A rock mass permeability model within the subsidence zone in workings of coal fields

Abstract

Based on mining works near water objects, a model of water permeability in an underworked site of a coalfield under the conditions of failure roof control is given. The secondary water permeability index varies in the section as a sawtooth function and depends on the strain intensity and lithology of rock beds. The coefficient of permeability reaches maximum values in intervals of split crack propagation, sandstones, limestones increasing towards the subfaces of beds, as well as towards the mined-out area in the lower part of the zone of water-conducting subsidence cracks. The coefficient of permeability in siltstone and mudstone beds normal to beds inside the upper and central parts of zones of water-conducting subsidence cracks is at a level of 0.003 m/day.