Instability Mechanism of Cohesive Soil Slope Based on Discrete‐Continuous Coupled Method

ABSTRACT This paper employed PFC 3D and FLAC 3D to conduct a three‐dimensional discrete‐continuous dual‐scale coupled simulation and stability analysis of cohesive soil slope through discrete‐continuous coupled algorithm and the gravity increase method. In the discrete element model zone, the progressive failure process of cohesive soil slope was studied by setting particles with different displacements to different colours, the evolutions of porosity and coordination number in the shear, sliding and stability zones of slope were analysed by arranging measurement spheres, and the variation law of particle position was obtained by the vertical layering of the soil. In the continuous model zone of coupled slope model, the horizontal and vertical stresses were verified with those of a pure FLAC 3D model of slope. Furthermore, a comparative instability analysis of cohesive soil slope and gravelly soil slope was also performed. The safety factor for the cohesive soil slope in this work was determined to be 1.7 according to the mesoscopic fabric evolution of slope particles and the gravity increase method. The work in this paper broadens the application scope of the dual‐scale coupled algorithm, highlights the differences in the mesoscopic instability mechanism between cohesive soil slop and gravelly soil slop, and provides new theoretical support for slope design and risk assessment in engineering practice.