The Seismic Source Parameters of Tremors Provoked by Long-Hole Destress Blasting Executed During the Longwall Mining of
- PDF / 1,618,237 Bytes
- 17 Pages / 547.087 x 737.008 pts Page_size
- 46 Downloads / 185 Views
Pure and Applied Geophysics
The Seismic Source Parameters of Tremors Provoked by Long-Hole Destress Blasting Executed During the Longwall Mining of a Coal Seam Under Variable Stress Conditions ŁUKASZ WOJTECKI,1
MACIEJ J. MENDECKI,2
Abstract—The underground mining of coal seams in the Upper Silesian Coal Basin is carried out at great depths and mostly in the presence of remnants or edges of other surrounding coal seams, i.e. under the condition of high stress level in the rock mass. Therefore, this mining is accompanied by rockburst hazard and suitable preventive action is required. Long-hole destress blasting plays an important role and is commonly applied in rockburst prevention in underground hard coal mines. Estimated blasting effectiveness is important when designing rockburst prevention. It is commonly estimated on the basis of the seismic energy of a provoked tremor. The seismic source parameters have already been considered for this purpose. Additional information about the effects of long-hole destress blasting could be contemplated in the planning of active rockburst prevention. The seismic source parameters of tremors provoked by long-hole destress blasting have been calculated and are presented in this article. Destress blasts were performed during the longwall mining of coal seam no. 506 in one of the hard coal mines in the Upper Silesian Coal Basin. They were executed from the longwall face, in order to destress the rock mass ahead of it. Parameters of the blasts were variable and they were modified according to geological and mining conditions and the observed level of rockburst hazard. The seismic source parameters have been determined for tremors provoked directly after firing explosives and for tremors occurring in the waiting time, and they have been compared with each other. Keywords: Seismic source parameters, long-hole destress blasting, rockburst prevention.
1
Central Mining Institute, 1 Gwarko´w Square, 40-166 Katowice, Poland. E-mail: [email protected] 2 Faculty of Environmental Sciences, University of Silesia in Katowice, 60 Be˛dzin´ska Str. 41-200, Sosnowiec, Poland. E-mail: [email protected]; [email protected] 3 Faculty of Mining, Safety Engineering and Industrial Automation, Silesian University of Technology, 2 Akademicka Str. 44-100, Gliwice, Poland. E-mail: [email protected]
IWONA GOłDA,3
and WACłAW M. ZUBEREK2 1. Introduction
Rockburst hazard accompanies underground coal mining in the Upper Silesian Coal Basin (USCB). There are many reasons for rockburst occurrence, but among the most important are the depth of mining and the presence of remnants or edges of previously mined coal seams. These factors are responsible for high stress levels in the rock mass and have an effect on the occurrence of the rockburst phenomenon. To minimize rockburst hazard, active rockburst prevention must be applied. To release the stress accumulated in the rock mass, long-hole destress blasting is executed. The explosive material is loaded into a single blasthole or more often into
Data Loading...
