Characteristics of vertical karst development and grouting reinforcement engineering practice of the Ordovician top in the Feicheng coalfield, China

• Mei Qiu ^[1] ; Fengjun Huang ^[1] ; Jingxue Wang ^[1]
  1. [1] Shandong University of Science and Technology

     Shandong University of Science and Technology

     China

     
• Localización: Carbonates and Evaporites, ISSN 0891-2556, Vol. 35, Nº. 3, 2020
• Idioma: inglés
• Enlaces
  • Texto completo
• Resumen

  • The mining of deep coal seams in the North China coalfields is threatened by the risk of water inrush from the Ordovician karst. As the mining depth increases, traditional methods of drainage depressurization and grouting reinforcement of the coal floor are increasingly ineffective at solving the problem of water inrush from the Ordovician karst. Grouting reinforcement of the Fengfeng Formation in the Ordovician (Ordovician top) was applied 10 years ago to solve this problem, prevalent recently, and mastering the vertical karst development is fundamental and prerequisite work. This paper carried out a study on the vertical karst development and grouting reinforcement of the Ordovician top in the Feicheng coalfield, China. Macroscopic and microscopic characteristics of the karst were researched by analysis of borehole cores and water inflow, slice identification and X-ray testing results to reveal the vertical karst development of the Ordovician top. Five layers were developed, from top to bottom: confining zone, fissure network zone, karst fissure and pore zone, karst channel zone and confining zone. Then the suitable grouting reinforcement layer was determined to be 5–45 m below the Ordovician top interface. The engineering practice of grouting reinforcement was carried out in the No. 8806 working face in the Baizhuang coal mine. The grouting technology and the evaluation of the grouting effect were analyzed comprehensively from the perspectives of the water inflow characteristics obtained from drilling and the apparent resistivity characteristics before and after grouting, which confirm the vertical karst development interpretation and good grouting effect. The study provides guidance for the prevention and control of Ordovician water disasters of the Feicheng coalfield, as well as other coal mines in North China.