戒台寺古滑坡体受多期构造运动控制,边坡岩体中裂缝发育,结构破碎,风化卸荷引起局部滑移严重。2005年,对古滑体Ⅰ级和Ⅱ级平台进行了综合治理,但2013年后期,戒台寺大雄宝殿后墙和后花园地面又发育多组裂缝,且在Ⅲ级平台坡脚处发现大量新断口崩塌坡积物,古滑体有复活征兆。为探索戒台寺古滑坡体从二次稳定到开裂破坏的变形机制和破坏特征,文章首先采用杂交有限元-离散元法(FDEM)建立戒台寺古滑坡体数值模型;然后,将模拟计算结果与现场GPS地表位移监测曲线和破坏特征进行对比分析,结果显示FDEM数值模型较好地再现了戒台寺古滑坡体局部开裂、扩展、贯通、脱离、滑移、碰撞和堆积全过程;最后,判断出戒台寺古滑坡体的危险区域,为古滑坡体深部力学监测点设置提供科学依据。
The Jietai Temple ancient landslide body is located in the Ma'an Mountain area in the Mentougou district of Beijing. Slope rock mass fractures and broken structures developed because of the multiple tectonic movements in history and the weathered unloading, causing a severe localized slip. In 2005, comprehensive managements, including retaining anchor, flood control and grouting were performed on the Class-I and Class- I1 platform of the ancient landslide body. However, late in 2013, a multi-component fracture developed on the floor and back wall of the main hall of the temple, as well as in the rear garden, and collapse of the slope sediments appeared in Class-11 platform at the foot of the slope, which could be the resurrection sign of this ancient landslide. To explore the ancient landslide stability and protect the temple from the secondary damage, the mechanisms and failure characteristics of landslide deformation were studied. With the hybrid Finite Element-Discrete Element Method (FDEM) , a numerical model for the ancient temple landslide was set up, and the simulation results with the live GPS monitoring surface displacement curves and the failure characteristics were analyzed. The FDEM numerical model can reproduce the whole process of the ancient landslide partial cracking, expansion, cut-through, separating, slipping (or rolling) , collision and stacking. Finally, according to the results, the danger zone of the temple ancient landslide body was determined, and they provide scientific basis for field slope monitoring points design.