ABSTRACT

The exploitation of deposits is a limited activity in time and soon or later every mine exploiting the given deposit will come to a phase of liquidation, which is accompanied by termination of pumping out the mine waters. This is shown by a rise of the groundwater table in the region of the deposit negatively affected by exploitation up to the elevation defined by natural or by anthropogenic discharge conditions. The inundation occurs in rock environment, which was negatively affected by previous exploitation accompanied by the origin of empty areas, roof fall zones and rock discontinuities. The inundation of these space formations that were drained off in the course of extraction from technological reasons, changes stress-deformation conditions in rock mass that were in the balanced state until this time. In fact, due to the influence of lifting force in the water on rock mass, the existing stress conditions is relieved, while inducing the deformation changes in rock mass. These changes depending on the size of anthropogenic disturbance of rock mass and the extent of inundation of deposit are shown on the surface in the form of its uplift. After the phase of subsidence during exploitation the upheaval of surface will follow. This upheaval can reach dimensions causing the secondary mining damages on the buildings situated on the surface. This phenomenon was recorded by the survey, e.g. on the surface of the Rosice-Oslavany coal basin where, after inundation, the uplifts were encountered up to +85 mm. Such an upheaval is significant from aspect of the protection of surface buildings.

INTRODUCTION

Exploitation of raw material deposits causes irreversible changes in the earth crust. Impacts of mining activity are encountered in rock environment in the vicinity of the deposit, its surface and landscape situated on the surface and such impacts can outlast the tens of years after termination of exploitation. Such impacts are the movements and deformations of the surface occurring in direct connection (during exploitation) and in indirect connection (after the end of exploitation) with underground extraction. Many theories deal with the issue of surface subsidence during exploitation while stating that after termination of exploitation it is expected that these movements will die away.

The theory of movements of the surface depending on advance of underground exploitation works has been systematically worked out in Europe since the end of the 19th century, primarily with respect to exploitation of vast coal deposits in the Ruhr basin, Upper Silesia and in the Ostrava-Karvina Coalfield and at present it is at the level corresponding in principle to common practical needs of prediction of movements and surface deformations at exploitation of Coal deposits by means of longwall methods, while it is generally assumed that after the completion of exploitation of such sedimentary seam deposits, the movements of surface will die away and will be consolidated relatively early, in the order of units of years (Neset, 1984; Whittaker & Reddiseh, 1989).

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