11 / 2023-05-11 17:36:43

Integration of geophysics and safety engineering for dynamic disaster prediction in complex mining environments

mining fractures,rockburst,Steeply Inclined and Extremely Thick Coal Seam,microseismic monitoring,Seismo-Frac Model

The deep underground non-depletable resources play a substantial role in conforming to the growing sustainable energy demands, however, increasing depth and complex mining conditions lead to serious geological disasters. Among these, the rockburst is globally considered as the most dangerous dynamic disaster and frequently occurring in Chinese as well as worldwide coalmines (He et al., 2022). For the effective predictions of rockbursts, integration of geophysical techniques and safety engineering provides better accuracy.

The microseismic monitoring has proved to be a powerful and practical technology for continuous real-time monitoring, assessment, and mitigation of dynamic disasters in both tunnels and coalmines (Maxwell, 2010). Due to complex geological and geo-mechanical conditions in Steeply Inclined and Extremely Thick Coal Seam (SIETCS) mines, the prediction and prevention of dynamic disasters remain quite challenging. The drilling tests and physical models are generally time-consuming and uneconomic providing miniature coverage. Whilst, rockburst driven disasters require detailed regional geological understanding and mechanical behavior of rock mass. This paper introduces a robust geophysical workflow to understand minefield geological changes for accurate identification and prediction of rockburst in SIETCS mine. The spatiotemporal distribution of induced-microseismicity, three-states stress theory, and mapped fractures helped in the identification of three rockbursts, several high-energy tremors, and the prediction of two new rockburst-prone regions. A new Seismo-Frac model is introduced to map fracture networks, and regional lineaments (Fig 1). The mapped fractures showed that for the simultaneous excavation in B3+6 and B2+1 coal seams subjected to repetitive episodes of seismic deformation, the shear-displacement accumulation, prying effects of rock pillar and roof coupled with dynamic stress are the primary modes of deformation. This study also introduces decreasing occurrence frequency of fractures and lineaments as the new prediction indicators.

Furthermore, through conditional probability analysis, the prediction efficiency of source parameter averages (E and N), seismological parameters (b-value and Δb), and maximum potential magnitude (Mm) was compared. A sharp-increase in source parameter averages while a sharp-decrease in the seismological parameters proved to be effective rockburst prediction indicators. This method, while a panacea for imaging the entire fracturing phenomenon, provides insights with widespread implications for academic researchers and industry practitioners to mitigate dynamic disasters in global underground engineering excavation.