Study on shear strength characteristics of loess dam materials under saturated conditions

A loess accumulation dam in Ansai Area, Yan'an, Shaanxi province is selected as the research object, and the remolded soil of the dam body is taken as the test material to conduct the saturated loess indoor triaxial test. The test shows that the peak stress of saturated remolded loess increases with the enhancement of confining pressure and dry density, and the pore water pressure rises rapidly in the shear of the samples with a dry density of 1.4-1.6 g/cm(3)and gradually flattens out. When the samples with a dry density of 1.7 g/cm(3)in the process of shearing, the pore pressure rises rapidly and then decreases as the volume increases. The total internal friction angle and effective internal friction angle increase with the augment of dry density, and the total cohesion and effective cohesion show a changing trend of first rising, then falling and then rising due to the different development of original cohesion, sliding friction and rolling friction. Meanwhile, combined with field monitoring, it can be determined that the dam a total of three times more obvious damage. According to the comparison of field test and laboratory test, the concept and calculation method of "inspection threshold" are put forward.