Analysis And Countermeasure Research On The Main Engineering Geological Problems Of Deep Buried Long Highway Tunnel

A series of geological disasters such as landslide,rock burst and large deformation of the surrounding rock will inevitably occur.Because that the deep buried long highway tunnel which most of them past through the mountains and other complex geological structure has the characteristics of large depth,long hole length,long construction period,high cost and difficult construction.Therefore,it is of great significance to analyze and study the main geological disasters and corresponding measures in the construction of deep buried tunnels.The engineering geology of the tunnel area is analyzed by means of geological data and field investigation,based on the practical engineering background of Yingerling Tunnel of Rongwu Freeway.Combined with engineering example,a deep research on the Shed-pipe treatment effect in deep buried landslide,rock burst and large deformation by Midas GTS NX finite element analysis software is made in this paper.The main research contents are given as follows:(1)By simulating of the stress field,displacement field and plastic status of the surrounding rock in different conditions(different thickness of grouting reinforcement area),a quantitative analysis of the support effect of the shed-pipe combined with grouting technology is presented.It is concluded that the grouting reinforcement area is not the thicker the better.To take the 5m of the thickness of the reinforced area is the most reasonable in terms of comprehensive construction safety and economic rationality.(2)By simulating the construction process of shed-pipe combined with grouting reinforcement section of soft surrounding rock in deep buried tunnel,the stress and deformation characteristics of surrounding rock after excavation are analyzed,and the stability under different reinforcement conditions is evaluated.The results show that the grouting reinforcement effect of shed-pipe plays a decisive role in the stress redistribution around the tunnel and the convergence deformation of the surrounding rock,while the beam effect of shed-pipe which can effectively control the vault settlement of working face shows a key influence on the stability of the excavation face.(3)The numerical simulation of hard rock and soft rock under different buried depth is done to forecast the possibility of rock burst or large deformation.Based on the study of the stress characteristics of surrounding rock around the tunnel and the judgment basis of rock burst,it is concluded that rock burst may occur in yingerling tunnel.The length of slight rock burst tunnel is about 38% of total tunnel,the length of medium rock burst tunnel is about 7%.The hard rock with a depth of more than200 m will have a slight rock burst or even a medium rock burst which occurs in the side wall and arch foot.Based on the study of the vertical and horizontal deformation characteristics of tunnel and the judgment basis of the large deformation,it is concluded that the soft rock with a depth of more than 600 m will have a large deformation of Slight degree.