early cycle of loading stage. Also a change in suction of specimen during cyclic loading under undrained condition is observed. Due to the presence of air in unsaturated soil volume change occurs during cyclic loading. It can be observed that void ratio decrease while saturation ratio increases. Matric suction is almost constant during cyclic loading until pore air pressure reached at maximum value and by increasing pore water pressure matric suction decrease. During cyclic loading axial strain is small until pore water pressure reached the effective confining pressure. In this case sudden increase in axial strain occurs and liquefaction starts. Accordingly, it is seen that during the cyclic loads all tested specimens reached to the liquefaction state. The liquefaction potential within the soil is represented according to CSR20 and is found to be a function of fine content. It is appeared to be initially decreased within the increment of fine content up to 20%, and consequently, it is slightly increased with increasing the percentage of fines up to 30 percent. The above behaviour aspect was obvious in all the range of degree of saturation considered. Additionally, it is seen that at a given fine content, a slight desaturation of specimens caused a significant increment in the liquefaction resistance ratio (LRR) within the soil and was more evident within the decrement of the fine content. The trend observed for the variation of liquefaction resistance ratio versus the potential volumetric strains in pure sands appeared to be consistent to the logarithmic relationship as suggested in the literature.

One major weakness of concrete is the brittle fracture behaviour in tension, with low tensile strength and ductility. This brittleness has been recognized as a bottleneck hindering structural performances in terms of safety, durability and sustainability. The lack of structural ductility is due to brittle nature of concrete in tension which may lead to loss of structural integrity. Many infrastructure deterioration problems and failures can be traced back to the cracking and brittle nature of concrete. Many attempts have been made in the recent years to overcome these problems. To effectively solve these severe problems, a new type of composite, called as Engineered Cementitious Composites (ECC), reducing the brittle behaviour of concrete has been developed in recent decades. ECC with its flexible processing has emerged from laboratory testing to field applications leading to speedy construction, reduced maintenance and a longer life span for the Structures. Micromechanical design allows optimization of ECC for high performance, resulting in extreme tensile strain capacity while minimizing the amount of reinforcing fibers, typically less than 2% by volume. Tensile strain capacity exceeding 5% has been demonstrated on ECC reinforced with polyethylene and polyvinyl alcohol (PVA) fibers. Unlike ordinary cement-based materials, ECC strain hardens after first cracking, similar to a ductile metal, and demonstrates a strain capacity 350 to 550 times greater than normal concrete. Even at large imposed deformation, crack widths of ECC remain small, less than 80 μm. With intrinsically tight crack width and high tensile ductility, ECC represents a new generation of high performance concrete (HPC) material that offers significant potential to naturally resolving the durability problem of reinforced concrete structures. In the past few decades, substitution of mineral admixtures, such as fly ash (FA) and Ground Blast-Furnace Slag (GBFS), has been of great interest and gradually applied to practical applications of ECC. It has been found that incorporating high amount of FA can reduce the matrix toughness and improve the robustness of ECC in terms of tensile ductility. Additionally, unhydrated FA particles with small particle size and smooth spherical shape serve as filler particles resulting in higher compactness of the fiber/matrix interface transition zone that leads to a higher frictional bonding. This aids in reducing the steady-state crack width beneficial for long-term durability of the structure. In this study, the workability, mechanical properties and durability of ECC different mixtures contains two mineral materials (slag / fly ash) as to replace part of the cement weight and two types aggregate (Silica/ River sand) were evaluated. The results showed that mixtures containing fly ash despite lower mechanical strength to compared with mixtures containing slag, significantly have higher performance in strain- hardening behavior at post- cracking portion. ECC mixtures performance against the durability testing (Rapid chloride penetration, Electrical Specific Resistivity, Drying Shrinkage and Accelerated Reinforcement Corrosion) were appropriate and quantitatively was to form of slag> fly ash. In this study, in order to calculate the direct tensile strength of ECC mixtures, a new model (different geometry) compared to other models (used by prior researchers) proposed and tested. The its results showed that the tensile strength measured by the new model compared to the previous models, was higher 10% to 17%.

