The Timeliness of Delimiting Caving Areas under the Circumstances of a Drastic Decrease of Mining Activity in the Baia Mare Basin

摘要

The deposits from Baia Mare Basin are characterized by a vein shape presentation form, with vertical extension to hundreds of meters, and a horizontal one of kilometers. Related to dip, these veins are framed in the high dip vein group, their thicknesses being extremely variable, with maximum values comprised between 40 and 60 meters. As a consequence of repeated changes suffered by the basic rocks, the roof and the floor of deposits are weakened from a geomechanical point of view. Taking into consideration that in the future, a significant number of mining fields from the basin will be closed, a delimitation of influence areas of the abandoned cavities mainly due to the following reasons: the exploitation of the great majority of veins was carried out in the proximity of surface; in depth, the sublevel caving method of mining was applied in most of the cases; in certain cases above the cavities are located objects which will be removed or will require protection (roads, rivers, buildings, high voltage lines); cavings are occuring usually instantaneously, without visible forecastable signs.Taking into account the above presented considerations, which are common for all the deposits, these issues have been analysed from geomechanical, technical and mining points of view and, finally, forecasting and monitoring methodologies of rocks around underground cavities were established.