A Numerical Study on Dilation of a Saw-Toothed Rock Joint Under Direct Shear

The roughness of a rock joint gives rise to the phenomenon of dilatancy. Numerous studies have been conducted to examine their dilation behaviour partly due to its importance as a stabilising effect. While previous researchers have improved the understanding of dilation behaviour and identified important parameters affecting the magnitude of dilation during shear, there is still a lack of quantification of the method for predicting the dilation angle. This paper describes a systematic parametric study to investigate the effect of relative normal stress and geometric properties on the dilation of a saw-toothed rock joint by using a distinct element method code with Voronoi tessellation. The applicability of the numerical model was assessed by calibration with a series of standard laboratory tests. The simulation results indicate that the magnitude of relative normal stress plays the most important role among parameters and quantify how much those parameters affect the dilation behaviour during shear. The findings of this study, presented in a normalised relation, can be employed when dilation values need to be determined in rock engineering practice.