我国不同类别煤层顶板水害致灾机理与防控路径

Disaster-causing mechanism and prevention and control path of different types of coal seam roof water disasters in China

我国是世界上成煤和赋存条件最复杂的国家,煤层顶板水文地质条件的多样性和复杂性,采动覆岩裂隙场与渗流场耦合的相互性和时变性以及煤层顶板突水的独特性和危害性,造成顶板水害是我国尤其是西部煤矿区的主要矿井灾害之一。为了更好地认识顶板水害和推广现有技术和探索新技术防控此类矿井灾害,在全面分析近年来我国煤层顶板水害事故规律与顶板充水含水层的赋存条件、突水模式、动力特征、力学行为等基础上,系统划分了顶板水害的类型、特征、主要类别的致灾机理及梳理了现有顶板水害的防治技术,并展望了未来顶板水害防治领域的发展方向。研究发现:①顶板水害主体架构包括巨厚基岩含水层涌(淋)水、薄基岩弱胶结层水-砂耦合溃涌、离层空间蓄水储能突水、天窗补给型突水、围岩烧变增透致突等5种类别,集中分布于秦岭—淮河沿线以北地区,陕、蒙、宁是顶板水害主要聚集地。②采动诱发巨厚基岩含水层下覆岩原生裂隙互馈-贯通发育“Z”型离层空间,导致采场出现大面积涌(淋)水现象;基于复合关键层破断力学条件,阐明了薄基岩弱胶结层水-砂耦合溃涌致灾的动力源;构建了离层失稳突水临界判别准则,将离层突水划分为静载扰动、“动+静”载复合扰动、复合煤层开采重复扰动3种模式;红土隔水层缺失及红土薄弱区采动劣化损伤是产生天窗越流补给的主要根源;围岩烧变增透,孔隙度增大,接受临近水源补水后形成新的含水结构体,在采动诱发下烧变岩水涌入采场发生水害事故。③梳理了当前煤层顶板水害“探-放-治”三位一体的解危防控技术体系,提出了井上下共轭联动、钻-采(掘)高位协同地质勘探系统,以防治水“三区”划分为导向的地质保障工作,“煤-水-生态”多目标齐抓共管的绿色开采和防治水理念,以及数智化、透明化矿山水文地质灾害信息维护系统等未来发展方向。

China is the country with the most complicated coal-forming and occurrence conditions in the world.The roof water disaster,caused by the diversity and complexity of the hydrogeological conditions of the coal seam roof,the mutuality and time-varying coupling of the mining overburden fracture field and the seepage field,and the uniqueness and harmfulness of the coal mine roof water inrush,is one of the main mine disasters in China,especially in the western coal mining area.In order to better understand the roof water disaster,promote the existing technology and explore new technologies to prevent and control such mine disasters,based on the comprehensive analysis of the law of roof water disaster accidents in China’s coal mines in recent years and the occurrence conditions,water inrush mode,dynamic characteristics and mechanical behavior of roof water-filled aquifers,the types and characteristics of roof water disasters are systematically divided.The disaster mechanism of the main categories and the existing prevention and control technologies of roof water disasters are reviewed,and the future development direction of roof water disaster prevention and control is prospected.The study found that:①The main structure of roof water disaster includes five types:gushing(leaching)water in thick bedrock aquifer,water-sand coupling inrush in weak cementation layer of thin bedrock,water storage and energy storage water inrush in abscission layer space,skylight recharge water inrush,and surrounding rock burning and permeability enhancement.They are concentrated in the north of the Qinling Mountains-Huaihe River.Shaanxi,Inner Mongolia and Ningxia are the main gathering places of roof water disasters.②Mining-induced“Z”-type separation space is developed in the primary fractures of overlying strata under the super-thick bedrock aquifer,resulting in a large area of water gushing(leaching)in the stope.The fracture conditions of composite key strata are established,and the power source of watersand coupling inrush disaster in weak cemented layer of thin bedrock is clarified.The critical criterion for assessing the instability of water inrush from bed separation is constructed,and the water inrush from bed separation is divided into three modes:static load disturbance,“dynamic+static”load composite disturbance and repeated disturbance of composite coal seam mining.The lack of laterite aquiclude and the mining-induced deterioration damage in the weak area of laterite are the main causes of skylight leakage recharge.The surrounding rock is burnt to increase permeability and porosity,and a new water-bearing structure is formed after receiving water supplement from adjacent water sources.Under the induction of mining,burnt rock water pours into stope and causes water disaster accidents.③The current prevention and control technology system of coal mine roof water disaster“exploration-discharge-treatment”is evaluated,and the future development direction is put forward,such as the conjugate linkage of upper and lower wells,the drilling-mining(excavation)high-level collaborative geological exploration system,the geological guarantee work guided by the“three zones”division of water prevention and control,the green mining and water prevention concept of“coal-water-ecology”multi-objective co-management,and the digital intelligence and transparent mine hydrogeological disaster information maintenance system.