The Research On Diversion Tunnel Landslip Of Yalong River Jinping Hydroelectric Powerstation

There is an extreme large scale landslip on the left bank diversion tunnel during construction at the first class hydroelectric power station of Jinping, which is 120 m in length, 42 m in height, about 50,000 m~3. This paper mainly introduces the landslide processing and mechanism analysis. The key point is to analyze stability of each section of the wall rock of the diversion tunnel, especially the research on high land stress and mass section tunnel construction. The stability of the diversion tunnel excavation is given a non-linear finite element analysis. Moreover, it has stimulated the excavation process and reinforcement measures. The result which is based upon the analysis will provide reference for similar project design. Meanwhile it talks about the choice and decision of dealing methods against landslip and the process of treatment for landslip.The paper is mainly about:1. Analyse the geology condition in the area of the diversion tunnel, and analyse the cause of the landslip considering the aspect of geologic constitution ;2. Analyse the stability of the tunnel in virtue of burying a lot of monitors of deformation and seepage ;3. Analyse the stress and the deformation in the two typical sections of the diversion tunnel in use of non-linear finite element analysis method, suggest the reasonable supporting and reinforcing proposal, and employ the corresponding technology of construction for the landslip treatments. And the result of monitor proves the validity of the reinforcing treatments.The treatment of landslip adopts the I-shaped steel support and carrying arch in concrete and reaches the anticipating result. This proposal breaks through the limits of actual theory of wall rock, tries and proves the stability problem of partial arch; employs grouting and pre-stressing force for the 12 m high wall for deeply reinforcing and achieves the purpose. This treatment of landslip is the most rapid considering its dimensions.After the discussion of experts from every party on processing plan, the fact proves that this proposal of steel bridge frame concrete is easy to pout into practice with highly effective security. The key point in landslip processing is closing mouth and hermetic arch. The treatment of landslip is completed within 6 months in the case of volume more than 50,000 m3, and the target of diversion during water passing through is accomplished on time, which provides reference for landslip processing and requires prevention against landslip. It provides precious practice information for supporting theory research of tunnel landslip treatment.