Two?surface progressive failure mechanism and stability quantitative evaluation of water?induced weakening retrogressive landslides: case study for clay landslides, China

摘要

This study investigates water-induced weakening retrogressive landslides and proposes a stability evaluation method basedon the two-surface progressive failure mechanism. A new test device was designed to reproduce retrogressive landslidesby injecting water into the sliding zone soil from bottom to top, and the inclination angles of trailing edge fracture surfacesand horizontal displacement were measured. Then, the calculated inclination angles were taken as slice types, which werecombined with the shear stress?shear displacement constitutive model and the shear displacement model of the slidingsurface to characterize the stability change caused by deformation development of slopes and define the quantitative relationshipbetween horizontal displacement and safety factor. The model test reproduces the progressive formation processof multistage sliding masses. Each sliding mass showed two failure surfaces, a bottom sliding surface and a trailing edgefracture surface. The inclination angles of the trailing edge fracture surfaces were 66 ～ 90°. Moreover, the relative errorsbetween the theoretical and experimental inclinations were 1.33 ～ 9.09% for the model slope. For the actual landslide, therelative errors (SM3 ～ SM7) between the theoretical and actual inclinations were 1.45 ～ 10.94%, and the relative errors ofSM1 and SM2 were larger because of large deformation, so the calculation of inclination angles was not suitable for slopeswith large deformation. The relative error of the total displacement was 2.33%. These tiny differences suggest that the theoreticalapproach is applicable. This theoretical method can infer the stability of landslide through macroscopic deformationand drilling sampling.