forecasting safe conditions for developing coal bed suites under aquifers on the basis of geomechanics of technogenic water conducting fractures

Studies of the processes of displacement of rock massif layers in the course of their initial underworking indicate that their maximum curvature tends to decrease in the inverse proportion to squared distance to coal bed from the layer in question. It manifests itself in the distribution of vertical extension deformations: these are the largest in the vicinity of the coal bed and decrease towards the surface. Such is the consequence of the mechanism of bending the massive layers: the curvature of underlying layers is higher than that of overlying ones. In the zone of complete underworking the maximum curvature of each layer of the repeatedly underworked bedded formation is equal to the maximum curvature of the surface, that is the curvature of the overlying layer repeats the curvature of the underlying one. Hence, the maximum curvature of any layer  in the massive is inversely proportional to squared depth of the coal bed suite. Note that the distribution of vertical deformations of the massive differs in both its quality and quantity from that of the initially underworked massive: vertical deformations are an order of magnitude fewer and their distribution is presented by alternating deformations of extension and compression. Such is the consequence of the mechanism of layer bending in case the massive is underworked repeatedly and it explains why the height of the zone of water conducting fractures does not grow in such conditions with respect to the one formed during the excavation of the initial layer of the suite. The technique of forecasting the development of zone of water conducting fractures developed  on the basis of such geomechanical processes makes possible safe excavation of coal beds under aquifers.