Mechanical Analysis Of Shield Tunnel Lining Undering High-speed Railway Subgrade

Because of the rapid development of high-speed railway and urban rail,there will be a large number of engineering examples of the shield tunnel cross the railway.At present,the domestic and foreign research on the high speed railway cross the shield tunnel is mainly focused on the the high speed railway.The study on the influence of shield tunnel is relatively rare.Therefore,this paper studies the stress of the shield tunnel segment under the high speed railway.In this paper,by using ABAQUS software established a model of shield tunnel crossing high speed railway.In order to anaylysis the dynamic response of shield tunnel with different depth and different assembly methods when the high-speed train passing at different speeds.(1)On the whole,at the surface of the segment,the maximum acceleration caused by train decreases with the increase of the depth of the tunnel.On the basis of the existing research,this paper come to the conclusion that determine the vertical acceleration of the train vibration is decaying in the form of exponential function.The specific formula is y=2.3e^(x/1.61)where x is the buried depth of the node,and Y is the maximum vertical acceleration amplitude.(2)For screw in the segment,load of train,first affect the soil,and then the vibration energy will transmitted to segment conduction,finally reach the screw.Because the concrete damping is smaller than the earth,so the vertical acceleration of segment screw attenuation is slower than the shield segment.(3)The vertical acceleration of the segment increases with the increase of train speed.However,the faster the speed,the faster the dynamic stress decay of the depth of penetration,and the dynamic stress is closer to the agreement when the depth is deeper than 13 m.(4)Because of the train loads,the segment pressure decays rapidly with the increase of depth.In most regions of segment.The stress produced by the dynamic load is less than 1% of the one produced by static stress,and only when the depth is less than 6m the ratio of the two can reach 1%.(5)The whole shield segment stress increases with the increase of train speed,but the shallower part of the buried depth is more affected.when the train load is 350km/h,The stress produced by the dynamic load is less than 4% of the one produced by static stress.Therefore,the equivalent stress produced by dynamic load has still little influence on the shield segment.