FIELD TEST AND STATISTICAL CHARACTERISTICS OF WHEEL-RAIL FORCE FOR SLAB TRACK WITH PASSENGER AND FREIGHT TRAFFIC

The increase of axle load of a freight vehicle for railways with passenger and freight traffic will certainly lead to an obvious increase of train load. Since the track structure sustains the dynamic load of moving train directly, it is necessary to do further research for statistical characteristics of wheel-rail forces of railways with passenger and freight traffic. In order to measure the vertical wheel-rail forces of the passenger vehicle and freight vehicle on CRTS I slab, two field tests at Caijia station of Suining-Chongqing railway and at Yuzui No.2 tunnel of Chongqing-Huaihua railway were carried out by applying the IMC dynamic data acquisition system. Meanwhile, a vertical vehicle-track coupling dynamic model was established to calculate the wheel-rail forces of a passenger vehicle and a freight vehicle with respect to the different velocities and the irregularity excitations. The statistical characteristics of wheel-rail forces for slab track with passenger and freight traffic were investigated by comparing the computational results with the experimental data. The results show that: a) wheel-rail forces for slab track with passenger and freight traffic were similar to normal distribution, and more than 95% of the values concerning the wheel-rail force caused by passenger vehicles and freight vehicles range in the domain of 45 kN~90 kN and 100 kN~150 kN respectively, which correlates well with the actual experimental observations; b) the probability density curve of the wheel-rail forces caused by passenger vehicle and freight vehicle become fatter and shorter with the increase of velocity and amplitude of irregularity, and thusly, the distribution range of the wheel-rail force will be broaden due to the increase of velocity and the degradation of railway condition, and the latter factor affects the distribution of the wheel-rail forces more seriously than the former's; c) if the 1.5 times of the static wheel load and the maximum value of the wheel-rail force are set as the control indexes, it is suggested that the velocity of passenger vehicle for slab track with passenger and freight traffic should be controlled under 180 km/h, whereas the freight vehicle should be no more than 100 km/h.