About the mean area of a joint set

Abstract

The general expression, giving the mean area of a joint set as a function of the mean trace length of that sei on an observation surface, as well as the formulas for the usual types of observation surfaces - general closed convex surface (ISM borehole core), general plane convex surface (rectangle, square, circle), and limited stretch of an adit with a rectangular cross-section - are deduced, assuming that the joint areas follow a Bessel distribution. A case history, concerning a location where three different joint samplings - on limited adit stretches, on ISM boreholes, and on circular surfaces - were successively carried out, is presented, showing a good agreement between the three independent mean area values obtained for each joint set. Finally, some remarks about an attempt to deduce those mean areas, based on the sampling performed in three neighbour parallel boreholes at the same location, are made