Space grids are highly modular structures assembled from components that are almost exclusively factory fabricated. The components therefore, are usually produced with high dimensional accuracy, with a high quality of surface finish and they are generally easily transportable, requiring little further work except assembly on site. Because of their modular nature, space grids may be extended without difficulty and even taken down and reassembled elsewhere. One of the most popular types of connectors that are widely used in the construction of double layer grids is the MERO system. The Mero KK space truss system, the first commercially available, is still considered to be one of the most elegant solutions for the construction of space grid structures. The elegance and simplicity of the Mero system means that it is not only used in buildings but also for shop displays and exhibition stands using lightweight materials. Circular tube members are connected to cast ‘ball’ joints at the nodes by a single concealed bolt for each tube. A double layer grid is combination of prefabricated tetrahedral, octahedral or skeleton pyramids or inverted pyramids having triangular, square or hexagonal basis with top and bottom members normally not lying in the same vertical plane. The connector is an extremely important part of a grid design. The type of connector depends primarily on the connecting technique, whether it is bolting, welding, or applying special mechanical connectors. It is also affected by the shape of the members. This system is multidirectional system allowing up to fourteen tubular members together at various angles. The system consists of tubular elements that are connected together by means of a MERO connector. The ball is located at the intersection of the longitudinal axes of tubular elements. The longitudinal axis of tabular element and all the constituent parts of its end connectors are along together. This axis is referred to as axis of member. The MERO system had only one type of standard joint, a sphere with 18 threaded holes and machined bearing surfaces at angles of 45, 60 and 90° to each other. A model of MERO connector is presented in this paper for double layer grid structure. The internal forces in the members of double layer grid are found using SAP software. These forces are applied as pressures on the MERO connector. The deflection and rotation patterns of the connector are studied under different loading conditions using the ABAQUS software. The forces to be applied on the connector are calculated using of displacementg control.
In order to take into account the connector effects in structural analysis, their behavior under combined load should be predicted. In double-layer grids that are an important family of space structures, the main internal forces are axial forces. In the present study, to determine the force-displacement relationship of MERO jointing system, some tensile, compressive and bending simulation tests were carried out on a connector of this type using 3D finite element method. The obtained force-displacement and moment- rotation relationship were used under different load. The results of the finite element simulation with experimental results have a good match. It was also found that in both compressive and tensile loading, the ball came to the plastic stage. Compressive axial force increases the flexural stiffness of the connection and with increasing compressive force decreases the elastic bending moment.

Today, large dams, including the type of soil or concrete offshore structures are the most important that in water supply needs of human societies play a major role. Dam stability in recent decades has been of particular interest to designers of earth dams. Soil arching in zoned embankment dams is a phenomenon where stresses are transferred from the softer core soils to the stiffer shell soils due to differential movements between the core and shell materials. In these structures, excessive stress transfer due to soil arching will lead to hydraulic fracturing occurrence in the low permeability core soils; which can cause significant internal seepage and erosion problems. This process is usually accompanied by internal erosion of soil particles, which leads to the formation of soil pipes or other erosion features that eventually cause failure of the dam. statistically shown that progressive piping and erosion are the primary contributing factor in 30% to 50% of earth dam failures. The easiest way to prevent hydraulic fracturing from occurring is to ensure that the total stresses along the upstream side of the clay core are always greater than the seepage-induced pore pressures. Thus, some authorities argue that making use of highly soft materials in core of dam which have not enough shear stress to suspend on shell materials is useful. Installation of instrumentation and monitoring during construction and initial operation will help to assess important parameters. Statistics show that the highest number of failures unstable dams, Respectively is related to earth dams, gravity, pebbles, multi-arc and arc. In this research, by modeling the Baft earth dam in finite element software PLAXIS and compare the results with the instrument results, confirmed the authenticity modeling and then, the arching phenomenon has been studied in the earth dam desired. Investigated parameters include the width of the core (core slide slope), the upstream filter layer thickness and compressibility foundation. The effect of the core side slope angle on soil arching between the clay core and the upstream shell was investigated by simulating three different core side slopes for a vertically oriented clay core: 1V:0.25H, 1V:0.33H and 1V:0.50H. To further investigate the impact of transition layer thickness, three different models with upstream filter thicknesses of 1, 3 and 6 m were analyzed. The effect of foundation compressibility on soil arching between the clay core and the upstream shell was investigated by simulating foundation rock having three different levels of compressibility. The elastic rock modulus values used in the current study were: 4×105, 8×105 and 12×105 kN/m2. that the effective parameters between these parameters to reduce of arching, is core slide slope that The core slide flatter ratio arching dramatically reduced. Then the thickness of the layer filter, which increases its thickness is reduced ratio arching. Thicker filter layers also have the additional advantage that, if they are designed properly, they can help prevent erosion of core materials into the downstream soils if a crack in the core does occur. The effect modulus of elasticity of the foundation had little influence and is negligible.

