ANALYSIS OF LOOSENED ZONE DISTRIBUTION OF SOIL-SIMILAR CUTTING SLOPE BASED ON DEVIATORIC STRESS

The stability of soil-similar slope is controlled by the strength of soil mass and geological structural planes simultaneously, and its mechanism of landslide and distribution of slide zone are quite different from those of rock slope and homogeneous soil slope. In this study, a numerical analysis method, which is mainly based on the deviatoric stress, was proposed to predict the loosened zone distribution of the soil-similar slope. This method was performed by the FLAC3D software, and the post-processing program for deviatoric stress was written by the FISH language. A cutting slope was chosen for the case verification, and its stability state in both excavation and rainfall condition was calculated. It is shown that the new and original deviatoric stress contours will be characterized by the phenomena of cross, separation, coincidence or gradient mutation, which are especially remarkable near the structural planes. So the potential failure mode and range of loosened zone can be found out according to change of deviatoric stress contours, on the combination with plastic zone, displacement field and construction record. For the slope case in excavation condition, the deviatoric stress decreased at the early elastically unloading state driven by crustal stress; then increased because of the transformation of gravitational potential energy; and decreased again when getting into nonlinear unloading stage of plastic damage. After large deformation and landslide took place, obvious partition between increase and decrease of deviatoric stress would come into being. Correspondingly, the slope in excavation condition was characterized by the unloading rebound, crack propagation and shallow slide in sequential order fundamentally. The completely weathered stratum slid along the interface with the intensely weathered stratum in rainfall condition, and deep landslide with circular slip-surface occurred further in overall saturated state.