SPATIO-TEMPORAL DISTRIBUTION OF LAND SUBSIDENCE AND WATER DROP CAUSED BY UNDERGROUND EXPLOITATION OF MINERAL RESOURCES

ABSTRACT

Underground exploitation of mineral resources is often carried out in a watered rock mass. Dewatering of rock layers disturbs its geomechanical equilibrium, consequently resulting in deformations occurrence on the terrain surface. Furthermore, modeling of rock strata dewatering and related land subsidence is still a complex issue, mostly due to unambiguous qualitative and quantitative characteristics of rock mass. Presented research aimed at determination of dynamics of hydrogeological changes and land subsidence induced by water withdrawal in fractured rock strata. They were carried out in the area of “Bogdanka” hard coal mine in Poland, at a depth of 1000 m, in a multi-layered aquifer system. Spatio-temporal distribution of depression cone and land subsidence in the period 1982-2018 was analyzed. Furthermore, based on the results of observations of water table in aquifers, land subsidence and geomechanical characteristics of rock mass, trend lines of logarithmic functions were estimated. Afterward, based on logarithmic functions, prediction of water table fluctuation and land subsidence was carried out in the entire area of hard coal mining in the period 2018-2025. Subsequently, a novel time factor was introduced. It determines the delay of deformation occurrence on the terrain surface induced by rock strata dewatering as a function of time and distance from drainage center. Finally, computation results were successfully compared with field data. On the whole, the presented research provide better insight into mechanics of lands subsidence development and water flow in the fractured rock mass due to rock strata dewatering accompanying underground exploitation of mineral resources.

Keywords: time factor, depression cone, water pumping, land subsidence, mining