Investigation Of Construction Method And Mechanical Response On The Shallow Soft Rock Tunnel

Import and export section in the mountain tunnel and city rail tunnel,most of them are shallow soft rock tunnel,It contains poor hydrogeological conditions,buried depth,poor stability of rock and soil,weak ability to resist disturbance,and even the existence of a tunnel through or close proximity to other existing buildings,structures and other phenomemons.Once engineering measures(including design measures)and construction methods are not properly,initial support will be prone to limit deformation and it will even occur some engineering accidents,such as tunnel collapse,so these issues need to be solved urgently.In this paper,based on the engineering practice of the shallow buried soft surrounding rock section of Guangxi Yong He highway tunnel,the following research has been carried out by the comprehensive application of theoretical calculation,finite element numerical simulation and field measurement and so on.(1)Analyzed and summarized the application of finite element method in tunnel engineering,analyzed the stress state of surrounding rock of circular tunnel by using the analytic formula method,and then the stress analytic solution of circular tunnel under the condition of elastic and elastic plasticity is obtained,analyzed the relationship between each index and the radius of plastic zone.(2)Studied and analyzed the mechanical characteristics and deformation characteristics of shallow buried soft rock tunnel by using the method of finite element numerical simulation,focuses on the comparative analysis of the "Front of Face Deformation ahead","working face deformation," "rear working face distortion" proportional relationship during the construction of shallow tunnel with soft V level,The vault settlement found in advance deformation is the most significant,Advance Pre reinforcement and pre support at the crown have important significance.(3)This paper compared and analyze the variation of displacement field with advance pre-reinforcement measures or not and proved that the advanced prereinforcement measures are effective measures to control the structure of shallow tunnel with weak surrounding rock through 3 typical shallow tunnels with weak surrounding rock with construction measures of CRD,CD and so on by finite element numerical simulation analysis method.Through the quantitative comparison of the finite index,three kinds of shallow buried soft rock,four different construction methods,the adaptability of the advanced pre reinforcement measures are obtained.(4)Relying on Guangxi Yong He highway Da Lingtou tunnel shallow buried weak surrounding rock in the engineering practice,using the finite element numerical method,the simulation and analysis of the use of advanced small duct grouting pre-reinforcement left core soil bench construction process,this paper summarized and analyzed the stress,strain and displacement,the supporting structure of the safety factor were within the safe range to verify the safety.(5)On site measurement of the high ridge tunnel of Guangxi Yong He highway,the monitoring measurement data processing and regression analysis,and comparative analysis of monitoring measurement data processing results and numerical simulation results,which show that numerical simulation results in monitoring and measurement results are in good agreement.