Spatial Characterization of Single-Cracked Space Based on Microcrack Distribution in Sandstone Failure

Abstract

To further understand the rock damage zone, an approach based on microcrack distribution was proposed to characterize the crack space of rock specimens in this research. Acoustic emission (AE) technology was utilized on sandstone to obtain the spatial distribution of microcracks in which uniaxial compression forms the single-cracked fracture. The proposed theoretical distribution pattern space (TDPS), 3D convex hull, and the minimum volume enclosing ellipsoid (MVEE) algorithms were adopted to analyze the geometric features of the crack space. It was found that the 3D convex hull method returned the smallest results in both area and volume of the crack space, and the largest results were provided by the proposed TDPS method. The difference between the results of the proposed TDPS method and the MVEE method became smaller after 85%. The deviation angle of the principal axis of the cracked space gradually decreased as the spatial scale decreased, while the other two major axes exhibited a tendency to increase at the 65% scale. The results indicate that a spatial scale from 65% to 85% is a reliable range for the characterization of crack space.

Identification and Evolutionary Characteristics of Major Fractures in Beishan Granite

“…Panteleev et al [8] researched the micro mechanisms of granite fracture during three-point bending and found that during threepoint bending of granite, AE events are localized in the zone of formation of the future main crack. Hou et al [9] used AE to analyze sandstone and obtained the spatial distribution of micro-cracks formed due to uniaxial compression. Damaskinskaya et al [10] analyzed the spatial distribution of hypocenters of AE signal sources, and revealed that the transition to correlated defect formation occurs in some regions in the case of continuous electrical exposure, despite the accumulation of almost uniform spatial defect.…”