Research On The Influence Of Metro Shield Construction On The Deformation Of The Surface Railway Ballastless Track Structure

When high-speed railway construction,in recent years,makes great success,the urban rail transit construction is also in full swing in China.It’s of great possibility that the construction of subway will underpass the high-speed railway.Therefore,the article comprehensively uses technical methods such as literature research,numerical simulation and theoretical analysis to explore the deformation transmission mechanism from the stratum to the rail,and the following conclusions are obtained:(1)Shield excavation will simultaneously affect the displacement of the soil at the rear,at the excavation site,and at the front at the same time.These areas could be divided into Zone I,Zone II and Zone III in turn.The supporting functions existing in Zone I is the lining layer;Zone II,the shield machine shield;and Zone III,the lining layer,the natural unexcavated soil below.The order of supporting strength from strong to weak is: Zone II>Zone III>Zone I Area.The order of the settlement magnitude of the soil in each area of a single excavation should be Zone I>Zone III> Zone II.(3)It’s the weight of the track structure that maintains the vertical connection between the track structure and the subgrade.When the shield tunnel is in construction under the ground,there will be a subsider on the subgrade and the track structure will deform by gravity.If the depth of the subsider is small,there will be incomplete flexural deformation on track structure,first,whose value is approximately equal to the depth of the subsider,and then the track structure will be in contact with the subgrade with deforming together.If the depth of the subsider is large,there will be complete flexural deformation on track structure with void area between the track structure and the subgrade.(4)The mechanical model of the track structure under the vacant condition can be simplified to a beam model fixed at both ends under a uniform load,and the material mechanics solution is used as its deformation calculation formula.The deformation of the track structure under non-empty conditions is composed of two parts.One part is the deflection deformation of the track structure which can be approximated by the Peck correction formula;the other part is the coordinated deformation of the track structure and the subgrade.which can be calculated with the mechanical model simplified as a short beam on the elastic foundation fixed at both ends under a uniform load,and the Long Yuqiu solution is used as the calculation formula for the coordinated deformation part.