Experimental study on dynamic response of a new type of concrete-filled steel tube sleeper ballastless track
The concrete-filled steel tube(CFT)sleeper was formed by connecting the sleeper block with the concrete-filled steel tube member.Based on the CFT sleeper,the CFT sleeper ballastless track structure for urban rail transit was designed.In order to master the mechanical properties of CFT sleeper ballastless track structure under the condition of train operation and verify the safety and rationality of structural design.CFT sleeper ballastless track structure including vibration reduction section and ordinary section was constructed.The dynamic response of rail,sleeper and bed structure of ballastless track at different train speeds was tested and analyzed.The results show that under the operating conditions of train speeds of 40,60 and 80 km/h,the maximum wheel-rail vertical force is 86.18 kN,the maximum lateral force is 13.99 kN,the maximum derailment coefficient is 0.21,and the maximum wheel load reduction rate is 0.23,the test values are significantly less than the corresponding safety limits values,and the ballastless track structure meets the requirements of traffic safety.Under the dynamic load of the train,the maximum compressive stress of the concrete-filled steel tube sleeper steel tube is 3.55 MPa,and the maximum tensile stress is 3.77 MPa,the maximum compressive stress of the sleeper block is 1.32 MPa,the maximum compressive stress of the steel bar in the ballast bed is 2.30 MPa,and the maximum tensile stress is 3.54 MPa,the maximum compressive stress at the bottom of the ballast bed is 0.22 MPa.These dynamic response are meet the stress limit of materials,including that the structure maintains good mechanical performance.The structural design is reasonable and feasible.
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