Study On The Dynamic Response And Fatigue Life Of The Tunnel With Lining Void Under The Load Of High-speed Train

The high-speed railway tunnel will bear the dynamic load of the high-speed train when it operates.At present,there is no systematic study on the dynamic response of the high-speed railway with voids under the action of the high-speed train.Therefore,on the basis of the National Natural Science Foundation-the joint fund for high speed railway(U1434211),this paper uses the data of previous field tests for reference,adopts the research method of finite element numerical simulation,and takes the current typical double line high speed railway tunnel as the prototype,systematically studies the lossless tunnel and the tunnel with cavities,the single cavity tunnel and the double cavity tunnel,the cavity void size Under different working conditions,such as void location,the dynamic response characteristics and laws of tunnel lining arch ring under the action of train vibration load.The results of the study can reveal the long-term structural dynamic behavior,structural damage evolution law,structural safety coefficient evolution and structural damage precursor of tunnel with void operation,improve the safe operation environment of high-speed railway tunnel,and increase the service life of tunnel It has important practical significance and reference significance.The research contents and achievements of this paper are as follows:(1)Based on the literature review and field investigation,this paper makes a statistical analysis on the lining defects of the general speed railway tunnel.It is concluded that the main form of tunnel defects is the void in the lining,and the probability of void in the lining vault is the largest(2)Using the finite element method to establish a two-dimensional tunnel model,the influence of the cavity behind the tunnel lining on the tunnel lining structure is studied.By setting different variables such as the position,thickness and angle of the cavity,the different forms of the cavity behind the tunnel lining are studied.The stress of the tunnel lining structure is analyzed,and the load of the tunnel lining structure on the high-speed train is obtained The law of dynamic response under load is:side wall>arch waist>arch crown(3)The influence of the cavity behind the tunnel lining on the stress of the tunnel lining structure is studied by using the finite element method to establish a three-dimensional tunnel model.By setting different variables such as the position,depth and space distance of the cavity behind the tunnel lining,the safety evaluation of the tunnel lining structure is carried out under the conditions of different forms of the cavity behind the tunnel lining,With the increase of the void depth of single cavity or the decrease of the void space distance of double cavities,the safety factor of tunnel lining structure will decrease.Under the same working condition,the safety factor of vault position is the smallest,the arch waist is the second,and the side wall is the largest(4)In view of the different forms of cavity defects behind the tunnel lining,the concrete fatigue equation and damage variable are introduced to show more intuitively the influence degree of different void conditions on the normal operation of the tunnel.