Geological analysis of the overburden as a tool for safe and effective exploitation of the Bełchatów opencast browncoal mine (Central Poland)

Abstract

Exploitation of a huge opencast browncoal mine in central Poland is facilitated by a detailed analysis of the Tertiary and Quaternary overburden. The overburden could not be removed effectively using the common methods for forecasting the material and structures to be encountered. The geological structure in the area is so complex that additional measures had to be taken to ensure safe and effective exploitation. Studies of the Quaternary geology — detailed, but still following the normal style — carried out during the preparatory phase and continuing during working of the mine, were shown to provide sufficiently accurate prediction of future mining conditions by defining a 3-D build up of the overburden. Knowledge of the Quaternary could be used to obtain accurate information on the structural development of the Tertiary and the Mesozoic. However, it was also necessary to have a clear insight into the characteristics of the hard-rock substratum as this made some structures in the Quaternary more understandable. The analytical studies carried out within this framework had to be fully integrated, because of the interdependence between the conditions of browncoal exploitation and the (primarily structural) characteristics of the browncoal and the overburden. Slope stability, geotechnical safety and comparable properties could thus be greatly improved.