Kinetics of the structural changes in the counterpressure zone of a stressed gas-saturated coal bed

Mineev, S.P.; Prusova, Alla

doi:10.1007/bf00710734

Cited by 4 publications

(7 citation statements)

References 4 publications

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“…It can also be noted that formulas (28) and ( 29) are completely analogous to formulas (21) and (22), respectively. The only difference is in the recording of material constants.…”

Section: Figure 5 To the Determination Of The Critical Height Of A Watersaturated Vertical Slopementioning

confidence: 95%

“…Up to date, many scientists and research teams are involved in such issues [18]- [21], however, the issue has not been sufficiently studied from this point of view [22]- [26]. Thus, Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine (Dnipro, Ukraine) employees of Ukraine has performed the studies related to gas-dynamic assessment of coal and rock massif [27]- [28], and particular attention is paid to methane release into the face of underground mine workings, to the gas pressure in the stratum, and other factors [29]- [31]. The physical and chemical processes occurring in the rock massif are quite well presented in the works of V.V.…”

Section: Figure 1 the Scheme For The Determination Of The Critical Pressure P Critical Load Q Onto The Roof Of The Watersaturated Or Gas-mentioning

confidence: 99%

“…Having set the pore pressure equal to zero in (28), we find the critical height of the water-free mine rock. We obtain:…”

Section: Figure 5 To the Determination Of The Critical Height Of A Watersaturated Vertical Slopementioning

confidence: 99%

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Stability assessment of the slopes and side-hills with account of the excess pressure in the pore liquid

Shapoval¹,

Shashenko²,

Hapieiev³

et al. 2020

Min. miner. depos.

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The strength criteria substantiation of water-saturated soils and mine rocks, which make it possible to obtain the analytical solutions necessary for determining the stability of water-flooded soil slopes and side-hills. Methods. The methods are applied of analysis and generalization of the theoretical and numerical experimental studies results. The rocks and soils characteristics are taken into account: specific cohesion c, internal friction angle φ, compressive strength R c and tensile strength R p of the rock, as well as the bulk density. The load q was imposed to the water-saturated seam roof from the overlying mine rock or soil seams, the weight of equipment or structures located on the surface. It was accepted that the seam is saturated with water (gas) with the excess pressure Р. A point on the mine working surface (or vertical slope surface), located at a depth z is considered. It is determined at which ratio of q, P and z parameters the soil or rock seam will be destroyed. The problem solution is based on the Mohr-Coulomb strength criterion. Findings. The strengths of water-saturated rock and water-free rock are compared. The ratios have been obtained that make possible to determine the critical load on the daylight surface of water-saturated and water-free vertical slopes, side-hills, trenches and foundation pits, as well as various mine workings in soil bases and mine rocks. The analytical solution has been obtained, which makes it possible to determine a value of the critical pressure on the water-flooded vertical surfaces and soil slopes. The generalization has been made of a certain one-dimensional Mohr-Coulomb strength condition for a water-saturated base characterized by the strength characteristics с and φ for the dimensional case. Originality. It has been theoretically proved that for any pore pressure value in the water-saturated mine rock (or soil) their strength will be less than in their water-free state. New solutions have been formulated for determining the critical height of a water-saturated vertical soil slope or the wall in the vertical mine working. Practical implications. The obtained results make it possible to solve the practical engineering problems on determining the stability of water-saturated slopes and side-hills with a load-free daylight surface, therewith, taking into account the weight of the equipment, stored material and the stability of vertical walls of water-saturated seams of open-cut mine workings.

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“…It can also be noted that formulas (28) and ( 29) are completely analogous to formulas (21) and (22), respectively. The only difference is in the recording of material constants.…”

Section: Figure 5 To the Determination Of The Critical Height Of A Watersaturated Vertical Slopementioning

confidence: 95%

Section: Figure 1 the Scheme For The Determination Of The Critical Pressure P Critical Load Q Onto The Roof Of The Watersaturated Or Gas-mentioning

confidence: 99%

See 1 more Smart Citation

Stability assessment of the slopes and side-hills with account of the excess pressure in the pore liquid

Shapoval¹,

Shashenko²,

Hapieiev³

et al. 2020

Min. miner. depos.

View full text Add to dashboard Cite

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“…На відміну від закритих мікропор, фольмерівські пори є стискувані. У межах зміни напруженого стану поблизу вибою виробки до максимуму опорного тиску зміна пористості зі збільшенням навантаження, в загальному вигляді, описується наступним виразом [11]:…”

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“…Рисунок 3 -Залежність параметрів апроксимації А і В від діаметра пор в співвідношенні (11) Залежності на рисунку 3 апроксимуються експоненціальними функціями, що подібні функціям ( 7) -( 9). Коефіцієнт достовірності апроксимації R2 склав не менше 0,95.…”

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Calculation of the changing cofficient of the folmerov diffusion of methane desorped from coal in the face area of the coal layer at great depths

Minieiev¹,

Prusova²,

Yanzhula³

et al. 2021

Geoteh. meh.

