Determination of Destress Blasting Effectiveness Using Seismic Source Parameters

Abstract

Underground mining of coal seams in the Upper Silesian Coal Basin is currently performed under difficult geological and mining conditions. The mining depth, dislocations (faults and folds) and mining remnants are responsible for rockburst hazard in the highest degree. This hazard can be minimized by using active rockburst prevention, where destress blastings play an important role. Destress blastings in coal seams aim to destress the local stress concentrations. These blastings are usually performed from the longwall face to decrease the stress level ahead of the longwall. An accurate estimation of active rockburst prevention effectiveness is important during mining under disadvantageous geological and mining conditions, which affect the risk of rockburst. Seismic source parameters characterize the focus of tremor, which may be useful in estimating the destress blasting effects. Investigated destress blastings were performed in coal seam no. 507 during its longwall mining in one of the coal mines in the Upper Silesian Coal Basin under difficult geological and mining conditions. The seismic source parameters of the provoked tremors were calculated. The presented preliminary investigations enable a rapid estimation of the destress blasting effectiveness using seismic source parameters, but further analysis in other geological and mining conditions with other blasting parameters is required.

Mechanism and Prevention of Rockburst in Steeply Inclined and Extremely Thick Coal Seams for Fully Mechanized Top-Coal Caving Mining and Under Gob Filling Conditions

“…Destress blasting can loosen and crack the hard roof, destroy the integrity of the suspended roof, reduce the suspended length and static stress and partially release the energy accumulated in the hard roof [52][53][54]. Simultaneously, destroying the integrity of the roof can increase the attenuation of the shock wave velocity and amplitude, reducing the transmission of large horizontal stresses and overburden loads, thus decreasing the lateral pressure coefficient [55]. However, unreasonable blasting hole designs not only increase the costs but also induce secondary disasters.…”

Source Analysis of Post-Blasting Events Recorded in Deep Copper Mine, Poland

“…The explosive parts of sources could be connected with rock fracturing due to explosion. Although such sources are characterized with a significant isotropic component, other reasons are not excluded since the seismic processes are associated with the new stress state in the vicinity of the blasted area (Wojtecki et al 2017). This observation is supported by the lower ISO values visible in sub-group IB.…”

“…This division of the spectrum leads to two independent components: the low-frequency spectral level (X) and the corner frequency, which are obtained by the intersection of the high-and lowfrequency asymptotes of the spectrum. A procedure based on the inspection of seismograms in the frequency domain is often used in mining seismology for estimating the source parameters although, not for blasting effects (Wojtecki et al 2017). In this study, spectral analysis was applied to estimate the source parameters: scalar seismic moment, seismic energy, source radius, stress drop and apparent stress.…”

“…On the other hand, there is no direct seismological evidence that the physical processes for events triggered by blasting are similar or different from seismicity occurring spontaneously beyond the established timing criteria. The current stage on this area is still challenging (Konicek et al 2013;Caputa et al 2015;Wojtecki et al 2016Wojtecki et al , 2017 and is essential for improving exploitation under high seismic hazard conditions in different mining environments.…”

Improving the efficiency of blasting operations in mines with the help of emulsion explosives

“…Methods to prepare producing blocks by means of access ramps make it possible to improve mechanization level of mining operations, blasting operations and non-productive operations; delivery of rock mass, materials and equipment; safe and comfortable way for workforce to leave faces; and to improve the control over ventilation and other technological processes (Kozan & Liu, 2016;Khademian & Bagherpour, 2017;Wojtecki, Mendecki, & Zuberek, 2017). That is why the improvement of blasting operations in mines while using emulsion explosives and taking into consideration upgrading of extraction equipment, intensification of production processes with the use of self-propelled highproductive mining equipment of a new generation are the scientific and practical problems to be solved urgently (Navalkar, 2001;Jha, Jha, & Kumar, 2015).…”