| With the vigorous development of underground space and urban rail transit construction in China,as well as the continuous improvement of urban transportation facilities,the tunnel project of newly built tunnel crossing the existing operating rail transit interval at a short distance will also increase.The construction of a new tunnel close to an existing rail transit tunnel will cause disturbance to the soil layer around it,thus leading to the deformation of the soil layer and the tunnel structure,and even causing different degrees of damage to the tunnel structure or leaving a hidden danger of safe operation.Therefore,it is necessary to fully realize the operational safety risks of the existing rail transit tunnel in the construction process of the new tunnel,grasp the causes of the risks,and put forward targeted risk control measures,so as to better ensure the operational safety of the existing rail transit shield interval and the construction safety of the new tunnel foundation pit excavation.In this paper,the risk and control measures in the construction process of Xiangfu Road municipal tunnel project in Changsha city are analyzed and studied by taking the construction of shield tunnel in line 1 of the existing rail transit as an example.Firstly,by referring to literatures,this paper studies the relevant research results of risk analysis and control measures in similar projects at home and abroad,mainly from the three aspects of soil layer deformation control,tunnel structure deformation control and tunnel construction risk analysis during the construction of new municipal tunnel.On investigating the domestic across has been operating on the basis of the orbit transportation construction difficulties of shield interval,not only from improve the elastic modulus of soil,increase soil effective stress and the isolation of soil soil deformation control research was conducted on the three angles,but also improve the stiffness of the structure itself and set up two aspects has carried on the uplift pile has been operating rail transit tunnel structure deformation control research.Second,in the basis of the research on risk analysis and control theory,established a fit closely the engineering characteristics of risk index system,using the analytic hierarchy process(ahp)to the project of basic risk factors of hierarchical processing,calculate the various risk factors in the overall construction of the project risk weights of sorting,and for the operation of rail transit operation safety assessment.Thirdly,Xiangfu Road municipal tunnel after excavation of soil deformation ofrisk control measures to related research,this project mainly adopts MJS method("Metro Jet System ",can be translated as "all-round high pressure injection method",used to call "MJS" method)and hierarchical ribbon and excavation way to effectively control deformation of soil,at the same time with the help of fem software,numerical simulation analysis,the effect of soil deformation control is suitable for the engineering actual situation of soil reinforcement scheme.Finally,the construction has been operating rail transit tunnel structure deformation in the process of risk has carried on the related research,has put forward operating tunnel structure,on the basis of criteria and indicators for deformation control,respectively by finite element software of "bench" and "pipe curtain method" two kinds of structure deformation control measures on numerical simulation analysis of comprehensive multi-index comparison analysis,select "bench" as the rail traffic has been operating measures for the control of the deformation of tunnel structure. |
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