Reaseach On Unsupported Bearing Block Effect And Regulation Of Low Vibration Track

Currently, low vibration track is widely applied in railway tunnel in China, the track structure has appeared diseases because of the effect of construction quality,natural environment,train loads, and the disease of unsupported bearing block is more typical. Unsupported bearing block is kind of dynamic irregularity, refers to interspace appears in the bottom of the bearing block, track geometry maintains good under static case, unsupported bearing blocks appear to float up and down significantly when the train passes the track. This thesis takes the serious disease of unsupported bearing block in the Yindongpo and Dingshuiba tunnel of Guiyang-Guilin line as the research object, based on field survey and the existed research materials, in order to ensure safe operation and extend track structure service years, the effect on the track structure and maintance of unsupported bearing block is studied systematically.Firstly, based on the field survey on the phenomenon of unsupported bearing block, the unsupported bearing block is divided into two types, one type is that the viod exists between the bottom of bearing block and rubber mat, rubber coat boot, the other type is that the viod exists between rubber coat boot and block-monolithic roadbed. The method of Ground Penetrating Radar is used in detecting and the value of unsupported bearing block, which obtained range from 1mm to 10mm, and mainly concentrated in 1 mm to 4 mm.Secondly, the mechanics model of rail-bearing block-monolithic roadbed-tunnel foundation which considers unsupported bearing block is established, the effect of vertical displacement and stress of track structure is analyzed under train load, the disease of unsupported bearing block is divided into â… ,â…¡,â…¢ three damage levels through introducing damage level assessment of high-speed railway ballastless track, determining the regulation methods of unsupported bearing block according to damage level.Finally, taking the method of padding gasket under the rail and filling repair material in the bottom of bearing block to regulate the â…¡,â…¢ damage level of unsupported bearing block. Mechanical model of repairing the unsupported bearing block is established to evaluate the efficacy of the regulation through analyzing mechanical characteristics of repair material and track structure. According to the performance requirements of repair material, epoxy resin mortar is finally chosen as the repair material of regulating unsupported bearing block.