Experimental investigation of mechanical behavior of geosynthetics in different soil plasticity indexes

Abstract

Nowadays, in-depth research is done to evaluate the behavior of geosynthetics in cohesive soil. However, it is still unclear how the plasticity index (PI) of soil affects the mechanical behavior of reinforced cohesive soil. The behavior of distinct geosynthetic types in soils having different PI is likewise uncertain. To bridge this gap, the mechanical behavior of three cohesive soils designated as S1, S2, and S3 reinforced with four types of geosynthetics (woven/non-woven geotextile, geocomposite, and geogrid) were studied by executing multiple triaxial compression and interface direct shear tests with and without reinforcement. The results show that the soils reinforced with woven geotextile (GTW) produce higher shear strength than other reinforcements because of their higher interface frictional resistance and tensile strength. It was found that three layers of GTW to S1 soil increased its stiffness, cohesion, and shear strength parameters by 150%, 307%, and 161%, respectively. On the other hand, the increase in shear strength caused by adding three layers of GTW to S2 and S3 soil was only about 59% and 37%, respectively. The interface properties indicate a strong interaction between GTW-S1 soil lasted, whereas a weak interaction between GTW-S2 or S3 soil existed. These findings demonstrate that an increase in the PI of soil significantly reduces the performance of reinforcements due to the reduction in interface friction, lateral constraint, and interlocking effect. The geosynthetic reinforcement performed better in lower plastic soil rather than in higher.