ABSTRACT
Rock mass discontinuities such as joints and faults often intersect to form discrete blocks that are individually stronger than the rock mass as a whole. Block theory and related analytical techniques have been developed to address problems of block identification and kinematic stability, but such methods are only beginning to be used by practicing engineers. Design considerations for excavations in jointed rock involve block locations, maximum possible block sizes, frequency of block occurrence, and block stability. Block theory and related analytical techniques provide tools with which the rock engineer can identify potentially unstable blocks that might be encountered by an excavation. The screening process helps to reduce the scope of the design problem and helps focus further effort on the block shapes that require attention. The identification and screening sequence is best illustrated by applying it to the analysis of an existing or planned underground opening.
