Architecture, stress state and permeability of a fault zone in Jiulishan coal mine in China: Implication for coal and gas outbursts

Wei Li, Tianwei Ren, Andreas Busch, Sabine A. M. den Hartog, Yuanping Cheng, Wei Qiao, Bin Li

Research output: Contribution to journalArticle

17 Citations (Scopus)
36 Downloads (Pure)

Abstract

The Mafangquan (MFQ) fault zone, transecting a coal seam in Jiulishan coal mine in China, was investigated in detail in view of coal mining safety, including its architecture, stress and permeability features and implication for coal and gas outburst. 10 boreholes have been drilled for formation testing as well as coal sample retrieval for laboratory analysis. Gas content, Protodyakonov strength, gas emission index and pore volume are tested and analysed at different distances from the MFQ fault. A fault structure that can be split into three distinct zones can be identified, including the fault core, the mylonitized zone and the granulated/cataclastic zone. In-situ stress tests, numerical simulations and model predictions show a principal stress rotation and fault zone stress regime. It is found that the maximum principal stress has shifted to a lower angle pent to the fault zone extend direction gradually with a decrease stress zone from fault core to the damage zone. The permeability of the fault zone has a correlation to fault zone architecture and stress regimes in the coal seam with a high permeability in the mylonitized coal zone. The coal weakened due to deformation, high pore pressure and stress superimposition have a negative impact on coal and gas outburst. In particular, the stress ratio limits the formation of hydrofractures in the case of high pore pressure and reduces fault zone strength, which may have an orthogonal relation to the mining galleries, favouring coal and gas outburst.
Original languageEnglish
Pages (from-to)1-13
Number of pages13
JournalInternational Journal of Coal Geology
Volume198
Early online date3 Sep 2018
DOIs
Publication statusPublished - 1 Oct 2018

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