Laboratory evaluation of railroad ballast behavior under heavy axle load and high traffic conditions

Abstract Repeated loading of railroad track results in deformation of the track foundation materials. The degree of ballast fouling and the amount of moisture affect the rate and magnitude of both elastic and plastic deformation of the track. As train traffic accumulates, the track deforms to a point where maintenance is required. Studying the effects of fouled ballast in different moisture conditions under different loads leads to a better understanding of the risk factors and maintenance needs of the track. In this study, a large ballast testing box was used to simulate the degradation of fouled ballast at different moisture conditions under heavy axle loading and high traffic conditions. The ballast compression tests were conducted on ballast with different fouling and moisture conditions up to 2,500,000 cycles of repeated heavy loading. The ballast was also tested in saturated conditions that simulated heavy rainfall events. The laboratory results have been compared with an accepted settlement model and different measured field settlements. The ballast box test results show comparable results with field measurements and analytical modeling. This paper presents conclusions regarding the effects of various factors on the rate and magnitude of the plastic and elastic settlement.