Modeling Rock Fracture Intersections and Application to the Boston Area

An algorithm for determining the intersections between fractures is presented in this paper. The algorithm is implemented in GEOFRAC, a stochastic fracture pattern-modeling program. Previously, GEOFRAC allowed one to subdivide a fracture network into isolated subnetworks to assess connectivity. A new GEOFRAC feature can be used to analyze length and orientation distributions of the fracture intersections. Connectivity parameters such as the number of intersections per unit volume, C-1, and the intersection length per unit volume can be calculated. Intersections and connectivity are important because they govern the fluid flow and stability behavior of rock masses. The program is used to model fracture intersections in the Boston area. The simulations show that for fractures in the Boston area, the mean fracture intersection length ranges from 0.5 to 0.7 m. The results also show that the relative frequency of long intersections (>2.0 m) increases with increasing modeling volume size. In contrast to these effects of volume, it appears that intersection orientation is not affected by the volume being considered. DOI: 10.1061/(ASCE)GT.1943-5606.0000699. (C) 2012 American Society of Civil Engineers.