A Review of Field Occurrence of Crack Types and Crack Coalescence in Rocks

Abstract

This paper briefly reviews the literature on the general crack formation mechanisms and the typical occurrence of crack coalescence in natural rocks, but with no particular reference to specific locations or geologic settings. The field occurrences of tensile wing cracks, horsetail cracks, anticracks and shear cracks, as well as their coalescence are described. In contrast to the tensile wing cracks which develop in the tensile quadrant, anticracks develop from the pre-existing discontinuities in the compressive quadrant. The discussion will be illustrated with plenty of field examples, supplemented by a review of commonly used terminologies.