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Complex analysis of thermal and gaseous states of chosen coal dumps performed by the authors made it possible to initially evaluate risk of spontaneous combustion of these objects and their classification based on indicators of a certain risk group. Thanks to the observation of coal dumps using a thermovisual camera, non-contact visualization of temperature distribution of the coal dump was obtained in the form of colored thermograms, which led to identifying areas of higher thermal activity. Use of a thermovisual camera is an example of adaptation of modern technology for research purposes. Properly planned measurement, swift development, and comparison of results gives complex information about object structure and thermal reactions on its surface. Analysis of thermal anomalies found on coal dumps allows us to draw conclusions about the causes of these events and repeating characteristics of environmental physicochemical condition variability accompanying such events. The process of endogenic fire formation is a complex mechanism that is not yet fully understood. Doubts were dispelled in the matter of main spontaneous combustion, which is the oxidation process of coal and which is the main burning by-product material of a mining operation. However, the reason for the activation process of self-heating and leading coal substance to critical temperature (60-80ºC) is not fully understood. According to this, the author has reviewed knowledge related to experiences with spontaneous combustion of coal dumps.
On the basis of three selected examples, some problems attributed to the presence of voids resulted from mining operations in already commissioned underground coal mines are discussed. Continuous and discontinuous deformations of the ground surface (sinkholes and subsidence troughs) of anthropogenic origination implicate hazards for the ground surface, even many decades after completion of mining work. Nowadays, when decommissioning and flooding of numerous mines happens, ground movements as well as seismic events related to flooding of abandoned underground mines can be observed. The first case study draws attention to the problems of effective voids localisation methods as well as the reliability of grout injection operations for road construction purposes. The second case emphasizes a problem occurring often in areas with long and complex mining histories, meaning appropriate determination of origin, process and protective measures regarding occurred ground deformations, or damage to buildings. The third case describes specific effects on the surface (shocks and ground surface elevation) generated by the flooding of decommissioned mines.
Water that floods the mining complexes is drained on a constant basis when a mine is still active, but the situation changes the moment the mine is closed. This article presents the influence that flooding of mine workings has on a surface of a mining area using computer simulation. The evaluation of potential changes to the surface and scale of this phenomenon has been done using as examples the exploitation of mine deposit layers 702, 705, and 718 of the old Gliwice and Pstrowski mines. The performed numerical simulation showed that using numerical modeling of rock mass demonstrates the possibility of predicting uplifting of the surface caused by flooding of underground workings. Maximum designated value of surface uplifting amounts to around 34 mm/m. This value is relatively small and does not exceed 2% of subsidence caused by previous mining activity.
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