颗粒离散单元法地震动力时程计算黏性人工边界及其应用

 采用颗粒离散单元法(PFC)进行地震动力时程计算时，人工截断边界上需设置吸收边界条件，以防止波的反射。鉴于PFC数值计算模型的人工边界上颗粒单元半径大小不一、边界面凸凹不平，在连续介质的黏性吸收边界条件方程基础之上，推导出适用于离散介质的等效方程。在离散介质的等效方程中引入微调系数，建立确定其最优值的方法，以实现对波的最佳吸收。采用合成岩体方法(SRM)建立顺层岩质边坡和逆层岩质边坡结构面网络模型。基于提出的方法，在边坡颗粒流数值模型的人工边界上设置黏性吸收边界，对含有正交次级节理的顺层岩质边坡和逆层岩质边坡的地震破坏过程进行模拟，对其地震破坏机制进行系统分析，相关研究结论对边坡地震破坏机制研究具有重要意义。

Viscous artificial boundary for seismic dynamic time-history analysis with granular discrete element method and its application

In order to avoid the outward waves being reflected back into the simulated domain at the artificial boundaries，the absorbing boundaries must be used in applying the granular discrete element method(PFC). To consider the various radii of particle elements on the artificial boundaries and the irregular boundary surfaces，the equivalent equation applicable for this discrete elements method was obtained based on the continuum viscous boundary condition. The calibration factors were introduced into the equivalent equation and a method to determine their values necessary for the optimum wave absorption was proposed. The joint network models of bedding and reverse bedding rock slopes were established with the synthetic rock mass approach (SRM). The viscous boundary conditions were built on the artificial boundaries in PFC models of rock slope based on the proposed method. At the same time，the seismic failure process of bedding and reverse bedding rock slopes with orthogonal secondary rock joints were simulated and systematic analyses of the seismic failure mechanism were conducted.