Research Specifications

In this research, the effect of specimen sizes with different dimensions and displacement rates was studied on the behavior of two fine-grained soils via conducting consolidated undrained (CU) triaxial test. Two cohesive soils with different plasticity were retrieved from Jingyang and Nanyang cities in China, which were classified as CL and CH, respectively. Outcomes revealed that the specimen size, displacement rate (DR) and soil plasticity have significant impacts on the soil behavior. Small specimens of both soil, exhibited high strength at a DR of 0.1 mm/min in comparison with those obtained at Dr values of 0.005 and 0.01 mm/min. The shear strength of other specimens (i.e., medium and large sizes) was reduced by increasing Dr from 0.005 to 0.1 mm/min). When Dr was high, as the specimen size increased, the shear strength reduced. At a high Dr, an increase in the specimen size led to a reduction of shear strength. Excess pore water pressure of the soils in small specimens showed a similar trend during shearing at DR of 0.005 and 0.1 mm/min, while the values increased when the DR value rose to 0.1 mm/min in CH soil. For medium and large specimens, the pore water pressure increased by increasing the strain rate for both soils. In small specimens, the effect of the plasticity index by changing DR values is considerable, while for other specimens the effect of plasticity is negligible. Small specimens exhibited more compressibility than large specimens in both soils.