Analysis of Stability of Concealed Cataclinal Slopes with Talus Deposits Accumulated at Their Toes with Respect to Biplanar Failure

Abstract

Talus deposits naturally form to a certain height in the toes of slopes because of the accumulation of collapsed material and small landslides. However, the stability of concealed cataclinal slopes with talus deposits accumulated at their toes (referred to as TDAT-CC slopes) with respect to biplanar failure is rarely studied. In this work, the typical geological profiles associated with TDAT-CC slopes are summarized and generalized and their failure modes are classified. A qualitative analysis of their stability is also carried out. The biplanar failure process is investigated by analyzing the development of plastic failure and displacement deformation using Universal Distinct Element Code. The analysis reveals the penetration process occurring in the biplanar sliding planes and clarifies the compression–shear failure processes taking place in such slopes. A new method for determining the stability of TDAT-CC slopes and predicting the failure surface formed is proposed based on limit-equilibrium theory and a model consisting of sliding mass blocks. Finally, the proposed method is used to calculate the stability of TDAT-CC slopes with deposits of different shapes and strengths and the results compared with the results of numerical simulations. The results obtained using the two methods are generally consistent. The talus deposits at the toe of the slope play the role of a toe buttress and help improve the slope’s stability. The safety factor of the slope increases as the inclination of the toe deposits becomes gentler; it also increases as the height of the toe deposits increases. The method proposed offers a sound basis for investigating biplanar failure in TDAT-CC slopes.