Bulletin of the Geological Society of Malaysia, Volume 35, July 1994, pp. 157-168
Institute for Advanced Studies, University of Malaya, 59100 Kuala Lumpur
Abstract: The set spacing and general spacing of joints in granitic rocks in the eastern Kuala Lumpur area were studied. The set spacing which is the perpendicular distance between two joints of the same set was measured in the field. It was found that the set spacing parameters for the major joint sets do not vary significantly. The set joint spacings are mainly less than 50 cm. More than half of the modal spacings are about 15 cm and the mean spacing mainly ranges from 35 to 45 cm. Photographic prints were used to obtain the general spacing, which is the distance between points where two adjacent joints intersect a scanline. 90% of the general joint spacings are less than 1 m and 50% are less than 30 cm, and generally, the mean values lies between 20 to 43 cm, and the modal values between 10 to 30 cm. The frequency distribution of the general joint spacings can be fitted to the negative exponential model. The Rock Quality Designation (RQD) calculated from the general joint spacings is generally more than 90% and it is also shown that the RQD can be estimated from the joint frequency.