Test Research On Ballast Mat Of Heavy Haul Railway

The ballasted track is used for heavy-haul railway. The track stiffness in bridge section is significantly larger than that in subgrade section. The wheel/rail impact load in bridge section is obvious. The life of ballast track is short, and the maintenance is difficult. The ballast mat is a effective technology to improve the ballast track performance, and the life of the ballast track can be prolonged.The references related to the ballast mat were studied in this thesis. Based on the conditions of heavy-haul railway in China, the principle of stiffness design of ballast mat was proposed by the continuous deformation between bridge and subgrade sections. The stiffness and loading range were calculated using the track strength theory. The heavy-haul freight and elastic track model was put forward under vehicle-track coupled theory to analyze the dynamic responses of ballast mat. The reasonable stiffness value was determined by the comprehensive comparison of simulation results. The technical requirements and testing methods were proposed. The sample test was conducted in lab. The effect of ballast mat was evaluated by tests in lab, and in Shuohuang and Shanxi Central South railways.The elasticity of track can be improved because of ballast mat according to the references from all over the world to reduce the impact on the subgrade and prolong period of maintenance. The effect of ballast mat can be maintained in the long term. The static module of ballast mat for heavy-haul railway is 0.15±0.01 N/mm3. The ballast mad height and width is 15mm and 1.25m. The pilot ballast mat was manufactured in related factories. The tests of static, dynamic stiffness and fatigue were conducted. The static module of ballast mat is 0.140～0.154 N/mm3, which meet the technical requirement of 0.15±0.01N/mm3. The ratio of dynamic stiffness to static stiffness is 1.30-1.58, which meet the technical requirement of less than 2.4. The change rate of static module of ballast mat is 4%, which is less than 10% specified in technical specification. The crushing rate of ballast particle was very slight because of ballast mat. The elasticity of track can be maintained very well. The deformations of track between with and without ballast mat was similar. The dynamic results in Shuohuang and Shanxi Central South railways showed that derailment and deloading coefficients and wheelset lateral forces were under the criteria. The ballast mat can be safely used for heavy-haul railway with 30t axle load. The elasticity of track can improved by ballast mat which is also good at the track stiffness consistent in section where the foundation is rigid. The rail-seated load is reduced by 30～40%, compared to bridge sections without ballast mat. The acceleration and vibration in high frequency range of bridge deck were reduced. The loads applied on the track were reduced.