Stability analysis and control technology of gob-side entry retaining with double roadways by filling with high-water material in gently inclined coal seam

Xie, Shengrong; Wang, En; Chen, Dongdong; Li, Hui; Jiang, Zheng; Yang, Huaidong

doi:10.1007/s40789-022-00524-x

Cited by 30 publications

(17 citation statements)

References 45 publications

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“…Coal seams undergo significant changes due to hydraulic measures, resulting in significant changes in their mechanical characteristics and geophysical properties as a result [12][13][14][15]. In the application of geotechnical engineering, water relates to geological disasters, since it affects the mechanical characteristics of coal [16,17]. For example, the increase in humidity in summer leads to frequent falls of roofs and the degradation of pillars in the mine [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Analytical Damage Model for Predicting Coal Failure Stresses by Utilizing Acoustic Emission

Ali

Wang

et al. 2023

Sustainability

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Overburden collapse and water inrush in mines are primarily caused by rock fractures. Mining safety can be enhanced by monitoring and identifying early signs of coal failure in the mines. This article collected acoustic emission data synchronously throughout a series of uniaxial compression (UC) experiments on natural and water-saturated coal. The influence mechanisms of water, mechanical properties, and acoustic emission signals on the stress–strain curve and the SEM results of water-saturated and dry samples are investigated. As a result, the mechanical properties of coal are not only weakened by water saturation, such as elastic modulus, strain, stress, and compressive strength but also reduced acoustic emissions. In comparison with saturated coal, natural coal has a uniaxial stress of 13.55 MPa and an elastic modulus of 1.245 GPa, while saturated coal has a stress of 8.21 MPa and an elastic modulus of 0.813 GPa. Intergranular fractures are more likely to occur in coal with a high water content, whereas transgranular fractures are less likely to occur in coal with a high water content. An innovative and unique statistical model of coal damage under uniaxial loading has been developed by analyzing the acoustic emission data. Since this technique takes into account the compaction stage, models based on this technique were found to be superior to those based on lognormal or Weibull distributions. A correlation coefficient of greater than 0.956 exists between the piecewise constitutive model and the experimental curve. Statistical damage constitutive models for coal are compatible with this model. Additionally, the model can precisely forecast the stress associated with both natural and saturated coal and can be useful in the prevention of rock-coal disasters in water conditions.

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Section: Introductionmentioning

confidence: 99%

Analytical Damage Model for Predicting Coal Failure Stresses by Utilizing Acoustic Emission

Ali

Wang

et al. 2023

Sustainability

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“… 26 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. 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.…”

Section: Introductionmentioning

confidence: 99%

“…Some scholars have proposed studying the electromagnetic response characteristics of various flooded goafs by combining electromagnetic field theory, numerical simulation, and field verification . 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 .…”

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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“…It is usually called an extrathick coal seam when the thickness of the coal seam exceeds 8 m. However, the Datong mining area has developed to the mining of 15 m extra-thick coal seam at present, and more and more extra-thick coal seam working surfaces are gradually established. [1][2][3][4][5] The technology of longwall comprehensive mechanized top coal caving mining (LCMTCCM) has been generally used in the mining of extra-thick coal seams. The research on related technologies of fully comprehensive caving working faces has become a hot spot in the industry.…”

Section: Introductionmentioning

confidence: 99%

“…The thick coal seam is a typical characteristic of Carboniferous coal seams. It is usually called an extra‐thick coal seam when the thickness of the coal seam exceeds 8 m. However, the Datong mining area has developed to the mining of 15 m extra‐thick coal seam at present, and more and more extra‐thick coal seam working surfaces are gradually established 1–5 . The technology of longwall comprehensive mechanized top coal caving mining (LCMTCCM) has been generally used in the mining of extra‐thick coal seams.…”

Section: Introductionmentioning

confidence: 99%

Reasonable stopping method and retracement channel support at fully mechanized top coal caving working face of 15 m extra‐thick coal seam: A case study

Xie

et al. 2022

Energy Science & Engineering

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Extra-thick coal seams are widely distributed in the Datong mine area in China. The rapid stopping of mining and the support withdrawal technology for extra-thick coal seams need to be developed urgently. The reasonable stopping top coal caving distance, main roof's fracture line position, and large section roadway during the stopping period (LSRSP) support method of the header face of 15 m extra-thick coal seam are systematically studied by using field measurement, experiment, numerical simulation, and similar material simulation methods. With the increase in stopping coal caving distance, the range of the medium and low displacement zone of the LSRSP overburden gradually expands. In contrast, the depth of the plastic zone decreases. The scope and intensity of the high-stress area of the overlying rock in front gradually decrease and shift from deep to the outside, while the peak stress area shifts from the top coal area to the coal rib of the retracement channel.Comparing the stopping of medium-thick and thick coal seam working face, the interaction between "main roof−unmined top coal−supports" is analyzed.The unique characteristics of the extra-thick coal seam working face are derived: when the stopping coal caving distance is shorter than the length of the key block, the dropped coal body cannot effectively restrict the movement of key blocks. Mutual compression and subsidence occur between key blocks, making the broken coal rock block squeeze into the supports. By the simulation study of each index, the stopping coal caving distance of the extrathick coal seam is optimal when it is slightly larger than the length of the key block (i.e., the periodic weighting step), simultaneously, the main roof fracture line behind the supports is most favorable for stopping mining. After ensuring the stability of the LSRSP's overburden structure, the differentiated support scheme of "controlled zoning−strength grading" was proposed, and the

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Stability analysis and control technology of gob-side entry retaining with double roadways by filling with high-water material in gently inclined coal seam

Cited by 30 publications

References 45 publications

Analytical Damage Model for Predicting Coal Failure Stresses by Utilizing Acoustic Emission

Analytical Damage Model for Predicting Coal Failure Stresses by Utilizing Acoustic Emission

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

Reasonable stopping method and retracement channel support at fully mechanized top coal caving working face of 15 m extra‐thick coal seam: A case study

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