ABSTRACT
The bearing capacity of a ballast module allows one to determine the bearing capacity of ballast based on the limit equilibrium method. Prior to designing the track substructure, the bearing capacity of the selected ballast must be checked to ensure it meets the required design criteria. This module enables track engineers to decide whether or not to carry out a full design process, depending on the bearing capacity required. The friction angle of ballast is the effective friction angle at the in situ confining pressure; this plays a governing role in determining the allowable bearing capacity of the ballast layers. It has to be noted that as ballast is highly non-linear, the friction angle can vary with the confining pressure that prevails in the field. The Office of Research and Experiments (ORE) of the International Union of Railways has proposed a more comprehensive formulation to determine the value of the dimensionless impact factor.
