Microcrack nucleation in marble.
Int J Rock Mech Min Sci Geomech Abstr 1976 Feb; 13(2):A21-A22
In this study it has been found that in marble the inhomogeneous nature of plastic flow on the scale of the grain size can result in the nucleation of microcracks. Specimens of Tennessee marble were deformed in compression at confining pressures of 0-46 MN/m2 and at a strain rate of 10(-5)/sec. Four types of microcrack nucleation mechanisms have been identified. Types I and II operate at the intersections of glide lamellae with grain boundaries. The crack forms at a high angle to the lamellae in the type I case, and parallel to the lamellae in the type II case. The microcrack resulting from the operation of a type III mechanism forms at the intersections of lamellae; that from a type IV is caused by a wedging action of a combination of weak and strong grains. Mechanisms I, III and IV lead to microcracks subparallel to the direction of maximum compression. Mechanism II produces a crack lying in a plane of high shear stress. Faults are composed of en echelon arrays of subaxial cracks connected by packets of inclined twin lamellae.
Mining-industry; Rock-mechanics; Compression-tests
OP; Journal Article
International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts