Abstract

The analysis of microflaws on the surface of rock specimens subjected to diametrical compression (Brazilian test) reveals a statically relevant spatial and temporal connection between the surface damage and the level of the external load. Using the developed approach to interpretation of random and deterministic data, the retrospective study of induced seismicity in the operating mining enterprise is performed. Correlation analysis of space-time distribution of induced seismicity parameters and stresses in mine permits to find statistical relationships between the variation of stress field characteristics and the number of seismic events in different parts of an object. This provides a way to predict the induced seismicity parameters in course of mining.

Comprehensive approach to reconstruction of stress fields in rock mass at any stage of mining was offered and realized for Zapolyarnaya coal mine. The approach involves: lab test of rock for finding an empirical dependences of longitudinal velocity on stresses; straight-ray tomography taking impulses of dynamic events as the sounding signals; solution of inverse problem "determination of horizontal components of external stress field when the input data is the velocity field reconstructed by tomography". It appeared that coefficient of earth pressure equals to 0.6 in the line of mining and 0.45 in orthogonal direction.

1.
Introduction

Assessment of seismic risk and prediction of mine seismicity are the indispensable components of hard mineral mine planning and design (Durrheim et al, 2007; Leslie, 2013; Hirata et al, 2007). All mines (Hudyma and Brummer, 2007; Zhenbi and Baiting, 2012) and other business entities (Xu et al, 2007) operate microseism monitoring systems (MMS) which collect and process acoustic data. Interpretation of acoustic data in the seismic risk estimation uses statistic methods of "big" seismology, as a rule (Mendecki, 1993; Hardy, 2003), and the criterion of damage accumulation (Kuksenko, 2005). With few exceptions (Al Heib, 2012), the information on the stress state is left aside. In the meanwhile, numerous laboratory experiments (Mogy, 2006; Rao, 2012; Wang et al, 2013) exhibit a statistically relevant dependence between the microdefectiveness D and uniaxial stress level in a specimen. However, the univocal connection of D and stresses under triaxial or polyaxial loading yet remains to be revealed.

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