FORMATION MECHANISM AND DYNAMIC STABILITY OF JINGU HIGH-SPEED AND LONG-RUN-OUT LANDSLIDE
LIU Xiao1，TANG Huiming1，HU Xinli2，WANG Liangqing2，LIAO Shaobo2，ZOU Zongxing2
(1. Three Gorges Research Center for Geo-hazards of Ministry of Education，China University of Geosciences，Wuhan，Hubei 430074，China；2. Faculty of Engineering，China University of Geosciences，Wuhan，Hubei 430074，China)
Abstract：Based on integrating the theories and methods of multi-discipline，the research on formation mechanism and dynamic stability of Jingu landslide，a high-speed and long-run-out landslide induced by Wenchuan earthquake，was conducted. In the aspect of qualitative study of engineering geology，the formation mechanism of Jingu landslide was analyzed after comprehensive investigation involved in topography，lithology，tectonics and earthquake，as well as hydrogeology. As a result，the evolutionary stage of Jingu landslide was divided into two closely-linked phases. First，the upper sliding body was separated and thrown across the river standing at the toe of landslide. Second，the lower part of the slope was developed into a secondary landslide by the scratch from the upper body. On the other aspect of rock and soil mechanics quantitative study，three tasks were performed as follows：(1) Based on the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) dynamic analysis and a multilayer particle swarm optimization technique，a self-made parallel searching program was utilized to locate the non-circular critical slip surfaces of the landslide and its corresponding time-histories of dynamic factor of safety，of which frequency characteristics were revealed by spectrum analysis. (2) Based on the comparative study of two potential failure modes，the cluster #2 of slide surfaces is more possible to dominate the whole failure and trig the secondary landslide of slope?s lower part. (3) By aerodynamics calculation，long-distance throwing of upper sliding body is entirely possible. Comprehensive studies have shown that the quantitative analysis results of rock and soil mechanics are consistent with the engineering geology qualitative analysis results. The four prerequisites of the development of Jingu landslide were summarized as follows：poor mechanical properties，high position of shear crack，open terrain in lowering direction and enough initial velocity.
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2012, Vol. 31 
