Inhomogeneous Micro-structure Influence on Macro-crack of Sandstone

SEM scanning and fractal dimension estimation were adopted to study the inhomogeneous microstructure features and its influences on the failure pattern of sandstone. The results show that different sandstones are of different self-similarities of microstructure. The average homogeneities of lithic arenite, greywacke, and subfeldspathic arenite are 5.61, 3.39, and 4.57 and estimated fractal dimensions of microstructure are 1.94, 1.52, and 1.84, respectively, indicating that the homogeneity of microstructure is well consistent with fractal dimension. The resulted macro-cracks of lithic arenite, greywacke, and subfeldspathic arenite are vertical cleavages, unordered discontinuous macro-cracks, and inclined macro-crack, respectively. The brittleness of lithic arenite, greywacke, and subfeldspathic arenite are 2.46, 3.54, and 2.61, respectively. The sandstone of brittleness tends to be easily ruptured in an abrupt manner, accompanying a sudden release of large elastic energy.