The article discusses the validation process of a certain method of balancing gas contained in the pore space of rocks. The validation was based upon juxtaposition of the examination of rocks’ porosity and the effects of comminution in terms of assessing the possibility of opening the pore space. The tests were carried out for six dolomite samples taken from different areas of the ‘Polkowice-Sieroszowice’ copper mine in Poland. Prior to the grinding process, the rocks’ porosity fell in the range of 0.3-14.8%, while the volume of the open pores was included in the 0.01-0.06 cm3/g range. The grinding process was performed using an original device – the GPR analyzer. The SEM analysis revealed pores of various size and shape on the surface of the rock cores, while at the same time demonstrating lack of pores following the grinding process. The grain size distribution curves were compared with the cumulative pore volume curves of the cores before grinding. In order to confirm the argument put forward in this paper – i.e. that comminution of a rock to grains of a size comparable with the size of the rock’s pores results in the release of gas contained in the pore space – the amount of gas released as a result of the comminution process was studied. The results of gas balancing demonstrated that the pore space of the investigated dolomites was filled with gas in amounts from 3.19 cm3/kg to 45.86 cm3/kg. The obtained results of the rock material comminution to grains comparable – in terms of size – to the size of the pores of investigated rocks, along with asserting the presence of gas in the pore space of the studied dolomites, were regarded as a proof that the method of balancing gas in rocks via rock comminution is correct.

Rock and gas outburst is a phenomenon in which fragmented rock material is transported deep into a pit. The transport of rock material by gas is a two-phase process. The article deals with the fluidisation of rock material. Considerations on the fluidisation phenomenon were carried out, and experiments were performed to help clarify whether the fluidisation of dolomite is possible. In the last chapter, a discussion was carried out, and the results obtained were analysed regarding the possibility of occurrence in mine conditions.

The safety of mining operations in hard coal mines must be constantly developed and improved. There is ongoing multi-directional research focused at best recognition of the phenomenon associated with the properties of the coal-gas system and its connections with mining and geological conditions. This article presents the results of sorption experiments on coals from the Upper Silesian Coal Basin, which are characterized by varying degrees of coalification. One of the parameters that describes the kinetics of methane sorption, determining and providing valuable information about gas hazard and in particular the risk of gas and rock outbursts, is the effective diffusion coefficient De. It is derived from the solution of Fick’s second law using many simplifying assumptions. Among them is the assumption that the carbon matrix consists of only one type of pore – micropores. In fact, there are quite often at least two different mechanisms, which are connected to each other, related to the diffusion of methane from the microporous matrix and flows occurring in voids and macropores. This article presents both the unipore and bidisperse models and a set of comparisons which fit them to experimental curves for selected coals. For some samples the more complex bidisperse model gave much better results than the classic unipore one. The supremacy of the bidisperse model could be associated with the differences in the coal structure related to the coalification degree. Initial results justify further analyses on a wider set of coals using the methodology developed in this paper.

Coal mining tends to face increasing stress and gas conditions when it extends to deeper levels. The mining-induced high stress and gas pressure concentrations often result in gasogeodynamic phenomena such as rock bursts and coal & gas outbursts. Over the last decades, these gasogeodynamic events have been observed more often in the Upper Silesian Coal Basin, Poland. With the increasing mining depth, these hazards not only become a serious safety risk but also represent a significant challenge for coal mining. In order to eliminate future hazards and improve safety in underground coal mines, it is necessary to apply particular methods for the prevention and mitigation of possible hazards during mining operations. Inaction or incorrect use of preventive measures may lead to gasogeodynamic events, which may result in accidents and material losses, thereby affecting the mine’s economic performance. Several coal mines operated by Jastrzębska Spółka Węglowa S.A. (JSW group), such as Pniówek, Budryk and Zofiówka coal mines have been identified as the area most prone to rock bursts as well as coal and gas outburst. Generally, the longwall panels often experience a high degree of these mining hazards. Therefore, the main aim of this research is to examine and optimise the possibility of application of prevention methods in order to reduce the frequency and scale of dangerous gasogeodynamic phenomena such as coal and gas outburst. As a main part, the field testing of the selected preventive methods that were conducted in the JSW coal mines. Based on the obtained results, the possibility of application of an optimal method for the prevention and control of coal and gas outburst in the geo-mining conditions of the JSW coal mines was discussed. The research results could be an example for other coal mines in mine planning and designing in the gasogeodynamic (coal and gas outburst) hazard-prone conditions.

The analysis of natural hazards, including gas-geodynamic phenomena, requires study of the basic physical processes that take place at each stage of an event. This paper focuses on analysing the transport of fragmented rock material during rock and gas outbursts. Our theoretical considerations and experiments have allowed us to specify and verify the significant forces acting on fragmented rock during its transport, thus determining the speed of grains of each grain class in the stream of expanding gas. The above study may serve as a preface to a wide-ranging quantitative and qualitative energy analysis of the movement of material ejected during Gas-geodynamic phenomena.

A film stress measurement system applicable for hyperbaric environment was developed to characterize stress evolution in a physical simulation test of a gas-solid coupling geological disaster. It consists of flexible film pressure sensors, a signal conversion module, and a highly-integrated acquisition box which can perform synchronous and rapid acquisition of 1 kHz test data. Meanwhile, we adopted a feasible sealing technology and protection method to improve the survival rate of the sensors and the success rate of the test, which can ensure the accuracy of the test results. The stress measurement system performed well in a large-scale simulation test of coal and gas outburst that reproduced the outburst in the laboratory. The stress evolution of surrounding rock in front of the heading is completely recorded in a successful simulation of the outburst which is consistent with the previous empirical and theoretical analysis. The experiment verifies the feasibility of the stress measurement system as well as the sealing technology, laying a foundation for the physical simulation test of gas-solid coupled geological disasters.

A glacier lake outburst flood occurred on James Ross Island, Antarctic Peninsula region, during the 2004-2005 austral summer season. The source lake was located on the Lachman II ice-cored rock glacier, and formed prior to 1980. The size of the lake has been increasing gradually since the 1990s. The lake basin extended to approximately 220 m in length and 160 m in width by the end of February 2005. We observed that the lake had drained by February 2005, and found a deep gully on the south side of the lake rim. It appears that the lake level rose and water overflowed the lake rim here. James Ross Island contains a large number of debris-covered glaciers, ice-cored moraines, and rock glaciers with glacier lakes which are dammed by these features or which form upon them. As climatic warming has recently been reported for this region, further glacier lake outburst floods seem likely to occur.