重载铁路路基荷载条件及动力特性研究

Research on the Load Condition and Dynamic Properties for Heavy Haul Railway Subgrade

研究目的：重载铁路运输因其运能大、效率高、运输成本低而受到世界各国的广泛重视。重载铁路路基基床受列车载荷作用影响最为显著，其厚度设计通常按列车荷载产生的动应力与路基自重应力之比为0．2的原则确定。而分析轮轴力通过钢轨在轨枕上的荷载分担规律又是进行路基动应力计算的先决条件，因此分析列车荷载分担规律以及动应力在路基中的衰减规律是非常必要的。本文根据弹性理论建立轨道一路基有限元模型，进行不同荷载水平和基床结构形式下路基的荷载条件分析，求解路基面动应力分布和衰减规律，为基床厚度设计研究创建基础。研究结论：（1）轴重和基床结构形式不影响轨枕荷载分担规律，单轮轴作用时荷载由5根轨枕承担，双轮轴作用由8—9根轨枕承担，四轮轴作用由15根轨枕承担；（2）无论轮轴力作用于轨枕正上方还是两轨枕间的任何位置，其荷载分担比经Gauss函数拟合后的函数曲线形状、大小以及性质都保持不变，只随轮轴力的移动而移动；（3）单轮轴作用时，列车荷载产生的动应力与路基自重应力之比均在0．2左右，基床厚度满足设计原则，但双轮轴、四轮轴作用时，列车荷载产生的动应力与路基自重应力之比在0．3～0．5之间，基床厚度不满足设计原则；（4）该研究结论对重载铁路路基基床结构的设计具有指导意义。

Research purposes： The heavy haul railway is paid extensive attention by countries all over the world because of its large capacity, high efficiency and low cost of transportation. As the most significant part influenced by train loads, the thickness design of the subgrade is usually determined by the principle of the stress ratio of 0.2 between dynamic load produced by loads on sleepers train loads and gravity is the precondition of s stress of the subgrade itself. While the sharing law analysis of axle force by rail ubgrade dynamic stress calculation, it is essential to analyse the sharing law of train loads and dynamic stress in subgrade. Based on the theory of elasticity finite element model of track - subgrade is established to analyse the load condition under different load levels and subgrade structure, to further solve dynamic stress distribution and attenuation rule in subgrade, which lay a foundation for thickness design of subgrade.Research conclusions： （ 1 ） The sharing law of train loads is not effected by the axle loads and the structure of subgrade, train loads are shared by 5 sleepers for single axle wheel, shared by 8 to 9 sleepers for double axle wheels and shared by 15 sleepers for four axle wheels. （2）Wherever the axle load is acted directly above or on any position between the two sleepers, the shape,size and properties of Gauss function curve fited for the loads sharing remain the same, only the position moves as the position of the axle loads. （3）Under single axle wheel the stress ratio between dynamic stress produced by train loads and gravity stress of subgrade is about 0.2 which meet the design principle, while under multi axle wheels the ratio is between 0.3 to 0.5 which does not meet the design principle. （4） The above conclusions have important guiding significance to the structure design of heavy haul railway subgrade.