Study On The Limit Of Buried Depth Of Highway Tunnel With Small Clear Spacing

The classification of the buried depth of the tunnel is a very practical design parameter.Among the existing "Highway Tunnel Design Code" and many other documents only consider the depth of the tunnel under the circumstance of a single hole excavation.While,for small clear distance tunnel,the interaction between the two holes in the excavation can not be ignored,so many of the existing methods of calculating the depth of the buried limits do not apply to small clear tunnels.To this end,this article will rely on Wanxing Road tunnel in Jiangbei District,Chongqing to carry out the following research works:(1)Using the finite element software MIDAS/GTS toestablish the three-dimensional solid model of Wanxing Road tunnel to do the analysis and calculation,the paper analyzes the stress of the surrounding rocksin terms of the surface settlement and the excavation of the tunnel.To analyze the deformation and force law under the circumstances of leaving out the impact of two holes and considering the impact of two holes,respectively,the determination of the depth of the Wanxing Road tunnel buried limits can be obtained.(2)Through the analysis of the monitoring data of Wanxing Road tunnel,the paper analyzes the depth of the buried limit obtained from the monitoring data,and compares it with the calculated value.(3)The influencing factors of the depth of the small-distance tunnel are discussed from 4 aspects,the parameters of different rocks and soil,the different inclination angle of the ground,the different distances of the first hole and the rear hole.