The Stability Analysis Of The Tunnel Through The Valley

Along with the large-scale development and construction of the undergroundengineering, the particularity, randomness and the complexity of the rock-soil massgeological condition is increasingly prominent, which causes the design andconstruction of underground engineering to be relied on the experience and qualitativedependence stage since long-period. In the complex geological conditions, especiallywhen the tunnel through the valleys and other special section area, owing to tunnelexcavation, the initial stress state of surrounding rock will change, and thesurrounding rock has unloading deformation, when tunnel surrounding convergenceor vault sink more than its deformation value, will cause the tunnel instability, and thevalleys also because of their stress state changes may appear collapse damage, etc.Therefore, it is necessary to have special research on the factors that affect thetunnel’s stability and failure probability analysis for tunnel surrounding rockdeformation when the tunnel through the valleys.This thesis does some research respectively on the finite element model, tunnelconstruction and on reliability about the tunnel through the V type valleys in allusionto the gully area‘s complexity geological conditions.In finite element model, firstly taking YangLong zhangjiajie Lizi Ping highwaytunnel HuangTuling valleys for examples, I researched the gully types and formingmechanism, then based on this used the finite element software got the stressdistribution of V type gully area, and puts forward some disasters phenomenon it mayhappen when the tunnel through the gully area.Second, the factors that affect the tunnel stability when the tunnel through thevalleys were got by t the above analysis. Use the tunnel vault sink as the surroundingrock’s stability criterion, and then through the orthogonal experiment design principleof all factors affecting the test design, and through the finite element softwareANSYS to the simulation test, and on the basis of level analysis method of orthogonaltest results are analyzed processing, got each factors to tunnel through the gully areaof the stability of surrounding rock affect weight.In tunnel construction, first according to the existing grouting theory, this charteranalyses the depth, breadth and qulity of grouting to the tunnel vault sink influencewhen the tunnel goes through the valley area. And then, the commonly used tunnelexcavation blasting methods were introduced a controlled blasting method by combined the smooth blasting with the presplitting blasting based on the support ofthe tunnel in Zhangjiajie YangLong Lizi Ping highway tunnel TuFujie valleys was putforeward., the corresponding blasting design was provided, too. At last somecorresponding measures were proposed in allusion to the possible disastersIn reliability calculation, first the softrock tunnel lining structure stable functionbased on the surrounding rock-structure model and shear sliding theory wereestablished. Secondly, the Quasi-Monte Carlo method by replace the Hammerslybest uniform points to the pseudo random sequence in the traditional importantsampling method to solve the surrounding rock deformation’s probability failure ofthe intricate formation was utilizedI also summarized the steps of this method, andworked out the corresponding Matlab program. Using this method to calculate thesurrounding rock deformation ‘s probability failure of the zhangjiajie YangLong LiZiPing highway tunnel. It is found that this method can improve the sampling points ofquality, reducing the sample sizes, increase the calculation efficiency, and calculatedresults error is sure by camparing the result of this method to the result of theimportant sampling method.