Influence Of Subway Tunnel Excavation On Utility Tunnel

With the development and utilization of underground space,more and more construction of underground architectural structures are near the existing building structures,and new subway tunnel passing through the existing utility tunnel is a typical example.The construction of new tunnel will cause the changes of stress field and displacement field of stratum,and these changes will directly effect on the utility tunnel,resulting in the destruction of the utility tunnel.Therefore,the study on influence of subway tunnel construction on utility tunnel has important practical significance.In this article,the effect of subway tunnel construction on displacement and internal force of utility tunnel is studied by using numerical simulation and theoretical analysis.A set of control measures of for the influence of subway tunnel construction on the utility tunnel is also summarized in this thesis.The main research work and results are as follows:(1)The surface subsidence law caused by tunnel excavation is simulated by the finite element numerical analysis method.In the range of the distance from the center of the line 5m,the surface settlement is greatly influenced by the tunnel excavation.When the excavation step is close to a section,the influence of the surface settlement on this section is gradually increased.The reliability of the finite element model is verified by comparing the simulated value with the measured data.(2)The influence of the dynamic process of tunnel excavation on the upper utility tunnel structure is simulated by selecting two working conditions,one the tunnel parallel to the upper utility tunnel and the other the tunnel and the upper utility tunnel are orthogonal.The result shows that: when the tunnel and the upper utility tunnel are orthogonal,the overall settlement curve after the tunnel excavation is similar to the normal distribution curve;when the tunnel and the upper utility tunnel are parallel,the overall deformation of the pipe gallery in tunnel excavation is S shape.Compare these two working conditions,it is known that the maximum tensile stress and the settlement of the utility tunnel is more unfavorable when the tunnel is excavated parallel to the utility tunnel.(3)The factors of non-deformability of utility tunnel is analyzed.The influence of the thickness of wall,the size of the axils,the relative distance of the utility tunnel and tunnel,the radius of the tunnel excavation,structure form and stiffness distribution the utility tunnel on the settlement and stress of the utility tunnel were studied.The influence of wall thickness,axillary size and stiffness distribution on the settlement and stress of the utility tunnel was small.The influence of tunnel excavation radius,the relative distance of the utility tunnel and tunnel,structure form of the utility on the settlement and stress of pipe corridor is great,which should be paid more attention in the design and construction project.(4)The influence of subway tunnel construction on utility tunnel is studied through theoretical analysis.Based on the Winkler elastic foundation beam model and the sedimentation formula in buried depth of utility tunnel obtained by simulation in this study,the settlement and deformation control equation of the upper utility tunnel caused by the excavation of the subway tunnel is derived.The influence of tunnel excavation on utility tunnel settlement under different longitudinal stiffness is analyzed.The maximum settlement displacement of utility tunnel decreases with the increase of longitudinal stiffness(5)Based on the existing research results and the research results in this paper,the causes of failure,safety assessment methods and corresponding protection and control measures of utility tunnel are summarized.