岩堆边坡稳定性及破坏模式数值分析 Numerical Analysis of Stability and Failure Mechanism of Talus Slopes

岩堆是高山峡谷区较常见的一种地貌类型，公路、铁路、管线等工程穿过岩堆体时，可能成为一种不良地质因素。由于岩堆体物质组成的特殊性，常用的土力学和岩石力学理论方法在解决岩堆边坡稳定性等问题时遇到了一些困难。采用基于离散元法的PFC2D软件，在建模过程中模拟岩堆边坡的“自然”形成过程，研究颗粒表面摩擦系数以及岩石块体对岩堆边坡休止角的影响，以及两种类型岩堆边坡的开挖破坏模式。岩石块体一般可以显著增大岩堆边坡的休止角，但最终休止角的大小有较大的离散性；由岩石块体组成的岩堆边坡的开挖破坏模式更接近于整体式破坏，而均布颗粒的岩堆边坡则为表层的平移破坏。 Talus is a common geomorphologic and geological presence in mountainous areas. In the con-struction of transportation lines and pipelines, talus can develop to a geohazard if they are not appropriately treated. Talus is composed with rock blocks and debris and cannot be treated as common soil or rock mass. The discrete element code PFC2D is used to study the stability of talus slopes. In the model setup, PFC can simulate the “natural” process of the sediment of talus slope. The effects of particle friction coefficient and rock blocks on the rest angle of talus slope, and the failure mechanism of talus slope are considered. It is found that rock blocks will increase the rest angle of talus slope and the failure mode is also different with a uniform-sized slope. Slopes com-posed of rock blocks are prone to an overall failure mechanism while slopes composed by uni-form-sized particles are more like to take a shallow sliding mechanism.