| Xiluodu Hydropower Station is the third power station of cascade development planning on reach from Panzhihua to Yibin, the reach is belong to Jinsha river.There has a sedimentary slope on the platform of left bank deposits from middle Pleistocene, which is composed of ancient landslide,accumulation of ice water,diluvium,collapsing slope. As the project layout needs, some excavations have been implemented to the lower part of the slope which is at the top of diversion intake and spillway intake,so a excavated sedimentary slope is formed which is a width of 530 m, high slope excavation of about more than 90 m .The stable conditions of the slope have a amount of change,because the excavations had been implemented to the slope and the bedrock under the slope.There are the shear slip damage in the surface of the slpoe and the dislocation deformation located in weak levels which is in the inside of the slope.The relation between the slope's stability and the power station'sworking is very close. In this paper, the object of study is the slope of left bank deposits in Xiluodu hydropower station. Obtained that the deformation characteristics of the slope and the supporting effect of the Support Measure, through study of the engineering geological conditions,the deformation monitoring data,the stable computation and numerical simulation of the typical profile.The specific conclusions are as follows:(1) The deposit slope has a complex composing,which is mainly composed by the slope dilurium,the glacier ice deposit,the ancient landslide residue.Ancient slippery belt and Xuanwei group aluminum soil texture sandy slate are exist on the bottom of the deposit slope,which have weak character and have a very important function for the distortion adjustment and the stability of the excavated slope;(2) The deformation of the slope mainly appeared in the times when the support and protections haven't carried on the slope after the slope was excavated partially.The distortion was under the effective control when the supports and protections on surface of slope finished, the distortion becomes slower than before.It is important that the appropriate support should be followed by after the slope was excavated,in order to ensure the stability of the excavted slope.Because it will change the original storage environment that the slope is excavated, thus leading to the deformation of the slope and the adjustment of soil's stress and strain. It can be effective in controlling such an adjustment within a certain scope that is the timely construction of the supporting measures, thus ensuring the stability of the slope.(3) The deformation characteristics of the slope mainly experienced three stages from the point of view of time, which are the distortion development,the distortion to slow down> slow creep. The entire slope has deep dislocation deformation along the weak levels ( ancient slippery belt and Xuanwei group aluminum soil texture sandy slate ). This dislocation deformation can generally be divided into two forms in accordance with it's difference triggering reason, one kind is appear in II, IV area where have big deep dislocation deformation, which is mainly caused by the excavation activities and the stress diversity. the other kind is appear in the rest area where have small deep dislocation deformation, which is the long-standing and produced by own gravity effect.(4) The supports and protections structure can play the very good control action to the slope body's distortion. The supports and protections must be carried on timely, after the slope is excavated. The distortion of the excavated slope is appear becauses supports and protects are not created in time. It has a very major function for control the slope's distortion which is the shallow surface layer's supports. The depth pre-stressed anchor cable can provides the safety margin to the slope. The existing supports and protections measure can satisfy the slope requirements of the stability under the existing condition. |
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