Research On The Risk Monitoring Of Box Culvert Construction Cross Below The Existing Railway

The box culvert underpasses the existing railroad jacking construction method is the main method to solve the road and railroad crossing.The level crossing was changed to an interchange.Due to its unique advantages and applicability,it was widely used and popularized by major cities,which greatly relieved the pressure on urban traffic and solved the traffic bottleneck problem at level crossings.The construction of box culvert must cause the displacement of the surrounding subgrade soil.If the displacement exceeds the risk control value,it will lead to the failure of the engineering jacking.The method to effectively control the displacement is very important for construction safety.This paper selected the construction of a large box culvert underneath the Shide railway and used field monitoring and numerical simulation methods to control the construction culvert risk in all directions.The article selected reasonable construction techniques in light of engineering conditions;analyzed key and difficult points of the project to carry out risk assessment;analyzed the risk grades of box and culvert construction to monitor the unfavorable position of the project;established a sound risk monitoring system to ensure the normal construction of the box and culvert and the train safe operation.Organizing the monitoring data changes on the site to analyze the risk of the construction of the box culvert.Once the monitoring data exceeds the risk control range,timely selection of reasonable risk control measures to correct the construction,the obvious control effect can be constructed.A three-dimensional numerical model for the construction of box culverts was established to analyze the changes in subgrade settlement and track settlement caused by excavation,which was basically consistent with the changes in on-site monitoring data.Calculation results of the final subgrade settlement simulation,after comparing with the on-site monitoring data,the rationality of the model will be verified.The numerical model was used to further study the effect of single-factor excavation step size and the presence of dynamic load on the subgrade settlement,and reasonable construction parameters were proposed;finally,the risk control measures and emergency measures to reduce the displacement of soil layer are proposed to provide reference for similar projects.The research shows that:after optimization of the construction parameters,the prevention of the settlement of the roadbed by the protective piles achieves a reduction of 45%to 51%,and the control effect is obvious.Along the line direction,the maximum subsidence of the subgrade is not at the axis,but is about 10m away from the axis of the offset box culvert.The horizontal displacement of the box and culvert at the central axis position is the maximum.Considering the construction cost and construction safety,the optimal construction speed is determined to be 2m/d.