Research On Stabilityand Anchorage Design Of Slope On The Right Abutment Platform Of Yagen â…¡Hydropower Of Yalong River

The Yagen Ⅱ hydropower is the third planning cascade hydropower in theYalong River. The planning gravity dam is130m height, the maximum excavationheight on the right abutment and the cable machine platform is about210m while themaximum excavation depth of which is about100m. The slope breaks, the cracksdevelop, and the geological conditions is complex. More over, a set of structuralsurface along the slope of which the dip angle is small develops on the right abutmentand the cable machine platform slope. The angle of intersection with the river is small,and presents mostly in form of small faults and densely fractured zones. Beingcontrolled by the gently inclined surface structure, there are strong slope deformation,relaxation superficial crack rock and a great security risk after the excavation, whichbrought great construction potential threat. Therefore, the stability research and theappropriate support measures on this slope has important practical significance.This article is based on the investigation of the geological and engineeringgeological characteristics of environmental conditions of the slope, and has done adeep research on the structure and deformation and fracture characteristics of the rockmass and the deformation and failure mode of the slope is determined. On this basis,the conceptual model of the slope deformation and failure mechanism is established,the qualitative and quantitative evaluation of the slope is made by means of geologicalanalysis and limit equilibrium method, and then the comprehensive judgment on theslope stability is made by means of the numerical calculation of the slope stress andstrain state before and after the excavation, which achieved the following conclusions:(1)The bedrock of this slope is the early Yanshanian biotite, with thedevelopment of NW to slope gently dipping structural surface features, fh01, fh02,fh03internal development of slope, fh04, fh05, fh06grew up in low angle faultcontrol effect on slope stability. In addition to the development of NE and NWW-EW to steep steep two sets of steep dip structural plane. Controlled by the rock massstructure, rock slope is along the low angle fault creep cracking deformation, themaximum amount of slip deformation can reach more than5m (PD53adit f5303).Rock weathering and unloading of strong, strong unloading level depth of up to108m,and weak unloading the maximum depth of up to153m.(2) The Slope is controlled by The NW low angle structure face, its deformationfailure mode failure slip crack. Among them, fh02, fh03, fh04, fh05, fh06and a seriesof slope gently inclined fault properties, low mechanical strength, potential adverse tothe slope of small faults as the bottom sliding surface, using NNE or NWW to thesteep fault as the trailing edge surface, Henghe to the steep growth faults constituteside to the cut surface.(3)The Results of stability evaluation: the stability evaluation of dam abutmentstability is controlled by fh01+f53, fh02+f53, fh03+f53, fh04+f53, fh05+f53block.Natural conditions fh03+f53, fh04+f53, fh04+f555stability coefficient is between0.865-0.901, the slope is not steady state. Local fh03+f53, fh04+f53combinationblock stability coefficient is lowest, ranging from0.865to0.889. Fh01+f53, fh02+f53,fh05+f53combination of block stability coefficient is between0.954-1.033, the slopeis in limit equilibrium state. The rainstorm and earthquake working condition,fh01+f53, fh02+f53, fh03+f53, fh04+f53, fh05+f53combination block stabilitycoefficient is less than0.95, the slope is not steady state.（4）According to the results of stability evaluation, different parts of the damabutment and the corresponding supporting measures. Strengthening design of slopeshall be in accordance with the cautious excavation, reduce blasting, subregionprinciple level support, the overall stability of the engineering slope control as theprimary problem of slope design of supporting measures, stability control, from theglobal and local sequence. The stability of right abutment slope under the control oftypical low angle structure face slope structure control, this paper adopts the concreteshear hole replacement structure surface soft material, increase the mechanicalproperties of the low angle faults with prestressed anchor cable; and two supportingmeasures combined with the reinforcement method to control the overall stability ofthe slope on the slope; superficial rock mass and random unstable blocks using netguniting and full-length bonded anchor supporting, the relatively large size of thepotential unstable block body by prestressed anchor cable supporting.（5）The results of Midas numerical calculation shows that, after excavation, the stress adjustment and the stress concentration phenomenon and the toe of slopesurface near the trailing edge, slow obliquity faults appear larger tension stress area.With fh01, fh02, fh03fault, fh04, fh05, fh06cut open, along the low angle faults oflarge horizontal displacement of excavation, to the end, the maximum displacement ofslope up to56mm; vertical displacement of slope is mainly vertical unloadingrebound. The numerical simulation results, after the excavation of low angle structureface the upper rock mass deformation of free surface are shown to slip, the shearstrain region mainly along the low angle fault development, value is0.018~0.035,shows that the slope instability mainly along the low angle fault. After theimplementation of reinforcement measures, fh01, fh02, fh03, fh04, fh05, fh06, slowmaximum principal angle fault near the stress and the maximum displacementdecreased significantly, the slope surface stress in supporting and again becomesmooth and continuous, at the same time, hole arrangement of shear concrete shearstress increment break through concentrated area the.