| Stability analysis is an important issue in engineering construction. According tostatistics, landslide and slope disaster are common and vital geological hazards. Theeconomic loss every year caused by landslide is more than20billion RMB in China.Hence in the process of engineering construction, study of slope engineering isextremely important. The dam area of Xulong hydropower station is located insouthwest of China, where has complex geological conditions and high deep slope onthe both side. The study area is located in the important part of the engineering,which plays a key role in the entire project.In this paper, we take the dam abutment slope in Xulong hydropower station as aresearch object. Based on presenting the dam region geo-environmental condition,combining the rock mass structure and physical mechanic characters of dam abutmentslope, investigating the interlayer faults, bedding fault zone, the important fault indifferent scale and level in the open country and indoor analysis, we judge the slopeinstability model. Lastly, by analyzing the field data, this paper study the regionalgeologic background, topography, stratum and lithology, rock mass structure andcharacter of deformation failure of dam abutment rock mass etc, with thestereographic projection method, this paper established a numerical model of slope onthe left abutment of dam. According to the changes of slope stress field anddisplacement field in natural state and seismic state,2D dam abutment slope stabilityin the dam axis is analyzed and evaluated by means of finite element software. Theresults are as follows:(1) According to the adits dada of the left abutment slope, the abutment slopemainly developed three structural planes: a. SSE structural plane of middle and steepinclination. b. NWW structural plane of gentle inclination. c. SSW structural plane ofsteep inclination, which is the same with amphibolite schist foliation. (2) The top of the abutment is steep and below the abutment is slow. The rockability is overall hard, and the trend of large faults and the slope interacts as largeangle, partly small angle. According to overall analysis, we judge that the stability ofXulong hydropower station left dam abutment slope is stable. The deformation formof the abutment is mainly controlled by structural plane of gentle inclination and steepinclination. The failure modes are mainly plane sliding failure and wedge failure.（3）The left dam abutment may constitute some potential sub-stable block. Weuse stereographic projection to analyze the stability of dam abutment slope, determinethe faults, cracks and long-large unloading fracture. According to the deformation anddestruction features and the results of stereographic projection, we find that the rockbody from2270m to2308m altitude is more unstable than that from2170m to2270m.The wedge failure mode is more than plane sliding mode on the left abutment（4）We use Janbu method to calculate the block combination safety coefficient.We consider the natural、 seismic and rainstorm condition. The results indicate thatthe slope is in a steady state except very few block in potential unstable state.（5）By finite element analysis program to simulate the slope of the maximumshear strain, plastic strain, plastic state and displacement. The results show that thelevel of the left bank slope elevation and low elevation at large displacements. Thelower elevation of the left bank slope elevation area unsafe, Plastic zone tendsconnection, Slope mainly along the gently dipping structural surface have a greaterhorizontal displacement, whose stability is respectively low. Therefore, the abovestudies show that, the left abutment slope of Xu Long Hydropower is stable overall. |
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