(1. China Railway Eryuan Engineering Group Co. Ltd,Chengdu,Sichuan 610031,China;2. Key Laboratory of High - speed Railway Engineering of Ministry of Education,Southwest Jiaotong University,Chengdu,Sichuan 610031,China)
Abstract:Abstract:Research purposes: Heavy - haul railway transportation is the direction of railway freight development. The trend of large axle load and long marshaling of heavy haul put forward higher requirements to the selection of filler of railway subgrade. Compared with the foreign technical standards of heavy haul railway designing,the regulations about properties and compaction standard of subgrade filler of the existing specifications at home is relatively fixed single and on the safe side, besides, filler properties have large differences packing with regional change,therefore we should analyze the design standard of the foreign heavy haul railway and combine with the characteristics of China’s vast territory,put forward the improvement and optimization for the existing provisions. Combined with the control conditions of strength and deformation % check types of filling and compaction standard of the corresponding structure layer required design parameters such as filler in the known bedding of each structure layer dimension case, and provide optimization suggestions based on the method for the determination of parameters in the end. Research conclusions :( 1) According to the subgrade bed structure ( bedding facing and roadbed) of code for deigning heavy haul railway, design test cases and the packing parameters were determined and improved. The results showed : under the conditions of 27 t axle load and design vehicle speed of 100 km/h, the minimum compaction standard of filler for the bedding facing is K30= 190 MPa/m,meeting the requirements of specification; the minimum compaction standard of filler for the roadbed is K30= 110 MPa/m,equivalent to the compaction standard of lower level compared with specifications. The calculation results showed that the subgrade filling technology standard can be optimized further. (2) The bedding surface layer should make a preferred choice of graded stone to satisfy the bearing requirement of subgrade; Based on the minimum structures design standards,the thickness of the roadbed or the bedding facing graded stone layer can be appropriately reduced with the roadbed filler performance improved to achieve the effect of cost saving and obtain good economic and environmental benefits. (3 ) The research result has guiding significance to the improvement of the technical standard of heavy haul railway in china and the implementation of 11 going - abroad _strategy.