Shear behaviors of saturated loess in naturally drained ring-shear tests

Abstract

A series of ring-shear tests was conducted on saturated loess to investigate the effects of shear rates and normal stress levels on the shear behaviors. The test results revealed that the effect of shear rate on shear strength of loess is strongly dependent on the normal stress levels. The peak friction coefficient of the samples is positively dependent on the shear rate when relatively low normal stress was imposed, whereas shear rate do not significantly affect the peak or residual friction coefficient for samples under high normal stress levels. But on the contrary, the residual shear strength of samples with pre-exiting failure surface increase slightly with increased shear rate under high normal stress level while kept constant under low normal stress level. Excess pore pressure was estimated to have built up within the shear zone and then can lead to a reduction in the shear strength after failure occur and the degree of reduction in post-failure shear strength was evaluated by the brittleness index.