Instability and failure characteristics of surrounding rock of water drenching roadway in thick coal seam

Jia, Ce; Li, Sheng; Fan, Chunhua; Luo, Ming‐Xing; Yang, Zhenhua; Yang, Lei; Pu, Ziang

doi:10.3389/feart.2022.1013715

Cited by 3 publications

(5 citation statements)

References 36 publications

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“…where Q b is the anchor force of anchor rod, KN; D 1 is the distance between bolts, m; D 2 is the bolt row distance, m. The cable support resistance is P c as follows: (10) where Q c is the anchorage force of the cable, KN. D 1 ′ is the cable spacing, m. D 2 ′ is the cable row distance, m. The metal mesh support resistance for P sr is as follows: (11) where τ sr is the shear strength of metal mesh material, MPa; S sr is the cross-sectional area of the metal mesh in the axial direction, m 2 ; β sr is the shear angle of the metal mesh, (deg).…”

Section: Surrounding Rock Control Principle Of Water-drenching Roadwa...mentioning

confidence: 99%

“…Coal mining encounters complex geological environments. Therefore, roadway-surrounding rock support in complex and challenging conditions is one of the urgent problems in the process of coal safety production. , When the roadway is in a water-drenching environment, the mechanical parameters of the surrounding rock will be weakened under the action of water leaching for a long time. , The large deformation of the surrounding rock makes support extremely difficult . It increases the maintenance cost and volume of the roadway, which seriously hinders the safe and efficient production of the mine. , …”

Section: Introductionmentioning

confidence: 99%

“… 8 , 9 When the roadway is in a water-drenching environment, the mechanical parameters of the surrounding rock will be weakened under the action of water leaching for a long time. 10 , 11 The large deformation of the surrounding rock makes support extremely difficult. 12 It increases the maintenance cost and volume of the roadway, which seriously hinders the safe and efficient production of the mine.…”

Section: Introductionmentioning

confidence: 99%

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Bolt–Cable–Mesh Integrated Support Technology for Water Drenching Roadway in Thick Coal Seam

Jia

Fan

et al. 2022

ACS Omega

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Aiming at the problems of large deformation and difficult control of the mining roadway water drenching in a thick coal seam, the principle of double-arch zoning cooperative surrounding rock control is studied by using the combined method of theoretical analysis, numerical simulation, and industrial experiment. The water–rock interaction of the surrounding rock of water-drenching roadway is proposed, taking into account the damage to the mechanical parameters of the surrounding rock caused by soaking water. The water-mechanical-damage coupling model for surrounding rock of a coal seam roadway is constructed, and is numerically solved by the code development using the FISH language. The principle of “high prestressed bolt–cable–mesh” zone coordinated control is revealed, and the existence of a compressive stress arch is verified by FLAC3D software. The three support schemes were compared and analyzed by numerical simulation software. We affirmed the bolt length of 2400 mm, spacing of 0.9 m, row spacing of 1 m, cable length of 7300 mm, and arrangement 3–2–3 as the optimal support scheme and applied this scheme in the Zhangcun Coal Mine. The results show that the maximum deformation of the roadway roof is 142 mm, and the ultimate convergence of the two sides is 83 mm. The surrounding rock has been effectively controlled.

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Section: Surrounding Rock Control Principle Of Water-drenching Roadwa...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bolt–Cable–Mesh Integrated Support Technology for Water Drenching Roadway in Thick Coal Seam

Jia

Fan

et al. 2022

ACS Omega

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“…Furthermore, some scholars have proposed a new type of high-water material double roadway along-airway roadway retrieval support body for inadequate support resistance of traditional along-airway roadway retrieval support . To support rock surrounding thick coal seams, fish language can be used to embed the functional relationship between the mechanical parameters of the roadway surrounding the rock and water content into Flac3D software to simulate the surrounding rock failure law under different water contents . In recent years, hydraulic fracturing technology has been widely used in shale gas development, oil and gas storage in abandoned mines, and gas extraction borehole optimization. , Common fracturing techniques include multistage, clean water, synchronous, and hydraulic jet fracturing, as well as refracturing. , Some researchers have cycled in prefracture to reduce rock fracture pressure − or used thermochemical fluid pressure pulses , to increase the likelihood of damage around hydraulic fractures rather than simply increasing the pressure by traditional hydraulic fracturing.…”

