Effect of Slot Inclination Angle and Borehole-Slot Ratio on Mechanical Property of Pre-cracked Coal: Implications for ECBM Recovery Using Hydraulic Slotting

Zou, Quanle; Liu, Han; Cheng, Zhiheng; Zhang, Tiancheng; Lin, Baiquan

doi:10.1007/s11053-019-09544-y

Cited by 77 publications

(29 citation statements)

References 47 publications

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“…To realize the use of the Hoek-Brown-modified criterion in the numerical simulation using the UDEC software, the values of m and s can be obtained through laboratory experiment (Section 3.3.3). Then, the strength parameters of Mohr-Coulomb, such as the cohesion and internal frictional angle, can be obtained using Equations (5), (6), and (7) based on the Hoek-Brown-modified criterion. Finally, the strength parameters would be introduced into the numerical model.…”

Section: Hoek-brown-modified Criterionmentioning

confidence: 99%

“…With the advancement of working face, due to the function of in situ stress and self‐weight, a caving zone, a fracture zone and a curved subsidence zone are generated from the bottom upwards in the overlaying strata . Since the fractures of coal and rock mass are the main channels for fluid migration and infiltration, it is of great significance to accurately determine the water‐permeable fractured zone in the overlying strata caused by mining not only to ensure the safe production of coal mining under water, but also to improve the recovery rate of coal pillars and reduce the waste of coal resources . Numerous studies have been conducted with different methods to investigate the fracture evolution law of the overlying rock strata under different mining conditions .…”

Section: Introductionmentioning

confidence: 99%

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Development characteristics and field detection of overburden fracture zone in multiseam mining: A case study

Tian

Liu

Yang

et al. 2019

Energy Science & Engineering

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During the multiseam mining process, the overlying strata were damaged due to different mining disturbances, where a large number of fractures were produced which were the main seepage paths of gas and water, easy to cause gas or water inrush accidents. Thus, it is necessary to explore the development characteristics of the fractured zone in the overlying strata from multiseam mining. In this paper, laboratory triaxial compression tests were firstly conducted on the rock specimens subjected to different mining disturbances. In these tests, the specimen was loaded to different stress before a regular test to simulate the different damage effects on the rock strata caused by different mining disturbances. And the corresponding values of m and s could be obtained through a calculation based on the test results. Subsequently, the numerical simulation was conducted to simulate the field situation, in which the m and s values were used in the numerical model combined with the Hoek‐Brown–modified criterion, and the results show that the overburden failure height was increased with the mining disturbances from 48 to 120 m, and then, the effects of mining height and interval thickness on the development height of fracture zone were studied by numerical simulation. Finally, the leakage of roof drilling at different stages was tested and calculated in the field. The results showed that the loss of leakage drilling can directly reflect the development degree of roof cracks, and the detection results were close to the development height of the numerical simulation fracture zone. It is verified that the simulation method used in this paper is feasible and can be used as a reference for similar research.

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Section: Hoek-brown-modified Criterionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Development characteristics and field detection of overburden fracture zone in multiseam mining: A case study

Tian

Liu

Yang

et al. 2019

Energy Science & Engineering

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“…Spontaneous coal combustion depends on the oxidation of the raw coal itself, the LDRC of the gob, the thermal conductivity of the coal, and the air leakage intensity. In addition, it is affected by the advancing speed of the working face and the protective measures implemented . The loose characteristics of the coal body in the gob are directly related to CSC, which reflect the spatial‐temporal characteristics of the air leakage and oxygen supply during the CSC process .…”

Section: Analysis Of the Relevant Theoriesmentioning

confidence: 99%

“…In addition, it is affected by the advancing speed of the working face and the protective measures implemented. 19,20 The loose characteristics of the coal body in the gob are directly related to CSC, which reflect the spatial-temporal characteristics of the air leakage and oxygen supply during the CSC process. 21 Furthermore, gas migration within the gob is restricted by the spatial-temporal distribution of the fractures in the overlying coal-rock and the looseness of the caved coal-rock mass, while based on the rock pressure, the coal-rock mass in the gob exhibits obvious zoning.…”

