Test Research On Ballast Track Structure Of 35t ～40t Axle Load

In the United States、Australia and other countries,the iron ore transportation train axle load is 35t~40t.In order to meet the needs to participate in heavy-load railway market and to improve the heavy-load railway technical system,the researchers proposed the ballast track structure technology with 35t~40t axle-load.In order to demonstrate the structural safety and stability of ballast track with 35t~40t axle-load and to evaluate the safety reserve of track component strength,based on the analysis of the current situation of heavy-haul railway track structure,aiming at the structure and components of 35~40 tons axle load ballast track newly developed in China,theoretical analysis,indoor full-scale model test and dynamic test of large axle load vehicle were carried out.The results showed that the newly developed heavy-load ballast track structure can meet the operational requirements of 35-40 tons axle load.The paper has collected the relevant data of ballast track standard,track components,track structure,theoretical analysis and experimental research of heavy-haul railway.The characteristics and technical requirements of ballast track structure of heavy-haul railway were summarized and analyzed.The rationality of ballasttrack structure and components newly developed in China was analyzed.The ballast track structure of 35 t~40 t axle load is as follows:68 kg/m rails,IX or VIII fasteners,Ⅴb-1 or Vb-2 type sleeper.The dynamic response of the train passing through the linear section and the curve section with different radius at different speeds was analyzed by establishing the dynamic model of the track with high axle load.The analysis results showed that the safety and dynamic performance of heavy load vehicles meet the relevant requirements.When the radius of the curve is reduced from 1000m to 300m,the derailment coefficient increased from 0.22 to 0.59,rate of wheel load reduction increased from 0.3 to 0.37,lateral wheelset force increased by 35 kN to 51 kN and car body vertical acceleration increased from 1.15 m/s~2 to 1.23 m/s~2,lateral acceleration increased from 1.0 m/s~2 to 1.31 m/s~2,All the safety parameters are less than the safety limit,and the vertical and lateral vibration acceleration of the vehicle body meets the requirements of the limit value of operation quality evaluation.In the state key laboratory of track technology of high-speed railway,a full-scale model of a 7-meter-long ballast track with axle load of 35t~40t was laid,which verified the elasticity,load transfer performance and track structure stability of the ballast track with heavy load of 35t~40t.The experimental study found that the pressure of the middle fulcrum accounted for 38.5%of the vertical load,which was close to the theoretical calculation value of 40%.When the transverse movement of the rail reaches 4mm,the rail will not overturn and can maintain the state of transverse elastic deformation.The fastener used can ensure the stability of the geometric state of the track.In the bending moment test,the positive bending moment at the cross section under the rail and the negative bending moment at the cross section in the middle of the prestressed concrete sleeper are 12.7kN·m and 11.7kN·m,the prestressed concrete sleeper have a certain margin of safety under different load combinations.On the HTL ring line of TTCI in the United States,the test section of ballast track structure with 35t~40t axle load was laid.The dynamic test was carried out to study and analyze the dynamic response of track structure under the action of 35t~40t axle load train.The maximum derailment coefficient is 0.73,the maximum weight reduction rate is 0.49,the maximum transverse force of the wheel is 47.4kN,the test results are within the scope of the security limit.The measured results of the load bending moment are less than the design load bending moment.The experimental ballast structure can ensure the safety of the 35t~40t axle load cargo train.