Dynamic-response characteristics and deformation evolution of loess slopes under seismic loads

Abstract

The Loess Plateau is one of the most seismically and geologically active regions in China. The related catastrophic earthquakes and geological disasters have caused more than 1.4 million deaths in the plateau. In this study, the slopes on the edge of the loess tableland in Pingliang City, Gansu Province—the core area of the Loess Plateau—are investigated. Based on large-scale shaking-table model tests and discrete-element numerical simulation—particle flow code (PFC 2D), the dynamic-response characteristics and deformation evolution process of fissured and non-fissured loess slopes under different seismic loads are studied. The test results show that with increasing seismic load input, the peak ground displacement (PGD) of the loess slopes increases gradually with increasing slope height. For the two types of slopes, the acceleration amplification effects in the slope with horizontal direction load are larger than those of the vertical direction load. The amplification factor of the peak ground acceleration (PGA) at the shoulder of the fissured slope is significantly larger than that of the non-fissured slope. According to the numerical simulation results of the fissured slope, when the seismic load is small, the bond-failures are distributed densely in the initial fissured structural plane and at the model bottom. Regarding the non-fissured slope, the bond-failures in the slope are mainly distributed at the bottom of the model. With increasing acceleration amplitude, the number of bond-failures in the slopes increases rapidly. When the input load increases to 0.40 g, two potential slip surfaces occur in the shallow surface of the fissured slope and a potential slip surface appears at the back edge of the non-fissured slope.