Research On Deformation Characteristics And Control Technology Of Large Section Highway Slate Tunnel

In recent years,with the development of expressway construction,more and more tunnel engineering problems have emerged.The large deformation of soft surrounding rock tunnel construction has always been a problem that plagues tunnel builders.If control measures are not taken in time,it is prone to occur.Engineering disasters such as surrounding rock intrusion and tunnel collapse have seriously affected the tunnel construction period.Therefore,the deformation mechanism and control technology of the weak surrounding rock tunnel has always been an important research topic in the tunnel engineering community.This paper relies on the large-section highway tunnel that crosses the strong-middle weathered slate stratum,and relies on a large number of relevant specifications and literatures.Based on a combination of theoretical analysis,numerical simulation and on-site monitoring,The deformation characteristics and control technology of surrounding rock of large-section highway slate tunnel are comprehensively studied.The main work and the research results are as follows:(1)Based on the observation of tunnel surrounding rock stress and surrounding rock deformation monitoring standards and a large number of literatures,the monitoring scheme of tunnel surrounding rock is designed according to the surrounding rock stress and its convergence deformation after tunnel excavation,combined with on-site monitoring.The temporal and spatial distribution of stress and deformation of tunnel surrounding rock is analyzed.(2)Using MIDAS/GTS-NX finite element analysis software,the distribution law of surrounding rock stress and deformation of large-section highway slate tunnel under different excavation methods and different excavation steps is analyzed.The results show that the step method and CD When the excavation method is used,the stress of the surrounding rock of the tunnel is equivalent.When the CD method is excavated,the stability values of the arch settlement and horizontal convergence of the tunnel surrounding rock are 139.1mm and 110.9mm,respectively,which is 27.8 lower than that of the simulated step method.%,34.0%;when simulating the influence of different excavation steps on the deformation of tunnel surrounding rock,it is found that with the increase of excavation step,the deformation of tunnel surrounding rock gradually increases,the instability increases continuously,and the safety factor Gradually reduced,so small step excavation should be taken during tunnel excavation.(3)Comparing and analyzing the results of numerical simulation and on-site monitoring data,it can be seen that the stable deformation of the surrounding rock vault settlement and horizontal convergence of the tunnel is greater than the deformation value specified by the standard when excavation by the step method,and the CD method is used for excavation.The final deformation of the tunnel vault settlement and horizontal convergence is less than the deformation value specified in the specification.It can be seen that the CD method is better for the deformation of the surrounding rock of the tunnel.(4)Through the regression analysis of the measured data of tunnel vault settlement and horizontal convergence deformation,the exponential function is obtained as the best fitting function,and the corresponding deformation of surrounding rock after the surrounding rock is stabilized is predicted by this function.According to the actual working conditions of the tunnel,the method of controlling the surrounding rock deformation is proposed,and the method of “strengthening the overall stiffness of the supporting structure” is applied to the tunnel engineering.The rationality and feasibility of the method of controlling the surrounding rock deformation are verified.