Triaxial test of drained sand reinforced with plastic layers

During the past earthquake, the liquefaction phenomenon of saturated sand mixture has been the cause of severe damage to various buildings and other structures. The catastrophic nature of this type of failure obliged to build a structure on geosynthetics will be used to reinforce the soil and improve its mechanical properties. Reinforcing elements in the form of layers or sheets of waste materials in soil is important because of their use in practical civil engineering and geotechnical applications. The main advantages of such materials are they are locally available, inexpensive, and recyclable. Waste plastics have been successfully used as reinforcement in soil to improve shear strength parameters and the stiffness modulus. This paper focuses on the behavior of plastic reinforcement in sand under triaxial monotonic drained conditions. Laboratory triaxial compression tests were carried out to determine stress and strain, volumetric change behavior, and shear strength parameters and to estimate the strength ratio at various strain levels in sand reinforced with plastic layers. The test involved one to five plastic layers that were placed at regular vertical spacings within the sand. The results demonstrated that the inclusion of plastic layers increases the maximum deviator stress, shear strength parameters and ductility, with the maximum increase corresponding to the five layers of plastic. The inclusion of plastic layers reduces dilation and increases the strength ratio, with the percent increase being greater at higher strain levels. The lower secant modulus was measured in the unreinforced and reinforced sand, with the latter exhibiting higher values of secant modulus at axial strains of 1 % that tend to stabilize for higher values of axial strain.