Study On The Failure Mechanism And Safety Of Layered Rock Slopes Subjected To Dynamic Loads

Study on the deformation and failure mechanism and safety of layered rock slopes under dynamic loads, including seismic loads and explosions, is a difficult but also a hot problem in construction of hydraulic engineering in intensive earthquake areas of West China, and in construction of expressway and nuclear power engineering using drill and blast for foundation excavations. In this paper, the deformation characteristics and failure mechanism and stability of layered slopes under dynamic loads have been conducted in detail using three dimensional distinct element method (3DEC).At first, the dynamic response of an idea layered rock slope with a single discontinuity, including charatersitcs of velocity, and stress as well as displacement et. al., and amplitude effect of the slope subjected to seismic loads are conducted using 3DEC. Also the propagation and attenuation of seismic waves through the joints are analyzed. In addition, the deformation and failure mechanism of layered rock slopes under seismic loads are studied.The stability of the idea slope subjected to seismic loads is conducted using 3DEC. The force of potential sliding body is determined using the FISH program of 3DEC based on Limited Equilibrium Method. And the sliding force and resistance force of potential sliding body are obtained by the resolution of acquired body force along the potential sliding plane. Thus the varied factor of safety of the slope under seismic loads is obtained. In addition, the precise definition of stable status, limit balance status and failure status of the slope is formulated and the criterion of convergence judgment is proposed based on analyzing velocity and displacement vectors of critical points of slopes under the duration of seismic loads. And the factor of safety of the slope is determined based on the method of strength reduction. In addition, the result obtained by the method of combination of limited equlibirum method and 3DEC is compared with that by the method of strength reduction.The deformation and stability of the spandrel groove slope in Xiluodu hydropower station under both the excavation condition and seismic load are studied. It is suggested that the slope is stable under excavation condition and the factor of safety of the slope is computed using the strength reduction technique. It is also revealed that the slope losses its stability under the seismic load with the horizontal peak acceleration of 0.18g after the excavation of the slope without any supports. And the slope is stable under seismic load with the horizontal peak acceleration of 0.32g when support measurements finished.The deformation and failure mechanism of counter-tilt slope of Guangdong Taishan nuclear power station under explosions is studied. And a method to determine the limit balance status of the slope under explosions based on the plasticity zones transfixion of the slope is proposed. And the factor of safety of the slope is computed using the strength reduction technique and proposed method.