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<p>The groundwater in the karst aquifer of coal seam floor is a significant water source in North China and major focus for mine water hazard prevention. Investigating the karst development characteristics can provide basis for safe and water-conserving coal mining. This study involved drilling exploration of the fourth limestone aquifer of Taiyuan Formation (L<sub>4</sub> limestone aquifer) at different mining levels, recording the wash fluid leakage for each borehole. Water and rock samples were collected from different mining levels to determine the vertical zonation of karst media and the hydrogeochemical formation mechanisms. The wash fluid leakage of 25 boreholes revealing a distinct vertical pattern: leakage rates exceeded 10&#xa0;m³/h in shallow zones (above − 400&#xa0;m) but dropped below 1&#xa0;m³/h in deeper regions (below − 600&#xa0;m). Hydrochemical and petrological analyses of rock/water samples demonstrated that groundwater transitions from SO₄-Na-Ca to SO₄-Na type with depth, driven by evaporite dissolution and cation exchange. Karst development was categorized into three zones—strong (&gt; 5&#xa0;m³/h leakage, above − 400&#xa0;m), medium (1–5&#xa0;m³/h, -400&#xa0;m to -600&#xa0;m), and weak (&lt; 1&#xa0;m³/h, below − 600&#xa0;m)-based on leakage thresholds and elevation contours. A water-conserving mining technical framework based on “zonational reduction and storage” was proposed. Blocking and draining were conducted at different karst development zones, with 90&#xa0;m³/h of drainage reduced from strong and medium karst zones, thereby protecting and rehabilitating the groundwater. Deep replenishment storage technology enabled recharge of 200&#xa0;m³/h for the Ordovician aquifer. Validated in a representative North China coalfield, this methodology is replicable in over 50 mines with similar hydrogeological conditions, offering a scalable solution to mitigate groundwater depletion and high-salinity discharge while guiding enterprises toward sustainable practices and reduced environmental impacts from extensive drainage.</p>

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Zonation characteristics of karst development in Taiyuan formation limestone and its implications for water-conserving mining: a case study of Zhangshuanglou coal mine, North China

  • 期刊论文

  • 发表日期：

    2025年4月28日

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  • Tianci Chen,
  • Zhimin Xu,
  • Xianfu Zhang,
  • Weixiao Chen,
  • Ge Chen,
  • Yajun Sun

摘要

The groundwater in the karst aquifer of coal seam floor is a significant water source in North China and major focus for mine water hazard prevention. Investigating the karst development characteristics can provide basis for safe and water-conserving coal mining. This study involved drilling exploration of the fourth limestone aquifer of Taiyuan Formation (L4 limestone aquifer) at different mining levels, recording the wash fluid leakage for each borehole. Water and rock samples were collected from different mining levels to determine the vertical zonation of karst media and the hydrogeochemical formation mechanisms. The wash fluid leakage of 25 boreholes revealing a distinct vertical pattern: leakage rates exceeded 10 m³/h in shallow zones (above − 400 m) but dropped below 1 m³/h in deeper regions (below − 600 m). Hydrochemical and petrological analyses of rock/water samples demonstrated that groundwater transitions from SO₄-Na-Ca to SO₄-Na type with depth, driven by evaporite dissolution and cation exchange. Karst development was categorized into three zones—strong (> 5 m³/h leakage, above − 400 m), medium (1–5 m³/h, -400 m to -600 m), and weak (< 1 m³/h, below − 600 m)-based on leakage thresholds and elevation contours. A water-conserving mining technical framework based on “zonational reduction and storage” was proposed. Blocking and draining were conducted at different karst development zones, with 90 m³/h of drainage reduced from strong and medium karst zones, thereby protecting and rehabilitating the groundwater. Deep replenishment storage technology enabled recharge of 200 m³/h for the Ordovician aquifer. Validated in a representative North China coalfield, this methodology is replicable in over 50 mines with similar hydrogeological conditions, offering a scalable solution to mitigate groundwater depletion and high-salinity discharge while guiding enterprises toward sustainable practices and reduced environmental impacts from extensive drainage.