Study On The Stability And Prevention Of The High-steep Outwash Accumulation Bank Slope

With the gradual implementation of the strategy on Western development, there isa boom on the development of the western region. Meanwhile, the western region ofChina is a region with many rivers. Such specific topography and geomorphologyconditions and geological environmental conditions give a space to store pretty richwaters, however, they restrict the basic constructions such as the building of freewaysin this region. As a result, it incurs large numbers of engineering geological problemsupon reservoir slope when building roads in these mountain areas. The study area islocated at the tectonic zone in eastern Sichuan and Yunnan provinces, where thetopography landforms and geological structures are so complex, and a number ofregional faults are distributed,and where the ice-water accumulation body is one of thegeomorphological types which usually appeares in these regions. In this paper, bytaking high-steep reservoir slope of ice-water accumulation body in filter high speedK92+332~765as the research object, and the main research methods of which is usingthe overall thinking and analysis methods of the engineering geological analysisprinciple and combines with the specific engineering geological background of thereservoir slope, and by the laboratory test and in-situ test researching thecharacteristics of outwash accumulation, such as sedimentary characteristics, innerstructural features, strength characteristics and deformation properties and so on.Therefore, strength characteristics and deformation properties of ice-wateraccumulation body and other related engineering characteristics should be wellmastered. Above the basis of these studies, by takeing the future research about thestructural features of ice-water accumulation body, the contact relationship betweenrock and soil body, the deformation properties and failure mechanism, finally, thestability of the high-steep reservoir slope of the ice-water accumulation body could beanalysed and evaluated according to the different working conditions in the research area, which is relied on the qualitative and quantitative analysis methods such as limitequilibrium theory and2d or3d numerical value calculation. And then, the research forprevention measures of the reservoir slpoe could be put forward to, which is dependedon the above analysis and research results. The main research contents and results ofthis paper could be shown as follows:(1) The ice-water accumulation body in the study area is mainly distributed in theridge parts of790~1300m in altitude, of which the front width is about400m and thelargest depth is more than100m, and the lowest depth is only several meters,where thefront of the slope is so steep. The main components of the sample is about coarseparticle crushed-rock, among which the relationships are primarily calcium or muddycementation that make middle dense-compact structure and occlusion or chimericappearance, and the gradation of which is so poor. The structural characteristicshaving been described in previous paper makes the ice-water accumulation body havehigher physical and mechanical parameters and better strength characteristics.(2) According to the prophase exploration materials and the detailed field survey,the main composition materials of the the bank slope could be obtained, the result ofwhich is that the accumulation body of the bank slope is main consisted of the slightlydensity rubble soil in the superficial zone and ice-water accumulation body which iscomposed by middle dense crushed-rock clip soiland compact crushed-rock.Meanwhile, the contact characteristics among the rock and soil masses of the bankslpoe present very complex contact relationship.(3) According to the disclosed deformation damage phenomenas andcharacteristics on the reservoir slope, the main modes of deformation failuremechanism could be summarized as4modes, which are creepage sliding-tension type,erosion-denudation type,dredging and erosion-sliding-tension crack and dredging typeand erosion-tension crack-slumping type.(4) Based on the above-mentioned findings, the qualitative and quantitativeanalysis methods such as limit equilibrium theory and2d or3d numerical valuecalculation are used for the analysis and evaluation of the high-steep reservoir slope ofice-water accumulation body’s stability and deformation. The reservoir slope hasspecific characteristics that it is influenced by building dikes, excavation, drivingdynamic loads and reservoir storage. After division mileage section research analysis,the research result shows that in the earthquake condition the stability safety reserve ofthe section K92+332~765in the whole study reservoir slope is relatively low, andwhich may be easy instability and collapse,and in the other conditions including natural, driving loads, storm only the reservoir slope’s stability and deformation of thesection K92+400~K92+510can’t accord with the relevant safety standardsrequirements, so which needs to take special measures to prevent ang control the slopebetter.(5) On the basis of relatively clear understanding and detailed being grasped ofengineering properties of ice-water accumulation body, structure characteristics ofreservoir slope, models of deformation failure mechanism, and the slope stability, thecorresponding prevention measures can be taken into for reservoir slope with the lowerstability safety reserve. This paper mainly aims at the study on the model of dredgingand erosion and collapsing which is common in study area, and then puts forward to theprevention measures. Taking the high-steep reservoir slope of ice-water accumulationbody in section K92+400~K92+510for example, the analysis results of the preventionmeasures in the optimized scheme which is used of pre-stressed anchor sheet-pile wallsshows that the result of the scheme is able to obtain better control effect.