Research On Influence Of Jacking Construction Of Frame Bridge On Subgrade Settlement Of Existing Expressway

Bridge type of shield method as a new method of frame bridge jacking construction has a wide range of applications in the urban tunnel and is becoming more and more popular.However,my country has no corresponding control standards for the bridge shield method construction,and the surface settlement generated during the construction and the impact on the existing lines,ranging from affecting traffic flow,and causing life safety accidents,so the research in this article has important practical significance.This paper relies on the Chebei Road in Tianhe District under passing the Huancheng Expressway project,through case analysis,theoretical calculations,ABAQUS numerical simulation,and other means,when the bridge shield method is constructed,the double-hole tunnel with different friction coefficients under the condition of pushing pressure Analyze the stress and deformation of the bridge,and finally give the construction safety control points and construction monitoring plan to provide a reference for subsequent similar bridge-type shield construction projects.The main work content and research results of this paper are as follows:(1)Based on the soil and water documents of the project site,and based on the quality,schedule,cost,and safety requirements,the construction plan,and main construction technology of the bridge shield method were systematically studied,and the jacking force of the left and right lines was carried out.;(2)The Peck formula method and random medium theory method,the two commonly used prediction methods of strata subsidence theory,through the case analysis of different crosssection shape and depth calculation value contrast,explores the application of the two kinds of calculation methods,the calculated value and the actual engineering data contrast,found that the bridge type of shield method of rectangular cross-section,In the case of shallow buried depth,the random medium theory method should be used for calculation and analysis,and the theoretical calculation of stratum deformation of supporting engineering should be carried out,and the settlement deformation curves of left and right lines should be given.(3)ABAQUS finite element software was used to simulate the whole construction process of the bridge shield tunneling method,and the influence of changes of friction coefficient and pushing pressure on the settlement of existing roads and surface was discussed.The results show that the increase of friction coefficient increases the tensile stress and settlement value,but has no obvious influence on the compressive stress and uplift value.When the jacking pressure increases,the location of the extreme settlement point will change from the bottom side of the shield to the road surface above the hole of the jacking end.The settlement result simulated by the finite element method fits well with the theoretical value,and the variation trend is similar.(4)According to relevant laws and regulations during the period of construction traffic guideline scheme,construction risk and control measures,contingency plans,and work well,receiving pit and jacking construction monitoring design of tunnel interval,beltway during the construction of security operation,make the construction influence control to a minimum,provide a reference for other similar projects.