Study on the Coal Pillar Weakening Technology in Close Distance Multi-Coal Seam Goaf

Zhang, Jie; Zhuo, Qingsong; Yang, Shenglai; Yang, Tao; Wang, Bin; Bai, Wenyong; Wu, Jianjun; Xie, Shaoliang

doi:10.3390/en15186532

Cited by 9 publications

(10 citation statements)

References 11 publications

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“…On the basis of the difficulties in roadway support and support principles, [23][24][25][26][27][28][29] in view of the large area roof fall disaster of the broken surrounding rock of No. 11103 fully mechanized caving roadway under the double gob, the Usteel + anchor + prop coupling support structure is used to bear the broken surrounding rock, resist the top pressure, and prevent the U-shaped steel from appearing weak section under the eccentric load conditions of coal pillar stress concentration and gob stress reduction, which reduces the bearing capacity.…”

Section: Analysis Of Coupling Support Structurementioning

confidence: 99%

Coupling support technique for coal roadway under double gobs in close coal seams

Wu,

Nan,

Chen

et al. 2024

Energy Science & Engineering

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In the process of lower coal roadway support under double gobs in close coal seams, there are problems such as the whole destruction of the lower coal seam and the intermediate strata, the thin roof of the lower coal roadway with the smaller support space, the upper rock of the lower coal roadway without anchor bearing layer, the roof falling, the anchor cable offing, and so on. On the basis of the engineering background of No. 11103 haulage roadway in Fenxi coal mine, the research methods of theoretical modeling analysis, numerical simulation analysis and field engineering test are comprehensively adopted. In this paper, the layout of the roadway with floor insertion in the lower coal seam, the distribution characteristics of surrounding rock deviatoric stress, the control principle of broken surrounding rock and the coupling support method of shed–cable–prop are systematically studied. The study shows that many measures are needed to ensure the stability of the surrounding rock in the strong mining roadway of the lower coal seam. The lower coal seam roadway section was modified from the original rectangular section to adopt an arched section to counteract the broken roof. The staggered position of the lower coal seam roadway layout was modified from the original coal roadway position to a coal–rock roadway, so as to avoid the area of high deviatoric stress in the coal pillar and the area of crushed coal body, and to leave an effective support space for the roof. The support scheme of the lower coal seam roadway was improved to use anchor cable and single prop to support the weak section of U‐type steel shed with local coupling, and realize unequal force coupling by adjusting the size of the force at different coupling points. In the field monitoring the deformation of the roadway is small, and the support effect is good.

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Section: Analysis Of Coupling Support Structurementioning

confidence: 99%

Coupling support technique for coal roadway under double gobs in close coal seams

Wu,

Nan,

Chen

et al. 2024

Energy Science & Engineering

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“…In China, cracks in coal seams are widely developed and constitute over half of the nation's total coal mines [1][2][3][4][5][6]. The overwhelming presence of soft coal seams causes substantial damage to the coal body's structure and integrity.…”

Section: Introductionmentioning

confidence: 99%

A Numerical Simulation of the Coal Dust Migration Law in Directional Air Drilling in a Broken Soft Coal Seam

Zhang,

Han,

Chen

et al. 2024

Processes

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Abundant industrial experiences have shown that directional air drilling technology is effective for gas drainage when drilling broken and soft coal seams. In this paper, the Eulerian–Eulerian model was used to simulate the gas–solid two-phase flow behavior of compressed air transporting coal dust in broken soft coal seams. The relationship between the degree of coal dust deposition, annular air pressure law, transportation of coal dust, aforementioned factors of rotational speed, particle size, and air volume could be determined. The results indicate that the particle size plays a significant role in the transport capacity of coal dust. Smaller particle sizes and a higher airflow result in a lower deposition degree of coal dust. When the particle size of coal dust is 1.69 mm and the airflow is 300 m3/h, in the case of coal dust generation at a rate of 0.24 m3/h, the deflection angle of the coal dust collection zone is increased by 130% as the rotational speed of the drill rod is increased from 0 to 120 rpm. Similarly, the deflection angle of the coal dust collection zone is increased by 12.8% in a 500 m3/h airflow under the same condition. Additionally, fine particle-sized coal dust is transported in a spiral line. The coal dust with larger particle sizes tends to be in the middle and lower parts of the hole and move along a specific trajectory. Industrial experiences of medium-air-pressure drilling confirm that a rotary drilling speed between 80 and 120 rpm, with a minimum air volume of 400 m3/h and preferably 500 m3/h, can promote a smooth hole drilling effect and enhance the construction safety in the gas drainage process.

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“…Wang et al 14 , 15 analyzed the spatiotemporal distribution and dynamic migration laws of toxic gases in the goaf behind the panel during the mining process of close-distance coal seams, and formulated corresponding preventive measures. Zhang et al 16 , 17 elucidated the characteristics of the impact of residual coal pillar in close-distance coal seams on mine pressure, obtained the failure depth and mechanism in goaf floor, and revealed the evolution laws of stress before and after pressure relief in panel of close-distance coal seams. Lu and Ni 18 constructed a mechanical model of roadway floor rock in close-distance coal seams, and obtained reasonable support parameters, grouting material ratio, and grouting pressure for roadway surrounding rock.…”

Section: Introductionmentioning

confidence: 99%

Non-uniform failure and differential pressure relief technology of roadway under irregular goafs in deep close-distance coal seams

Yin,

Zheng,

Wang

et al. 2023

Sci Rep

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In response to the control problems of large-deformation roadways in close-distance coal seams, taking a typical roadway under irregular goafs and residual coal pillar in deep close-distance coal seams as the background, the characteristics of mine pressure and key difficulties in surrounding rock control of roadway are explored and an improvement strategy for controlling surrounding rock is proposed. The stress expression in roadway floor under the influence of residual coal pillar is derived by theoretical calculation. The peak lines of deviatoric stress and vertical stress in roadway after the mining of the upper coal seam are obtained by numerical simulation. The roadway is divided into two key zones: ordinary zone and disturbance zone by residual coal pillar, and the disturbance range of roadway below residual coal pillar is determined to be 44.60 m. It reveals the differential, asymmetric, and non-uniform distortion and failure laws of roadway at different positions under irregular goafs and residual coal pillar. The differential control technology named asymmetric support in ordinary zone of roadway and combined support and drilling pressure relief in disturbance zone below residual coal pillar is proposed. The feasibility of differential pressure relief and control technology has been verified through on-site engineering test, which ensures the safety and stability of roadway and provides technical references for surrounding rock control in similar deep and complex roadways.

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Study on the Coal Pillar Weakening Technology in Close Distance Multi-Coal Seam Goaf

Cited by 9 publications

References 11 publications

Coupling support technique for coal roadway under double gobs in close coal seams

Coupling support technique for coal roadway under double gobs in close coal seams

A Numerical Simulation of the Coal Dust Migration Law in Directional Air Drilling in a Broken Soft Coal Seam

Non-uniform failure and differential pressure relief technology of roadway under irregular goafs in deep close-distance coal seams

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