Section: Introductionmentioning

confidence: 99%

“… 27 To support rock surrounding thick coal seams, fish language can be used to embed the functional relationship between the mechanical parameters of the roadway surrounding the rock and water content into Flac3D software to simulate the surrounding rock failure law under different water contents. 28 In recent years, hydraulic fracturing technology has been widely used in shale gas development, oil and gas storage in abandoned mines, and gas extraction borehole optimization. 29 , 30 Common fracturing techniques include multistage, clean water, synchronous, and hydraulic jet fracturing, as well as refracturing.…”

Section: Introductionmentioning

confidence: 99%

Strength Degradation and Fracture Propagation of Repeatedly Immersed Artificial Dam Samples under Uniaxial Cyclic Loading–Unloading

et al. 2023

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The use of underground reservoirs is a critical technique for achieving sustainable coal and water resources in many ecologically fragile mines in western China. Concrete samples subject to repeated water immersion and cyclic loading−unloading (CLU) operations were obtained from an underground artificial reservoir dam in Chahasu Colliery to study their strength damage and fracture propagation behavior. The variation in water content of the samples according to immersion times were divided into the rapid growth stage (0−10 h), slow growth stage (10−60 h), and stable stage (>60 h). With an increase in immersion times (IIT), the saturated water content of the coal samples logarithmically increased to 7.02%, and the ultrasonic wave velocity decreased by 10.44%. According to the increasing trend of plastic damage energy density, the total stress−strain curve was divided into four fracture stages. The total energy and elastic energy densities increased nonlinearly with the increase in cycles, whereas the plastic damage energy density first decreased and then increased. The plastic damage energy ratio at the stress peak point of the samples under different sequential times of immersion was 0.18, 0.29, 0.28, 0.58, and 0.61. The initial fracture development and fracture damage thresholds of the samples decreased by 20 and 50% with IIT, respectively. However, the proportion of the fracture closure and initial fracture development thresholds of the samples showed an increasing quadratic trend with IIT. Based on the low ratio of rise time to amplitude and high average frequency, the fracture mode of the samples under repeated water immersion was mainly tensile fracture. Acoustic emission events with energy higher than 10 4 aJ spread from the center with repeated water immersion. When the CLU was greater than 6, the plastic damage energy of the fitted three-dimensional surface increased nonlinearly with IIT. The energy parameter−plastic damage energy ratio was introduced to help develop a theoretical model for describing the complete stress−strain damage evolution of repeatedly immersed concrete samples under CLU. The paper provides technical references for improving the long-term strength design of concrete artificial dams of underground reservoirs.

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Effect of thermal treatment and moisture content on the mechanical properties of soft sandstone under triaxial extension: an experimental study

Liu

Wei

2023

Geomech. Geophys. Geo-energ. Geo-resour.

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The problem of deformation damage of soft rocks and the effect of temperature and moisture content on the mechanical properties of rocks has received wide attention in recent decades. To investigate the effect of thermal treatment and moisture content on the triaxial extension mechanical properties and fracture characteristics of soft rock, triaxial extension tests were conducted on sandstone specimens with good homogeneity at different heating temperatures (T = 25, 100, 200, 300, 400, 500, 800 °C) and moisture contents (Kt = 0, 20, 50, 80, 100%) with the help of MTS815 testing machine. The results showed that: For rock specimens with Kt = 0, the mass of the specimens decreased monotonically with the increase of temperature, the elastic modulus (E) showed an overall decreasing trend, and the axial ultimate strain (εamax) was Ω-like pattern. The P-wave velocity (Vp) and axial stress showed a trend of increasing first and then decreasing around T = 200 °C. All the specimens fractured instantaneously, and the SEM images showed some grain expansion before T ≤ 200 °C. At the same time, microcracks expand and become more intense after T > 200 °C. In addition, the multiple mineral compositions in the specimens showed more complex changes after different thermal treatments, which was another main reason for the deterioration of the specimens. Furthermore, the E decreases while εamax increases with the moisture content, and before T = 500 °C and Kt = 20%, the Kt significantly influences the triaxial extension strength; after that, however, the effect is minimal.

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Instability and failure characteristics of surrounding rock of water drenching roadway in thick coal seam

Cited by 3 publications

References 36 publications

Bolt–Cable–Mesh Integrated Support Technology for Water Drenching Roadway in Thick Coal Seam

Bolt–Cable–Mesh Integrated Support Technology for Water Drenching Roadway in Thick Coal Seam

Strength Degradation and Fracture Propagation of Repeatedly Immersed Artificial Dam Samples under Uniaxial Cyclic Loading–Unloading

Effect of thermal treatment and moisture content on the mechanical properties of soft sandstone under triaxial extension: an experimental study

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