Study On The Tunnel Floor Heave Mechanism And Remediation Measures Of South Lv Liangshan Tunnel

With the increase of long distance and large deeply buried tunnels in our country,because of line selection and location constraints,it is inevitable to excavate the tunnels in the rock mass with poor geological conditions,complex and changeable,the tunnel floor heave disasters often occur.This paper combines with the remediation project of south Lvliangshan tunnel,to the deformation of tunnel floor heave carried out theoretical and numerical simulation analysis,on the basis of these putting forward the reasonable remediation measures of tunnel floor heave,and the simulation optimization were conducted on the relevant parameters of the remediation measures.The main contents and the results are as follows:(1)Through consulting the relevant data and the field investigation of the south Lvliangshan tunnel,the paper analyzes the reasons,the form and the process of the tunnel floor heave.(2)The ultimate bearing capacity of the tunnel floor is derived by using the limit analysis theorem;through the analysis of the stress and velocity slip line field of the surrounding rock of the tunnel bottom,the average stress and the distribution of the surrounding rock mass and the velocity and direction are obtained;through the analysis of the failure process of the surrounding rock in the bottom of the tunnel,the deformation of the surrounding rock of the tunnel floor is divided into three parts: the active damage zone,the compression transition zone and the passive damage zone,and its migration laws;through the establishment of the mechanical model of the tunnel floor and the calculation model of the failure depth,the maximum failure depth of the tunnel surrounding rock is derived.(3)The displacement,stress distribution,plastic zone,Migration and evolution characteristics of the floor heave deformation of the tunnel surrounding rock are simulated and analyzed by using the numerical software,and the results are compared with the measured results,the reliability of the numerical model is verified.(4)Based on the above analysis,the corner bolt of the tunnel floor,invert arch and both combination three kinds of the floor heave deformation remediation schemes are put forward.The remediation effect of different remediation schemes on the tunnel floor heave is analyzed by numerical simulation,and compared with the field monitoring results,in addition,through numerical simulation to conduct parameters optimization analysis that anchoring parameters(corner bolt angle,length,spacing and diameter)of corner bolt as well as invert arch parameters(arch thickness,radius of curvature)of the floor heave remediation schemes,and achieved good control effect in practical application.