Study On Deformation Response Of The Stratum Induced By Curvature Shield Tunneling Adjacent To Existing Tunnel

With the acceleration of urbanization and the continuous development and utilization of underground space,there are more and more curved shield tunnel projects.if not paid attention to,its unique over-excavation phenomenon and asymmetry are very likely to cause engineering disasters and even cause casualties.However,at present,the research on the proximity construction of curved shield is relatively few,and the deformation response law of stratum in the process of construction is not clear.Therefore,it is particularly important to explore the deformation characteristics of the adjacent construction of shield tunnel with small curvature radius.Based on the tunnel project of a curved section of Tianjin Metro Line 6,combined with on-site monitoring data,numerical simulation analysis and theoretical formula,this paper studies the influence of proximity construction of shield tunnel with small curvature radius on stratum deformation characteristics.The research results are as follows:(1)Based on a curved section project of Tianjin Metro,the monitoring data such as surface subsidence,tunnel subsidence and segment convergence are analyzed.It is found that the existence of over-excavation phenomenon will aggravate the surface subsidence and lead to the asymmetric distribution of the settlement trough curve.Combined with the numerical simulation data,the influence characteristics of shield tunnel construction with small curvature radius on stratum deformation and the influence law of existing tunnel on curved shield tunnel excavation are summarized.(2)The stratum deformation characteristics of shield tunnel with small curvature radius under different construction parameters(radius of curvature,proximity distance and grouting pressure)and different proximity forms(upper tunnel and lower tunnel)are explored.The radius of curvature has the most obvious influence on the construction of curved shield tunnel,and the surface settlement value and the maximum settlement offset increase with the decrease of curvature radius.(3)Based on the exploration of the stratum deformation characteristics of the proximity construction of curved shield tunnel under different construction factors,the construction disturbance mechanism of shield tunnel with small curvature radius is analyzed,and the parameters of the semi-empirical formula for predicting surface settlement are modified.By introducing the overexcavation coefficient,the prediction formula of surface subsidence caused by the proximity construction of curved shield tunnel is obtained and applied to practical projects to verify its effectiveness and reliability.