Study On Stress Dispersion Mechanism And Stability Analysis Method Of Slope Reinforced With Anchor Frameworks

The anchor frameworks is one of the effective measures to reinforce slopes,and the stability of anchored slope is an important problem in engineering practice.The traditional analysis method is not completely reasonable,because it considers anchor tensile forces as concentrated forces on the sliding surface but does not consider stress dispersion effect on the slip surface caused by the anchor forces.Aiming at the stability of slope with anchor framework,this thesis focuses on the additional stress dispersion effect caused by anchor tensile forces in the slope to establish the theoretical method for stability analysis of the anchored slope,and verifies the method via FLAC3 D numerical simulation program.The main research results are as follows:(1)A simplified analysis model of stress dispersion effect by anchor tensile forces in slopes is established.The anchor tensile force on frameworks is divided equivalently into normal and tangential uniform strip load along the slope surface.Based on Boussinesq's solution of normal concentrated force and Cerruti solution's solution of tangential concentrated force on the surface of semi-infinite elastomer,the additional stress field of slope under the uniform strip loads is obtained by integral method,and the expression of additional stress generated by anchor tensile force at any point in the slope is derived.(2)The stress dispersion characteristics of the anchor tensile force on the sliding surface of slope is revealed.Under the action of normal anchor tensile force,the additional normal stress in the slope is positive,which is mainly concentrated in the load range,and decreases along both sides and tends to zero.From the center of the load to its two sides,the additional shear stress increases first and then decreases.Under the action of tangential anchor tensile force,the additional normal stress varies similarly.The additional shear stress first increases and then decreases to both sides of the boundary,some of which are negative.(3)A novel method is established to analyze the stability of anchored slopes considering the stress dispersion effect of anchor tensile forces.Based on the algebraic expression of Morgenstern-Price method,Spencer method and transfer coefficient method,the additional force caused by anchor tensile force on the sliding surface is introduced,and the calculation expression of the factor of safety of the anchored slope is derived.(4)Based on two practical examples,the stability of the anchored slopes is analyzed by the proposed method and FLAC3 D.The comparison of the analysis results shows that the factor of safety calculated by the proposed method is smaller than that by the traditional analysis method,and more close to the numerical simulation results.The relative deviation between the proposed method and the traditional method is within 9%.(5)The reason why the factor of safety of the anchored slope calculated by the proposed method is smaller than the traditional method is explained.The proposed method reveal the fact that the additional stress caused by the anchor tensile force on the sliding surface is not totally anti-sliding.However,the traditional method assumes that the anchor tensile force is completely anti-sliding,and it cannot reflect the effect of the additional stress on the sliding surface.(6)Some important influence factors on the stability of anchored slopes are analyzed.These factors are location of the framework,framework stiffness,anchor spacing,anchor angle,soil properties of sliding surface and thickness of sliding mass.The factor of safety of the anchored slope decreases with the increase of anchor angle.And it increases with the decrease of the thickness of sliding mass,but the relative deviation between this method and the traditional method is progressively higher.The research results of the stress dispersion mechanism of anchor tensile force and the corresponding stability analysis method of the anchored slope can provide scientific guidance for practical engineering,and be of theoretical significance and greatly useful for engineering designs.