| With the widespread use of land,the ground space has gradually become saturated,Technological progress and economic development have led people to vigorously develop underground room,and urban subways and rail transit lines have also ushered in rapid growth and improvement.The more cities are building subways,the complexity of shield tunnel projects is getting deeper and deeper,and under passing projects continue to emerge.Under the constraints of the surrounding environment,how to ensure the safety and stability of the tunnel structure and the safe operation of existing tunnels has become an urgent problem in the development of rail transit.According to the actual project,the existing theoretical formula is used to calculate it reasonably,The appropriate numerical simulation software is used to numerically simulate the tunneling process of the shield tunnel.The academic calculation results are compared with the numerical simulation results,and the new construction is analyzed from different aspects.The impact of shield tunnel construction on existing tunnels.Based on the engineering background of a 58° obliquely underpassing an existing tunnel in a shield section of Hangzhou,this paper studies the soil settlement caused by the excavation of the subway shield tunnel and the deformation of the existing tunnel through theoretical calculations and numerical simulation methods.Obtain the deformation law of the soil and the deformation law of the existing tunnel at different crossing stages,and then compare and analyze the surface deformation before and after the reinforcement and the deformation of the existing tunnel structure on this basis,and the effectiveness and feasibility of the reinforcement measures are obtained.Sex.Finally,the internal force of the structure is analyzed for the maximum overlapping deformation section.The main research contents are as follows:(1)Actually,in the process of shield tunneling,the factor that causes ground deformation is more than the single factor of ground loss.This paper is based on the construction of the shield tunnel underneath the existing tunnel construction project,using Peck formula,unified soil solution,Loganathan formula and other formulas.Starting from a single-factor perspective and a multi-factor perspective,theoretical calculations are carried out and the theoretical values are compared with the model values.The curve trends are basically the same.Using the Peck formula,combined with the geological and monitoring data of the Shaoxing area,the formation loss coefficient and the width coefficient of the settlement trough in the Shaoxing area were revised,and a revised Peck formula that is more suitable for the Shaoxing project was obtained.(2)Study the impact of new tunnel excavation on existing tunnels.In this paper,the longitudinal deformation of the tunnel is deduced,combined with the current theory of calculating the longitudinal deformation of the tunnel,the two-stage method is used to check the project using the Winkler model,Pasternak model,and Vlasov model,And the theoretical values obtained are compared with the simulated values.Analysis shows that the trend of the curve conforms to the law of change.It is pointed out that there is not much error when using Winkler model for tunnel longitudinal deformation in soft soil area and when using two-parameter model to calculate.(3)Use Abaqus finite element software to establish a three-dimensional model of the actual project and analyze the calculation results.It mainly analyzes the surface deformation,the settlement of the existing tunnel,and the stress of the arch top and bottom of the existing tunnel under different working conditions.Based on the MJS reinforcement simulation of the existing Line 1,the ground settlement before and after the reinforcement was compared with the settlement of the existing tunnel.At the same time,the internal force analysis of the four lining rings at the maximum overlapping deformation positions is carried out. |
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