Dynamic Process Study of Earthquake-Induced Landslides Applying an Improved Discontinuous Deformation Analysis Method Considering Site Response

Earthquake-induced landslides are complex dynamic processes, a better understanding of which can be achieved by studying the entire dynamic process, including the propagation of seismic waves, cracking, instability, movement, and deposition. This paper explores the entire dynamic process in combination with the propagation of seismic waves and crack developing process of the slope under earthquake actions, while taking into account the strength attenuation, the major factor that causes the high-speed and long-runout movement. In this study, a simulation analysis tool called discontinuous deformation analysis (DDA) was used and improved by incorporating a seismic input method based on a viscous boundary and the free-field theory, virtual and real joints, and a shear strength attenuation criterion, to conduct a unified simulation analysis of the whole dynamic process of earthquake-induced landslide, and to analyze the influence of the dynamic response law on the instability and motion of landslide. Based on these improvements, the Donghekou landslide caused by the Wenchuan earthquake in 2008 was simulated. The dynamic characteristics of the slope showed an obvious amplification effect. At places with strong dynamic responses, cracks initiated rapidly. The progressive crack developing process of the landslide was represented. Owing to the low-friction effect, the speed increased sharply after the landslide began, promoting its high speed and long runout. From the crack propagation in the slope and the formation process of the sliding surface, it is evident that the Donghekou landslide was a typical tension-cracking and shearing sliding landslide.