Study On Influence Of Pipe Jacking Construction On Existing Structures In Urban Underground Engineering

Based on the Tongzhou branch line of South to North Water Diversion Project 4 tenders wear Jingha highway engineering pipe jacking,using FLAC 3D finite difference numerical simulation of pipe jacking method of software,research the method of pipe jacking construction of existing buildings(highway and gas pipeline)disturbance influence law,experiment research has been done in crossing the highway caused by pipe jacking method the construction of the road surface subsidence.The main contents and results are as follows:(1)The disturbance mechanism of pipe jacking construction soil analysis,soil displacement and pavement settlement by the construction caused by soil loss,soil loss is the main method in construction of pipe jacking is divided into two parts of excavation face and grouting soil loss,soil loss and the two parts in the construction process of the earth pressure,grouting pressure is directly related to.(2)The difference method and effect of grouting pipe jacking method and shield method based on the mechanism of pipe jacking grouting caused by soil loss is bigger,therefore in the study of 3-D numerical simulation of pipe jacking method is proposed by using the loss of soil stress release method to simulate the construction of grouting pipe jacking method caused by the loss,and achieved good results.(3)Through three-dimensional numerical simulation study shows that the earth pressure and grouting pressure caused by pipe jacking construction directly affects the pavement subsidence,the reasonable control of earth pressure and grouting pressure can effectively reduce the pavement settlement caused by construction,too large or too small earth pressure and grouting pressure will lead to larger settlement of road surface.(4)Through three-dimensional numerical simulation of vertical pipe jacking construction beneath the existing gas pipeline,the earth pressure displacement control of gas pipeline level caused by construction,earth pressure and grouting pressure controlled gas pipeline vertical displacement caused by construction;the earth pressure is too large,will cause the gas pipeline has great positive(along the direction of construction)the horizontal displacement,the earth pressure is too small,will cause the gas pipeline have a greater negative(inverse construction direction)horizontal displacement;too large or small grouting pressure and the earth pressure will lead to increase the vertical displacement of gas pipeline.(5)Through the measurement of parallel pipe jacking construction,pipe jacking construction after the roadbed subsidence caused by the construction of pipe jacking is significantly greater than the first settlement of road surface subsidence caused by pipe jacking;after the groove curve is not symmetrical;the total construction settlement after the construction side peak bias;in the process of construction,the shield earth pressure leads to uplift the road ahead,the earth the pressure is too small in front of pavement settlement.