In seismic active zones, large mainshocks usually follow by numerous aftershocks. Because of the short time intervals between consecutive shocks, additional damage due to the accumulation of inelastic deformations from all sequences is increased and the structures that has been already damaged by the preceding shock collapse before any repair is possible. Moreover, despite the importance of seismic sequence phenomena on increased damage and the evidence of structural damage caused by the recent multiple earthquakes such as Nepal and Hindu-Kush (2015), most structures are designed according to the modern seismic codes which only apply a single earthquake on the structure in the analysis and design process. In this case, the structure may sustain damage in the event of the "Design earthquake", and this single seismic design philosophy does not take the effect of strong successive shocks on the accumulated damage of structures into account. For this reason, the effect of various parameters such as Peak Ground Acceleration, Magnitude, Shear Velocity Wave, Effective Peak Acceleration, Peak Ground Velocity, Epicentral distance, the time gap between first and second earthquakes, Period of reinforced concrete frames and etc, is examined on the damage of reinforced concrete frames under single and consecutive earthquakes. At first, six concrete moment resisting frames with 3, 5, 7, 10, 12 and 15 stories, are designed according to the Iranian Code of Practice for Seismic Resistant Design of Buildings (i.e. Standard No. 2800 guideline) and analyzed under three different databases with/without seismic sequences phenomena. For each database, single and consecutive earthquakes are selected according to Peak Ground Acceleration (PGA), Effective Peak Acceleration (EPA) and Peak Ground Velocity (PGV) criteria from Pacific Earthquake Engineering Research (PEER) and United States Geological Survey’s Earthquake Hazards (USGS) centers. At next step, in order to train the multilayer artificial neural networks with back-propagation learning algorithm, period of reinforced concrete fames (T) and some of earthquake features including PGA, PGV, EPA, magnitude (M), shear wave velocity in the station (Vs), epicentral distance (Epc) and time gap between consecutive earthquakes (Tg) as artificial neural network inputs and Park-Ang (1985) damage index - as the results of nonlinear dynamic analysis in OpenSees software and neural network target – are selected. For each database, 400 neural networks are designed with a different number of neurons in each hidden layer from 1 to 20 and ideal neural network is determined with the least value of Mean Square Error (MSE) and maximum value of regression (R) among all networks. Then, for considering the effect of input parameters on structural damage (Park – Ang 1985) caused by single and consecutive seismic scenario, the range and reference values for each group of input parameters – single and consecutive cases in each database – are chosen to be close to the median values and introduce to ideal neural networks and damage indexes are determined. The results show that structural damage caused by with/without seismic sequence scenario is more sensitive than other parameters to Magnitude and Acceleration for single earthquakes and the ratio of these parameters in the second shake to first for consecutive shocks.

