Fractal secondary evolution mechanism of fractured rock mass in adjacent goaf areas under extremely thick coal seam lower slice mining
ZHAO Pengxiang
PEI Wenbo
LI Shugang
JIA Yongyong
LIN Haifei
REN Xinpeng
YANG Junsheng
Abstract：To master the mechanism of fractal secondary evolution of fractured rock mass in ad-jacent goaf areas disturbed by mining in Xinjiang's extremely thick coal seams,an experiment was conducted using a large-scale two-dimensional physical similarity simulation platform,taking a high-gas mine in Xinjiang with a extremely thick coal seam working face as the experi-mental prototype.The experiment aimed to explore the fractal secondary evolution mechanism of the fractured rock mass in adjacent goaf areas under mining disturbance.Combined with fractal theory,the fracture distribution characteristics of the fractured rock mass in the adjacent goaf areas were quantitatively characterized.The experimental results show that as the sublevel working face progresses,the original stable structure of the overlying goaf is reactiva-ted.The hinge structures within the rock mass are transmitted to the lower part of the frac-tured rock mass,complicating the fracture cracks in the adjacent goaf areas.Subsequently,the initially activated area gradually stabilizes,forming a new,more stable rock mass structure.This leads to the secondary evolution of the fractured rock mass in the adjacent goaf areas;Un-derstanding the fractal dimension secondary evolution mechanism of fractured rock masses in adjacent goaf areas,based on the characteristics of secondary evolution of the fractured rock mass fractal dimensions during different periods and regions as the working face progresses,shows that the fractured rock masses in adjacent goaf areas undergo a cyclical pattern of"acti-vation-construction-stabilization"with the advancement of the working face.The fractured rock mass in adjacent goaf areas is divided laterally into three zones:the activation zone of sec-ondary evolution of fractal dimension,the construction zone of secondary evolution of fractal dimension,and the stabilization zone of secondary evolution of fractal dimension.These find-ings provide theoretical guidance for optimizing the layout parameters of gas drainage boreholes in extremely thick coal seams.
Keywords：extremely thick coal seamsecondary evolutionfractal characteristicslower slice miningadjacent goaf
Publication Date：2024-07-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：14( 696-709 )