ABSTRACT
Traditional material and structural design of unsealed mine haul roads requires a thick pavement structure in order to dissipate stresses from heavy haul vehicles and thereby prevent structural damage to weak subgrade materials. Ramp roads in open pit mines are, however, generally constructed above solid or fractured bedrock and the placing of thick structural layers of imported material is therefore not required and expensive. The imported material is, in fact, often the weakest portion of the pavement and the thickness should be limited as far as possible. This paper evaluates the behaviour of the imported and in situ material in ramp roads under a range of typical haulage vehicles used in South Africa. Linear and non-linear material modelling was used to determine stress concentrations and areas of potential plastic failure. Recommendations for the quality of the wearing course aggregate are made and the influence of drainage, construction and maintenance of the ramp roads on vehicle operation is evaluated.
