ABSTRACT
The systems of discontinuities that traverse rock delimit rock blocks of many sizes, shapes, and positions in an excavation. By using block theory it is possible to determine the most critical of these, which are denoted as keyblocks. This paper deals with both individual, convex keyblocks, and multiple, non-convex (“united”) keyblocks. By means of a detailed, worked-out example, it shows how to compute whether or not a given region between discontinuity traces is a keyblock and then how to find the area and bolt forces on the perimeter in order to prevent key block movements.