Road accident is one of the most important factors which are treating the country general safety and it is a real national disaster. Statistics show that despite of different indicators, the traffic accident risk’s and its casualties are in high level. In driving accident pedestrians have the less immunity therefore it is the cause of the most damage then allocated the most percentage of damage and injury. One of the most important factors in traffic engineering is pedestrian crossing safety. Investigating the parameters affecting the pedestrian’s safety margins and their relationship on the identifying the main causes of accidents relate to pedestrians on the streets without the traffic signs and driving has an important role. Although the raise of vehicle use growth rate in Iran has become an unavoidable issue and every day urban activities as pedestrians are accounted as one of most necessary parts of modern days life, numerous challenges in regard with decreased speed and mobility of urban traffic flow in contact with pedestrian users are readily imaginable. Speed and mobility increase are counted as urban traffic management goals. On the other hand this speed increase causes an increase in hazard index at vehicle and pedestrian conflict points. Use of traffic signs is a solution to enhance the drivers’ caution, the performance of which depends upon a variety factors such as cultural, human, infrastructure of road and behavior of drivers and pedestrians factors. For this purpose, 69 hours videos were recorded in 13 days, were evaluated. This study was cross - sectional and conducted on the basis of observational data. Data analysis was performed using STATA 12 software and linear regression method.
In this research, using voice message signs before the pedestrian crossing place marked by ladder road horizontal signs as the crossing place and sending the voice message alarm of approaching the pedestrian crossing place on 4 different frequency channels on FM waves, the attempt was to draw incoming drivers’ attention to this situations causing a decries in number of conflicts and an increase in safety using a voice sign so that the vehicles receiver play the message for the driver. This research is based on use of traffic conflicts indexes, more precisely the Time to Collusion index (TTC). To do this, the data of conflicts was gathered using an automatic video data excavating system, analyzing videos from three different points in the city of Qom, Iran before and after using the voice message sign. The first point was near the Valieasr Hospital along with Jomhuri Eslami BLVD. The second point was also along with Jomhuri Eslami BLVD near the Basij square and the third point was along with the Shahid Navab Safavi BLVD near the Abal-Basir high school. In this research, after capturing videos from study points in both situations of usual traffic flow and traffic flow being sent the warning voice message, condition of vehicle-pedestrian conflict TTC index was evaluated. The models results showed that the use of voice sign decreases the overall conflicts by 10%, the critical conflicts by 26% and increases the time to collusion by 0.124 seconds

In the present study, a fuzzy finite element model is developed to apply uncertainty of soil parameters on dynamic behavior of coupled saturated porous media. The interaction problem in the analysis of elastic soil matrix with Darcy pore fluid flow which is formulated by Biot is one of the complicated problems and its exact solution is so difficult, therefore it can be solved numerically. Finite Element Method is one of the numerical methods to approximate the dynamic solution of these problems and for convenient approximation of solution, model parameters need to be precisely known. On the other hand due to inhomogeneous and anisotropic structure of soil matrix, it is not possible to define the soil parameters with the crisp numbers. Consequently results that are obtained only one specific crisp value for an uncertain parameter cannot be representative for the whole spectrum of the possible results. To solve this limitation, application of fuzzy arithmetic proves to be a practical approach. For this purpose uncertainties in the soil parameters are taken in to account by the fuzzy numbers and shape function of input fuzzy numbers are derived from experimental data. In this study the coupled equations governing saturated porous media which are known as u-p equations, are solved by fuzzification of input parameters. For this purpose input parameters, the Poisson's ratio and modulus of elasticity, are treated as fuzzy numbers. To fuzzify a parameter, a certain number of degrees of membership are considered and by using fuzzy rules for each degree of membership a range of parameters are obtained which has lower and upper bound and the calculations are done for this upper and lower bounds. As a numerical example, problem of elastic soil column consist of two layers, loose and compacted sand, is analyzed. For solving this problem a finite element Fortran code has been developed and verified. For verification of developed Fortran code, the support of input fuzzy numbers was adopted in a way that the most likely amount of input parameters (m) be equal to the crisp input numbers that had been used by previous studies. The results indicated solution at α=1(probability of one hundred percent, which is the definite solution) is in good agreement with results of literatures. For other degrees of membership, the problem was solved with two constitutive D matrix for each α level to compute lower and upper bounds of output for that level. At the end, displacement and excess pore water pressure of sandy soil column which are produced under rapid loading are reported as fuzzy numbers. It means that it can be seen if Poisson's ratio and modulus of elasticity increase or decrease what will happen to displacement and excess pore water pressure. The results showed that coupling, change of input parameters of soil skeleton influence pore water pressure too. And as time increase this effect can be seen well. Also increase drainage distance causes a decreasing in the interaction between soil skeleton and pore water and this effect decreases by depth. Obtained result show that the number of fuzzy parameters (uncertain parameters) in equations increase the range of answers.

