The Effect Of Sleeper Structure On Stress In Bonding Interface Of Young-Old Concrete Of The Casst-In-Place Ballastless Track

The paper systematically summarizes the domestic and foreign development and improvement course of the structure of sleeper in the cast-in-place Ballastless Track. It makes out that sleeper structure imposes great influence on the stresses distribution in bonding interface of the young-old concrete. Researching this influence makes sense to the Ballastless Track innovation.It introduces the structure of the widely-used doubled-block sleeper and the newly-designed longitudinal sleeper and the application of them on the ground, bridge and in the tunnel. It also compares the composition of the system and the design structure of the two style sleeper.Based on thermodynamics, using the APDL language of ANSYS by finite element method, the paper compiles a universe programme.which can carrys out static and thermal-structure coupled analysis to the cast-in-place slab. The programme can build cast-in-place Ballastless Track models with various structure of sleepers and can analyse the temperature field, temperature gradient, coupled thermal stress and structural sress in the bonding interface of the young-old concrete.at the same time. In the finite element model, the sleeper, the roadbed slab and the HGT slab are simulated by solid element; the rail is simulated by three-dimensional bridge element; the fasteners and the ground are dispersed into linear an nolinear spring elements and the reinforcing steel bars are simulated by link elements.First, the cast-in-place Ballastless Track model with doubled-block sleeper and that with longitudinal sleeper are respectively built. In the two models, the temperature field, temperature gradient and the thermal coupled stress in the bonding interface of young-old concrete are analysed by contrast in the couse of casting concrete and under the changeable air temperature.The structural stresses in the bonding interface caused by the vertical and transverse forces of the train and the asymmetric settlementment are also analysed by contrast. It makes out from the result that under the effect due to change of temperature, changing the structure of sleeper may impose great affecting on the situation of stress in the bonding interface of yong-old concrete. The result of contrastive analysis tells that the longitudinal sleeper is better than doubled-block sleeper somewhere,but also needs to be improved farther. Based on the contrastive analysis, the programme builds various structure of sleeper models to find out how the diffence of the length,width and the thickness of the sleeper and the gap between two sleepers in the model affects the stress in the bonding interface. From the result, the paper gets some important conclusions and suggestions when the sleeper is designed.