地震之后伴随的余震在地震诱发滑坡灾害中起着重要作用。主震中已对岩体造成了不同程度的损伤，这使得余震过程中岩体裂纹进一步发展和相互交互贯通过程更复杂。为了探究地震波荷载对类岩石试样破裂失稳过程的影响，通过采用基于颗粒元黏结模型（bonded-particle model, BPM）的数值方法，研究了在两个正交方向上循环地震波加载作用下的波传播规律和裂纹扩展过程。结果表明，由于计算试样尺寸（76 mm × 152 mm）远小于地震波纵波波长，试样内未观察到波的透射和反射现象；加载产生的裂纹均为微张拉裂纹，重复轴向地震波加载不能使微张拉裂纹进一步扩展；只有当加载方向由轴向变为侧向，再由侧向变为轴向时，裂纹才会进一步扩展并最终导致试样破坏。本文揭示了在地震波反射作用及余震作用下，大量滑坡灾害发生的内在机理。

An earthquake is usually followed by a considerable number of aftershocks that play a significant role in earthquake-induced landslides. During the aftershock, the cracking process in rocks becomes more complex because of the formation of faults. In order to investigate the effects of seismic loading on the cracking processes in a specimen containing a single flaw, a numerical approach based on the bonded-particle model (BPM) was adopted to study the seismic loading applied in two orthogonal directions. The results reveal that no transmission and reflection phenomena were observable in the small specimens (76 mm × 152 mm) because they were considerably smaller than the wavelength of the P-wave. Furthermore, under seismic loading, the induced crack was solely tensile in nature. Repeated axial seismic loading did not induce crack propagation after the first axial seismic loading. Cracks began to propagate only when the seismic loading direction was changed from axial to lateral, and then back to axial, ultimately resulting in the failure of the specimen.