| Building ballastless track on soil subgrade is at the initial stage in our country. The subgrade's vibrational and deformable characteristics under the train loads are needed to be carried out in-depth systematic study to ensure the operation safety of high-speed train operation Therefore, in this paper, numerical simulation is used to study the subgrade's dynamic response and its influencing factors of the high speed railway. The main contents and conclusions are as follows:(1)Based on a large number of literatures, this paper comprehensively summarizes the domestic and foreign ballastless track structure styles and their characteristics, elaborates on the subgrade's status and characteristic of high-speed railway, the development of high-speed railway's soil subgrade and the problems of building ballastless track on soil subgrade.(2)For the type I ballastless track, Dynamic numerical model of high-speed railway subgrade is established using software FLAC3D. Moving line source of non-uniform load is used as vertical excitation to simulate the dynamic load of 4 wheel of the adjacent railway carriages' adjacent two bogies. This paper calculates and analyzes the dynamic response generated by the high speed train in the embankment. It's obtained that the vertical dynamic stress and deformation exponentially weaken along depth; the subgrade's dynamic response is mainly within the base bed, and it behaves the most obvious in the surface of base bed.(3) With the numerical model, the subgrade's dynamic responses of the different train axle load and speed are calculated. The analysis indicates that there are approximately linear relationship between the amplitude of vertical dynamic stress and deformation and the speed and wheel load of the train.(4) It analyzes the influence law of each structural subgrade layer's thickness to the dynamic response of each subgrade structural layer, and proposes that the thickness of surface layer of the subgrade could choose 0.4-0.8m, the thickness of the underlying subgrade must be greater than 2m. (5) It analyzes the influence feature of each subgrade structural layer's stiffness to the dynamic response of each subgrade structural layer. The analysis shows:The changes of a layer's dynamic stress created by the change of the under-parte layer stiffness is the maximum; with stiffness increasing subgrade's vertical displacement is decreasing, The changes of subgrade's vertical dynamic deformation created by the changes of the stiffness of the embankment under subgrade bed is the maximum. |
