Relationship between grain size and some surface roughness parameters of rock joints

The influence of grain size on the surface roughness as well as its implication on the shear behaviour of rock joints has been studied. From the investigation which consists of the profiling of surface roughness, followed by the shear test of fresh rock joints in norite, it has been found that grain size distribution expressed in terms of average particle size index shows a good correlation successively with the root mean square of the first derivative and its modified version, the joint roughness coefficient and the peak friction angle. However, no correlation has been found between the grain size parameter and the average inclination angle nor with the fractal dimension.