The benefits of increased axle loading in the railway industry are well-appreciated to such an extent that increased axle loading has become a themed topic of interest across all disciplines of railway engineering. However, it remains important to understand the engineering behavior and performance of each track component under increased axle loading. This study was particularly interested in the behavior of railway foundation materials under increased axle loading, starting from a base load of 20 tonnes per axle for general freight to increased loads of 26, 30, 32.5 and 40 tonnes per axle for heavy haul. The methodology followed involved formulation of a theoretical model for analyses, characterization of the cyclic railway loading via finite element modelling, experimental laboratory work using a cyclic triaxial apparatus followed by detailed analyses, interpretation and discussion of the test results.

Based on the test results from the monotonic and cyclic loading, it was found that the critical state line was related to the various phase transitions in soil behavior and the resilient strain was found to be inversely related to the permanent strain. Stress states slightly above the critical state line resulted in a double-phase transition in soil behavior from dilation to contraction and then work softening with cyclic mobility. Stress states on the critical state line resulted in a single-phase transition in soil behavior from dilation to contraction with a combination of cyclic mobility and shakedown. Stress states below the critical state line resulted in a no-phase transition in soil behavior accompanied by dilation with shakedown. In relation to the effect of increased axle loading on saturated heavily overconsolidated railway materials, it was therefore concluded that resilience can be characterized by a no-phase transition predominated by linear permanent deformations and shakedown behavior while failure is characterized by a double-phase transition predominated by exponential permanent deformations and cyclic mobility behavior.

在铁路行业中，增加轴负载的好处得到了人们的充分认识，以至于增加轴负载已成为铁路工程所有学科都感兴趣的主题。但是，了解轴载荷增加时每个履带部件的工程性能和性能仍然很重要。这项研究特别关注铁路基础材料在轴负载增加的情况下的行为，从一般货运的每轴20吨的基本负荷到重型运输的轴的26、30、32.5和40吨的增加负荷开始。遵循的方法学包括为分析建立理论模型，通过有限元建模表征循环铁路荷载，

根据单调和循环载荷的测试结果，发现临界状态线与土壤行为的各个相变有关，而弹性应变与永久应变成反比。略高于临界状态线的应力状态导致土壤行为从膨胀到收缩的双相转变，然后以循环迁移率软化。临界状态线上的应力状态导致土壤行为从扩张到收缩的单相转变，并结合了周期性迁移和震动。低于临界状态线的应力状态导致土壤行为无相变，伴随着扩张和沉降。关于增加轴载对饱和的严重超固结铁路材料的影响，