Dam Shoulders Anti-sliding Stability Analysis For Xiluodu Hydropower Station On Jinsha River

DAM SHOULDERS ANTI-SLIDING STABILITY ANALYSIS FORXILUODU HYDROPOWER STATION ON JINSHA RIVERThe planned dam for Xiluodu Hydropower Station on Jinsha River is a hyperboloidal high arch.Anti-sliding stability of dam shoulders is one of the key engineering geological problems.Apparently, it is pre-requisite that their anti-sliding boundary is ascertained in order to analyzeand evaluate their anti-sliding stability.It is thought that the macroscopical boundaries controlling dam shoulders anti-sliding stability are sideslip surfaces, bottom slip surfaces, slope surfaces and pullapart surfaces of arch dam respectively. Of all the boundaries, the slop surfaces and pullapart surfaces are easy to identify. However, considering that there is no obvious steep fault in dam site, it makes sideslip surface boundary and bottom slip surface boundary (especially sideslip surface boundary) implicit and uncertain at some extent, therefore it becomes difficult to ascertain the anti-sliding boundary conditions of the dam shoulders.To find out the engineering properties of the boundary conditions, at first, a large amount of reliable and detailed in-site data are collected from specified field geological investigation. And then a easy-used and multi-functional database manage system is built up to manage and process, these data more efficiently, which lays a solid foundation for systematically ascertaining sideslip surface boundaries.By comparatively analyzing the 258 pieces of intrastratal and interlayer faults collected from field work, 8 pieces of intrastratal and interlayer faults are picked out as the potential bottom slip surfaces according to the criteria of being staggered intensely, large scale and their outcrop status being adverse to anti-sliding stability.With statistical methods, the forming conditions of discontinuities for sideslip surface is studied in detail. H-H algorithm is improved and a new trace length estimation algorithm for discontinuities of sideslip surface (H-H2 algorithm) is presented. Based on above study, a method for selecting trace length of discontinuities for sideslip surface is generalized and applied. By using 2-D network simulation techniques, 3-D network simulation techniques and H-H2 probability model, connectivity rate of discontinuities of sideslip surface and synthetically extracted connectivity rate for suggested shearing strength of sideslip surface are calculated.The specified geological investigation is carried so that bottom slip surface is ascertained. Basedon computer interact techniques and graphics theory, the 3-D geological model is developed. With rigid limit equilibrium vector method, dam shoulders anti-sliding stability analyzing program system is compiled and its reliability is insured by a large amount of comparative calculations. This program system is characterized by convenient interactive data input, visual geometric graph display, stability evaluation under any force, and multi-functional data change interface.And then, by using above program system, the anti-sliding stability of dam shoulders in different modes and different load combination patterns are calculated in respectively, and their stability is evaluated preliminarily. Furthermore, sensitivity analysis Is performed on some very important factors such as c, f. The analysis results indicate that the anti-sliding stability of Xiluodu dam shoulders can meet the need of arch dam design and has good safety repertory.