The Forced Mechanism Of Embedded Section Of Bedding Rock Slope Supported By Anti-slide Pile And The Study Of Horizontal Resistance Coefficient Of Rock Mass

Bedding rock slope is common in the engineering construction of mountainous cit-ies.In many supporting structures,anti-slide pile has been widely used in the treatment of bedding rock slope because of its good bearing capacity and flexible pile position ar-rangement.In the mountain city of Chongqing,due to the need of slope buildings built close to the mountain,we often encounter the secondary excavation under the slope sup-ported by anti-slide piles in the upper stage,resulting in the formation of bedding rock slope free surface in the rock mass in the embedded section in front of the pile.In this case,it is very important to reveal the force transmission mechanism of the embedded section of the anti-slide pile and determine the K value of the horizontal resistance coef-ficient of the rock mass.Therefore,it is necessary to study the force of rock mass and the value of horizontal resistance coefficient of rock mass in front of pile supporting bedding rock slope by anti-slide pile.Combined with the engineering example of environmental bedding rock slope treat-ment of a space solar power station in Chongqing,aiming at the situation that bedding rock slope is formed after secondary excavation of the embedded rock mass in front of the anti-slide pile,the force characteristics of the embedded rock mass of the anti-slide pile are analyzed,and the value of horizontal resistance coefficient K of embedded rock mass is studied.The main research contents and achievements of this paper are as follows:（1）By analyzing the failure mode of bedding rock slope in the embedded section in front of pile,the force mechanism of rock mass in the embedded section of bedding rock slope supported by anti-slide pile is studied.Based on the elastic foundation beam method,according to the relationship between shear and displacement of the embedded point,and using the principle of back analysis,the calculation formula of K value of rock mass in the embedded section in front of pile is put forward.（2）According to engineering examples and based on the similarity principle,We have carried out the single pile horizontal static load test of indoor anti-slide pile supporting bedding rock slope.The failure mode of the rock mass in the embedded section in front of the pile is revealed,and the horizontal thrust and horizontal displacement at the top of the embedded section of the anti slide pile,the strain of the pile body and the change of the earth pressure on the side of the pile are tested.Combined with the calculation formula of K value of rock mass in front of pile,the influence of the change of structural plane dip-angel of rock mass in front of pile on the mechanical characteristics and horizontal resistance coefficient of rock mass in front of sliding pile are studied.（3）Using FLAC^3D finite difference software,a three-dimensional numerical analysis model of bedding rock slope supported by anti-slide pile is established.The dip-angle of structural plane is taken as the influencing factor to analyze and the model test results are verified.The effects of the changes of slope angleα,cohesion of structural plane c,internal friction angle of structural planeφ,slope distance b and rock thickness h in front of the pile on the internal force of the sliding pile and the K value of the rock mass in the embedded section in front of the pile are simulated and analyzed.The results show that:the horizontal resistance coefficient K of the rock mass of bedding rock slope is positively correlated with the friction angle,cohesion,slope distance and rock thickness of the structural plane,and negatively correlated with the slope angle.When the dip angle of the structural plane is less than 45°,it is negatively correlated with the horizontal re-sistance coefficient K,and vice versa,and when the dip angle of structural plane is greater than 45°and less than 60°,it is positively correlated with it.（4）The sensitivity analysis of the horizontal resistance coefficient obtained by nu-merical simulation is carried out by using the normalization method.It is obtained that the order of the influencing factors of the K value of the horizontal resistance coefficient of the rock mass in the embedded section in front of the pile is slope angle in front of pileα>cohesion of structural plane c>rock thickness h>dip angle of structural planeθ>internal friction angle of structural planeφ>slope distance b.On this basis,accord-ing to the relationship between the horizontal resistance coefficient of the rock mass of the bedding rock slope and the influencing factors such as slope angle,structural plane cohesion and rock thickness,the multiple linear regression equation of the K value of the horizontal resistance coefficient of the rock mass of the bedding rock slope is established by using the regression analysis method,and compared with the analysis results of the model test.The results indicate that:the rock mass value of the embedded section in front of the pile calculated by the regression equation is in good agreement with the result ob-tained by the calculation formula of the rock mass value of the embedded section in front of the pile in the model test.