Study On Failure Mechanism And Reinforcement Of Side Slope At Tunnel Entrance

With the rapid development of the economy,traffic construction becomes a key project for urban development.In order to alleviate the problem of traffic congestion,the construction of the tunnel was favored.When excavating the tunnel,once the construction is improper,it will cause engineering disasters,especially tunnel entrance,the rock mass around the tunnel entrance is generally affected by various factors,the strength level is low,it is easy to cause damage.In addition,different geological conditions will inevitably cause technical difficulties in the construction process,which will easily affects the stability of the side slope of the tunnel entrance.Based on this point,it is necessary for us to conduct a project study on the failure factors of the slope of the slope at the entrance.This paper starts from the aspects of failure mechanism and failure mode,combined with actual data on the site of the Chejiaoshan Tunnel,using MIDAS/GTSNX for 2D plane and 3D simulations,Finally,through the on-site monitoring data for relevant analysis and discussion.Through the related research on the instability of the side slope of the mountain tunnel entrance,the research results and conclusions are as follows:(1)The failure mechanism and mode of the slope on the side slope are studied and summarized under the influence of different factors.(2)Using MIDAS/GTSNX two-dimensional simulation to influence the stress and displacement of surrounding rock in the case of different construction methods and embedding depths of mountain tunnels,Thus,the law of stability variation of the slope is obtained.(3)Analysis of advanced support without pipe shed and support without pipe shed by finite element three-dimensional simulation,By analyzing the vertical stress,displacement and horizontal displacement of surrounding rock,It is concluded that the advancement of the pipe shed is important to prevent the damage of the side slope.(4)Through the analysis of the monitoring results of the Chejiashan tunnel,the necessity of monitoring and the different countermeasures during the disaster are summarized.Combined with the actual engineering accidents of the Chejiashan Tunnel,the causes of the disaster were analyzed.