Study of automated top-coal caving in extra-thick coal seams using the continuum-discontinuum element method. (October 2019)

• Record Type: Journal Article
• Authors: Zhang, Qunlei; Yue, Jinchao; Liu, Chuang; Feng, Chun; Li, Huamin
• Is Part Of: International journal of rock mechanics and mining sciences. Volume 122(2019)
• Publication Date: 2019-10
• Subjects: Extra-thick coal seam -- Automated top-coal caving -- Continuum-discontinuum element method -- Constitutive model of hydraulic support -- Bergmark–Roos model; Rock mechanics -- Periodicals; Soil mechanics -- Periodicals; Mining engineering -- Periodicals; Roches, Mécanique des -- Périodiques; Sols, Mécanique des -- Périodiques; Technique minière -- Périodiques; 624.151305
• DOI: 10.1016/j.ijrmms.2019.04.019
• Languages: English
• ISSNs: 1365-1609

Abstract

Abstract: In order to investigate top-coal drawing regularity and automated top-coal caving technology in extra-thick coal seams, an approach coupling the particle element and the block element is presented based on the continuum-discontinuum element method (CDEM). Then, the constitutive model of hydraulic support is introduced into the CDEM to simulate the top-coal drawing process. Meanwhile, the Bergmark–Roos model for coal drawing of single support is extended into the collaborative coal drawing of multiple supports to optimize the automated top-coal caving technology. Finally, CDEM models of hydraulic support, armored face conveyer and coal-rock strata are established according to the field conditions of the "Tongxin Coal Mine". Then, the top-coal drawing mechanism is analyzed, and an automated top-coal caving technology is proposed. The results show that under the interaction between hydraulic support and surrounding rocks, the final drawing body of initial top-coal drawing appears as an irregular, deflected ellipsoid shape. During different support-moving cycles, the coal-rock structure affects the coal drawing amount and support resistance. A statistical comparison of the coal-rock drawing amount based on 100 drawing openings indicates that the standard deviation of the coal drawing amount in automated, one-round coal caving is 1.83 m 2 less than that in traditional coal caving (8.23 m 2 ), and the coal drawing amount from each drawing window is more uniform. For multi-round coal caving techniques, the average recovery rate remains at 79.4% and the rock mixed rate is less than 1%. Based on a comparison of several coal caving techniques, automated four-round coal caving technology is the optimal technology, in which the change rate of the standard deviation of the coal drawing amount as well as the top-coal recovery rate are both largest. Highlights: The drawing body of top-coal presents as an irregularly deflected ellipsoid. The work resistance of support front column is greater than that of the rear column. The Bergmark–Roos model is available for multiple supports coal drawing. The automated top-coal caving is better than traditional top-coal caving. Automated four-round coal caving is the optimal technology.