Research On Dynamic Response Of High-speed Railway Tunnel Lining Structure

In recent years,China's high-speed railway tunnels have developed rapidly,and many high-speed railway tunnels have been built and put into use.After a considerable number of stress and strain cycles,the high-speed railway tunnel structure has cracks of various degrees in the tunnel lining structure.The further development of cracks will lead to serious diseases such as falling blocks and water leakage in the lining,which will affect the safety and efficiency of train operation,and even extreme disasters that will be permanently irreparable.Therefore,by summarizing and comparing the field monitoring results of the Fuchuan Tunnel and the ABAQUS numerical simulation results,the dynamic response law of the high-speed railway tunnel lining structure under the vibration load of the train is obtained.This paper also analyzes the effects of train speed and voids at the back of the lining on the dynamic response of the high-speed railway tunnel lining structure.At the same time,this paper studies the development process of the high-speed railway tunnel lining cracks and the fatigue life of the tunnel lining structure under the action of the train vibration load cycle,and classifies the safety of the high-speed railway tunnel lining structure in order to provide a a certain reference for tunnel construction,maintenance and train operation safety.The main research conclusions of this article are as follows:(1)Under the vibration load of the train,the vibration acceleration response law of the lining structure of the high-speed railway tunnel is similar to the dynamic stress response law.The dynamic response of the lining structure at the moment of the train vibration load is the largest,and then recovers quickly,showing the impact characteristics.The dynamic response of the tunnel lining structure is transferred from the track bed to the inverted arch filling structure and then to the second lining with an attenuation of about 50%.When the dynamic response of the tunnel lining structure is transferred from the arch foot to the arch waist and then to the vault,the attenuation amplitude is about 30%.(2)The hollow structure behind the high-speed railway tunnel lining has a significant transmission and amplification effect on the train vibration.When there is a cavity at the vault behind the lining of the high-speed railway tunnel,if the cavity angle is small(less than 30 °)or the train running speed is small(less than 300 km / h),the vibration acceleration of the tunnel lining under the vibration load of the train: Arch foot part> Arch waist part> Arch top position.If the cavity angle is large(greater than 30 °)or the train running speed is greater(greater than 300 km / h),the vibration acceleration of the tunnel lining under the action of the train vibration load: arch foot > Arch top position> Arch waist position.(3)Based on the expansion finite element(XFEM)study of the crack propagation law under the vibration load of the train,it is found that the crack of the high-speed railway tunnel expands rapidly in the longitudinal direction under the vibration load of the train,and the crack propagation speed at the arch foot is particularly high.As the cracks expand,the vibration acceleration of the tunnel lining structure gradually increases,and the increase in vibration acceleration gradually decreases.(4)Miner's linear cumulative damage theory can better predict the fatigue life of high-speed railway tunnel lining structure.When the train running speed is 300 km / h and the maximum daily traffic volume is 100 pairs,the fatigue lifetime of the tunnel lining structure is less than 100 years,which does not meet the 100-year fatigue resistance design requirements.In order to improve the service life of high-speed railway tunnels,the design of the tunnel lining structure should be strengthened,and measures such as disease monitoring,remediation and structural reinforcement should be done for the currently operating tunnels.