Determination of the In situ Block Size Distribution in Fractured Rock, an Approach for Comparing In-situ Rock with Rock Sieve Analysis

摘要

An in situ block is defined as a part of the rock mass that is surrounded, but not cut, by fractures. In the proposed model this is transformed to the probability of lengths (spacings) between fractures in three directions. The three axes define a Cartesian coordinate system (Fig. 1), hence the model is termed orthogonal. The assumption of orthogonality is a fairly common approach and used in several other models. Early fracture network models like Imray (1955), Quids (1957) and Snow (1965) all use orthogonal models. More recent examples are LaPointe et al. (1997), Peaker (1990), Maerz and Germain (1996), Hadjigeorgiou et al. (1998). However, in this paper some additions are introduced, mainly the use of the middle sized side of the block as block size. This allows us to compare the calculated In situ Block Size Distribution (IBSD) with sieve analysis distributions.