A Laboratory Study of Railway Ballast Behaviour

Three types of railway ballast were tested to study its behaviour under traffic loading and tamping maintenance. The study involved two types of laboratory testing. They were the tests Railway Test Facility and the tests in large-scale triaxial test machine. The Railway Test Facility is housed in a 2.1m x 4.1m x 1.9m concrete pit and comprises subgrade material, ballast, and three sleepers. The sleepers are loaded with out of phase sinusoidal loading to simulate traffic loading. The ballast in the facility can also be tamped by a tamping bank which is a modified real tamping machine. The large- scale triaxial test machine was design for testing a cylindrical ballast sample with 300-mm diameter and 450-mm height and can perform both cyclic and monotonic tests with constant confining stress. The test results suggested that the ballast damage from tamping correlated well with Los Angeles Abrasion (LAA) and Micro-Deval Attrition (MDA) values. Furthermore, the stress conditions of the cyclic loading in both the RTF and triaxial tests could be related.