关键词: IBEM-DEM耦合方法, 近断层地震动, 边坡, 动力响应分析

Abstract: We develop a time-domain analysis framework that couples the indirect boundary element method (IBEM) with the discrete element method (DEM) to investigate the dynamic response patterns and failure mechanisms of rock slopes subjected to near-fault ground motions. This framework enables a nonlinear dynamic simulation approach for near-fault slope systems, capturing the discontinuous deformation characteristics of rock and soil masses. Firstly, we construct a high-precision numerical model of the kilometer-scale, semi-infinite near-fault seismic wavefield using IBEM. Subsequently, based on Green’s function theory and the IBEM solution of the wavefield, we derive an explicit formulation of the equivalent seismic loads on the boundaries of the DEM computational domain. This enables cross-scale energy transfer within the IBEM-DEM coupled system. Finally, the DEM resolves the nonlinear dynamic response of meter-scale rock slopes, yielding a multi-scale nonlinear seismic simulation framework that spans from kilometer-scale faults to meter-scale slopes. Numerical simulations combined with dynamic monitoring results demonstrate that the IBEM-DEM coupling algorithm can accurately capture the dispersion characteristics and energy attenuation patterns of near-field seismic wave propagation. Under near-fault seismic loading, progressive shear failure first occurs within weak interlayers, leading to strength degradation, the formation of through-going rupture surfaces, and subsequent accelerated instability of the sliding mass along the shear plane. This process induces significant displacement and velocity responses, ultimately forming a typical debris accumulation at the slope toe. The surface velocity of the sliding mass is markedly greater than that at the base, with the mean surface velocity reaching 3.6 times that of the base, and peak X- and Z-direction velocity components of 4.98 m/s and 5.92 m/s, respectively, exhibiting a pronounced surface-acceleration effect. The monitoring points of the sliding mass exhibit maximum displacements of up to 41 m in the X-direction and 35 m in the Z-direction from the initial slope surface to the final accumulation position, with the displacement-time history showing a distinct step-like growth pattern, indicative of abrupt sliding behavior during the alternating transformation of kinetic and potential energy. The IBEM-DEM coupled method developed in this study reconstructs the full evolutionary sequence from rock mass rupture to landslide formation, providing an innovative analytical framework for the dynamic failure analysis of landslides induced by near-fault ground motions, as well as theoretical and technical support for identifying landslide mechanisms and mitigating seismic hazards in complex geological settings.

Key words: IBEM-DEM coupling method, near-fault ground motion, slope, dynamic response analysis