Study On Slope Stability Based On Water-Rock Cycling Weakening Characteristics Of Rock Mass Structural Plane

Lianghekou Hydropower station is a control hydropower project in the cascade development of the middle and lower reaches of the Yalong River in China.In the reservoir area,the rock mass in the reservoir area is subjected to the periodic water-air drying with the periodic water-drainage process,which leads to the attenuation and weakening of the physical and mechanical indexes of the rock mass under the action of water-rock circulation,which will further affect the slope stability of the reservoir area.Taking Liang He Kou hydropower station reservoir area,ancient bridge engineering and rock mass slope as the research object,by weakening rock water cycle test,studies the reservoir rock physical and mechanical parameters and the structural plane of rock water cycle weakening laws,further analysis of rock mass and its structure surface water rock under the action of cyclic degradation los ancient bridge engineering change rule of the slope stability.The main results obtained through the research are as follows:（1）Through the uniaxial compressive strength test and shear strength test of rock mass in the test area,the basic physical and mechanical properties of rock mass in the test area are mastered.（2）Through rock water cycle experiment design,the rocks in the studied area,26 times rock water cycle experiment results show that with the increase of cycling times,uniaxial compressive strength of rock specimen,physical and mechanical parameters such as elastic modulus,and structure the interview sample shear strength of the physical and mechanical parameters,such as increased with the increase of cycling times all have different degrees of weakening,the attenuation rate by fast slow down.（3）Through the similar material design of artificial rock mass,the interview sample of artificial structure containing Barton standard roughness coefficient curve was made in the room.Through 26 water-rock cycling tests on four samples with different initial morphology（No.4,No.6,No.8,No.10）,the quantitative indexes of structural plane morphology,such as derivative root mean square Z₂ value and roughness coefficient JRC value,were dynamically tracked after each cycle.The test results showed that:The corresponding JRC and Z₂ values in No.4,No.6,No.8 and No.10 decrease with the increase of the number of water-rock cycles.Based on the regression analysis,the correlation between the mechanical parameters and the morphological parameters of the structural plane and the number of cycles was established.Based on the Barton model,the prediction model of shear strength of the structural plane considering the cyclic weakening of water and rock was established,and the prediction results were in good agreement with the experimental results.（4）The stability of slope after different water-rock cycles under different working conditions is simulated numerically by discrete element.The simulation results show that:In both natural and excavation conditions,the deformation of the slope increases with the increase of the number of water-rock cycles,and the stress concentration near the abutment becomes more prominent with the increase of the number of water-rock cycles.After 26 water-rock cycles,the slope is still in a stable state as a whole.