Study of the seismic response of a site, requires the accurate estimation of the Shear modulus (G) and damping ratio (D) of under ground layers in that area. According to the unsaturated condition of an extensive part of the earth surface, it is necessary to perform unsaturated tests to determine dynamic or cyclic parameters of these regions. On the other hand, because of inherent complications of unsaturated testing equipment, this field of experience has had less attention. But in recent years by development of advanced experimental equipment some studies have been developed based on the dynamic parameters of unsaturated soils.
A large amount of the researches related to cyclic and dynamic parameters of unsaturated soils are the studies about determination of these parameters in very small strain levels (initial shear modulus and initial damping ratio) and the effects of some factors such as suction, mean net stress, suction history, anisotropy and pre-consolidation on them, using bender element technique and resonant column torsional shear apparatus. But there is less attention in experimental studies in the strain ranges of medium to large and determination of the parameters G (shear modulus) and D (damping ratio), and also the normalized shear modulus reduction and damping ratio curves for unsaturated soils.
In this research, it is tried to determine the shear modulus and damping ratio parameters in medium to large strain levels using suction controlled cyclic triaxial apparatus and study the effect of changes in matric suction and mean net stress on these parameters in a kind of unsaturated clay with plasticity index of 24 under high loading rates. In this regard, some tests are performed on different paths including two suction levels (zero and 300 KPa), in mean net stress level of 200 KPa and three deviatoric cyclic stress ranges (18, 42 and 81 KPa) up to 60 loading cycles. Also a comparison is done between the results obtained from the current research and the results of another research which was performed in the same paths on a fine grained soil with plasticity index of 12 using the same equipment.
The results of this research show that increase in suction level results in raising shear modulus and decreasing in damping ratio values. In addition in the same strain level, by increasing the number of loading cycles, the shear modulus values are increased and the damping ratio values are decreased.
Considering the results of current research (unsaturated cyclic tests on unsaturated normally consolidated fat clay with plasticity index of 24) with the results of another experimental research in the field of unsaturated cyclic tests on unsaturated normally consolidated lean clay with plasticity index of 12, in the same sample preparation process and the same stress paths, is indicated that the changes of the shear modulus values of the high plasticity samples are in the lower level related to the values of the samples with plasticity index of 12. In the other word, the increase in plasticity index decreases the stiffness of the samples considerably. But the change in damping ratio values is shown relatively the same trend in both groups of the samples.

Portland-limestone cement (PLC) is a new, more sustainable version of portland cement that is becoming widely available in North America. Known as Type IL cement in the blended cement specifications of ASTM and AASHTO, it has already been approved by many transportation agencies and its use in structures and pavements is rapidly increasing. PLC implementation has been fueled mostly by interest in sustainability, but some experiences have also shown that it can be used to improve concrete performance and even mix economics. Beneficial performance synergies of PLC with fly ash and slag cement (SCMs) have been well documented. Recent research has also studied optimum PLC properties, the most beneficial types and characteristics of SCMs, and the extent to which SCM replacement rates can be extended. In addition to improved strength development, setting, and durability, this more sustainable PLC concrete has been found to improve finishing properties and the quality of formed or slipped surfaces. The webinar will review research and trial project data and highlight successful applications and project experiences to date, sharing implementation guidelines.
More recently, the composite concretes which is consisting of Portland cement, lime stone powder and different types of pozzolans are used in a few countries. This type of concrete is more beneficial as a certain percentage of lime stone powder and pozzolan is substituted by cement weight in concrete. However, considering Iran, although considerable number of cement factories is available, and the economic cost of composite cement, the practical use of such cement is not yet seriously taking into consideration. When designing a concrete structure using composite cement, some of its characteristics and engineering properties become different from those of normal concrete, NC. These differences in material properties may have important consequences in terms of the structural behavior and design of composite concrete members. The design provisions contained in the building codes are, in reality, based on tests conducted on NC. The design of these structural members is not covered in existing codes of practice.
