Research On Stability Of Slope On The Water Inlet Of Yagen Ⅱ Hydropower Of Yalong River

Slope stability is one of the major water conservancy and hydropower projectconstruction engineering geological problems, stability studies of slope carried outsmoothly with the project after the completion of full effect, has a crucial significancefor the construction land. In this paper, combined with problem of Research onStability of Slope on the Water Inlet of Yagen Ⅱ Hydropower of Yalong River, in alarge number of field geological survey, analysis of the structure of the slope of rock,weathered rock on the slope of unloading zones and rock quality classification studied,combined with the slope deformation and failure phenomena occur, the establishmentof appropriate slope deformation and failure modes. Limit equilibrium method and theuse of numerical simulation of slope excavation of stress and displacementcharacteristics were analyzed to evaluate the stability of the system engineering slope,obtain the following main understanding.(1).Slope rock lithology Yanshan early biotite monzonitic granite, mainlydeveloped three sets of steep slope inclination structural plane with a group of slowstructural surface inclination. Three groups of structural surface with steep dipstowards large angle to the slope, and slow structural surface inclination to tend to theslope of the output. Rock structure controlled by the natural slope of the overalldeformation is weak, better overall stability, deformation mainly for partial unloadingHera fission-shaped structure along the side of steep dip, by the slow steep dip angleof the structure and surface structure face a combination of fall style collapse, as wellas the upstream side of the plate cracking dumping of rock slope deformation.(2). According Unloading Characteristic rock weathering and structuralcharacteristics of rock combined with CSMR method RMR slope rock mass to bedivided, drawn mainly Class II slope rock mass, accounting for50%of the total rockslope, mainly in the non-weathered rock with no unloading in vivo; class III rockslope of the total accounted for30%of the rock mass, mainly under weak weatheredrock; IV-class rock12.8%of the total rock slope, mainly for unloading the weakweaker degree charge weathered rock; V-class rock slope accounted for6.6%of thetotal mass, mainly strong unloading rock mass.(3)Slope excavation works at the level of depth between62~85m, at2640melevation slope ratio is less than1:0.3,2640m elevation slope ratio of1:0.5. Massiveinstability does not exist after the block slope excavation, but the slope face random block cave by the combination produces crack-prone slip wedge block, the upstreamside of the partial plate crack-like rock slope prone to toppling deformation, theopening part of the distribution of a large number of engineering slope grade V rock iseasy to produce small-scale slumping destruction.(4)According to the analysis result of slope excavation stress and displacement withnumerical simulation approaches, during the excavation process, the maximum stressin the slope concentrates in the toe of the slope, and the overall changes are small. Theminimum principal stress occurs in positive value at the top of the excavation slope,meaning that there is pulling stress. It can be seen from the displacement vector graphthat there is displacement towards the free date on the top of the excavation slope,which proves the deformation characteristics of V-grade rock mass on the slope top.On the upright slope top formed by the third excavation, there is displacementtowards the outer side of the slope, and meanwhile, the displacement of the exposedrock mass in F15fault increases, suggesting that the rock mass at the intersection ofF15fault and slope may be unstable easily after the excavation, and the upright sloptop formed during the excavation may be unstable easily. It can be learnt from thedisplacement deformation analysis before and after the excavation with the UDFCnumerical simulation software that there is no great displacement in the cracking rockmass on the slope top after excavation and it is in stable state. The displacement of therock mass between the F29and F28faults is the greatest, with the displacementtowards the free face, and the displacement decreases gradually as it goes deeper, tillthe F25fault, there is no displacement towards the free face, suggesting that thecracking rock mass does not lose stability immediately after the excavation. But if nomeasures are taken for the rock mass and it is left exposed on the slope for a long term,it may not be stable in earthquakes.(5)For the exposed parts in the high dip angle of slope, it shall be supported byanchor cable; for the random block of the slope, it can be supported by anchor bolts;for the V-grade rock mass of the opening of slope, it shall be supported by shotcreteand rock bolt; and for the cracking rock mass on the upstream slope, it shall besupported by anchor cable.