| With the increasing demand for the utilization rate of underground space,the rectangular pipe jacking method is gradually popularized,but the rectangular pipe jacking has a great influence on the surrounding soil and structure during the construction process.Therefore,it is of great engineering significance to study the influence of rectangular pipe jacking construction on the settlement and deformation of overlying existing roads and pipelines.Based on the background of Dalian Road(Qinghai Road-Baohe Avenue)road and the comprehensive pipe gallery project of Hefei Binhu Science City Dalian Road(Qinghai Road-Baohe Avenue),this paper studies the general law of settlement and deformation of existing roads and pipelines in the process of rectangular pipe jacking construction utilizing theoretical analysis,numerical simulation,and in-situ monitoring.The grey correlation theory is used to analyze the contribution of each influencing factor to the settlement and deformation of existing roads and pipelines.The main conclusions are as follows:(1)Based on previous studies,the calculation formula of surface settlement caused by pipe jacking construction is derived,and the applicability of the formula is proved by combining the existing engineering cases.(2)Road settlement increases with the increase of the width-thickness ratio of pipe jacking,but its influence is limited;The road settlement increases with the increase of the width-height ratio of pipe jacking,and when the width-height ratio is 1.4～1.8,it is the most favorable for construction;When the ratio of excavation pressure to static earth pressure and the ratio of grouting pressure to overlaying earth pressure increases,the settlement of the road lowers.Following careful analysis,the grouting pressure should be kept at 0.64 to 0.8times the overlaying earth pressure,and the excavation pressure should be kept to within one time the static earth pressure;The elastic modulus and cohesion of the soil in the pipe jacking crossing section are negatively correlated with the deformation of the upper road.(3)The maximum settlement value of the pipeline and the differential deformation of the pipeline decrease with the decrease of the diameter-thickness ratio.The diameterthickness ratio should be controlled in the range of 40 ～ 53.3 as far as possible in the pipeline design;For pipeline materials,as the pipe-soil stiffness ratio increases,the maximum settlement value of the pipeline and the differential deformation of the pipeline decrease.PVC and concrete materials should be used as little as possible during pipeline fabrication;With an increase in the vertical-width ratio of the pipeline,the maximum settlement value and differential deformation of the pipeline decrease,albeit the degree of the decline weakens over time;The maximum settlement value of the pipeline steadily lowers as the angle between it and the tunnel grows,but the differential deformation of the pipeline gradually rises.According to a thorough investigation,the angle between the pipeline and the jacking tunnel should be kept between 45 and 60 degrees;The maximum settlement value and differential deformation of the pipeline decrease with the increase of tunneling pressure-static earth pressure ratio and grouting pressure-overburden earth pressure ratio.(4)The grey correlation theory is used to analyze the influencing factors,and it is concluded that the factors affecting the settlement of the overlying road are as follows: pipe jacking size,grouting pressure,overburden thickness,excavation pressure,soil elastic modulus,and soil cohesion.For the factors affecting the settlement of existing pipelines,the contribution degree from large to small is a relative angle,vertical spacing,grouting pressure,diameter-thickness ratio,excavation pressure,and pipeline material.(5)Determine the appropriate construction parameters,combined with on-site m onitoring data to verify the feasibility of the model.Figure [143] Table [6] Reference [70]... |
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