Occurrence of Linear Discontinuous Deformations in Upper Silesia (Poland) in Conditions of Intensive Mining Extraction—Case Study

Abstract

Currently, linear discontinuous deformations in mining areas are an important issue, both due to the frequency of their occurrence and the threat they pose to general safety. This paper presents a case study of an occurrence of such a deformation. The analyses of the geological and mining conditions, as well as the conducted calculations presented herein, indicate that the cause of the deformation was the occurrence of high-value horizontal tensile strains. It was triggered by mining exploitation carried out with caving in three seams at depths between 200 and 545 m. An additional factor conductive to the creation of the deformation was the tectonic structure of the rock mass. The subject matter of the paper is significant given the growing number of discontinuous linear deformations occurring on the surface due to underground mining—even if the mining was conducted at great depths. They were formed as a result of intensive underground mining operations and the occurrence of high-value deformations. These deformations were particularly dangerous to building structures on the surface, which were often damaged. For this reason, it was worthwhile to make arrangements regarding the correlation between the occurrence of the deformations and the values and the distribution of continuous deformations caused by underground extraction, as well as the existence of tectonic faults.

The Use of Geomaterials to Restore the Utility Value of Post-Mining Areas

“…The category of the "mining area", depending on the interpretation of the horizontal strain (including the relaxation (or not) of the horizontal strain), ranged from III (with relaxation) to V (without relaxation). Such high values of the terrain category and the occurrence of tectonic faults in Carboniferous beds were found to be the main causes of linear discontinuous deformations, which is confirmed by studies conducted in this field to date [6,7,9,10].…”

“…Linear discontinuous deformations of the surface type result from the formation of fractures and slippage of the near-surface soil layer, which is most frequently subjected to continuous deformations due to underground mining excavations [6,7,10,[50][51][52]. Kwiatek (2003) [50], analyzing the impact of horizontal loosening of near-surface layers of soil, stated that the cause of the formation of discontinuities is from bringing the near-surface layer of the rock mass made of soil to the state of limit equilibrium, as a result of which, slippage surfaces may appear, or, in the cases of horizontal loosening of the layer with cohesion c ≠ 0, vertical fractures separating soil masses that continue to move as non-deformable masses.…”

“…One of the main causes of their formations involves tensile strain zones of large values caused by mining exploitation [6,7,10,[50][51][52].…”

“…In the Polish Upper Silesian Coal Basin, underground coal mining is often carried out in urbanized areas, resulting in damage to buildings, communication, and technical infrastructure. Geomechanical transformations of land surfaces mainly constitute continuous deformations in the form of subsidence troughs, which may be accompanied by discontinuous linear and surface deformations [1][2][3][4][5][6][7][8]. Based on previous studies regarding the occurrence of discontinuous deformations, a significant predominance was found in the occurrence of linear deformations over surface deformations [9,10].…”

“…Energies 2022, 15 As previously mentioned, there are various threats (from mining exploitations) in mining and post-mining areas [4][5][6][7][8][9][10]. Keep in mind that mining excavations are often carried out under urbanized areas with technical and communication infrastructures.…”