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Coal Engineering ›› 2026, Vol. 58 ›› Issue (2): 61-69.doi: 10.11799/ce202602008

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Reasonable protective coal pillar retention and control for working faces in the footwall of a normal fault

  

  • Received:2025-07-19 Revised:2025-09-03 Online:2026-02-15 Published:2026-03-16

Abstract:

The mining roadway of Panel 232206 in Meihuajing Coal Mine is located near a fault zone where the surrounding rock is subjected to typical combined effects of mining-induced stress and fault tectonic stress. Under these conditions, the mining roadway is prone to deformation and failure, with distinct variations being observed in surrounding rock deformation at different stages. To address the deformation and failure issues of the mining roadway, the UDEC numerical simulation method is first employed to investigate the rational width of fault-protection coal pillars. The activation characteristics and patterns of faults under different protection pillar widths are obtained. When the fault-protection coal pillar is less than 50m during mining operations at Panel 232206, fault activation is observed. It is found that as the pillar width decreases, the vertical displacement near the fault gradually increases while its affected range reduces, indicating that fault activation becomes more pronounced and occurs at lower positions with decreasing pillar width. The vertical stress at the fault with 60m protection pillars is measured to be 34.5% lower than that with 30m pillars. The cusp catastrophe theory is then applied to analyze the relationship between the plastic zone and the width of fault-protection pillars. The rational width of fault-protection pillars is determined when the ratio of pillar width to unilateral yield zone width reaches 1.5. Based on field data, the calculated optimal width for fault-protection pillars is 51.66m. Finally, based on studies of deformation patterns under different fault-protection pillar widths, a control technology combining pressure relief and support is designed for the transportation roadway of Panel 232206. Comparative experiments are conducted to verify the control technology. Monitoring data from both test and control sections demonstrate significant improvement in roadway deformation control, with an average reduction of 58.55% in deformation. These results confirm the effectiveness of the current support measures in successfully controlling surrounding rock stress.

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