Characteristics of vertical karst development and grouting reinforcement engineering practice of the Ordovician top in t
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ORIGINAL ARTICLE
Characteristics of vertical karst development and grouting reinforcement engineering practice of the Ordovician top in the Feicheng coalfield, China Mei Qiu1,2 · Fengjun Huang2 · Jingxue Wang2 · Longqing Shi1,2 · Xingyue Qu1,2 · Tianhao Liu1,2 Accepted: 20 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract 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. Keywords Karst development · Ordovician limestone · Grouting reinforcement · Feicheng coalfield · china
Introduction Coal seams in the North China coalfields were formed in the Permo-Carboniferous period and are typically exploited via underground mining (Li et al. 2018; Sun et al. 2015; Wang and Meng 2018). After nearly a century of mining, most coal mines in the North China coalfields have started deep mining in the coal seams in the Carboniferous Taiyuan * Longqing Shi [email protected] 1
Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals, Shandong University of Science and Technology, Qingdao 266590, China
College of Earth Sciences and Engineering, Shandong University of Science and Technology, Qingdao 266590, China
2
Formation (F), lying above the Ordovician aquifer, and thus are threatened by Or
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