Study On Dynamic Response Characteristics Of Underpass Tunnel Under Traffic Load

In order to solve the heavy traffic pressure and vigorously develop the underground space,it is inevitable that the subway tunnels pass under the highway,and the subway tunnels are mostly shallow tunnels,which are not only difficult to construct,but also affected by the upper traffic load.At present,there is little research on the dynamic response of tunnel under the action of road vehicle load.Therefore,this paper takes the road vehicle load as the research object,studies the dynamic response of stratum and tunnel structure,and focuses on the dynamic change law of tunnel lining and interlayer between tunnel and subgrade under the action of vehicle load,The acceleration sensitivity of four factors was analyzed.The research contents are as follows:(1)Based on the existing research on vehicle dynamic load,several vehicle load forms are compared and analyzed,and the harmonic sine wave load is selected.This paper analyzes the influencing factors and generating mechanism of vehicle load,and analyzes the influence of vehicle load on the transmission law of underground structure vibration and the attenuation of vibration wave,which provides a theoretical basis for model test and numerical simulation.(2)Based on the similarity ratio and consulted the literature,the similar mix ratio of the stratum and lining materials was studied,and the tunnel stratum and the lining model were poured,the formation and the tunnel lining by applied harmonic sine wave single-point excitation force is studied the vehicle load,frequency,load the source location of the lower inside the tunnel vault acceleration,the change law of external dynamic stress and mezzanine dynamic stress between tunnel and road foundation.The three-dimensional power model is established,and the feasibility of the two methods of experiment and simulation is verified by comparing and analyzing the experimental results of the model by numerical simulation.(3)In the model test,the single vehicle point loading can not truly reflect the change of vehicle spatial position,so the multi-point vehicle loading method is used to simulate the real movement change of vehicle by numerical simulation.According to the four main factors of tunnel buried depth,speed,load and intersection angle,the tunnel structure acceleration,vehicle speed and intersection angle under different working conditions are analyzed The displacement and the dynamic stress of the interlayer between the tunnel and the subgrade provide a reference for the design and construction of the tunnel and the upper traffic restrictions.(4)Aiming at the most disadvantageous vault position of tunnel,the acceleration sensitivity of four factors under the action of vehicle load is analyzed,and the most influential factors and the sensitivity variation law of each factor are determined,which provides the basis for tunnel construction and design.