Title: A MODEL OF ROCK MASS FRACTURING AHEAD OF LONG WALL FASE AS A CONSEQUENCE OF THE INTENSITY OF EXPLOITATION |
Authors: Drzewiecki Jan and Makówka Janusz |
DOI: 10.13168/AGG.2013.0013 |
Journal: Acta Geodynamica et Geomaterialia, Vol. 10, No. 2 (170), Prague 2013 |
Full Text: PDF file (1.3 MB) |
Keywords: rock mass, longwall mining, strain and displacement, forecasting methods |
Abstract: In Czech and Polish underground hard coal mines of the Upper Silesian Coal Basin high-energy seismic phenomena are
periodically recorded, the sources of which are located ahead of the longwall. Generally, these types of tremors are rooted in
very strong, thick layers of sandstone, which are subject to the deformation border. The consequences are discontinuities and
cracks with a range depending on the mechanical properties of destroyed rocks: the mechanical parameters of layers.
Forecasting methods, developed in the Central Mining Institute, for stress concentration, seismic energy, fault zone and range,
together with methods of rock fracturing using liquid or explosives, ,allow precise identification of suitable locations for
controlled fracturing of rock mass with a pre-established direction.
The size and range of discontinuities have an impact on mining parameters, dependent on basic exploitation intensity and
expressed by the average daily progress of the longwall face. The rockmass is locally weakened because of exploitation or
technical measures of discontinuities in the roof-rock on the longwall face. To prevent rockburst, measures are needed to
reduce the amount of energy accumulating in the rockmass in the area of the longwall face.
Knowledge of where stress is concentrated is extremely important for the development and implementation of effective
preventative methods. For many years several research centres have been working on defining the range of these areas.
In this paper, basic information is presented on methods developed by Central Mining Institute and used in Polish hard coal
mines for forecasting energy concentration and assessing how it can be reduced. |