Study On Dynamic Response Of Utility Tunnel Under Dynamic Load Of Subway Train

In recent years,the development process of underground space is gradually developing towards the direction of integration,and synchronous planning and construction are usually considered in the construction process of rail transit and underground pipe corridor.In this paper,based on the concrete project of an underground comprehensive pipe corridor section in Beijing,the vibration response characteristics of the pipe corridor structure under the dynamic load of subway trains during the subway operation period are studied through field tests.In this paper,the numerical simulation method is used to study the dynamic response of pipe corridor under the dynamic load of subway train,which provides a reference for studying the dynamic response law of comprehensive pipe corridor.The main research work is as follows:（1）In this paper,the dynamic response data of underground utility tunnel under the specific vibration of metro train dynamic load are obtained based on the project of Beijing Rail Transit Line 7 East extension underground utility tunnel.Through fast Fourier transform,the frequency spectrum of vibration acceleration time history of pipe gallery is analyzed.Under the influence of subway train vibration,the vertical vibration frequency of pipe gallery structure is mainly concentrated in 40 ～ 110 hz,and the main frequency distribution is relatively concentrated;the horizontal vibration frequency is mainly concentrated in 40 ～ 200 Hz,and the main frequency distribution is relatively scattered.（2）In this study,the influence of the vibration characteristics of the comprehensive pipe gallery on the safety of the pipe gallery structure,internal pipelines and precision instruments was evaluated by analyzing the environmental vibration evaluation and control standards at home and abroad.The results show that the subway train vibration does not directly affect the safety of the pipe gallery structure and the pipeline in the gallery.However,the precision components of the monitoring and detection system in the pipe gallery are sensitive to train vibration.（3）Through the dynamic analysis module of MIDAS,a three-dimensional finite element model of tunnel-soil-structure was established.Linear time-history analysis（direct integration method）was used to numerically analyze the dynamic response of the tunnel structure under the influence of train vibration.The results show that under the influence of subway train vibration,the longitudinal stress of the pipe gallery structure changes obviously,showing a trend of increasing first,then stable and finally decreasing.The transverse stress distribution of the pipe gallery structure is not uniform,and the stress concentration phenomenon exists in the side wall and the end of the middle partition of the pipe gallery.（4）Finally,the influence of deformation joints and their spacing on the vibration response of pipe gallery structure is studied by numerical simulation.The results show that the vibration amplitude of the pipe corridor increases with the decrease of the deformation joint spacing,and the longitudinal vibration of the pipe corridor changes most obviously.The vibration of the pipe gallery is mainly concentrated near the bottom floor and deformation joint of the water tank with the largest span.The deformation joint spacing has little effect on the dynamic stress of pipe gallery structure.