Abstract
Many mines in the Ukraine are in the process of being closed as part of the coal industry restructuring programme. The termination of pumping operations results in the flooding of abandoned mine workings. This causes changes in the hydrogeological characteristics and geomechanical stability of the rock mass. There is no reliable method for predicting the effect of these processes. In the Central Donbass Basin, if only one mine horizon is flooded, surface subsidence of up to 500 mm can occur when the mine is abandoned. The period required for the stabilization of areas liable to subsidence after the mines are closed can be as long as 10 years.
The mechanical properties of caved rock can change significantly during the long-term operation of coal mines in the Central Regions of Donbass. The permeability of the strata overlying working faces is increased by numerous thirls, crosscuts and zones of cracks to heights of 10 to 40 times the thickness of the worked seam. The mechanical properties of the rock can also change during flooding. The rock can compress and reduce in thickness. The plasticity of the rock can increase also. It is therefore necessary to study the physical-mechanical properties of the caved strata when they are saturated during the flooding of abandoned workings. Research into methods of estimating the amount of additional surface subsidence caused by the reactivation of the geomechanical caving processes during flooding is reported.
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