Study On Non-stop Reinforcement Technology In Underground Shield Tunnel

With the increasing density of crowds in cities,people begin to pay more attention to the development and application of underground space.At present,underground space engineering and tunnel across the river are inclined to adopt shield construction,shield method has become a mainstream construction method of underground engineering.This paper mainly studies the subway shield tunnel.In the process of shield tunneling,there will be a certain gap between the surrounding soil and the pieced segment after the shield tail is protruded,which will lead to the deformation of the surrounding environment above the shield.In general engineering,the influence of stratum disturbance on the surrounding environment is controlled by the non-stop reinforcement method in the tunnel.The effect of non-stop reinforcement in the cave will affect the deformation degree of the stratum,and the choice of synchronous grouting parameters can lead to different reinforcement effects.Therefore,it is necessary to study the deformation law of the surrounding environment under different synchronous grouting parameters.In this paper,the section between Zhaobaoshan Station and Honglian Station of Ningbo Metro Line 2 Phase Ⅱ Project is taken as the background,combined with the engineering practice,the finite element software ABAQUS is used to establish a model to simulate the tunneling process of subway shield,and the settlement curves of monitoring points at different locations in the surrounding environment are obtained.After coMParative analysis,it is found that the deformation curve shape of the settlement data measured in the actual engineering site is basically consistent with that calculated by numerical simulation.The results show that:When the subway shield tunnel is excavated,it will cause shear failure to the soil in a certain range of influence.The surface settlement is the largest just above the central axis of the two tunnels.When the projection distance between the monitoring point and the axis increases gradually,the surface settlement decreases gradually,and the settlement shows a stable trend after a certain range.On this basis,this paper studies the influencing factors of metro shield construction non-stop reinforcement,and studies the influence laws of grouting pressure,grouting volume and grouting material on the transverse and longitudinal deformation of the surface respectively.By analyzing the influence of a single grouting parameter variable on the deformation of the transverse and longitudinal surface,the following conclusions are drawn:in shield tunnel with the same or similar geological conditions as this paper,the value range of grouting pressure should be 0.35～0.45MPa when carrying out non-stop reinforcement in the tunnel;Grouting volume should be less than 1.5 times of theoretical grouting volume;The range of elastic modulus of grouting material should be 0.5～1.0MPa,and the Poisson’s ratio of grouting material should be less than 0.4.Based on the analysis of a single grouting parameter as a variable,the orthogonal test method and ABAQUS three-dimensional numerical simulation software were used to comprehensively analyze the influence of different grouting parameters on the surface deformation around the shield tunnel,and the significance of the influence of different grouting parameters on the lateral and longitudinal surface subsidence was obtained as follows:Grouting volume>grouting material elastic modulus>grouting material Poisson’s ratio>grouting pressure。...