Study On Seismic Dynamic Response And Seismic Performance Of Anchor For Portal Section Of Tunnel

Because of the Development of Western Regions,lots of tunnels have been or are being built in high seismic intensity regions in western of China.The excavation and support problems of tunnels have become common problems.The mountain tunnel is often located in unfavorable geological conditions section where the surrounding rock property is poor,front slope is steep,and geological movement is active.Tunnels are vulnerable to high-intensity earthquake disasters.Therefore,there are dual purpose of social and academic to study the seismic dynamic response of tunnels and their supporting structures.In order to reduce or prevent the earthquake damage,it is an important topic to optimize the supporting construction of tunnel.First of all,consult a large number of real cases of tunnels and other underground structures damaged by earthquakes,sort out the influencing factors of tunnel damage and seismic design.And then study the seismic response of the portal section of tunnel and the anti-seismic effect of anchor supporting with FLAC3 D.Finally,the effectiveness of the anchor support was validated in connection with the MuZhailing tunnel project.The main research contents of this article are as follows:1)Introduce the key principles and characteristics of dynamic analysis of FLAC3D(finite difference method numerical simulation software),According to the research of this paper,the corresponding tunnel dynamic analysis process is proposed.2)Analyze the mechanical response during the excavation process and initial support for shallow tunnels,and further in-depth study effect of rock property,gradient of front slope and seismic excitation direction on the lining dynamic response and the surrounding rock deformation.Determined the dynamic disturbance zone of surrounding rock and the dynamic response depth of the lining.3)Further study effect of seismic performance of anchor for Portal Section of Tunnel of the soft surrounding rock tunnel,optimize the length and spacing of the anchor,and obtain the best support scheme.4)Based on the analysis method of seismic dynamic response and the research result of the anchor seismic design,the MuZhailing tunnel has been studied in depth.The result shows that: the earthquake has a strong destructive effect on the tunnel support structure,but the appropriate anchor support system can effectively resist earthquake.The above studies indicate that the seismic response of the portal section of tunnel is affected by the surrounding rock property,seismic wave excitation direction,and the front slope gradient.When the surrounding rock property is poor,the seismic wave excitation direction is horizontal,and the slope is steep,the seismic dynamic response to the tunnel is considered more adverse.After applying reasonable anchor support,it can effectively reduce the seismic dynamic response of the portal section and play a role in seismic performance.Reasonable anchor arrangement should fully consider the dynamic disturbed zone of surrounding rock and the distance between bolts.The research in this paper can provide some technical support for seismic dynamic response analysis and seismic design research for portal section of tunnel.