The Genetic Mechanism And Stability Study On Hydropower Station Diversion And Power Intake Tilting Body Slope For Ciha Gorge Of The Yellow River

Ciha Gorge hydropower station locates in the Ciha gorge of xinghai county and tongde county Qinghai province junction. It is a comprehensive water conservancy and hydropower project which takes power generation as primary, combines flood-prevention and sand-blocking function. The power station initially works out dam height 250m, installed capacity 1800～2000MW. The abutment slope vertical height difference of Ciha Gorge hydropower station is probable 400m. Under the influence of stream trenching, the whole gorge slope is steep, nature slope general extras 40°,partial regain accesses to 60°. The intake slope mainly locates on top of one-layer structure toppling. The cutting slope vertical height difference is probable 90m. Hence, how to scientifically investigate and analysis the intake slope toppling depth,toppling range and cutting slope stability becomes this stage problem.This paper detailed expose slope engineering geology environmental condition of drawing water intake for the hydropower station in the ciha gorge of the yellow river, analysis and study on forming mechanism and space distributing character of the intake slope tilting body and slope characteristics of rock mass structures and mechanical property, adopt field qualitative analysis and SMR quantitative analysis method to study slope rock mass quality. on that basis, the paper adopt Stereographic projection,Block theory and Limit equilibrium method to analysis Engineering slope block and integral stability . Main research results as follows:(1) The intake slope mainly locate in the sandstone and argillite slate rock of the third rock group and thin—interbedding layer layer circular granular bedding structure of middle Triassic. The structural plane of slope is comparative development, meanwhile party fracture ( weakly structural surface) of the most development general parallel rock tendency and is One-layer bedding fault zone or extrusion-belt. (2) On the theory, the rock toppling deformation is divided into four stages: initial state namely rock formation non-deformation stage; unloading and rebound, steep crack stage; rock bending,tension crack surfaces to expand depth and to lapse slope-back stage and rock because of bending extent too great from root breaking,crushing stage. The intake slope tilting body is mainly cause by slope topography and structural characteristics,steep thin-layered rock,insitu stress direction and rock diversity unloading and rebound.(3) By site to statistic analysis flat hole and drilling hole inclination angle of rock stratum: tilting body on the section spreading, its toppling depth has the consistency with rock strongly weathering zone and strongly unloading zone; on the Characteristics of toppling body plane distribution, number 10 tilting body mainly spreads over some prominent mountain ridge, up-down stream boundary is separately two larger gully, bottom altitude is between 2849m and 2853m, top elevation is next to slope flat roof.(4) From the structural characteristics analysis of intake slope, the structural surface of intake slope is divided intoⅢ,Ⅳ,Ⅴthree stages, meanwhile,Ⅳ,Ⅴinterlayer structural plane being the most development.(5) Adopt the method of field qualitative classification and SMR quantitative classification to classify slope rockmass quality. In the high side slope intake with layered structure, under the influence of rock dumping and deformation,Ⅳ-order rock dominate toppling range of rock.Ⅲ2-order rock is main in the rock around dumping bottom boundary. Because rock inside toppling have generally entried moderately weathered zone,Ⅲ1-order is main.(6) On the base the intake slope growth structural plane statistics, adopting stereographic projections analysis,block theory and limit equilibrium method to analysis and study block stability and integral stability which slope is under various working conditions. Under slope block stability and integral stability with higher stability coefficient, only local block stability coefficient under rainstorm condition or earthquake condition fell below 1.0 to these blocks probable appear instability failure phenomenon; under various working condition, slope whole stability coefficient is behind 1.3, slope whole stability is better.