Undrained shear behavior of sand-clay mixed soil (using direct simple shear machine).

摘要

The objective of the research is to evaluate the undrained shear strength parameters of various mixtures of clay minerals with sand. Several samples having different proportions of clay minerals, i.e., kaolinite and montmorillonite and sand were prepared. The proportion of kaolinite ranged from 0 to 100 percentages whereas the proportions of montmorillonite ranged from 0 to 30 %. The undrained shear strength of the samples was measured using direct simple shear (DSS) machine.;The results obtained from the DSS tests were complied and comparisons of different soil behavior are done to study the influence of clay minerals on soil behavior. Various relationship were developed between total shear stress, effective secant frictional coefficients, pore water pressure, shear strain, and shearing rate for different proportions of clay minerals. Unchained strength parameters of the samples having different proportions of clay minerals are calculated under 3 different normal pressures.;The specimens used in the soil testing were supposed to be fully saturated, but it is difficult to measure the degree of saturation in DSS machine. A fully saturated condition is maintained by making a slurry of samples with water content more than liquid limit of corresponding samples obtained by previous study and as per the ASTM manual. The inability to determine the degree of saturation is weakness of this study.