Research On The Stability Of Surrounding Rock For Shallow Bias Tunnel With Super Large Cross-section

With China's increasing investment in infrastructure construction,the tunnel industry in China has also developed rapidly.The past two lane tunnel has been unable to meet the increasing traffic problems,and it has little effect on the existing urban traffic problems that need to be solved.The following are the gradual increase of single tunnel,3 lane,4 lane,large section and super large section.So this puts forward higher requirements for the stability of tunnels.Taking the Ganggou Tunnel which links Beijing and Shanghai to be the background,combining with researches about tunnels and the current situation of tunnel construction methods in China and abroad,the study,which is about the surrounding rock stability of the shallow tunnel under unsymmetrical pressure with a super large section,is made in the following directions :(1)Summarize the characteristic,the judgment method of the shallow tunnel under unsymmetrical pressure and the influence factors to the surrounding rock stability of a super large section tunnel by consulting related materials.(2)By applying the finite element program MIDAS/GTS,numerical simulation of two-dimensional is used in the double-side-drift,the bench cut method and CRD method which is used during the construction of Ganggou Tunnel,in order to get the most reasonable tunnel excavation method under this mentionned calculation condition.(3)By using the numerical simulation of the finite element program MIDAS/GTS,an optimization study on the excavation method of Ganggou Tunnel is made to get the most reasonable step lenth during the construction using the the bench cut method.7 different working conditions(3m,6m,9m,12 m,15m,18 m,21m)are selected to analyze in order to get the most reasonable step lenth in the symmetrial loading section of Ganggou Tunnelunder this mentionned calculation condition.(4)Combining with the measured data about the ground surface settlement,the horizontal convergence and the settlement of vault,analyze the data of monitoring measurment in the typical section of the Tunnel to evaluate surrounding rock stability and the rationality of the supporting structure.