Study On Train-induced Vibration Response Characteristics Of Road-metro Shield Tunnel And Surrounding Soil

With the development of shield technology and the expansion of the application requirements,large section and multi-function tunnel has become an important trend in the development of shield tunnel.This kind of multi-functional shield tunnel with large crosssection contains complex internal structures such as lane slabs and side walls,which brings new challenges to accurately predict the dynamic response characteristics of tunnel structure and surrounding soil.In this paper,the influence of internal structure on train-induced vibration response of lining segment and stratum are studied,and the frequency composition and energy distribution characteristics of each frequency band of subway vibration are obtained by wavelet analysis.The main work and research results are as follows:(1)The dynamic response of shield tunnel with internal structure is smaller than that without internal structure.The peak acceleration difference between the two models on tunnel structure is up to 78%,and the maximum average difference between the two models in frequency domain is 17 d B.The maximum difference of peak acceleration between the two conditions is 70.3%,and the average difference of acceleration level between the two conditions is 11 d B.(2)The train-induced vibration response of tunnel structures can be amplified by train running effect.Under the action of moving load,the peak acceleration at the track bed increases by about 105%,the side wall of the internal structure increases by 41.9%,the connection between the side wall and the upper lane increases by 47.3%,and the center of the upper lane increases by 22.3%.The train speed is one of the important factors affecting the acceleration response of tunnel structure.The higher the train speed is,the greater the acceleration response is.When the train speed is increased from 40km/h to 80km/h,the peak acceleration increases of track bed position,lane board on the side plate and the upper part of the internal structure are 180.2%,252.6% and 329.2%.(3)With the increase of train speed,the influence of train speed on environmental vibration will gradually increase,but the influence of train speed on environmental vibration will gradually weaken.When the train speed is 80km/h and 60km/h,the maximum acceleration level at the side wall of the internal structure decreases by 3.7d B.When the train speed is 60km/h and 40km/h,there is 18.5d B difference in the vibration stage of the internal structure side wall.In addition,the surface Z-vibration level decreases first,then increases,and then decreases rapidly.There is an amplification area of the surface Z-vibration level,and the approximate range of the amplification area is between 14 m and 32 m,that is,when the distance is greater than 40 m,the surface Z-vibration level is less than the limit value of environmental vibration control.(4)The vibration wave energy is mainly distributed in the frequency band range of31.54～63.0 Hz,and the energy proportion of the vibration signal at the side wall of the structure reaches 85.95% in this frequency band.The energy in the arch foot accounted for88.22%.As the propagation distance of vibration wave increases,the energy proportion in this frequency band decreases.The vibration energy of the center of the surface in this frequency band accounts for 49.13%,and the vibration energy of the measuring point 4.0m away from the center line of the surface accounts for 42.04%.In addition,with the increase of vibration wave propagation distance,the energy proportion in the 0～31.5Hz frequency band increases.For example,the energy proportion in the frequency band at 14 m,18 m and 22 m from the center line of the ground is 7.21%,10.74% and 13.72%,respectively.