Study On Influence Of Shield Tunneling On Pipe Culvert In Sandy Pebble Formation And Control Measures

This article is based on a certain section of the Chengdu Subway as an engineering support.The working condition of the project is that the shields in sand and gravel formations pass through large-scale pipe culverts and highways.The construction conditions of the interval sections are complex and require high construction technology.In the early period of shield construction,there were five abnormal shutdowns of the shield machine at different times,and settlements exceeded the limit at individual measurement points.The shield machine is about to wear a large-scale pipe culvert in the next phase of construction.It needs to take certain pre-control measures to ensure the safety of the pipe culvert.This paper adopts a combination of practical engineering and FLACD3 D numerical simulation.The main research contents are as follows:(1)Model the preliminary construction section and verify the reliability of the numerical simulation modeling program by using the actual survey data of the previous construction section;(2)The four main factors of culvert settlement were numerically quantified and processed into the model for calculation.The parameter optimization program for the shield tunneling machine was found;(3)the parameter optimization program was applied to the engineering case,and the numerical simulation results for the culvert were calculated.Comparing the measured values of the project with the allowable values of the specifications,confirming that the optimized solution is feasibleAfter the above studies,the following conclusions are obtained:(1)The results of numerical simulation can meet the error requirements,the modeling scheme is feasible,FLAC3 D software can accurately simulate the settlement of the actual engineering of the working conditions;(2)Simulation of different factors in different Under the influence of numerical values on pipe culverts,compare the codes to find out the working limit state of pipe culverts and determine the shield parameter optimization plan.This method is verified by engineering cases;(3)In this project case,the shield excavation speed should not exceed 3m./ Step,the pressure ratio of the excavation face support should not be less than 0.4,the grouting thickness should not be less than 50 cm,and the grouting pressure should not be less than 0.20 MPa.This data can providereference for similar projects.