Seismic Dynamic Response Analysis Of Xintongziling Tunnel With Dome Lining Thinning

The thinning of tunnel lining is a common disease in operating tunnels.Under normal circumstances,the safety hazard of tunnel lining thinning will not be revealed.Once an earthquake occurs,the defects of tunnel lining thinning will bring us immeasurable consequences..Based on the Xintongziling tunnel in Pengshui County,Chongqing,this paper studies the dynamic response of the tunnel under the high-intensity earthquake.The research results can provide basis and reference for the reinforcement of similar tunnel projects in the future earthquake zone..The main research contents and results of this paper are as follows:1.Statistics and analysis of the insufficient thickness of the tunnel lining were carried out by collecting relevant information on the operating tunnels in the southeastern Chongqing.The results show that the dome position is the most frequently occurring part of the tunnel lining thickness defect,and the lowest pass rate of the dome position is only 58%.2.Through the study of the selection of constitutive model,the selection of seismic waves,the time-frequency analysis of seismic waves and the correction of baseline,the reasonable method for the initial conditions of finite element software dynamic calculation input is determined,which lays a foundation for subsequent research.3.The numerical simulation method is used to analyze the stress characteristics of tunnel lining under different seismic depths,different under-thickness of arch lining and different under-thickness of arch lining.The dynamic response law of tunnel lining structure is obtained.The results show that the tunnel depth 12D(tunnel diameter)is a limit value.When the buried depth is less than 12 D,the lining bears the greater stress with the increase of the buried depth.After the buried depth exceeds 12 D,the stress on the lining tends to be stable.The thickness of the vault lining is only thicker,which has a greater influence on the position of the vault.As the thickness of the vault lining decreases,the stress on the lining is larger and the safety factor is smaller.The thickness of the tunnel vault lining increases from 0° to 30°,the first principal stress of each monitoring point on the lining is gradually increased,and the safety factor is gradually reduced.When the tunnel vault lining thickness is increased from 30° to 60°,the first main point of each monitoring point on the lining is The stress gradually decreases and the safety factor gradually increases.4.When the thickness of the vault lining is one-fifth of the design thickness and the depth is 10 D,12D,14 D,the safety factor of the vault lining is less than the minimum safety factor in the design code of the railway tunnel.At this time,the lining will be under the action of earthquake.Destruction occurred.