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DISPLACEMENT AND MINE SEISMICITY PROCESSES DURING UNDERMINING OF A TECTONICALLY ACTIVE FAULT AREA AT THE SINVAY DEPOSIT

Andrian Batugin

Abstract

The hazard of tecnogenous earthquakes caused by mining of mineral deposits is increased if they occur at economically developed regions with ecologically dangerous objects. A deep coal mine of the Sinvay deposite in China is an example when seismicity due to mining was an important factor influencing both the mining conditions and ecological environment. At a more than 1000m mining depth the power of rock bursts rose to 107 J and they manifested themselves as minor earthquakes on the earth surface. The increasing threat of catastrophic events associated with mining required complex field and computed studies. The field observation involved geophysical, surveyor and geodynamical investigations. The study results were processed according to the procedure well known in Russia as the method for geodynamical zoning. The field study was supplemented with computed modeling of geoprocesses. The computed modeling was used to study changes in the stress-strain state of the rock mass as the mining depth was increasing. The field study discovered that development of mining seismicity demonstrated temporal and spatial relationship with earth surface deformation. The spatial relationship involved penetration of mining into a large tectonic zone represented by multiple surface disruptions. The temporal relationship manifested itself as correlation between the seismic energy and development of surface cracks. The crack orientation was related with direction of the underground mining front and natural rock mass faults. The computed modeling was used to discover a mechanism of the interaction between the block rock mass and the technical system of excavation, to find regularities for development of technogeneous main tensile cracks in the undermined rock mass and to show that technogeneous earthquakes might be caused by vertical dynamical displacement under the effect of own weight of a large block limited by technogeneous and natural cracks at its sides.

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