Failure Mechanism of Horizontal Layered Rock Slope under the Coupling of Earthquake and Weathering

In order to further reveal the dynamic failure process of horizontal complex layered rock slope in the coupling action of earthquake and weathering, based on the three-dimensional particle flow software PFC3D, the rock triaxial test was first carried out to obtain the macroscopic rock mechanics parameters. Secondly, PFC3D was used to establish a three-dimensional discrete element model of slope under 4 modes. Finally, the Wenchuan earthquake wave dynamic input is used to simulate the coupling effect of each model slope on earthquake-weathering. Under the progressive failure process, the results show that, during the triaxial test, the mudstone particles and sandstone particles exhibited shear failure and tensile failure, respectively. The seismic failure mode of the horizontal complex layered rock slope model is divided into tensile fracture-horizontal sliding failure (cavity depth 1.5 m and fissure depth 25%), tensile cracking-caving-dumping failure (cavity depth 3 m and fissure depth 37.5%), caving-dumping-rotation failure (cavity depth 4.5 m and fissure depth 50%), and caving-slip-rotation failure (cavity depth 6 m and fissure depth 62.5%), and the maximum vertical displacement of Model 2 can reach 6.2 m, and the maximum positive horizontal displacement is 7.8 m. With the deepening of the weathering degree, the coordination number of the rock block shows the attenuation advance effect and the elevation attenuation effect during the seismic period of 2–15 s. The total energy dissipation of the slope can be divided into two stages: fracture collision and overall collapse. The energy dissipation is more concentrated in the rock fracture collision stage, accounting for 89% to 95% of the total energy.

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