新近系和薄基岩下突水溃砂防治的风险机制:古剥蚀面起伏与风化程度的影响

Risk mechanism of water and sand burst under the Neogene and thin bedrock:The influence of ancient erosion surface undulation and weathering degree

我国近些年发生了多起损失惨重的溃砂灾害,在三区管理、顶板防治水探查和开采可行性论证等多环节多措施约束下,灾害仍时有发生,因此进一步进行灾害机理及风险识别研究十分必要.本文在总结泉店煤矿新近系和薄基岩下十多年开采经验基础上,揭示了新近系下勘探精度对古剥蚀面形态、特征认知的影响规律,比较研究了两种勘探程度下古剥蚀面起伏、风化深度与宽度、充填物与充水性对开采风险分区的影响,明确了古剥蚀面控制的突水溃砂机理,总结了新近系和薄基岩下矿井突水溃砂查治、评价和开采监控的技术经验.研究表明,基于现行有关规范进行的水体下开采设计,受认知程度、地质条件复杂性等影响,仍不能排除某些隐蔽性较强的致灾风险;新近系与薄基岩之间的隐伏古剥蚀面起伏、风化深度与宽度、充水与充填物特征在由粗到细的勘查过程中存在明显的差异且不具一致性,勘探孔终孔间距以不大于薄基岩区最小基岩厚度为好;隐伏古剥蚀面起伏、风化深度与宽度、充水与充填物的几何分布与开采破坏范围的空间关系明显构成了临界基岩厚度条件下局部风险区划分条件;五节点四阶段的风险防治技术体系是查治古剥蚀面起伏与风化等致突水溃砂灾害的重要技术途径.

In recent years,China has experienced multiple devastating sand burst disasters,and it is necessary to invest huge efforts in disaster mechanism research and risk prevention/control.Due to the inconsistency between exploration and cognitive levels,there may still be many risks of potential disasters that have not been identified in“Three Zones Division for Water Prevention and Control”and mining feasibility design based on macroscopic control of geological conditions.On the basis of summarizing more than 10years of mining experience in Quandian coal mine under the Neogene and thin bedrock,this article reveals the significant differences include the undulation of ancient erosion surface,weathering depth and width,filling material and infiltration of weathering zone,which have different impacts on risk zoning of water and sand burst assessment,that obtained in exploration and supplementary survey stages.Research has shown that the design of underwater mining based on current relevant regulations has undergone extensive engineering inspections,but still does not exclude the risk of disaster caused by strong concealment.The hidden ancient erosion surface undulation between the Neogene and thin bedrock,weathering depth and width,water filling or clay filling characteristics of bedrock show outstanding differences and inconsistency in the exploration process from coarse to fine.It is recommended that the distance between exploration holes is not greater than the minimum thickness of the bedrock.The spatial relationship between the undulation of the hidden ancient erosion surface,the depth and width of weathering,the geometric distribution of water filling and filling materials,and the extent of mining failure clearly constitute the conditions for dividing local risk zones under the critical bedrock thickness condition.A technical system consisting of five nodes and four stages may be the important technical approach for investigating and controlling sudden water and sand burst disasters caused by the undulation and weathering of ancient erosion surfaces.