Research On Stability Of Surrounding Rock Of Shallow Buried Urban Tunnel Based On Mine Method

In this paper,the first phase of Qingdao Metro Line 1,the first phase of Qingdao Metro Line 3,the section tunnel and the Qingdao Chaoyang mountain highway tunnel as the background.First,collecting and reading related literature,through field test and monitoring measurement,measured data obtained;secondly combining with the actual situation to build a tunnel model,on the basis of numerical simulation by using computer software LS-DYNA and ABQUAS,respectively.The blasting vibration and initial support impact on the stability of surrounding rock of tunnel are analyzed;finally,combined with the the measured data of three engineering background,by using gray relational analysis method of important degree of influence on construction factors of tunnel surrounding rock stability,finally draws the following conclusion:(1)By using LS-D YNA software to span shallow 4m,10m tunnel is simulated,get the influence of blasting on the surrounding rock stability,when the tunnel span is 10m,to meet the maximum quantity of explosive blasting rock critical vibration velocity is 14.62kg;when the tunnel span is 4m,to meet the maximum quantity of explosive blasting rock critical vibration velocity is 4.51kg.(2)Using ABQUS software to span shallow 16m tunnel is simulated by the supporting effect on surrounding rock stability,the maximum principal containing tunnel surrounding rock supporting wall stress,radial shear stress and the maximum principal strain was much less than that without support of tunnel.It can be seen that the tunnel with side wall support is better than the tunnel with no side wall in resisting the deformation of surrounding rock and resisting the stress and strain of surrounding rock.Therefore,the support plays a vital role in the stability of surrounding rock.(3)Based on the principle of grey relational grade,the factors affecting the stability of surrounding rock in tunnel are analyzed and evaluated.It is known that the factors influencing the stability of surrounding rock are arranged from large to small according to the influence degree.They are Circulation footage,excavation width,water content,depth,spacing,arch tunnel excavation and support interval,excavation height,shotcrete strength,thickness of concrete injection.