Research On Slab Track Based On Polyurethane Elastic Filling Layer

Based on the analysis of the track structure for urban rail transit and the experience of slab track in high speed railway,the paper developes the scheme of slab track based on polyurethane elastic filling layer,to improve the construction efficiency and durability,to reduce the cost of vibration attenuation measures.Based on the results of theoretical analysis and engineering practices,it is suggested that the width of the track slab should be 2.1m ~ 2.3m,the length should be 2.8m ~ 5.6m,the thickness of the track slab should be 0.24 m in general section and 0.3m ~ 0.35 m in vibration attenuation section.The support stiffness of the polyurethane elastic filling layer is 1MPa / mm in general section and 0.05 MPa / mm in vibration attenuation section,the length of polyurethane elastic filling layer should be the same length as the track slab,and the support width should be 0.3m.Dynamic analysis results show that the maximum displacement of the rail and track slab does not exceed the relevant requirements in ?Technical Code for Floating Slab Track? when the stiffness of polyurethane elastic filling layer is 0.05 MPa / mm,and the stiffness of polyurethane elastic filling layer is feasible.Laboratory test study on polyurethane elastic filling layer was carried out,the dynamic and static ratio and fatigue performance were investigated under the compressive stress 0.03~0.3MPa.The results show that the dynamic and static ratio of polyurethane filling is below 1.5,the maximum change rate of stiffness after fatigue is 14%,and the maximum change rate of thickness is 2%,which meets the relevant limit requirement.The experimental results show that the tensile strain of the track slab is increased by the design load of the train(2 times static axle load),but the strain amplitude is smaller than the concrete design strength.Under the action of train static axle load,the maximum vertical displacement amplitude of the track slab does not exceed the relevant specification requirements.The dynamic loading test shows that the dynamic strain of track slab is within the relevant limit range.The experimental results by means of falling weight show that the vibration damping effect in the range of 1 ~ 200 Hz is 10.6 ~ 11.4 dB.The field test results reveal that the safety parameters such as derailment coefficient,load shedding rate and axle lateral force are smaller in the range of safety limits when the train passes the test section at different speeds.There is no significant difference in the vertical force of the wheel and rail in different sections,and it is much smaller than the design load.In vibration attenuation section(0.05 MPa / mm)the maximum displacement between adjacent track slab is 0.34 mm and does not affected the smooth operation of the train.Compared with the ordinary rigid track bed with DTVI2 fastener,In vibration attenuation section(0.05 MPa / mm),the vibration reduction effect is 13.3 ~ 16.7dB in the range of 1 ~ 200 Hz.