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An algorithm for calculating the Volmer diffusion coefficient of methane adsorbed in coal in the bottomhole zone of the formation to the maximum reference pressure is developed with taking into account the change in the Folmer porosity and the size of the space of this zone. The algorithm is based on the using of the exponential law of compression, which describes the structural changes in the reference pressure of the coal seam. This allowed us to determine the diameter of the Folmer pores in the study area depending on its stress state. Based on these data and the calculation of the exponential nature of the change in porosity, the regularity of the Folmer diffusion in the bottomhole region at its fixed length and initial porosity of coal is established. By using a method of step-by-step approximating the solution of this problem for different parameters, the research results are generalized to the existing ranges of change in the Folmer porosity of coal and the size of the bottomhole region of reference pressure in mining conditions at great depths. The functional approximation dependence is established, which allows to perform calculations of the Volmer diffusion coefficient of methane desorbed from the coal layer, with simultaneous change of two parameters - initial porosity of coal and distance between the bottom to the maximum reference pressure zone. Calculations showed that when reference pressure approached its maximum at a distance of up to 10 m from the face the coefficient of Folmer diffusion of methane in coal decreased slightly. In this case, there is a strong dependence of the Volmer diffusion coefficient on the diameter of the Folmer pores in the virgin coal layer. For example, when this diameter increases twofold - from 8 А to 16 А at the distance of 20 m from the face to a maximum reference pressure, the coefficient of Folmer diffusion increases by 1.5 times. That is, Folmer's diffusion is the most intensive in the disturbed zones of the coal layer. This can be the area of maximum reference pressure, if there is a zone of disintegration, or in that part of the face zone, which is characterized by the developed system of fractures. Key words: adsorbed methane, coal layer, face zone, Folmer pores, Folmer diffusion coefficient.

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Regularity of change in the volmer diffusion coefficient of methane adsorbed in the microsorption structure of the elastic zone of the coal seam bearing pressure

2023

Geoteh. meh.

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The Volmer diffusion coefficient of methane adsorbed in the micropores of coal in the elastic zone of the coal seam bearing pressure, which normally is under conditions of significant compressive stress, was calculated with taking into account the energy of the methane sorption connection with coal, the energy of Volmer diffusion activation in the porous space of coal, and the stressed state of the elastic zone with its influence on the change of Volmer porosity. During the calculations, such parameters as the diameter of Volmer micropores and the length of the descending branch of the bearing pressure diagram were varied. As a result of the approximation of these calculations, both pairwise dependences of the Volmer diffusion coefficient on the listed parameters and its multifactorial relationship with them were established. Therefore, it is concluded that the process of methane diffusion in the elastic zone of bearing pressure is not blocked by the rock pressure, as previously thought, but is actively developing. The diffusion of free methane will be determined by the established regularity of changes in the Volmer diffusion coefficient in the elastic zone of the coal seam bearing pressure. The calculations show that as the distance from the maximum of the bearing pressure increases, the Volmer diffusion coefficient of methane in the coal seam increases, which is due to a decrease in the pressure of rocks in the descending branch of the bearing pressure diagram. However, this growth is not great due to the weak compressibility of pores. Therefore, for pores of the same diameter, the Volmer diffusion coefficient in the elastic zone of the coal seam bearing pressure for the given mining geological conditions can be considered a constant. For depths of, for example, 1000 m and pore diameters of 10 Å, the value of the Volmer diffusion coefficient will be approximately 3.77·10-8 m2/s. This confirms that methane gas release is caused not only by filtration of free gas, but also by Volmer diffusion of adsorbed methane. In turn, the reserves of the latter are known to be the main reserves of methane in coal. Therefore, the established regularity makes it possible to more accurately calculate the volumes of methane, which will be released from the coal massif during mining operations, in order to assess safety of conditions for coal deposits mining and to develop technologies for coal mine methane production.

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Kinetics of the structural changes in the counterpressure zone of a stressed gas-saturated coal bed

Cited by 4 publications

References 4 publications

Stability assessment of the slopes and side-hills with account of the excess pressure in the pore liquid

Stability assessment of the slopes and side-hills with account of the excess pressure in the pore liquid

Calculation of the changing cofficient of the folmerov diffusion of methane desorped from coal in the face area of the coal layer at great depths

Regularity of change in the volmer diffusion coefficient of methane adsorbed in the microsorption structure of the elastic zone of the coal seam bearing pressure

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