نشریه پژوهش های تجربی در مهندسی عمران
سال سوم شماره 1 (پیاپی 5، بهار و تابستان 1395)

Combination of soil and plant roots can increase the strength of soil and stability of slope riverbanks. Structural methods are more commonly used to stabilize the riverbanks. Erosion and slumping of soil occur along the significant length of riverbanks, the protection of which involves substantial costs. Therefore, protection of riverbanks with Bio-Engineering methods not only is consistent with environmental aspects and protection of river ecology but also lowers the costs. Mechanical and hydrological properties of plant are important in applying vegetation point of view. Technical properties and engineering of plant species can be understood better by using field investigations. However, it is more complicated and difficult to undertake field works due to the effect of various factors in comparison with laboratory research. Considering the increasing trend of using Bio-Engineering in slope stability, this study aims to investigate problems associated with undertaking field research in Bio-Engineering projects. The results of this study show that, selecting appropriate site to undertake research project, ensuring adequate number of relevant plants in the site, determining the best time to start and end the research project, choosing appropriate excavation methods, considering and resolving mapping problems, determining the number and diameter of roots, performing tests to determine root resistance, looking after roots until performing relevant tests, using appropriate device for tension tests and determining proper clamp are among important problems in undertaking soil Bio-Engineering research.

South Pars gas reservoir is considered one of the largest gas fields in the world. The present study in PSEEZ that surveyed the environmental groundwater aquifers and strategies to deal with, draw down of water and increasing impurities through mapping of isobaths, isosulfate, isochlorine, isosalt, hardness and electrical conductivity contours. Results indicate that the soil is contaminated with heavy elements, progressing serious growing problems that can strongly affect the aquifers of pars region in the near future. Furthermore, aquifer recharge in Assaluyeh Plain is approximately 4.5 million cube meters per a year in which currently more than 3 (million m3/year) is not essentially gathered. Specific storage of alluvial fan deposits of about 5%, one percent of the flood plain and in other regional is less than one percent, so the capability storage of aquifers is low and cannot save a considerable amount of water, or discharge from the aquifer. Future water resources requirements will be provided from outside of the region, but it will take a long time for implementation. In this period, water necessities must be supplied from such aquifers.

Rutting is one of the pavement distresses that mainly occur as a result of excessive loading on roads and it can cause roughness on the surface of pavements. The accumulation of water in rutted areas at rainy conditions results in reduced skid resistance, creating accident risk conditions for road users. One of the rapid and cost effective practices in filling ruts is using Microsurfacing mixes. Microsurfacing is a road maintenance tool that consists of laying a mixture of dense-graded bitumen emulsion mix, water, polymer additive, and mineral filler to correct deficiencies of pavement surfaces. In this research, a rather coarse size microsurfacing mix was designed and tested under load wheel, cohesiometer and wet track abrasion tests. The content of bitumen binders varies from 6.3 to 10% (i.e. percentage of the remained bitumen) and various amounts of latex was applied, ranging from 3 to 5%. Based on the above testing results it was revealed that microsurfacing mixes containing latex provided enhanced mechanical properties in the field. In addition, it was shown that among the above mentioned testing methods, abrasion and rutting tests were the most promising ones. The addition of latex modified binders resulted in improving characteristics of surface treatment mixes. In summary, it was resulted that the addition of 5% latex to emulsion mix containing 8.2% residual bitumen resulted in optimum conditions. With this formulation the mix showed almost 50% increase in both abrasion resistance and wheel load rut testing.

In the past decade significant research on strengthening, repair and increasing load capacity of concrete structures is carried out by the researchers. Meanwhile, the new methods including the use of polymer fibers to provide confinement for concrete and injecting resin under pressure to fill the concrete cracks for a better continuity of a failed member are introduced. This paper introduces a new approach for strengthening a concrete member based on epoxy injection and in addition to strengthening and increasing the load capacity to repair concrete members. In this study, nine cylindrical samples were prepared, three as control specimens, two specimens with four holes and four specimens with eight holes. All holes with a diameter of 10 mm provided by drill and then epoxy injection were carried out. The purpose was to determine the strength increase and to reduce the lateral strain under axial loading. Two specimens with eight holes confined with carbon fiber reinforced polymers (CFRP) to observe the effect of such a confinement comparing to the normal confinement provided by CFRP. These holes were created in specimens with specific angles and distances from each other. The results show that the suggested epoxy injection method increased the strength and load capacity of the specimens in the non-linear range and the lateral strain is reduced. Epoxy injection plus confinement provided by CFRP resulted in a better performance.

Crump weir is a kind of short edged weir. This weir with its particular design is used to measure the flow discharge in channels. The experimental dataset used in this research are taken from the others to study the performance of ANFIS and M5 tree models for predicting discharge coefficient (Cd) in crump weir. The 174 experimental data from physical models, considered as 16 scenarios with input parameters consist of Fr, Re, h1/p, Sup and Sdo; and Cd as output using for M5 tree model and ANFIS for modeling and evaluation of the coefficient of crump weir. The obtained results show that both methods give almost near results in scenarios with equal training and testing dataset. The best scenario in ANFIS model achieved for randomized dataset with 70% of training and 30% of testing as scenario 12 with the highest correlation coefficient (R=0.988) and the lowest error (RMSE=0.069). Also the best scenario of M5 tree model for randomized data with 75% of training and 25% of testing as scenario 1 with highest correlation coefficient (R=0.988) and lowest error (RMSE=0.007) was calculated. The results suggest a better performance by the ANFIS approach with this dataset, but M5 model trees, provides simple linear relations for prediction of discharge coefficient for the data ranges used in this study.

Soil improvement techniques are important and necessary to increase stability and bearing capacity of soils so that they can successfully sustain loads of the superstructures and lead to saving time and cost of projects. There are many methods of improving soil characteristics which includes lime stabilization and geosynthetic reinforcements. These methods have been widely investigated by many researchers separately. In the current research effects of lime addition and geogrid reinforcement concurrently on clay soil characteristics have been investigated. Clay samples with diameter and height of 50 and 100 mm, respectively have been stabilized with 1, 3, 5 and 7 percent lime and reinforced with two different geogrid arrangements and cured for 1, 7, 14 and 30 days at 35 degree centigrade before being subjected to unconfined compression tests. Results show that lime addition up to 3% significantly increases compressive strengths and reduces strains at failure and using geogrid as reinforcement for stabilized samples does not enhance these characteristics which are attributed to the small size of geogrids used.

Weaknesses of the conventional flood management approach, lack of integrated view to the basin, no attention to the social impact, and low level of non-structural measure considerations, have the reason for a new approach to integrated flood management. Applying the new approach, this paper proposes an effective plan for flood management in the Kan River basin, north of Tehran. The main challenges in the study are quantification of social vulnerability and selection of optimal combination of feasible measures such a way that maximum potential of damage reduction be achieved while the least funding be spent. Therefore, flood flow with 100 yr and 200 yr return periods was simulated applying MIKE11 coupling with NSGA-II to minimize the implementation cost. Based on the prepared model, various combinations of applicable methods were proposed considering different level of fund allocations. Results showed that out of structural measures flood wall and retention dam and out of non-structural measures watershed management, reinforcement, and flood warning have been the most effective measures. The optimal combination of these measures can reduce 2 to 50 percent of flood peak discharge at downstream. Moreover, the obtained results showed that about 100 billion Rials investment in the basin would reduce up to 30% flood damage.