松散岩溶陷落柱发育特征及其对煤岩煤质的改造作用

    Development characteristics of loose karst collapse columns and their transformation effect on coal properties and coal quality

    • 摘要: 岩溶陷落柱是华北地区众多煤田的主要隐蔽致灾地质因素之一,尤其是柱体的松软破碎给矿井陷落柱的探查、防治和安全生产工作带来巨大挑战。以霍西煤田新良友井田为例,通过现场调查、资料统计、样品镜下鉴定、工业分析、扫描电镜分析等手段,揭示了岩溶陷落柱的贯穿关系、分布规律、内部组构特征,并发现了陷落柱对边缘煤层的改造作用。研究表明:井田已揭露的多数陷落柱平面上呈椭圆形,轴长小于30 m;下组煤中陷落柱数量远多于上组煤,且贯穿的陷落柱均是以群簇形式分布;由于煤层埋深小、地层压实作用弱且煤层和顶板岩层力学性质差异大,陷落柱在剖面上呈不规则漏斗形,柱体内部胶结极弱,多为破碎的泥岩夹杂砂岩岩块松散堆积;受陷落柱发育的影响,柱体向外依次为破碎带、风氧化带、过渡带、正常煤层带,陷落柱对煤岩煤质的改造范围在5~10 m以内;从柱体向外,风氧化煤无机矿物含量和灰分产率依次降低,且风氧化煤中含有大量含硅铝质的黏土矿物;作为陷落柱外围的标志岩性,风氧化煤的出露能够为陷落柱近距离超前探测提供新的指示。

       

      Abstract: Karst collapse column is one of the main geological factors that cause hidden disasters in many coal fields in North China. Especially, when the columns are soft and fractured, they will make great challenges to exploration, prevention, and safety production work in the coal mines. The penetrating relationship, distribution pattern, and internal structural characteristics of karst collapse columns in Xinliangyou Coal Mine in Huoxi Coalfield were revealed, and the transformation effect of collapse columns on edge coal seams were discovered, through on-site investigation, data statistics, sample microscopic identification, proximate analysis, and scanning electron microscopy analysis. Result shows that most of the exposed collapse columns in the coal mine are elliptical in plane, with an axis length of less than 30 m. The number of collapse columns in the lower coal group is much greater than that in the upper coal group, and the collapse columns that run through are distributed in clusters. Due to the small burial depth of the coal seam, weak compaction of the strata, and significant differences in mechanical properties between the coal seam and the roof, the collapse columns present an irregular funnel shape on the profile. The internal bonding of the columns is extremely weak, in which consist of loose accumulation of broken mudstone mixed with sandstone blocks. Additionally, influenced by the development of collapse column, the column are arranged outward in order as fracture zone, weathered oxygenized zone, transition zones, and normal coal seam zone. The transformation range of coal property and coal quality is within 5-10 m. From the column outward, the inorganic mineral content and ash yield of weathered oxygenized coal decrease. The weathered oxygenized coals contain a large amount of clay minerals with silicon and aluminum. As a marker property of the collapse column, the exposure of weathered oxygenized coal can provide new indications for close range advanced detection of the collapse columns.

       

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