High-speed Railway Subgrade Dynamic Response Analysis And Model Experimental Apparatus Developed

In Central South University, there is a ballastless track - roadbed test system which belongs to the National Engineering Laboratory of High-speed Railway Construction Technology, the roadbed model is 30 meters long, 15 meters wide and 6 meters high (including 3 meters geosyncline), that is mainly used to study the dynamical response of roadbed structure under the strain loads. At the train speed of 350km/h, how to simulate the effects by setting actuators is very importment. We design the loads referring to CRH3 EMU, considering the superimposed effect caused by the live load from adjacent wheelsets of the adjacent carriages, setting several actuators at sleepers in the middle of the roadbed to simulate the transferring load of fasteners, getting the referring parameters of actuators and load reaction frame by numerical analysis.The studying contents are as follows:1,ANSYS finite element analysis software is used. Plate-ballastless track-roadbed analysis system model is set up according to the deformations and vibration characteristics of all the parts of the track-roadbed system and the actual size of the model.2,Aiming at the condition that train speed is 350km/h, wheel load is 85kN, analysing the relation between vertical stress, equivalent stress, vertical displacement, vertical strain, equivalent strain, velocity, acceleration and time at different depth below the rail on the middle section of the roadbed, and the relation between the amplitude of each response and depth also be studied. Uperimposed effect can be seen among the wheel loads, the answer of roadbed is diffusing and attenuating following the increasement of depth, and the effects of resonance is adviced to been considered under the design of loadbed.3,Numerical analysis is used, fastener reaction amplitudes, frequencies and track board displacement amplitudes are obtained at different velocities and wheel loads. According to the similar previous-information, under the condition that wheel load is85kN, and train speed is 350 km/h, the actuator parameters at 11.05m setting length of 0.65m space are obtained: strength amplitude is 76.5kN, route is 0.78mm and frequency is 40Hz; under the same condition, the actuator parameters at 11.05m setting length of 1.95m space are also obtained: strength amplitude is 164.07kN, route is 1.05mm and frequency is 40Hz.4,We discuss the simulating transmission effect of fasteners under setting eighteen actuators at 0.65m space and six actuators at 1.95m space, it is find that they all have good simulation.5,In considering the model size, actuator parameters requirements and the biggest displacement of beams should be≤1.0m under load of 50t, with static force, mode and harmonic response analysis, obtainning the design size of the load reaction frame according to the design of MTS load frame.