Salt caverns are used for the storage of natural gas, LPG, oil, hydrogen, and compressed air due to rock salt advantageous mechanical and physical properties, large storage capacity, flexible operations scenario with high withdrawal and injection rates. The short- and long-term mechanical behaviour and properties of rock salt are influenced by mineral content and composition, structural and textural features (fabrics). Mineral composition and fabrics of rock salt result from the sedimentary environment and post sedimentary processes. The impurities in rock salt occur in form of interlayers, laminae and aggregates. The aggregates can be dispersed within the halite grains or at the boundary of halite grains. Mineral content, mineral composition of impurities and their occurrence form as well as halite grain size contribute to the high variability of rock salt mechanical properties. The rock or mineral impurities like claystone, mudstone, anhydrite, carnallite and sylvite are discussed. Moreover, the influence of micro fabrics (in micro-scale) like fluid inclusions or crystals of other minerals on rock salt mechanical performance is described. In this paper the mechanical properties and behaviour of rock salt and their relation to mineral composition and fabrics are summarised and discussed. The empirical determination of impurities and fabrics impact on deformation mechanism of rock salt, qualitative description and formulation of constative models will improve the evaluation and prediction of cavern stability by numerical modelling methods. Moreover, studying these relations may be useful in risk assessment and prediction of cavern storage capacity.
Salt caverns are used for over 70 years to store power sources and dispose of industrial wastes. The design of cavern shape and dimensions is still considered as a difficult engineering problem despite progress in geotechnical, construction and exploration methods. The rational design of cavern depends on mechanical parameters of rock salt and nonsalt rocks, stability conditions, safety requirements and stored material. However, most of these factors are related to geological factors like depth of cavern location, the geological structure of salt deposit, lithology of interlayers, petrology and mineralogy of rock salt and interlayers. The significant diversity in the geological conditions of different rock salt deposits contributed to the variety in shape and dimensions of salt caverns worldwide. In this paper, the examples of caverns developed in various salt deposits are presented. The shape of these caverns and its relation to geological features is presented. The influence of geological factors on the formation of irregularities in a cavern shape is described. Moreover, the evaluation of storage caverns located in Polish salt deposits in a view of the aforementioned geological factors is performed. The information and analysis described in this paper provide input which can be useful in future plans connected with the development of underground storage in Poland.
W artykule przedstawiono problematykę oceny stateczności skarp i zboczy. Przybliżono rozwój prac badawczych realizowanych w Katedrze Geomechaniki, Budownictwa i Geotechniki w tym zakresie. Zaprezentowano wybrane przykłady prac badawczych koncentrujących się na ocenie stateczności zboczy wyrobisk odkrywkowych. Wskazano wyzwania i trendy w metodach oceny stateczności.
EN
This article presents problematic aspects of the assessment of slope and slope/flank stability. It describes development of research work carried it out on this topic in the Department of Geomechanics, Civil Engineering and Geotechnics. Selected examples of research works focused on the assessment of the slope stability of opencast excavations are presented. Article also stipulates challenges and trends in stability assessment methods.
Microhardness tests were carried out on single halite crystals. They were conducted on the (001) surface, with the indenter set in two directions: parallel to the halite face (010); and parallel to the (110) face. The halite crystals represent salt formations of different ages (Devonian, Zechstein, Badenian), depths (from 1835.5 to 195 m) and intensities of tectonic disturbance (horizontally stratified, salt dome, strongly folded). The measurement results revealed specific features of the halite crystals analysed. Firstly, the data obtained show microhardness anisotropy in halite crystals. Moreover, microhardness correlates with the depth of the salt-bearing formations. Halite crystals from deeper levels showed higher microhardness, though there was no correlation between the intensity of tectonic deformation and the average Vickers hardness (HV). The samples analysed show a variability of HV values and and of the shapes of imprints. These indicate zones where halite crystals are deformed at the atomic level and reflects the presence of defects in the crystal lattice. Such deformation is reflected in an irregularity of the strike of cleavage planes. Consequently, the analysis of imprint shapes is a useful method for the examination of ductile minerals and materials.
Ograniczenie zagrożenia wodnego stanowi jeden z priorytetów Kopalni Soli „Kłodawa”. Pole soli kamiennej białej nr 1 zlokalizowane jest wzdłuż wschodniej granicy wysadu. Granice Pola od strony północno-wschodniej stanowi konstrukcyjnie wyznaczona powierzchnia filara brzeżnego, który do poziomu 600 m ma grubość 50 m. Źródłem zagrożenia wodnego przy eksploatacji Pola nr 1 są północno-wschodnia granica wysadu solnego oraz południowo-zachodnia granica Pola. W artykule przedstawiono metodykę likwidacji wyrobisk chodnikowych w filarze brzeżnym, w których stwierdzono zjawiska wodne. Odpowiedni dobór technologii likwidacji, uzależniony od miejsca występowania zjawisk wodnych ogranicza zagrożenie wodne omawianego rejonu kopalni.
EN
Water hazard reduction is one of the priorities of the “Kłodawa” Salt Mine’s management. White rock salt Field No. 1 is situated along the eastern border of the Kłodawa salt dome. The boundaries of the field on the north-east side are equivalent to the structurally designated area of the peripheral pillar, which is 50 m thick down to the level of 600 m. The source of water hazard during the exploitation of Field No. 1 is situated in the north-eastern boundary of the salt dome and the south-western boundary of the Field. This paper presents a methodology of the liquidation of the salt mine’ workings in the peripheral pillar where water hazard has been identified. Appropriate selection of the mine decommissioning technology, depending on the places of occurrence of water leaks, can reduce the water hazard in the specific areas of the salt mine.
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