Permeability variations within mining-induced fractured rock mass and its influence on groundwater inrush

Wang, W. X.; Sui, Wanghua; Faybishenko, Boris; Stringfellow, William T.

doi:10.1007/s12665-015-5064-5

Cited by 39 publications

(22 citation statements)

References 33 publications

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“…In-situ monitoring of water inflow and pressure variations with time and mining distance in the water inrush process (Wang et al 2016) In the same coalfield, a borehole TV viewer system was used to monitor the fracture closure after the coal excavation 15 years ago. The results shown in Fig.…”

Section: Figmentioning

confidence: 99%

Closure of Fracture Due to Cover Stress Re-establishment After Coal Mining

et al. 2016

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In situ measurements of deformations, stresses, and closure of fractures, affecting water inflow following coal mining, are challenging due to the inaccessibility of fractured rock. In this paper, the authors studied the closure process of the fractured rock mass with the cover stress re-establishment based on a theoretical analysis and a scale model testing. A quantitative analysis is used to study the fracture distribution in the fractured zone. A function to describe a fracture aperture distribution in the fractured zone is proposed, which takes into account the curvature and thickness of the fractured rock. The theoretical analysis and a scale model testing both indicate that the cover stress re-establishment with mining distance increasing and the relationship between the fracture closure and cover stress reestablishment both satisfy a logarithmic function. The scale model test also shows the following features: (1) the fracture ratio (which is the fracture area divided by the total area of fracture and intact rock with a unit width in the vertical or horizontal direction) in the lower part of the fractured rock mass is greater than that in the upper part; (2) the initially fast decreased of fracture ratios is then followed by a slower decrease during the cover stress re-establishment process; (3) in the upper part of the rock mass, the vertical directional fractures with small apertures are being closed with cover stress reestablishment, which indicates an increase in the water resistance reducing the seepage from these parts of the fractured zone. This study improves the general understanding of the fracture closure process and cover stress re-establishment in the fractured rock mass after coal mining ceased, and provides a theoretical basis for water resource protection in case of underground coal mining.

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Section: Figmentioning

confidence: 99%

Closure of Fracture Due to Cover Stress Re-establishment After Coal Mining

et al. 2016

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“…Nourani et al and Poulsen et al revealed that the overlying strata permeability was directly related to porosity and proposed a method for rock permeability evaluation based on the porosity parameters [18,19]. Wang et al and Karacan et al reported that rocks in the goaf gradually supported the overlying roof with the panel advance, while the stress redistribution in the overlying strata caused the overlying rock permeability decline [20,21].…”

Section: Introductionmentioning

confidence: 99%

Impact of Mine Panel Size on Hydraulic Permeability of Weakly Cemented Strata

et al. 2020

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The effect of underground coal mining on groundwater, ranging from minimal to severe depending on the mined-out panel size, is primarily associated with the change in ground hydraulic permeability. This paper presents a novel panel design method, taking consideration of reducing water loss during the mining operation, which is based on evaluating and ranking the impact of panel size on the hydraulic permeability of weakly cemented strata. The permeability test results of weakly cemented rock samples collected in the Yili No.4 Coal Mine in Xinjiang, China strongly indicates that, in contrast to common rock, their post-peak permeability during the total stress-strain process is lower than the initial permeability due to high porosity and the presence of clay minerals. A numerical modeling based on strain-permeability functions reveals that the post-mining permeability distribution in the weakly cemented overlying strata could be subdivided into three zones: the permeability reduction zone, the permeability restoring zone, and the permeability high-increment zone. The impact significance of different size factors on the post-mining permeability of overlying strata can be ranked in decreasing order as follows: mining height, panel width, and panel length, the quantification of which was based on the variance analysis of such indices as maximum pore pressure and maximum flow velocity. Based on the above findings, the optimal size of panel 21103 in the Yili No.4 Coal Mine was determined and validated by water level field observations.

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“…Zou et al [40] examined the fracture surface of natural granite rock using laser and established the fracture model of roughness characterization and fluid flowing simulation. Wang et al [41] acquired the roughness of the joint surface in the rocks using 3D-laser-scanning-based rock surface meter.…”

Section: Introductionmentioning

confidence: 99%

Study on the Permeability of Weakly Cemented Sandstones

et al. 2019

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Fractured rocks are a type of complex media that widely exist in various projects including energy, hydraulic, and underground space engineering, whose permeability properties are a hotspot in current rock mechanics domain. Aiming at investigating the seepage characteristics of the fracture surfaces in different rock strata, uniaxial compressive test and permeability test were performed on single-fracture homogenous and heterogeneous rocks. Specifically, rock’s physical and mechanical parameters were measured in uniaxial tests while the initial width of the single fracture was determined through CT scanning. In combination with test results and the calculation model of the displacement of single-fracture heterogeneous rock under triaxial stress condition, the calculation formula of the permeability coefficient of single-fracture heterogeneous rock was derived. Results show that hydraulic pressure in the fracture can affect the permeability coefficient of the fractured rock. Hydraulic fracturing effect occurred with the increase of hydraulic pressure in the fracture, which then generates slight normal deformations of the rock masses on both two sides of the fracture surface, decreases the contact area in the fracture, and leads to the increases of both fracture width and permeability coefficient. For single-fracture rock, the lithological properties of the rock masses on both two sides of the fracture surface impose significant effects on the permeability coefficient. Under same hydraulic pressure and confining pressure, the permeability coefficient of single-fracture coarse sandstone is greatest, followed by that of single-fracture heterogeneous rock, and finally by single-fracture fine sandstone. Theoretical calculation results agree well with the test results, suggesting that the derived theoretical formula can adequately describe the variation tendencies of permeability coefficient with confining pressure and hydraulic pressure in the fracture.

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Permeability variations within mining-induced fractured rock mass and its influence on groundwater inrush

Cited by 39 publications

References 33 publications

Closure of Fracture Due to Cover Stress Re-establishment After Coal Mining

Closure of Fracture Due to Cover Stress Re-establishment After Coal Mining

Impact of Mine Panel Size on Hydraulic Permeability of Weakly Cemented Strata

Study on the Permeability of Weakly Cemented Sandstones

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