Seyed Alireza Nosrati - Department of Civil Engineering, Faculty of Civil and Earth Resources Engineering, Central Tehran branch, Islamic Azad University, Tehran, Iran
Alireza Negahdar - Faculty of Engineering, Department of Civil Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
Hassan Negahdar - Department of Civil Engineering, Faculty of Civil and Earth Resources Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran
Mehdi siavoshnia - Assistant professor, Faculty of Engineering, Islamic Azad university, central Branch, Tehran, Iran

Combining soil with some adsorbents improves soil structure and shear strength.Thus,an optimal ratio of some adsorbents in the soil composition enhances soil adsorption capacity,reduces the possibility of groundwater contamination with these hazardous compounds,and leads to increased soil resistance parameters.This paper investigates the effect of heavy metals and adsorbents on the geotechnical behavior of Clayey sand soils contaminated with lead and zinc as well as zeolite and rice husk ash(RHA) as adsorbents.clayey sand was considered as a base composition and the behavior of it was studied in both contaminated and uncontaminated states.Then,for increasing the heavy metal adsorption capacity of clayeysand,two types of adsorbents were added to the base composition and their behavior were investigated in the case of Lead and Zinc contamination.The results revealed that replacing the RHA and zeolite adsorbents in the Soil combination significantly reduced the concentration of Heavymetal in the solution.Replacing۱۵%of RHA with kaolinite heightened the absorption of lead nitrate and zinc nitrate by۲۲۸.۸%and ۲۹۱.۶%in kaolinite sand.It was also found that adding nitrate to kaolinite increased the liquid and plastic limits.According to the results,in kaolinite,the value of the liquid limit rose from۴۹.۸ to۵۹.۱upon elevating the concentration of lead to۵۰۰۰ ppm,while the plastic limit also increased from۳۱ in the non-contaminated state to ۳۶.۴in۵۰۰۰ppm in the infected state.According to the results,the dispersed structure is formed by increasing the concentration of lead nitrate in composition of sandy clay with low plasticity adsorbent,thus shear resistance decrease.changing in type of clay minerals to high plasticity cause the different trend in shear resistance parameters.

Shear strength, heavy metals, Rice Husk Ash, Zeolite, Soil structure modification