ABSTRACT
The interface between compacted loess and cement mortar and the loess under different moisre content was tested by a strain-controlled direct shear instrument. The shear mechanical displacement characteristics of the smooth interface, rough interface, and loess were compared and analyzed. The effect of water content on the shear strength of different interfaces was studied. The results show that the shear characteristics of the smooth interface are strain hardening, while the shear stress displacement curves of rough interface and soil show strain softening when vertical pressure and water content are low. The water content and vertical pressure conditions of the rough interface are close to those of the soil under the strain softening phenomenon, but the softening degree is relatively weak. The shear strength of the smooth interface and rough interface obeys the Mohr-coulomb strength criterion. The cohesion of the smooth interface is close to 0 and does not change significantly with the water content. The cohesiveness of the rough interface decreases nonlinearly with the increase in water content. When the water content increases, the cohesiveness decreases at a smaller speed, which is greater than that of a smooth interface and less than that of soil. The friction angle of the smooth interface and rough interface decreases nonlinearly with the increase of water content. When the water content increases, the friction angle decreases faster, and the friction angle of the rough interface is larger than that of the smooth interface under the same water content. Aiming at the interface of strain hardening and strain softening properties, the exponential model and the statistical damage model were used to fit and compare with the experimental data respectively. It was found that the two models can better describe the mechanical displacement behavior of the interface between loess and cement mortar.