Section: Establishment Of the Asmmentioning

confidence: 99%

Study of the influence of the characteristics of loose residual coal on the spontaneous combustion of coal gob

Shu

et al. 2019

Energy Science & Engineering

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Mine fires are becoming a serious issue as the intensity of mining increases, especially in deep mines. Loose coal gob has a hidden ignition location and a high possibility of spontaneous combustion, which makes fire prevention difficult. Therefore, based on the theory of gas seepage and the characteristics of loose coal, a model of air leakage and spontaneous combustion in gob is established in this paper. Using working face #10414 in the Yangliu coal mine as an example, the relationship between the three spontaneous coal combustion (CSC) zones and the three stress zones is analyzed and verified by combining a FLAC3D simulation with field monitoring. In addition, the influence of advancing speed on the CSC is discussed, and suggestions for fire prevention are presented. The results show that the variation in the calorific value of the CSC with increasing degree of looseness of the residual coal in the gob forms an arch‐shape. There is a one‐to‐one relationship between the distribution of the three stress zones and the three CSC zones. In addition, as the advancing speed increases, the contact time between the loose coal body and the air decreases and the possibility of CSC decreases. This study provides a scientific basis for fire prevention and control in mines.

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“…Many scholars have conducted a large amount of research in this area [3][4][5][6]. Some studies focused on sealing materials [7][8][9], while others concentrated on the sealing process [10][11][12][13]. Quanle Zou et al established an improved coalbed methane combined mining model and proposed a combination method of borehole-grooving-separation-blocking to improve coalbed methane permeability and coalbed methane recovery [14].…”

Section: Introductionmentioning

confidence: 99%

Sealing Performance of New Solidified Materials: Mechanical Properties and Stress Sensitivity Characterization of Pores

Zhang

Jin

Liu

et al. 2020

Advances in Polymer Technology

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Borehole-sealing solidified material plays a significant role in improving sealing quality and enhancing gas drainage performance. In this study, the MTS815 electro-hydraulic triaxial servo test system and MR-60 NMR test system were adopted to conduct triaxial compression control experiment on the coal sample material, concrete material, and new solidified sealing material, respectively. This paper aims to analyze the difference of support effects, porosity, and stress sensitivity between those materials. Experimental results show that under the same stress condition, the stiffness of traditional concrete solidified material is the largest, while the new solidified material is the second, and the coal sample material is the smallest. Compared with the traditional concrete solidified material, the new solidified sealing material has better strain-bearing capacity and volumetric expansion capacity under each confining pressure in the experiment. The axial strain and volume increment of new solidified material is higher than those of the traditional concrete solidified material at the peak stress. Meanwhile, the confining pressure has a certain hysteresis effect on the postpeak stress attenuation. Fracture has the strongest stress sensitivity in three pore types, and its T2 map relaxation area has a larger compression than adsorption pore and seepage pore under the same pressure. The relative content of seepage pore and fracture in the new solidified material is less than that of coal and concrete samples, and the stress sensitivity of the new solidified materials is weaker than that of coal and concrete materials, thence, new solidified material will have better performance in borehole sealing. Outcomes of this study could provide guidance on the selection of the most effective sealing materials for sealing-quality improvement.

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Effect of Slot Inclination Angle and Borehole-Slot Ratio on Mechanical Property of Pre-cracked Coal: Implications for ECBM Recovery Using Hydraulic Slotting

Cited by 77 publications

References 47 publications

Development characteristics and field detection of overburden fracture zone in multiseam mining: A case study

Development characteristics and field detection of overburden fracture zone in multiseam mining: A case study

Study of the influence of the characteristics of loose residual coal on the spontaneous combustion of coal gob

Sealing Performance of New Solidified Materials: Mechanical Properties and Stress Sensitivity Characterization of Pores

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