Abstract
Investigations into the Wenchuan earthquake (2008, China) demonstrated that landslides were concentrated in the near-fault areas, and numerous large-scale landslides occurred in slopes with weak interlayers. A mathematical model was established based on the shear beam theory, while a numerical model was developed based on the discrete element method which perfectly matched layer boundary theory. Through a theoretical analysis and numerical simulation, the dynamic response and failure modes of the slope with a weak interlayer under the near-fault ground motion were studied. It was found that a combined effect took place between the near-fault ground motion and the weak interlayer, causing the slope near a fault to be destroyed more easily. The coupling between the near-fault ground motion and the weak interlayer leads to a maximum amplification effect of the slope. The existence of a weak interlayer induces nonconforming vibration between the upper and the lower rock masses of the interlayer. The variation in the amplification effect along the slope elevation is related to the ratio of the input seismic period to the natural slope period. Under horizontal ground motion, weak interlayers will be subjected to impacting and shearing action. The failure mode of the slope with a weak interlayer under near-fault ground motion can be expressed as a trailing edge tension crack, as well as weak interlayer impacting and shearing failure.
Highlights
Post-earthquake surveys have demonstrated that damages are concentrated in the epicentral area, regardless of the engineering structure or geological body. e damage amount and degree generally exhibit a negative correlation with the distance from the fault, with a nonlinear attenuation
Taking a strike-slip fault as an example, when the near-fault site is at the end of the fault along the fracture strike, the energy produced by each rupture will be superimposed. us, a velocity pulse will appear, which is produced by the rupture directivity effect, and its direction is perpendicular to the fault strike. e characteristic of the velocity pulse produced by the rupture directivity effect is that the pulse appears at the initial stage of ground motion and is bidirectional [7]
A two-dimensional numerical model to study the failure process of a slope with a weak interlayer was established based on the discrete element method (DEM) and perfectly matched layer (PML) boundary theory. rough the theoretical analysis and numerical simulation, the dynamic response and failure mode of the slope with a weak interlayer under the near-fault ground motion were studied. e following conclusions can be drawn: (1) e weak interlayer in the slope will increase the first-order natural period of the slope
Summary
Post-earthquake surveys have demonstrated that damages are concentrated in the epicentral area, regardless of the engineering structure or geological body. e damage amount and degree generally exhibit a negative correlation with the distance from the fault, with a nonlinear attenuation. Under the action of ground motion, a slope with a weak interlayer will exhibit several different response characteristics compared to a homogeneous slope [12, 13]. Existing studies on the seismic response of a slope with a weak interlayer have mainly focused on the failure mode, amplification effect, and spectral characteristics of the slope [20]. The effect of near-fault ground motion, which exhibits special characteristics, on the weak interlayer has been of less concern, with only few relevant research studies available in the literature. Near-fault ground motion has many different characteristics from far-field ground motion, and the slope with a weak interlayer exhibits numerous special dynamic response characteristics compared with the homogeneous slope under the action of ground motion. In the Daguangbao landslide (at a 4.8 km distance from the fault), the largest landslide triggered by the Wenchuan earthquake, it was found that the slip zone was the interlayer dislocation zone, and the strength and stiffness of which were smaller than those of
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
