| The toppling deformation in front of the dam of gushui hydropower station is a typical anti-dip rock high slope.In the long-term evolution of geological history,the slope has a strong toppling deformation phenomenon.Although the slope has a large degree of toppling deformation and a wide range,the toppling deformation in front of the dam can maintain its own stability in the natural state without human disturbance.However,the reservoir area after the construction of hydropower station inevitably needs water storage,and the stability of the toppling slope after water storage is particularly important for the operation of the hydropower station and the safety of the downstream people.And the research on reservoir response of toppling deformation slope is relatively scarce.In view of this,taking the toppling deformation in front of the dam of gushui hydropower station as the research object,based on previous data collection and on-site geological survey,the indoor physical test method was used to study the water storage response of the anti-dip layered rock slope,and UDEC software was used to numerically calculate the deformation and failure characteristics of the toppling deformation body in front of the dam under water storage,then according to the results of experiment and numerical analysis,the corresponding reinforcement plan is designed,and the Supporting effect is verified.It has greater theoretical significance and engineering value,the main research results obtained are as follows(1)Through the systematic catalogue and analysis of the adit(PD15,PD17)with exploration conditions on the toppling deformation body in front of the dam,from the slope surface to the inside of the slope body,it is concluded that the development types of it are toppling overburden,toppling creep,toppling bend,toppling break,respectively.With reference to the research experience and results of toppling deformation bodies of other large hydropower stations on the upper reaches of the Lancang River,according to the strata dip Angle,the maximum tension in the layer,other relevant indicators,the intensity of the rock mass toppling deformation is divided into: "extreme strong toppling area A","strong toppling area B(upper section B1,lower section B2)" and "weak toppling area C" and "original area D"(2)Taking the toppling deformation in front of the dam of gushui hydropower station as the geological prototype,the model of the slope is established.The size and parameters of the model is determined according to the similarity principle,and the slope is built with prefabricated rock blocks and cracks according to the design diagram.The water storage simulation test was completed with suction pump.Results show: under the water storage,the deformation of the anti-dip layered rock slope is from bottom to top,from low elevation to high elevation,but it is not a single failure mode,The main deformation of slope foot is break,the main deformation of middle and lower part of the slope is bend-slide,the main deformation of middle part of the slope is rrittle fracture,the main deformation of the back of slope is settlement deformation.The deformation and failure of the anti-dip layered rock slope under water storage is obviously staged and segmented.It can be roughly divided into the following two stages: Long-term creep failure of slope foot and short-term collapse failure of slope surface(progressive collapse of middle and lower rock mass and short-term collapse failure of middle slope surface rock mass).(3)Based on the geological prototype of the toppling deformation body in front of the dam,The UDEC software was used to study the characteristics of response under water storage.The results show: the deformation and failure process of the toppling deformation body in front of the dam under water storage can be divided into three stages:(1)Sliding of slope foot causes destruction of slope;(2)Hierarchical sliding of middle and lower part of slope;(3)Rock mass toppling,rotation and collapse stage in the middle of the slope.Its deformation and failure mode is " Tension failure in the upper part and shear failure in the lower part ".(4)In the effect of water storage on the toppling slope,the degree of deformation and damage caused by dynamic water pressure is stronger than that caused by static water pressure.In the process of water storage,the stability of the toppling deformation slope will be slightly improved in the early stage of water storage,at this time,the slope is dominated by compaction deformation.(5)According to the deformation and failure characteristics of the slope obtained from the physical test and numerical test,according to two reinforcement methods,suppressing slope foot by accumulation of rock mass and the anchorage of the frame anchor cable,three reinforcement schemes were designed,and the reinforcement effect was calculated and analyzed by UDEC software.It can be concluded that after scheme 1(suppressing slope foot below 2250 m elevation)and scheme 2(suppressing slope foot + arrangement of prestressed anchor cable at elevation 2250 m ? 2310m),the shallow surface rock mass in the middle and lower part of the slope will still produce a certain degree of deformation after reinforcement,none of the effects can meet the safety requirements;scheme 3(suppressing slope foot + arrangement of prestressed anchor cable at elevation 2250 m ? 2310m),after the reinforcement,the deformation of shallow surface rock mass is effectively suppressed,the effect meets the safety requirements.The results show: that the reinforcement measures under the water storage condition of the toppling deformation body in front of the dam should focus on the inhibition of the slope foot slip and the shear slip-collapse failure of the shallow surface rock mass below the water level line.suppressing slope foot and anchoring in the middle rock mass can effectively prevent the deformation and development of the deformation body and en sure the stability of the slope during and after water storage. |
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