Research On Rational Track Stiffness Of Slab Track On The Subgrade

Track stiffness is the key factor affecting track structure vibration and the transmission of dynamic characteristic, and it is the important factor influencing wheel/rail dynamic interaction and train running quality, governing the maintenance workload of the track. The stiffness of ballastless track structure is greater than ballast one. Therefore rational track stiffness, fine track stiffness matching and the longitudinal evenness of track stiffness have been subjects for the ballastless track.Take slab track on the subgrade for instance, this article shows the calculation methods for integral stiffness and every single part of ballastless track structure. Also it presents four fix methods for rational track stiffness, which consist of rail permit stress method, rail permit deformation method, critical velocity method and dynamical response method.To summarize local and foreign vehicle-rail system control standards, this article considers that vehicle-ballastless track system dynamics evaluation includes three aspects, which are dynamic performance of rail structure, vehicle safety and stationarity in operation. The article supplies CA mortar surface dynamic stress and subgrade surface dynamic stress as evaluation index of rail structure.According to vehicle-rail coupling dynamics, this article builds the model of high speed train-slab track-subgrade vertical system. According to the unevenness of concave welding joint, it studies dynamic performance of high speed trains running on the slab track. Referring to vertical system evaluation criterion, the article adopts wheeltrack vertical force, rail reaction of supports, rail dynamic flexure stress, rail displacement, acceleration of body, and otherwise as evaluating indicator. It studies rational stiffness span of every single part of slab track structure, and finally gets these spans of stiffness and damping of the fastener, CA mortar, and subgrade surface stiffness.At the meantime, the article suggests a new model of track analysing,that is three-point support model. More than this, it applies the notion of secondary flexure of rail, and gets reasonable corresponding relation between rail support stiffness and supporting spacing from statics angle.