| STUDY ON THE STABILITYOF SPANDREL GROOVE HIGH SLOPE OF XILUODUHYDROELECTRIC POWER STATIONABSTRACTThe features of formation and evolution of rock mass in the dam areas of Xiluodu Hydroelectric power station are discussed, and the engineering geological conditions of rock mass of spandrel groove high slope are carefully studied. The rock mass quality classification of high slope is explored by the modified CSMR and the fuzzy evaluation method , the result of which is combined with the macroscopic stability of the high slope. On the basis of these, the methods of geological diagnosis and the FEM analysis are applied to analyze and compute the overall stability of the high slope. The block theory is used to evaluate the local stability of the high slope. At last, the optimizing design slope ratio of spandrel groove high slope is determined by the geological diagnosis, engineering analogy and the result of FEM analysis. The main achievements are obtained as follows in the paper:(1)The rock mass quality of spandrel groove high slope is fair. The natural slope and manmade slope of spandrel groove is stable as a whole.(2)The local unstable block of the spandrel groove high slope is a few. There are about 11 unstable blocks in natural state, whose scale is small, influenced depth is limited and dissected boundaries are undeveloped. The reinforced measures should be adopted in the unstable blocks and the interlayer disturbed density belts.(3)After the high slope is excavated, the rebounding displacement of rock mass is 22Ocm,and the depth of relaxation is 2-30m.(4)The optimizing design ratio of spandrel groove high slope is recommended as 1:0.25 in the fresh rock mass or weakly weathered rock mass(lower band), 1:0.35-1:0.50 in the weakly weathered rock mass (upper band), and 1:1.25 in the overburden. Meanwhile,3m berm in width is located in the excavated slope per 50m height in the fresh or weakly weathered rock mass(lower band),per 30m height in the weakly weathered rock mass(upper band).
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