Temat: main roof - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Numerical modelling of gas pumping in inner interlocked tail roadway of coal mine based on coupled fracture-seepage model
Autorzy:: An, Huaming
Wang, Hongsheng
Tematy:: goaf
collapse of roof
fluid-solid coupling
main roof
immediate roof; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Wydział Geoinżynierii, Górnictwa i Geologii. Instytut Górnictwa
Powiązania:: https://bibliotekanauki.pl/articles/2016497.pdf Link otwiera się w nowym oknie
Opis:: This paper focuses on modelling of pumping high overrun gas in an upper corner and fully mechanized caving face of a coal mine with extra-thick seam. The process of roof fracture and fall in goaf is analyzed. Then the numerical model of the immediate roof and main roof collapse in goaf is established. On the basis of the numerical model, FLUENT is employed to simulate the gas seepage process in the accumulation of the rock and coal in goaf. In addition, the influence of the inner interlocked tail roadway at different positions for the gas concentration in goaf is analyzed. To calibrate the proposed numerical model, it is implemented to a coal mine. It is concluded that numrical results are similar to those in the coal mine.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Study on pressure relief mechanism of hydraulic support in working face under directional roof crack
Autorzy:: Zhang, Jun
Liu, Jianning
Wang, Yajun
Yang, Gang
Hou, Shilin
Wang, Yuanjun
He, Manchao
Yang, Jun
Tematy:: ciśnienie hydrauliczne
wydobycie węgla
podpora hydrauliczna
directional roof crack
pressure relief mechanism
main roof
hydraulic support pressure; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/59111434.pdf Link otwiera się w nowym oknie
Opis:: When mining coal from the working face, the main roof withstands the overlying strata. The main roof’s first weighting and periodic weighting may cause accidents, such as crushing the working face hydraulic supports. A mechanical model of the main roof was constructed, and the contributing factors of first and periodic weights on the main roof were examined in order to prevent such accidents. The thickness of the main roof was found as the most contributory factor to the main roof’s stability. Therefore, a new directional roof crack (DRC) technique is proposed, which produces directional cracks in the main roof through directional blasting and makes part of it collapse in advance so as to reduce the thickness and relieve the first and periodic weighting. To verify the effectiveness of DRC, the mechanism of DRC was analysed. A mechanical model of the hydraulic support was constructed, and the DRC techniques were tested on-site. Field experiments with a complete set of monitoring schemes showed that, with DRC technology, the roof periodic weighting interval decreased by 35.36%, and the hydraulic support pressure decreased by 17.56%. The theoretical analysis was consistent with the measured results. Therefore, the DRC technology is feasible and effective to ensure mining safety at the working face.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Internal mechanism of asymmetric deformation and failure characteristics of the roof for longwall mining of a steeply dipping coal seam
Autorzy:: Luo, Shenghu
Wang, Tong
Wu, Yongping
Huangfu, Jingyu
Zhao, Huatao
Tematy:: odkształcenie
pokłady węgla
szyb kopalniany
steeply dipping seam
gangue
slip filling
deformation failure
main roof
angle effect; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/1853910.pdf Link otwiera się w nowym oknie
Opis:: Stability control of the roof is the key to safe and efficient mining of the longwall working face for a steeply dipping coal seam. In this study, a comprehensive analysis was performed on the roof destruction, migration, and filling characteristics of a steeply dipping longwall working face in an actual coalmine. Elastic foundation theory was used to construct a roof mechanics model; the effect of the coal seam inclination angle on the asymmetric deformation and failure of the roof under the constraint of an unbalanced gangue filling was considered. According to the model, increasing the coal seam angle, thickness of the immediate roof, and length of the working face as well as decreasing the thickness of the coal seam can increase the length of the contact area formed by the caving gangue in the lower area of the slope. Changes to the length of the contact area affect the forces and boundary conditions of the main roof. Increasing the coal seam angle reduces the deformation of the main roof, and the position of peak deflection migrates from the middle of the working face to the upper middle. Meanwhile, the position of the peak rotation angle migrates from the lower area of the working face to the upper area. The peak bending moment decreases continuously, and its position migrates from the headgate T-junction to the tailgate T-junction and then the middle of the working face. Field test results verified the rationality of the mechanics model. These findings reveal the effect of the inclination coal seam angle on roof deformation and failure and provide theoretical guidance for engineering practice.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Fracture Mechanism of Hard Main Roof and Determining the Width of Coal Pillars when Extracting Flat-lying Coal Seams
Autorzy:: Le, Quang Phuc
Dao, Van Chi
Nguyen, Phi Hung
Vu, Thai Tien Dung
Tematy:: failure mechanism
coal pillar
stress distribution
roadway deformation
retained roadway
hard main roof
gob-side entry
węgiel
filary
stabilność
Wietnam; Pokaż więcej
Wydawca:: Polskie Towarzystwo Przeróbki Kopalin
Powiązania:: https://bibliotekanauki.pl/articles/27323252.pdf Link otwiera się w nowym oknie
Opis:: In underground coal mining, the stability of roadways and gob-side entry depends on the coal pillar width. An unreasonable width of the coal pillar will cause the roadway to be in a dangerous zone of influence of the abutment pressure, leading to severe roadway deformation. This paper studies the fracture mechanism of the hard main roof and reasonable coal pillar width to protect the stability of gob-side entry driving. The research results show that when mining a coal seam under a hard main roof, the console of the main roof on the edge of the coal seam has the form of hinge structure. The great load of the roof layers and the rotation of the console are the main causes leading to the variation of the stress field in the coal seam. According to the development law of the stress field, after the main roof completes the collapse process, the peak of the maximum stress will move deep into the solid coal seam, and on the edge of the coal seam it will form a low-stress zone. Research results from the case of Seam #11 of Khe Cham coal mine, Vietnam show that the gob-side entry will be well stabilized when the narrow coal pillar between it and the boundary of the gob is 4–5 m.
Dostawca treści:: Biblioteka Nauki

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