Degradation of railway ballast under compressive loads considering particles rearrangement

ABSTRACT

The performance of the railway track structure is highly affected by degradation of the ballast aggregate in which breakage and abrasion of coarse angular particles result in production of fine grains. Maintenance activities including ballast cleaning and tamping operation can intensify ballast degradation during service life. In addition, initial gradation of ballast aggregate can influence the level of ballast degradation. The main purpose of the present study is to simulate the effect of rearrangement of aggregate during maintenance activities on the degradation of ballast by evaluating the influence of initial gradation of aggregate and rock type. For this purpose, a series of lab-scale compression tests with multiple-step loading are conducted during which ballast particles are taken out from the mould after each step and remoulded before the next step. According to the obtained results, multiple-step loading compression test results in more degradation as well as more axial strain of aggregate samples. In addition, gradation comprised of broad range of ballast particles leads to less degradation of ballast under applied loads. Furthermore, less degradation of ballast particles subjected to compressive loads results in lower axial strains in the specimens.

KEYWORDS:

• Railway ballast
• degradation
• ballast grading
• compressive load
• ballast maintenance