INDAGINI GEOGNOSTICHE NELLA VALUTAZIONE DEL RISCHIO DI SUBSIDENZA DA COLTIVAZIONI MINERARIE PER VUOTI

Due to mining activity, both during operation and also after closure, induced subsidence represents one of the most important possible consequences: the related phenomena are different, depending on the depth and pattern of the voids, and also related to geomechanical characteristics of the geological formations. In particular it is possible to put in evidence the case of wide subsidence basins (e.g. coal mining, gypsum mining) and the case of local collapses (e.g. gypsum mining, limestone quarrying, salt mining) which can develop to chymneying and to the formation of sinkholes. The paper refers on some possible key issues in order to better understand these phenomena, focusing the fact that each situation is demanding for a proper investigation plan, by adopting geophysical, hydrogeological and geomechanical methods, by the illustration of some case histories followed by authors. Consequences of the possible failures have to be carefully evaluated by considering the presence of underground water: in such circumstances phenomena can significantly change the gravity and the evolution, thus involving also wide surface areas.