Study On The Stability Of The Water Inlet Slope Of Baihetan Hydroelectric Power Station

Baihetan hydroelectric station ,magnitude of the project whose installed capacity of station is 14000MW, is the double-curvature arch dam and it is one of the cascade leading station on Jinsha river. The water inlet is one of the important hydro-projects of the hydroelectric power station.The slope stability condition is very important for the safty of the following excavation and reservoir filling.The paper mainly study following this order:study the engineering geology prototype, analyzing the genesis mechanism, analyzing and calculating the stability, evaluating the the engineering geology condition. Based on ways that literature review and verifying the transformation feature of the rock structure and eigenetic,carry on an investigation into the engineering geology condition, characteristic of the rock structure,rock mass quality and deformation mode of the slope of the water inlet slope. Moreover, it was investigated into the slope partial and holistic stability condition,then, arrives at such conclusion below:(1) Project area is located at the western margin of the Yangtze plate, Sichuan-Yunnan block east,Longmen Shan-Red River Arc nappe southeast ; located East Wing at the Joint Township anticline, syncline Mountain West Wing span , belong to monoclinic structure of the tendency of the South East . In lithology, the terrance is mainly made of lower Permian Mt. Emei basaltstratum. The stratum is gently inclined slope, has not seen the regional fault.Themain reasons for the slope stability are that the level the decantation angle structure moving out of place belt and the steep dipping angle structure crevasse;(2) The rock structure of the water inlet slope on the right bank is relatively poor. Particularly,the slope of the superficial department is unloading,overall catal-astic texture ,local mosaic structure.The rock structure change and distribution of development appeared to have a certain law with the unloading, height, lithologychanges.(3) According to the engineering geology condition, the rock mass graded of the water inlet slope is adopted the method of qualitative judgement and CSMR method, and get such a conclusion that the structural integrity of rock slope is well, mainly forâ…¢1,â…¢2-graded rock mass, account for 70%,most lie inside theweakly weathering rock and a little fresh rock.On the influence of special discontinuity,relaxation takes place and the rock mass quality dips.(4) It depended upon analyzing the engineering geological, limiting equilibrium mathematical method, FLAC^3D numerical simulation to carry on the stability estimation of the water inlet natural slope on the right bank.It is considered that there are no mass soft discontinuity gently out slope. Relaxation loose of the partial slope rock shallow maybe happen by the transformation of eigenetic. The mainly distortion-destruction model:unloading and rippingdeformation, block failure, SSI collapse and fall-block in partial unloading loose rock.(5) Based on the analogy of the excavating slope ratio and deformation of the post-operation situation,it is suggestted that the excavating slope ratio of the water inlet on the right bank is designed: 735⁷75m vertical slope,775⁸43m theexcavating slope ratio: 1:0.25,843⁹15m the excavating slope ratio: 1:0.3,915m the excavating slope ratio: 1:0.4; the excavating slope ratio of the covering layer: 1:1.25, according to relevant specifications published and literature review. A service road of 3m wide have to be fixed every 40m. if rock slope.(6) On the basis of designing the excavation slope ratio, evaluation the stability of right bank of the inlet side of water,using limit equilibrium and numerical simulation FLAC^3D, the results show that , with the excavation carried out, c5 level fault zone exposed surface, the stress generated on the dislocation belt plate of the slope rock , and produce lateral unloading rebound on excavation face, unloading deformation produced on tunnel portal slope,downstream side of the hole side of the slope generate small-scale shear displacement to Dazhaigou overhead direction, bottom inlet Vertical unloading produced rebound ,and it is very possible bulging uplift occurred.(7) Left bank of the inlet side of water is accumulation slope, on the basis of analysis the structure of matter and base cover interface, evaluation the stability of left bank of the inlet side of water,using limit equilibrium, the results show that , natural slope in steady state in the case of natural and heavy rain conditions,slpe will in critical steady state after excavation.(8) On the basis of the failure mode and stable state of the slope, give proposals about slope protection and treatment measures.