轴重40 t重载铁路路基基床结构设计技术探讨

针对大轴重货运车辆轴距小的技术特点,分析重载铁路路基承受列车荷载的空间分布规律;基于列车荷载引起路基累积变形效应区沿深度的变化机制,讨论主要承受列车荷载的基床结构与路基填料之间的相互影响关系;根据工程设计的强度、变形、长期稳定性控制要求,探讨40 t超大轴重下基床结构的设计方法。研究表明:提出的“4Z1800/2400”四轴标准轴型荷载模式能较好反映超大轴重列车荷载的路基应力叠加效应;建立的路基累积变形效应不超过基床厚度的设计方法,综合考虑了荷载与填料多因素的影响,是对单因素应力比值法的完善。以累积变形处于缓慢收敛状态的长期稳定性为主控因素,提出轴重40 t重载铁路路基基床层状结构设计指标建议:基床厚度3.5 m,对应基床以下路基K30不低于110 MPa/m;基床表层采用级配碎石强化,厚度0.7 m,要求基床底层K30大于等于130 MPa/m。

Discussion of Design Technology for Subgrade Structure of 40 t Axle-load Heavy Haul Railway

According to the technical characteristics of small wheelbase of heavy axle-load freight vehicles,the spatial distribution law of the train load on the subgrade of heavy haul railway was analyzed.Based on the mechanism of the cumulative deformation effect zone caused by the train load along the depth,the interaction between the subgrade structure mainly bearing the train load and the subgrade filler was discussed.According to the requirements of strength,deformation and long-term stability control in engineering design,the design method of subgrade structure under 40 t super-large axial load was discussed.The research shows that the“4z1800/2400”four axis standard axle load model can better reflect the superposition effect of subgrade stress under super-large-axle train loads,The design method with the cumulative deformation effect of subgrade not exceeding the thickness of subgrade,which comprehensively considered the influence of load and filler,is a improvement of the single factor stress ratio method.With the long-term stability of cumulative deformation in slow convergence state as the main control factor,the design index of layered structure of subgrade for heavy haul railway with axle-load of 40 t was proposed.The thickness of subgrade should be 3.5 m.The K30 of subgrade below corresponding subgrade shall not be less than 110 MPa/m.The surface layer of subgrade shall be strengthened with graded crushed stone,with a thickness of 0.7 m.The K30 of bottom layer of subgrade shall be no less than 130 MPa/m.