Abstract
The statistical properties of the profile-area (PA) method of calculating fracture spacings are derived analytically and the results are presented in readily available charts. Comparison of the classical rock quality designation (RQD) with the PA values indicates that the former is dependent on the arithmetic mean of intact lengths only whereas the latter takes into account, additionally, the variance and the serial correlation structure of successive intact lengths along the scanline. The proposed methodology also helps to avoid the tedious procedure of area calculation by planimeter and presents straight forward formulations that relate the PA values to simple statistical parameters of the intact length measurements along a scanline. Furthermore, definitions of dimensionless and standard PA concepts are proposed. The former is useful in comparing scanline measurements of different units whereas the latter shows the sole effect of a serial correlation coefficient only on the rock quality.
