Study On The Degradation Mechanism Of The Glued Ballast

A new type of ballast structure is formed by spraying the special ballast glue on the surface of the ballast or pouring it into the interior of the ballast to make all or part of the granular ballast adhere.Generally,it is set between ballasted track and ballastless track,which plays the role of track stiffness transition and has the advantages of ballastless track and ballasted track.However,under the long-term repeated load of the train,the glued ballast track bed,like all other structures,will undergo degradation of service performance.Because the structure of the glued ballast track bed is different from that of the traditional ballasted track and ballastless track,it has different deterioration rules.At present,the relevant research mainly focuses on the mechanical properties of the glued ballast track bed,but the performance degradation of the long-term service state has not been carried out.The operation practice shows that under the long-term reciprocating load of the train,the ballast glue will crack and the solidified ballast will disperse.Based on this,this paper aims at the research of the deterioration problems of the glued ballast track bed,such as the cracking of the ballast glue under the long-term train load.In this paper,the mechanical analysis model is established by using the discrete element software PFC to study the formation process and the mechanical mechanism of the cracking and damage of the glued ballast track bed,the influence of the change of external factors on the mechanical properties of the glued ballast track bed,and the deterioration mechanism of the glued track bed is revealed to provide theoretical guidance for maintenance and repair.At the same time,the influence of the dirty material mixed into the track bed is considered.Therefore,this paper has carried out the following research work:1.Based on the theory of bulk mechanics and structural dynamics,the micro contact model between the ballast particles and between the ballast particles and the ballast glue is established by using the discrete element method,and the cracking mechanism of the ballast glue is introduced to form the deterioration evolution model of the glued ballast track bed.The cracking process of ballast glue under long-term train load is simulated,and the whole process of the degradation of the glued track bed is analyzed.The difference of load transfer path between the initial state and the deteriorated state is analyzed,and the influence rule of ballast glue cracking on the load transfer is obtained.Based on the classification and statistics of the fracture types of the bond action between the ballast particles,the main failure forms of the crack of the ballast glue are analyzed.At the same time,the particle size distribution of contact fracture of ballast is studied by statistical analysis.2.Based on the discrete element deterioration model,the mechanical characteristics of the whole deterioration period of the glued ballast under different train axle load and different operation speed are analyzed.This paper studies the evolution law of stress,vibration and deformation with deterioration degree,discusses the influence law of the change of external factors on the mechanical characteristics of the glued ballast track bed,and analyzes the sensitivity degree of different mechanical indexes to external factors.3.Considering the situation that the dirty material adheres to the surface of ballast particles for bonding,the appropriate dirty material parameters are determined,and the discrete element model of dirty glued ballast is established.By selecting reasonable evaluation indexes,this paper discusses the difference of dynamic response of the glued ballast track bed under the action of train load under different dirty conditions,studies the influence law of the content of dirty materials on the mechanical properties of the glued ballast track bed,and analyzes the influence degree of the dirty materials on the stability of the track bed and the smoothness of the line.There are 96 pictures,6 tables and 64 references.