Research On Mechanical Mechanism And Treatment Technology Of Tunnel Floor Heave In Swelling Rock

During the operation period of the swelling rocks tunnel,the floor heave will seriously affect the normal operation of the tunnel and endanger the safety of the tunnel structure.However,due to the different causes,processes,and mechanisms of floor heave damage,as well as the complex state of surrounding rock during operation,the impact on the tunnel structure is significantly different.In view of this series of problems,this paper takes the Lingshan highway Hengshan tunnel disease remediation project as the engineering background,analyzes the mechanism and rules of the tunnel floor heave during the operation period of the swelling rocks tunnel.Simulation study on the relationship between the stability of tunnel bottom and the range of swelling rock and moisture content.Finally,a method for assessing the status of disease in the tunnel bottom and treatment measures for the floor heave of the tunnel bottom were proposed.The main research results are as follows:(1)In this paper,by investigating the cases of floor heave in more than 30 tunnels in China,various factors affecting the floor heave of swelling rocks tunnels during operation period are summarized and analyzed.Based on the break modes of floor heave during,Its external performances are "?","Z" and "W" shape,and the break mechanism,development process and deformation characteristics of the floor heave of the tunnel were analyzed.(2)Based on the plastic limit analysis method,the stress and displacement characteristics of the surrounding rock of tunnel floor under plastic deformation are analyzed.The ultimate bearing capacity of the tunnel floor and the break depth of tunnel floor heave are deduced.The depth and the width of the plastic limit zone on the side wall of the tunnel are linearly increasing.(3)Taking the typical section of the Hengshan tunnel disease section as the calculation model to simulate the mechanical response of the tunnel in the process of humidification and expansion of the surrounding rock of the tunnel floor.The axial force,bending moment and safety factor of the tunnel lining structure at the different expansion depths and moisture contents of the tunnel surrounding rock are calculated.As the depth of water seepage and the amplitude of humidification increase,the axial force of the tunnel lining will increase accordingly,and the tunnel safety factor will decrease.The bottom corner and the invert arch are the most unfavorable points in the tunnel lining during the process of humidification of the surrounding rock of the tunnel;for the lithology of the expansive mudstone at the tunnel bottom of the tunnel section of the Hengshan tunnel,the smooth drainage of the surrounding rock within the 3m of the tunnel can effectively suppress the floor heave.Phenomenon to ensure that the tunnel bottom structure is stable.(4)Based on the characteristics of tunnel floor heave during the operation of the swelling rock tunnel,a fuzzy evaluation hierarchy process was used to propose a method and process for rapid assessment of the status of the tunnel bottom structure,and to evaluation of the Structural Disease Status of Tunnels in Hengshan Tunnel.Divide the treatment measures for the floor heave of of the swelling rocks tunnel,and summarize the conditions for the use of the treatment method and the construction process.Finally,compare the treatment of the tunnel bottom disease of the Hengshan Tunnel,and verify the rationality of the treatment plan based on the monitoring data of the diseased section...