The Optimization Of Construction Process Key Parameters In Shallow Buried Large-span Box Culvert Underpasss Railway

Bridge-shield construction technology has been widely used in engineering, but the research of construction technology is still insufficient, lacking of analysis and optimization of key parameters of construction,so this paper combines the project of Wuhua road overpass underpasss Shanghai-Kunming railway in Fengcheng, Jiangxi province, and adapts the way of model test and numerical simulation to study the construction method of shallow buried bridge-shield underpasss railway. Box culvert jacking tests analyze the influence of the friction coefficient of box culvert jacking construction by drag reduction materials and the relationship between construction key parameters and displacement deformation of soil surface, the finite element software ABAQUS is used to the optimization analysis of key parameters. The key research contents and results are as follows:(1)Through the test, the change rule of friction coefficient with different drag reduction materials, which is between concrete and different water content of soil、concrete and concrete, indicates that wax-oil mixture is recommended as the drag reduction material when doing the jacking construction of shallow buried large-span box culverts.(2)The model tests were conducted to analyze the displacement deformation during bridge-shield construction process, analysis shows the influence of different jacking footage to soil surface displacement deformation and different jacking force point location to the max jacking force.(3)Numerical simulation was conducted to give a finite element analysis of stress of culvert structures and displacement deformation of the surrounding soil, by selecting different jacking footage and jacking force point location. The result shows: it is suggested to select 0.4m as the optimal jacking footage and the position at the distance from the bottom 0.8m as the optimal jacking force point location.