Earthquake-induced slope failure is one of the major observed hazards associated with the earthquakes in mountainous area. Understanding the topographic amplification effects of ground motions and post-failure deformation behaviors of the slopes can provide scientific guidelines for the design of buildings and evaluation of the slope stability. This study aims to apply the material point method (MPM) combined with the modified Lysmer-Kuhlemeyer absorbing boundary to simulate the wave propagation inside the slope and seismic slope failure. The major findings of this thesis are as follows:

(1) The MPM combined with a modified Lysmer-Kuhlemeyer absorbing boundary is developed to study the topographic amplification effects of ground motions in seismic slope analysis. Steps to apply the abso...[ Read more ]

Earthquake-induced slope failure is one of the major observed hazards associated with the earthquakes in mountainous area. Understanding the topographic amplification effects of ground motions and post-failure deformation behaviors of the slopes can provide scientific guidelines for the design of buildings and evaluation of the slope stability. This study aims to apply the material point method (MPM) combined with the modified Lysmer-Kuhlemeyer absorbing boundary to simulate the wave propagation inside the slope and seismic slope failure. The major findings of this thesis are as follows:

(1) The MPM combined with a modified Lysmer-Kuhlemeyer absorbing boundary is developed to study the topographic amplification effects of ground motions in seismic slope analysis. Steps to apply the absorbing boundary to the lateral and bottom boundaries of the model are discussed. The results show that the MPM combined with the modified Lysmer-Kuhlemeyer absorbing boundary can achieve accurate results in modeling topographic amplification of ground motions as compared with published results. Key influencing factors are identified as the slope inclination i and the normalized height H/λ (H is slope height, λ is wave length). The slope topography amplifies the peak acceleration in front and behind the crest, which produces vertical ground acceleration that cannot be neglected in seismic slope displacement analysis.

(2) Seismic analysis of slope deformation using MPM is compared with a Newmark-type slope deformation analysis. The results show that the predicted earthquake-induced slope displacements using MPM are always larger than these predicted by Newmark deformation analysis, which can be attributed to the neglect of dynamic resistance in the latter method. The correlations of predicted earthquake-induced slope displacement and different intensity measures (PGA, PGV, and I_a) are compared and the Aria Intensity (I_a) is found to be the most correlated intensity measure. Moreover, the failure mode of soil slopes with different inclination and material properties are analyzed using the fully nonlinear MPM. The results indicate that seismic slope failure mode depend on different factors, including residual soil strength and intensity of ground motions. Instead of a single shear band, displacement on multiple shear bands should be considered in estimating seismic slope displacement.