Research On The Key Technology Of Ground Deformation Control Of Metro Shield Tunneling Under Expressway

Since the 21 st century,with the rapid development of China's national economy,metropolis such as Beijing,Shanghai,Guangzhou,Shenzhen,and Suzhou etc.have ushered in the climax of building a subway.The subway has occupied an increasingly important position in the transportation of modern metropolises,and the subway network has been continuously improved.In this progress,there is a phenomenon that the subway construction continues to expand from the urban center and the subway shield construction crosses the expressway.Studies of surface deformation and deformation law formation process of metro shield tunneling expressway at home and abroad has just started.The content of this paper is based on the Suzhou Rail Transit Line 4 under the Sujiahang highway.Sujiahang highway is the main transportation link connecting Jiangsu Province and Zhejiang Province and the vehicle flow is large.Meanwhile,the project is the first time that Suzhou Rail Transit crosses the subgrade section of the expressway.Therefore,the comprehensive research to control surface deformation in the high-speed construction of the shield tunnel crossing is necessary.The main contents of this paper include the following aspects.1)Theoretical Analysis of Surface Deformation of Shield Crossing Expressway;2)By analyzing the influence of different propulsion pressures on the deformation of the soil in front,this paper analyzes the internal stress generated by the soil silo pressure on the soil in front and the stratified settlement deformation of the soil.And the down-traversing parameters of the shield is determined to ensure the down-traversing by analyzing the data of the test section.3)The analysis of settlement deformation in the middle section of the shield.Through the analysis of the cause of deformation in the middle section,the stratification pressure and stratified settlement of soil layer of the soil layer during the middle section of the shield,the main factors affecting the deformation of the middle section are determined,and effective measures are taken to reduce the deformation of the middle section during construction.4)The analysis of the influence of shield tail clearance on formation settlement.By analyzing the characteristics of formation deformation under different grouting parameters,the stratification pressure and stratified settlement of soil under different grouting pressures provide the basis for the setting of synchronous grouting parameters.5)The analysis of the continuous formation deformation after the passage of the shield.Through the analysis of the control of the formation deformation by the secondary grouting and the later grouting,determine the principle of secondary grouting and post-replenishment grouting.6)The analysis of long-term ground settlement after shield construction.The pre-control measures are proposed after analyzing of the factors affecting long-term settlement.Finally,a brief discussion of the further work direction is given.