A model for rock interfacial behaviour

A model is proposed to describe the frictional resistance offered by two sliding bodies, with application to rock mechanics. In the model, frictional resistance is attributed to three components. In addition to basic sliding and dilational components, which are widely accepted in geomechanics, a third component is introduced, due to plough resistance. This component is due to ploughing of the surface by asperities and wear particles. The dilation and plough components are functions of the interacting surface profiles (surface roughness), relative hardness between the sliding bodies, normal stress and sliding distance. Degradation of surface roughness, and hence reduction in dilation and plough resistance, is formulated using wear theory. The resulting model shows a peak behaviour followed by a postpeak softening response which is often observed in load transfer curves of rock socketed piles. Good agreement with published experimental data is obtained. The model demonstrates that wear theory can be applied to problems in geomechanics to describe the complex behaviour of two sliding bodies.