Research On Settlement And Control Technology For Construction Of Adjacent Houses And Pipelines In Pipe Jacking Tunnels

In recent years,in order to improve the unified planning,design,construction,and maintenance of municipal pipelines,and reduce the frequent occurrence of "road zipper" problems caused by pipeline maintenance,the proportion of urban pipe gallery construction in old urban areas has been increasing year by year.The soil pressure balance pipe jacking method,as the main construction method for pipe gallery tunnels,has the advantages of wide applicability,simple and safe operation,and low economic cost.Currently,it has been widely used in the construction of comprehensive pipe galleries in China.This article relies on an underground comprehensive pipe gallery tunnel in Xi’an to conduct a detailed study on the risks of soil pressure balance pipe jacking tunnel construction in the environment adjacent to building basements and municipal pipelines.Corresponding control measures are proposed to address the existing problems,and finally applied to practical engineering to verify the effectiveness.The main research content is as follows:1.This article is based on a soil pressure balance pipe jacking tunnel project in Xi’an,and uses Midas GTS NX finite element software to establish a model and simulate excavation.By comparing the simulated surface settlement caused by tunnel excavation with on-site monitoring data,the rationality of the model parameters and the usability of the model were verified.2.Through numerical simulation,the paper analyzes the law of surface settlement changes above the tunnel axis and near buildings during the excavation of earth pressure balanced pipe jacking tunnels under different grouting pressures and different soil warehouse pressures,the displacement changes on the retaining wall adjacent to the basement,the stress changes,the displacement changes at various locations of the surrounding underground pipelines,the overall displacement trend changes of the pipeline,and the stress changes.The results show that a.The impact of grouting pressure on the surrounding environment is significantly greater than the impact of soil warehouse pressure.Within a suitable pressure range,the surface settlement curve above the tunnel axis assumes an "S" shape,and the presence of buildings will cause the surrounding soil mass to be more prone to displacement when the tunnel passes.When grouting pressure is suddenly applied to the vertical displacement of the soil mass at the end of the portal,there will be a relatively large uplift and then settlement.The pressure of the soil bin will cause the soil mass behind the excavation surface to uplift and then settle after the excavation surface passes.B.When the pressure increases,the rotational amplitude of the basement of the building decreases,and the trend of stretching increases.The overall vertical and horizontal displacements gradually increase,moving away from the tunnel.The greater the grouting pressure,the greater the displacement of the pipeline at the section where the grouting layer is located,and the vertical displacement is less than the impact of the horizontal displacement,resulting in a smaller overall inclination deformation of the pipeline;The greater the pressure in the soil silo,the closer the pipeline position is,the greater the vertical and horizontal displacement is,and the higher the displacement direction is,the greater the pipeline deflection angle is.Under both factors,the pipeline moves in a direction that is away from the tunnel.3.Based on the problems and laws found in the numerical simulation,and on the basis of fully grasping the on-site working conditions,corresponding control measures for pipe jacking engineering such as advanced grouting,hole reinforcement,control of soil silo pressure,radar monitoring,and pipeline deviation correction are proposed.After using Midas-GTS NX finite element software modeling to verify its feasibility,it is finally applied to practice.Through the implementation of linkage control management inside and outside the tunnel,precise control of key processes in each link is implemented.On the premise of ensuring construction quality,the maximum ground settlement is controlled at about 10 mm,effectively ensuring the safety of surrounding pipelines and buildings.