Therefore for the aim of practical usage of composite cements, it is necessary to investigate seriously the plastic phase, engineering properties and durability considerations of this type of composite cement. In this paper, the chemical analysis of composite materials including cement, lime stone powder and Rafsenjan’s pozzolan are performed and the results and analysis of ten designed concrete mixes which are constructed and tested are discussed. The mixes are including control and nine composite (ie. cement type II of Kerman cement factory, Rafsenjan’s pozzolan and limestone powder) concrete. In plastic phase; the tests on slump, setting time and volume expansion of control and composite cement and in hardened phase; the tests on compressive strength for two wet (w) and %5 sulphate sodium (s) curing conditions, different type of tensile strength (i.e. splitting, European and flexural tensile strength) at short and long time ages and water capillary absorptions are carried out. Also, for concepts of practical use of such concretes in reinforced concrete structures, the compressive and tensile stress-strain diagrams are plotted by attaching sensors on two types of concrete. It was concluded that: i) the setting time of composite specimens were lower than that of control concrete specimen, ii) replacing of lime stone powder and pozzolan by cement weight caused to reduce the compressive strength of composite to that of control concrete at early and long ages however, ultimate compressive strain (εcu) of almost all the specimens reached 0.003 which is recommended by ACI standard. and iii) no considerable effect on the compressive strength of specimens was observed for two curing regimes of sulphate (s) and wet (w).

This article compares the behavior of spread footing on rammed aggregate piers and spread footing on cast in place concrete piers as two types of semi-deep foundation with small-scale on-site. In this study, the area replacement ratio (pier on spread footing), composite (spread footing-pier) stiffness modulus and the bearing capacity of spread footing-pier are three main factors of the aim. For this purpose, 18 compressive load test in three groups with 6 elements composed of the following circular spread footings, spread footings on rammed aggregate piers, spread footings on concrete piers with constant diameter and length of piers and variable diameter of spread footing were built and tested in the coastal area of Bushehr port, Iran. In all three groups, the diameter of spread footings were 200, 250, 300, 350, 400 and 450 mm and in two groups of spread footings on piers, nominal diameter and length of concrete piers and rammed aggregate piers were 135 and 600 mm, respectively. The trial site was composed of a wet soil layer of low plasticity silt (ML). Underground conditions at the site were evaluated using in-situ and prevalent laboratory tests. Measurements performed in the site were composed of applied load and top settlement in spread footings on piers and pier's bottom settlement. The results show that, for the area replacement ratios (pier/spread footing) greater than 20%, the average of design limit stress and stiffness modulus of spread footings on concrete piers are 1.1 and 1.3 times of the corresponding values of spread footings on rammed aggregate piers, respectively. Also, for the area replacement ratios (pier/spread footing) less than 20%, the use of cast-in-placed concrete piers or rammed aggregate piers havent any effect on the stiffness modulus and bearing capacity of spread footing on piers. In general, comparison of the results of load tests on spread footings on concrete piers and rammed aggregate piers and two types of piers shows that the performance of them is desirable in practice. Based on the results obtained in this study and previous research by the author in 2015 at the same site testing, the bearing capacity and stiffness modulus of concrete piers and spread footing on concrete piers are relatively greater than of rammed aggregate piers type. However, it is unclear in other local soil type, layering and other technical characteristics of such a result occur. On the other hand, as for the diameter and length of the trial piers, tip stress (against bulging) was governed on two types of piers and spread footing on piers. While, it is not clear with the occurrence of bulging deformation on the top of pier and effect of spread footing on it, such an outcome to be repeated. However, very little research has been done in this field, and as long as more research is done in this regard, for the decision to choose any one of these systems in action, case study should be done in this field. In this field, conducting a case study with a fewer loading tests and numerical modeling with validation of results can significant help to reduce the cost and duration of initial studies, prediction of results and to choose any of the systems.

