The Effect Of Logarithmic Subsidence On Internal Force And Deformation Of Railway Track Due To Dewatering

The regional land subsidence caused by groundwater exploitation seriously disturbs track regularity and endangers the safety of line operation.Most of the existing studies are based on the cosine settlement curve for numerical simulation analysis,without considering the specific causes of uneven settlement.Compared with post-construction settlement of subgrade,land subsidence under subgrade caused by overexploitation of groundwater is the main cause of track deformation.Different from cosine type land subsidence,pumping from aquifers causes logarithmic land subsidence.Based on this formula,a calculation method considering the influence of logarithmic subsidence on the mechanical properties and deformation of the track of local hanging under rail is presented in this paper.With subsidence increasing,ground surface separates from railway track.The railway track on ground was simplified as a mechanical model of a Bernoulli-Euler beam on elastic foundation with uniform material quality.The elastic foundation implied shear action of soil,and the beam was divided into two segments: hanging segment and non-hanging segment.The control differential equations and the boundary conditions for these two beam segments were presented.The internal force and deformation of two beam segments were obtained by finite difference method.Sensitivity analysis of each parameter is made through programming.On this basis,the general law of the influence of concentrated load and concentrated couple on the static characteristics of track under the most unfavorable conditions is further studied.A numerical analysis model is established by using finite element software to reflect the mapping relationship between land subsidence and deformation and internal force distribution of high-speed railway track layer,thus the rationality of the method is verified.The results show:(1)The slope of the land subsidence curve and the distance between the track and the center of subsidence funnel have great influence on the track.Keep far away from the center of subsidence funnel and prevent the slope of subsidence funnel from increasing can reduce the hanging length and the influence on the deflection,rotation,moment and shear of the track.(2)The long-term action of concentrated force P and concentrated couple M on the rail surface at the center of the settlement funnel will lead to the acceleration of the deformation of the track structure and the sharp increase of internal force,which seriously endangers the traffic safety.