<p>The squeezing ground condition in pillar basement pose challenges to the long-term stability of basement roadways, particularly in multi-seam mining. This research aims to assess the mechanisms and factors contributing to squeezing deformation and develop a squeezing control strategy. The stress and displacement fields in the pillar basement are analysed by modelling it as a semi-infinite plane under the nonlinear load of the pillar. The findings reveal that the squeezing condition characterises a critical distance within which stress concentration and rock strain are significant, as well as a critical period during which basement rocks experience early intense settlement of the upper panel. In this context, roadway deformation can be exacerbated due to limited rock mass strength and incompetent ground support capacity. Following these insights, numerical simulations are conducted to identify that excavating the roadway along the longwall retreat direction with an offset of 12 m away from the pillar rib largely reduces roadway convergence. A reinforced ground support system is developed, consisting of a coupled short- and long-cable configuration, extended anchorage, and enhanced pretension. A field trial is conducted, proving that the roadway remains stable during mining, and its convergence is reduced by 75% on average. Through discussions, it is recommended to enhance the quality control of support element installation and incorporate advanced monitoring and geotechnical assessments for more effective ground management. The research consolidates the understanding of mining-induced rock compression in the pillar domain and provides insights that contribute to enhanced ground control practices in underground mining.</p>

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Assessing squeezing ground conditions in pillar basement due to mining and a squeezing control strategy

  • Mingwei Chen,
  • Gangwei Fan,
  • Dongsheng Zhang,
  • Shizhong Zhang,
  • Wanqi Zhang

摘要

The squeezing ground condition in pillar basement pose challenges to the long-term stability of basement roadways, particularly in multi-seam mining. This research aims to assess the mechanisms and factors contributing to squeezing deformation and develop a squeezing control strategy. The stress and displacement fields in the pillar basement are analysed by modelling it as a semi-infinite plane under the nonlinear load of the pillar. The findings reveal that the squeezing condition characterises a critical distance within which stress concentration and rock strain are significant, as well as a critical period during which basement rocks experience early intense settlement of the upper panel. In this context, roadway deformation can be exacerbated due to limited rock mass strength and incompetent ground support capacity. Following these insights, numerical simulations are conducted to identify that excavating the roadway along the longwall retreat direction with an offset of 12 m away from the pillar rib largely reduces roadway convergence. A reinforced ground support system is developed, consisting of a coupled short- and long-cable configuration, extended anchorage, and enhanced pretension. A field trial is conducted, proving that the roadway remains stable during mining, and its convergence is reduced by 75% on average. Through discussions, it is recommended to enhance the quality control of support element installation and incorporate advanced monitoring and geotechnical assessments for more effective ground management. The research consolidates the understanding of mining-induced rock compression in the pillar domain and provides insights that contribute to enhanced ground control practices in underground mining.