Microseismic Characterization of Brittle Fracture Mechanism in Highly Stressed Surrounding Rock Mass

Abstract

Brittle fracturing of rock mass is a major problem for deep tunnelling or mining in highly stressed rock mass, which could evolve into rockburst hazard and severely undermine the safety of engineering project. In this paper, an advanced microseismic approach is proposed to analyse the mechanism clearly. The results suggest that brittle fracturing contains three energy development stages (i.e. energy accumulation, energy transfer and energy release). Therefore, based on the seismic energy moment and the apparent stress criteria, microseismic events can be classified into six categories that corresponding to the three major categories of stress-adjustment event, deformation-driven event and bursting event. The Energy index develops steadily at first, then followed by a drastic drop and finally ends with a large increment. Cumulative apparent volume grows slowly before a sudden increase. For brittle fracturing development, tensile cracks appear firstly, then the shear cracks and finally the mixed types of cracks.