鸡尾山高速远程滑坡运动过程PFC^(3D)模拟

MOVEMENT PROCESS SIMULATION OF HIGH-SPEED LONG-DISTANCE JIWEISHAN LANDSLIDE WITH PFC^(3D)

利用三维颗粒流软件PFC3D,对重庆武隆鸡尾山滑坡进行模拟,研究滑坡体在关键块体失稳后,在重力作用下,沿着滑动面在视倾向滑动力主导下的运动过程。结果显示:(1)对于大型远距离滑坡,在滑坡体运动路径上坡面形态确定的情况下,坡面摩擦因数和滑体强度主要影响堆积颗粒在滑坡堆积区的分布,滑坡发生区域微地形则更多地影响滑坡体所能达到的最大位移;(2)鸡尾山高速远程滑坡的发生过程是分阶段完成的;第一阶段主要是滑源区岩体的破裂化,第二阶段为破裂块体的运动及滑出;(3)通过监测速度、位移等发现滑体外围区域块体速度首先达到最大值,并具备二次加速的特征,综合速度及位移可以认为在滑体中处于上部边缘部分更有可能远距离运动;(4)对于鸡尾山滑坡,当墙面摩擦因数为0.05,黏结强度为中等(250～200 MPa)时,得到的结果与实际情形最为契合。通过模拟发现,PFC3D软件对于此类高速远程滑坡具有较好的适用性,尤其是其三维堆积形态及影响范围的初步确定可以对划定安全避让范围等防灾减灾工作提供有益参考。

The particle flow code in three dimensions（PFC3D） is adopted to simulate the movement process of Jiweishan landslide in Wulong County, Chongqing City. The movement process of landslide mass along the sliding surface is studied under the gravity and apparent sliding force after instability of key blocks. The following conclusions can be drawn. （1） For large long-distance landslides, if the morphology of sliding surface along the landslide movement path is determined, the friction coefficient of sliding surface and strength of sliding mass just significantly affect the distribution of sliding mass in deposited areas; and the micro-topography would have more influences on the maximum displacement of landslide. （2） The whole process of the high-speed long-distance Jiweishan landslide can be divided into two stages. The first stage is mainly the fragmentation of rock masses in source area, and the second stage is the movement and run-out of fragmental blocks. （3） It is found that the velocity of blocks in surrounding regions of sliding mass firstly reaches the maximum according to velocity and displacement monitored in field. The blocks have the characteristics of second acceleration. Combining the velocity and displacement, it is considered that the sliding body at the upper edge of sliding mass is more likely to move for a long distance. （4） For Jiweishan landslide, when the friction coefficient of sliding surface is 0.05 and the bond strength is medium（250 - 200 MPa）, the results obtained by PFC3D are in accord with the actual ones in the maximum degree. For such high-speed long-distance landslides, PFC3D has a good applicability, especially its three-dimensional deposition state and influential extent initially identified could provide useful references for disaster prevention and mitigation works such as determination of safe avoidance range.