The Stability Analysis Of Soft Surrounding Rocks Of Big-span Diversion Tunnel And The Research On The Support Measure In Goupitan Hydroelectric Station

In this paper, based on Goupitan hydroelectric station, soft surrounding rocks of big-span diversion tunnel is taken as the research object and engineering geology problems of the stability of soft surrounding rocks are analyzed .based on this analysis, the finite element numerical analysis is done on the case of V classes soft surrounding rocks of big-span diversion tunnel in left bank and the research on the support measure is done:Utilizing the former perambulation, this paper does the engineering geology research on the soft surrounding rocks and classifies surrounding rocks of diversion tunnel and estimate the stability.Aiming at stability of the soft rocks surrounding diversion tunnel during excavating. On the case of V classes soft rocks surrounding diversion tunnel in the left bank, this paper selects the typical geological section and establishes the simplified model geologically, and does the finite element numerical analogy on the choosing tunnel layout and construction excavation and support measure adopting the two dimensional elastoplastic mohr-clulomb model. In addition, this paper researches the excavating course and the stress state and deformation degree of the surrounding rocks and distribution of plastic zone. Referring the related failure criterion, this paper puts forward the related evaluation criterion of the surrounding rocks and estimates the stability of the surrounding rocks and discusses the effect of earlier support measure and amends properly the support measure according to different surrounding rock classed. At last, the final support measures ofdifferent surrounding rock classes of the soft rock tunnel are enacted.This paper does the endogenic force analysis on the repeated linings that adopted by the rock sections under the condition of earlier support measure of the soft surrounding rocks.