Real-time observation of meso-fracture process in backfill body during mine subsidence using X-ray CT under uniaxial compressive conditions

Sun, Wei; Wu, Aixiang; Hou, Kepeng; Yang, Yi; Лю, Лэй; Yan, Wen

doi:10.1016/j.conbuildmat.2016.03.050

Cited by 90 publications

(29 citation statements)

References 2 publications

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“…Underground voids often lead to stope instability and ground subsidence, causing damage to residential buildings and infrastructures [1,2]. In China, the subsidence area caused by mining activity has reached 314,765 km 2 , resulting in 535 deaths and economic losses of $1.9 billion [3]. Meanwhile, massive tailings generated from mineral processing have been deposited into more than 3000 tailings dams (ponds) without any further steps due to its low cost [4,5].…”

Section: Introductionmentioning

confidence: 99%

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Use of Cemented Super-Fine Unclassified Tailings Backfill for Control of Subsidence

et al. 2017

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Known for its advantages in preventing geological and environmental hazards, cemented paste backfill (CPB) has become a topic of interest for scientists and mining engineers in recent decades. This paper presents the results of a study on the use of cemented super-fine tailings backfill (CSUTB) in an underground mine for control of surface subsidence. An analytical solution is developed based on the available model to calculate the required strength of backfill when in contact with non-cemented tailings (NCT). The effect of solid contents on the rheological properties of CSUTB is investigated. A reasonable mix proportion (RMP) of CSUTB is determined for Zhongguan Iron Mine (ZGIM) based on laboratory experiments. The validity of RMP in surface subsidence control is verified by a 3D numerical model. The obtained results show that CSUTB requires higher strength when in contact with NCT than when in contact with orebody. Rheological characteristics, e.g., slump, fluidity, and bleeding rate of fresh CSUTB, decrease with higher solids content, of which values with a certain solids content can be determined by quadratic polynomial regression equations. RMP with a cement to tailings (c/t) ratio of 1:10 and a solids content of 70% is recommended for ZGIM, as it shows favorable mechanical and rheological abilities. The deformation parameters (curvature, inclination, and horizontal deformation rate) obtained from numerical modeling are acceptable and lower than critical values, meaning CSUTB can feasibly be used with RMP in subsidence control.

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Section: Introductionmentioning

confidence: 99%

“…For example, a tailings dam located in Shanxi province, China collapsed in 2008, causing 277 casualties and direct economic losses of $14.59 million. More seriously, the quantity of tailings in China is still increasing at a speed of 600 million tons per year [3].…”

Section: Introductionmentioning

confidence: 99%

Use of Cemented Super-Fine Unclassified Tailings Backfill for Control of Subsidence

et al. 2017

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“…14 Shear failure is a common failure form in engineering. [22][23][24][25] Previous studies have investigated how macroscopic features, microscopic composition, and structure affect the shear behavior of rocks under compression. 15 Acoustic emission (AE) technology has been used to nondestructively detect cracks and assess damage 16,17 and may be used to divide the crack development process in brittle materials into five stages: crack closure, elastic deformation, stable crack development, unstable crack development, and the postpeak stage.…”

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confidence: 99%

“…21 In addition, high-resolution three-dimensional (3D) X-ray microscopy (3D-XRM) or computed tomography of rock offers another route to study the internal pore and crack distribution in rock materials and solid waste. [22][23][24][25] Previous studies have investigated how macroscopic features, microscopic composition, and structure affect the shear behavior of rocks under compression. 26 However, few studies have investigated the mechanical properties and crack propagation of coal samples with different water content and under compression shear.…”

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confidence: 99%

Experimental study of shear failure and crack propagation in water‐bearing coal samples

Tang

Yao

et al. 2019

Energy Science & Engineering

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The design of dam bodies for underground reservoirs must account for how water affects shear failure and the evolution of fractures in coal pillars. In this work, we detect acoustic emissions in raw coal samples with different water content (0%, 5.35%, 17.88%, and 20.40%) and under uniaxial compression shear and use computed tomography to analyze the failed samples. The results show that the shear strength, shear displacement, cohesion, and internal friction angle all decrease with increasing water content, which is described by the revised Mohr‐Coulomb model for the case of water intrusion. The acoustic emission counts correlate strongly with the change in stress, and the cumulative acoustic emission counts are combined with shear stiffness to separate the fracture evolution process into five stages: crack closure, elastic deformation, stable crack propagation, unstable crack propagation, and failure. The ratios of the crack closure, initiation, and damage stress to the corresponding peak shear stress are essentially unaffected by the water content. Most cracks are tensile cracks, and an increase in the water content promotes the development of parallel fractures. These results are helpful for determining the size of coal pillars in underground reservoirs and for solving other underground engineering problems, such as support for water‐rich coal roadways.

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“…This technique fills the goaf area with solid waste, such as gangue, to effectively control the movement of both the roof and the overlying strata. Numerous case studies [14][15][16] have demonstrated that backfill coal mining can effectively control the movement of both the roof and the overlying strata. In comparison with the traditional longwall caving method, backfill coal mining can greatly reduce the abutment stress around the excavation surface.…”

Section: Introductionmentioning

confidence: 99%

Deformation Behavior of Hard Roofs in Solid Backfill Coal Mining Using Physical Models

et al. 2017

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Solid backfill coal mining technology has been widely applied in coal seams that are at risk of hard roof. Using actual measured strain-stress curves of the backfill body and the similarity theory, this study designed and employed four experimental models for physical simulation, corresponding to roof-controlled backfilling ratios of 0%, 40%, 82.5% and 97% using the geological conditions of Face No. 6304 in the Jining No. 3 coal mine-a solid backfill coal mining face under a hard roof. A non-contact strain measurement system and pressure sensors were used to monitor the deformation of the overlying strata and changes in abutment stress ahead of the face during mining of the models for varying roof-controlled backfilling ratios. The results indicated that the solid backfill body was able to support the roof. As the roof-controlled backfilling ratio was increased, the maximum subsidence of the roof and the maximum height of the cracks decreased. When the roof-controlled backfilling ratio was 82.5% or higher, the working face did not display any obvious initial fractures or periodic fractures, and both the value and the impact range of the abutment stress ahead of the face decreased.

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Real-time observation of meso-fracture process in backfill body during mine subsidence using X-ray CT under uniaxial compressive conditions

Cited by 90 publications

References 2 publications

Use of Cemented Super-Fine Unclassified Tailings Backfill for Control of Subsidence

Use of Cemented Super-Fine Unclassified Tailings Backfill for Control of Subsidence

Experimental study of shear failure and crack propagation in water‐bearing coal samples

Deformation Behavior of Hard Roofs in Solid Backfill Coal Mining Using Physical Models

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