纵横波时差耦合作用的斜坡崩滑效应离散元分析——以北川唐家山滑坡为例

 运用离散元数值模拟技术，对北川唐家山斜坡体在具地域性和空间非均质性的地震纵横波时差耦合作用(同时考虑水平和竖向地震力作用)下产生崩滑破坏的动力全过程进行研究，确定该斜坡体在强震动力作用下产生崩滑破坏的形成机制及主控因素。研究表明：(1) 该斜坡体的初期崩滑破坏是受到地震纵波产生的水平与竖向拉裂耦合作用所致，并以竖向拉裂作用占优，而后期的抛射及运动过程则是受到地震纵横波的耦合作用所致；(2) 地震纵波产生的水平与竖向拉裂耦合作用是触发斜坡体产生初期崩滑破坏的主控因素，而斜坡所处地形(如高程差、沟谷延伸方向)则是促使破坏后的斜坡体形成后续碰撞解体及碎屑流等运动过程的控制诱发因素；(3) 该斜坡体动力响应特征值的放大效应表明，其放大系数值从大到小依次是：竖向加速度＞水平加速度＞竖向速度＞水平速度，该结果与斜坡体发生先期崩滑破坏的形成机制及主控因素相符合，即地震纵波产生的竖向加速度起到了优势破坏作用。以上结论对研究动力耦合条件下的斜坡崩滑效应具有较高的理论和现实价值。

DISCRETE ELEMENT ANALYSIS OF COLLAPSING AND SLIDING RESPONSE OF SLOPE TRIGGERED BY TIME DIFFERENCE COUPLING EFFECTS OF P AND S SEISMIC WAVES--TAKING TANGJIASHAN LANDSLIDE IN BEICHUAN COUNTY FOR EXAMPLE

Collapsing and sliding responses of Tangjiashan landslide near Beichuan county and its running out process triggered by time difference coupling effects(considering horizontal and vertical seismic force effects all together),the regionality and spatial heterogeneity of P and S seismic waves generating horizontal and vertical seismic loads are elaborated;and formation mechanism and key controlling factors of collapsing and sliding of the slope are confirmed by applying DEM numerical simulation. The result shows that initial collapsing and sliding of the slope are triggered by combined action of horizontal and vertical tension caused by P seismic wave,and the vertical tension plays a superiority role. Ejecting and flowing of the broken slope mass are triggered by combined action of P and S seismic waves. Secondly,combined action between horizontal and vertical tension of P wave is the key controlling factor inducing the slope collapsing and sliding. At the same time,slope topography is the key controlling factor leading to collision and debris flow of the slope mass fractured in latter process. Finally,amplification effect of parameters in slope dynamic response shows that the amplification coefficient of vertical acceleration is larger than that of horizontal acceleration,and the vertical velocity and horizontal velocity decreasing one by one,and this trend is consistent with key controlling factor inducing slope fracturing,i.e. vertical seismic loads playing a superiority role. It is of great theoretical and practical value for studying collapsing and sliding of slopes triggered by seismic loads.