Stability Analysis Against Deep Sliding Of The Dam Foundation Of Two Dam Section For Xiangjiaba Hydropower Station

The foundation rock-mass, locating at the overflow dam sections of Xiangjiaba hydropower station, is composed of sandstone, mudrock and coal layers. And its lithology and lithofacies vary widely. There are several faults, weak rock beddings, and large scale fissures with steep angle across the foundation. The rock quality is relatively low due to the influence of tectonic activities and weathering. These aforementioned engineering geological characteristics are disadvantageous to the stability against deep sliding of overflow dam sections. Since bad engineering geological conditions, there are potential dangers to slide in the deep foundation of the overflow 4 dam section (S4#) and the overflow 12 dam section (S12#). Accordingly, it is necessary to study the stability against deep sliding of these two dam sections.Based on the analysis of engineering geology and hydrogeology, the stress and displacement characteristics of the two dam sections in construction period and operation period were studied by means of numerical simulation. Besides, the present study also includes the mode and process of failure, the safety factor, and comprehensive evaluation about deep sliding under the dam foundation. This thesis included four major aspects:(1) Studying on the possible sliding modes of two dam sections according to engineering geological conditions(2) Researching the stress and displacement of the dam and the rock foundation in construction period and operation period(3) Evaluating the stability against deep sliding using the FLAC with strength reduction method, and simulating the failure process to get the failure mechanism and developing track of the interface between the dam and the foundation(4) Calculating the safety of stability against sliding of two dam sections with results of other methods as reference.The results showed that the failure modes of two dam sections are two sliding planes model. And the dam and foundation were safe in the construction period andoperation period. The minimum factors of stability safety against deep sliding were 2.6 and 3.6 in S4# and S12# separately. Integrated analysis showed that there were potential dangers on the safety of two dam sections and some reinforce structure should be applied.