Shear Strength of Slip Surface in Loess-Mudstone Interface Landslide

The loess-mudstone interface landslide is one kind of the loess landslides with special characteristics, such as continuous and low-rated deformation. Because of the relatively lower rate of deformation before the landslide initiated, the damage of this kind of landslides is always irreparable. In order to investigate the mechanism of loess-mudstone interface landslide and provide better controlling measures, triaxial tests and ring shear tests on the slip surface were carried out. It is aimed to analyze the shear strength characteristics of slip surface. Eight groups of consolidated undrained triaxial tests and five groups of consolidated drained ring shear tests were set. As the slip surface consisted of loess and weathered mudstone which is different from normal ones mostly containing the same material, there must be differences of shear strength characteristics between them. The results of the tests showed that the stress-strain curves of triaxial tests of the slip surface were significant strain-hardening, and the shear strength of slip surface is higher than that of pure loess but lower than the pure mudstone. The shear strength of the slip surface in ring shear tests increases with the growth of normal pressure. However, the shear stress of multistage ring shear test is much larger than the value of single-stage ring shear test. In conclusion, shear strength characteristics of slip surface in loess-mudstone interface landslide showed that this kind of landslides moved slowly but continuously. The stability of slip surface would be enhanced if the groundwater was prevented in time.