| As a fast and convenient means of transportation,high-speed railway plays an important role in economic and social development of China.In recent years,the frequency of extreme rainfall events in China has increased gradually.Mud pumping of high-speed railway subgrade will occur under the combined action of extreme weather such as heavy rainfall and intensive train operation,adversely affecting the safe operation of trains.Injection with polymer materials is a potential technology for subgrade remediation.The key problem about maintaining good dynamic behaviors of track-subgrade system is to determine the appropriate elastic modulus of injection filler and the range of injection remediation.Based on the full-scale model tests of ballastless track-subgrade,mud pumping under train moving loads could be repeated in the laboratory,and the influence of mud pumping and injection remediation on the dynamic behaviors of track-subgrade was researched.3D finite element numerical models for vehicle-track-subgrade were established,realizing the responses analysis of track slab with different elastic modulus of injection filler and range of injection remediation.The main contents are listed as follows:(1)A full-scale model of ballastless track-subgrade was established with an auxiliary rainfall simulation device to repeat mud pumping under train cycle loads.Injection remediation was carried out in the area where mud pumping occurred.The dynamic behaviors of track-subgrade were researched by conducting uniaxial harmonic sweep frequency tests.The vibration responses of track-subgrade and cumulative settlement of subgrade were obtained under train moving loads.(2)Based on the full-scale model of ballastless track-subgrade,3D finite element numerical models for vehicle-track-subgrade were established by using the finite element software ABAQUS.The correctness and validity of numerical models were verified in normal condition,before and after remediation of mud pumping.The vibration responses of track-subgrade and strain of track slab were analysed based on the authenticated finite element models.(3)Based on the established numerical models,parameter optimization analysis of the clastic modulus of injection filler and the length of injection area was carried out.The influence of these two key parameters on the vibration of concrete base along the longitudinal orientation,the vibration of subgrade along the horizontal orientation,the strain of track slab were studied.The aforementioned research work can provide theoretical basis for the evaluation of the influence of mud pumping of ballastless track-subgrade on the operation safety of trains and the optimization of key parameters of injection remediation. |
