ABSTRACT
Joints are the most ubiquitous structural discontinuity in the earth’s crust, occurring in a wide variety of rock types and tectonic environments, and they represent the most common result of brittle fracture of rock under natural conditions. The numerical method that has been chosen for the analysis of crack propagation and interaction is the displacement discontinuity method of boundary elements as formulated by Crouch and Starfield. One of the most intriguing observations related to joints in sedimentary sequences is that members of the same set commonly have a well defined spacing that increases with the thickness of the jointed layer. Starting with a randomly spaced array of initial flaws of uniform length located along the upper layer boundary, a remote displacement or internal pressure is added to cause propagation. All flaws are allowed to grow incrementally at the same rate until a layer boundary is encountered.
