Sensitivity tests on rock block size distribution

An intensive sensitivity test was made on the block size distribution for various rock joint parameters, specially for the orientation of joint planes and their statistical models. The shape of block size distributions was altered drastically when the concentration factor of β-distribution was lowered from 700 to 200; unimodal skewed distribution to an exponential distribution. The dispersion of pole vectors over the mean attitude was rather sensitive to the block size distribution than the number of joint sets and their relative orientations in the space. The block size distribution is a better parameter to characterize the fractured rock mass for various geotechnical and geohydrological analyses.