Design Method And Optimization Of Three Rail Track Concrete Sleeper

Infrastructure connectivity is a priority area of the Belt and Road Initiative.The different railway gauges in the world seriously restrict the implementation of the Belt and Road initiative.Dual-gauge railway technology is an important method to connect two kinds of gauge railway lines.The sleepers are subjected to two kinds of train loads,and there is no relevant research on the distribution law of the supporting reaction of the ballast bed.Due to the asymmetric characteristics of the track,the stability of the sleepers is low,but the existing sleepers are difficult to meet the high lateral resistance requirements of the ballast bed.Regional materials may also become a limiting factor for high-performance concrete sleepers.In order to solve these problems,taking 1435mm/1000 mm three rail track sleepers as the object,the structural design method,the ballast lateral resistance lifting method and the material performance optimization method are studied,which has theoretical value and engineering significance.The main research work is as follows.(1)Based on the relationship among sleeper dimensions,the goal of sleeper structure design is put forward,the ballast support reaction mode of three rail track sleepers is determined,and the method of three rail track sleepers structure design is constructed.By sorting out the design parameters of sleeper structure,the design objectives of sleeper structure are put forward,and the preliminary design and trial production of sleepers are carried out accordingly.The distribution force beam which can simulate the 1435mm/1000 mm wheel load and the rubber pad which can simulate the ballast bed are customized.The ballast bed support reaction mode of three rail track sleepers is determined by full-scale test and simulation method.The results show that the ballast bed support reaction has obvious asymmetry characteristics.Based on the objective function of sleeper design,dimensional constraints and the bearing reaction distribution of ballast bed,the design process of three rail track sleepers is proposed.(2)The relationship between the lateral resistance of ballast bed and the critical temperature rise is analyzed,and the calculation method of the lower limit value of the lateral resistance of ballast bed in three rail track CWR track is put forward,according to which the method of raising the transverse resistance of the bed is studied.The finite element method is used to simulate and analyze the relationship between the lateral resistance of ballast bed and the critical temperature rise under various unfavorable working conditions,and the calculation method of the lower limit value of the lateral resistance of ballast bed on three rail track CWR track is put forward.The roadbed lateral resistance of the trial sleeper obtained by field test and correction is 12.54 k N/sleeper,which can not fully meet the global temperature difference conditions;For this reason,according to the basic dimensions of narrow waist type,double-block type and occlusion type sleepers with equal weight,the lateral ballast resistance of different types of sleepers under the same working condition is analyzed by using the method of combining discrete element method simulation with field full-scale test.The results show that the lateral resistance of the ballast bed is increased by about 5%,8%,10% and 75% respectively when the sleeper adopts trapezoidal cross-section,double-block type,narrow waist type and occlusion type structures,which fully indicates that the lateral resistance of the ballast bed can be significantly improved by optimizing the sleeper shape.Based on the results of ballast lateral resistance research,the objective function of sleeper geometry optimization based on ballast lateral resistance and the comprehensive optimization design process of sleepers are proposed.(3)The influence of regional materials on high performance concrete(HPC)for sleepers is analyzed,and the characteristics of porous basalt aggregate concrete and the optimization method of its working performance are studied.The test verifies that the bearing capacity of sleepers with improved concrete performance is basically not affected by the pore structure of basalt.The pore structure characteristics of porous basalt aggregate and concrete in East Africa were analyzed by X-ray computed tomography imaging technology,and the workability and appearance quality of porous basalt aggregate concrete were improved by admixture.The results show that:After the adjustment of admixture components and the introduction of triterpene saponin air entraining agent,the inner pore structure of concrete is improved;The micro-pump effect of aggregate micropores,the strong mechanical occlusion effect of surface roughness,and the “pin” effect of filling the coarse pores by the slurry all strengthen the compactness of the aggregate itself and the interface transition zone between the aggregate and the slurry,and also reduces the potential pore connectivity in aggregates.Through the fatigue test,it is verified that the porous basalt aggregate sleeper is not affected by the pore structure,and there is no obvious damage around the pore structure,and the bearing capacity is basically not affected by the pore structure.This paper innovatively studies the supporting force mode of track bed of three rail track sleepers,puts forward the calculation method of the lower limit value of the transverse resistance of jointless track,analyzes the way to improve the transverse resistance of track bed of three rail track sleepers,and puts forward the optimization method of porous basalt aggregate concrete performance for sleepers,which provides theoretical basis and data support for the design of three rail track sleepers in China.