Polycyclic Aromatic Hydrocarbons such as naphthalene are dangerous for humans and the environment due to their carcinogenic and toxic properties. Thus, removing these pollutants from the environment is necessary. In this study, Graphene NanoSheets (GNS) was synthesised and applied for the removal of naphthalene from aqueous solution. The structure of nano-adsorbent studied using Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Optimal absorption studies for naphthalene removal from aqueous solution has been carried out at batch technique under various experimental conditions including adsorbent dosage (0.01 - 0.2 g/l), pH of solution (3 - 10) and initial concentration of naphthalene (3 – 15 mg/l). The isotherm of adsorption data was analyzed using Langmuir and Freundlich models and the kinetic of adsorption data modeled in optimum conditions using Pseudo-first-order, Pseudo-second-order, Elovich and Intra-particle diffusion models. The optimum condition has been achieved in the pH=10, initial concentration 13 mg/l and the adsorbent dosage 0.11 g/l and in these conditions, the removal percentage and absorption capacity of naphthalene was obtained 80.19% and 90.18 mg/g, respectively. The results indicated that adsorption isotherm and kinetic followed Freundlich isotherm (R2=0.97) and pseudo-second-order kinetic (R2=0.99) models, respectively. According to present study GNS can be used as an efficient adsorbent for the naphthalene removal from aqueous solutions.Polycyclic Aromatic Hydrocarbons such as naphthalene are dangerous for humans and the environment due to their carcinogenic and toxic properties. Thus, removing these pollutants from the environment is necessary. In this study, Graphene NanoSheets (GNS) was synthesised and applied for the removal of naphthalene from aqueous solution. The structure of nano-adsorbent studied using Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Optimal absorption studies for naphthalene removal from aqueous solution has been carried out at batch technique under various experimental conditions including adsorbent dosage (0.01 - 0.2 g/l), pH of solution (3 - 10) and initial concentration of naphthalene (3 – 15 mg/l). The isotherm of adsorption data was analyzed using Langmuir and Freundlich models and the kinetic of adsorption data modeled in optimum conditions using Pseudo-first-order, Pseudo-second-order, Elovich and Intra-particle diffusion models. The optimum condition has been achieved in the pH=10, initial concentration 13 mg/l and the adsorbent dosage 0.11 g/l and in these conditions, the removal percentage and absorption capacity of naphthalene was obtained 80.19% and 90.18 mg/g, respectively. The results indicated that adsorption isotherm and kinetic followed Freundlich isotherm (R2=0.97) and pseudo-second-order kinetic (R2=0.99) models, respectively. According to present study GNS can be used as an efficient adsorbent for the naphthalene removal from aqueous solutions.Polycyclic Aromatic Hydrocarbons such as naphthalene are dangerous for humans and the environment due to their carcinogenic and toxic properties. Thus, removing these pollutants from the environment is necessary. In this study, Graphene NanoSheets (GNS) was synthesised and applied for the removal of naphthalene from aqueous solution. The structure of nano-adsorbent studied using Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Optimal absorption studies for naphthalene removal from aqueous solution has been carried out at batch technique under various experimental conditions including adsorbent dosage (0.01 - 0.2 g/l), pH of solution (3 - 10) and initial concentration of naphthalene (3 – 15 mg/l). The isotherm of adsorption data was analyzed using Langmuir and Freundlich models and the kinetic of adsorption data modeled in optimum conditions using Pseudo-first-order, Pseudo-second-order, Elovich and Intra-particle diffusion models. The optimum condition has been achieved in the pH=10, initial concentration 13 mg/l and the adsorbent dosage 0.11 g/l and in these conditions, the removal percentage and absorption capacity of naphthalene was obtained 80.19% and 90.18 mg/g, respectively. The results indicated that adsorption isotherm and kinetic followed Freundlich isotherm (R2=0.97) and pseudo-second-order kinetic (R2=0.99) models, respectively. According to present study GNS can be used as an efficient adsorbent for the naphthalene removal from aqueous solutions.