Calculation Method of Trailing Edge Failure Surface of Retrogressive Landslide

Slope failure is induced by retrogressive slide, forming a trailing edge tension crack surface. The shape of the trailing edge surface has an important influence on landslide stability analysis and thrust calculation. However, it is difficult to determine the spatial characteristics of the landslide. In order to explore the formation mechanism and calculation theory of the trailing edge fracture surface, a reasonable mathematical and mechanical model was established. The calculation method of the trailing edge fracture inclination angle was put forward, from which the most dangerous fracture inclination angle of each level slider was found. Finally, the fracture surface was used as a stripe type to calculate the stability coefficient of each level slider and carry out the stability analysis of the landslide progressive failure process. Simultaneously, an indoor model test was conducted for verification. A new model test device was developed as well. Its main body was composed of a number of permeable boxes, thereby forming sectional sliding surfaces of various geometric shapes. By injecting water into different permeable boxes, step-by-step instability process of retrogressive landslide was realized. Then the trailing edge inclination of the final form of the sliders at each stage was measured. The results show that the calculated value of the inclination of the trailing edge is in good agreement with the test value. It is mainly concentrated at about 70°, with a relative error between 2% and 4%. The stability of the sliders is different at each level. Thus, the stability of the first stage is the worst, whereas the stability of the backside of the landslide body is better. These research results can provide a new procedure for conducting the stability analysis of retrogressive landslide.