Study On The Effect Of The Differential Settlement Of Subgrade On The Mechanical Properties Of Ballastless Track In Switch Area

The control of Settlement is the key issue to pave Ballastless switches on the roadbed. Structural and geometric features of the switch cause a complex interaction mechanism between the train and the switch in high-speed operating conditions. Switch irregularity caused by deformation of foundation will increase the dynamic response of the train-switch system, which will seriously affect the safety, comfort and stability of the operation. This paper studies the deformation and stress distribution of Ballastless track structure in differential settlement regions through the quasi-static analysis. And this text finds out the parts that are most liable to be affected by the differential settlement.This paper mainly discussed the mechanical analysis of the ballastless switches in differential settlement regions by FEM programme. Elastic point support unit model is used to simulate the rail. The support spring unit is used for fastening. Rail boards, mortar bed, supporting bed are simulated by solid element, the supporting of foundation is simulated by nonlinear spring element, the change of differential settlement curves is simulated by regulating the rigidity of nonlinear spring. All the mechanical analysis is based on the assumption that the changes of roadbed settlement follow the cosine curve.This paper simulated the displacement deformations and the forces of the track structure in the switch area under the longitudinal differential settlement; it considered the influence of transverse differential settlement for the first time and analyzed the displacement deformations and the forces of the ballastless track in subgrade settlement area by different settlement chords, different subsidence amplitudes and different speeds. The major tasks are as follows:built the subgrade-ballastless track-switch static modal and transient dynamic modal by the general finite element software ANSYS, which to simulate the displacement deformations and the forces of the track structure under the longitudinal differential settlement and analyzed the displacement deformations and the forces of the ballastless track in subgrade settlement area in the different settlement chords, different subsidence amplitudes and different speeds through the deformation curves combinations of solid elements, quality element and nonlinear spring, and found out the sensitive parts of track; proposed the differential settlement limits in accordance with ensuring the track does not appear empty hanging phenomenon; analyzed and summarized the response to the law in the switch area under the longitudinal differential settlement.