风化裂隙岩体渗流失稳突水溃砂灾变机理研究

Many diggings design sand-resistant coal and rock pillar in North China, the protective layer consist of weathered rocks, which cause disastrous water and sand burst. Aiming at this problem, water and sand burst disaster accident caused by mining under unconsolidated aquifer and thick weathered zone is made as the research object in this project. The comprehensive methods consist of laboratory test, numerical simulation, theoretical analysis and field application are used to research the mechanism of water and sand burst induced by the instability of weathered fracture rock under high water pressure. Obtaining the water and sand resistance engineering characteristic of weathered rock and crack extension path and evolvement rule under loading through measuring the mineral substance composition and physical and mechanical property. Based on the characteristic of stress field, designing weathered rock seepage tests under different triaxial confining pressure and water pressure. Developing seepage testing apparatus of fracture weathered rock to proceed the seepage test of prefabricate fracture weathered rock. Researching fracture extending rule of weathered rock and water and sand burst mechanism under different mining states. Establishing seepage instability mechanical model of weathered fracture rock based on micro fissure extending under multi-field coupling effect, putting forwards water and sand burst criterion caused by transfusion instability of weathered fracture rock. The research results of the project can be conducive to perfect the theory of water and sand burst and have practical significance and application prospect for safety and high-efficient mining and disaster prevention of water and sand burst under unconsolidated aquifer in China.

针对我国华北矿区留设风化岩体保护层的防砂安全煤岩柱后所发生的灾难性突水溃砂事故问题，本项目以松散含水层下厚风化带工作面突水溃砂灾害事故为研究对象，采用室内实验、数值模拟、理论分析及现场应用相结合的方法，开展风化裂隙岩体渗流失稳突水溃砂灾变机理研究。通过测定风化裂隙岩体的矿物质组成成分及物理力学性质，获得风化裂隙岩体阻水阻砂工程特性及载荷作用下裂隙扩展的路径与演化规律；根据应力场特征，设计不同三轴围压和水压力风化岩石渗流试验，研制风化岩石裂隙渗流扩展试验装置，进行水压作用下预制裂隙风化岩石渗流突水溃砂试验，研究不同采动状态条件下风化岩体裂隙渗流扩展规律及渗流失稳突水溃砂机理；建立基于微裂隙扩展的多场耦合风化裂隙岩体渗流失稳力学模型，提出风化裂隙岩体渗流-管涌突变力学判据。项目研究成果有利于完善突水溃砂致灾理论，对我国松散含水层下煤层安全高效开采和突水溃砂灾害防治具有重要的实际意义和应用前景。

近年来，我国华北、华东等许多矿区在井田浅部薄基岩厚风化带区域提高了开采上限。若基岩顶部存在厚层风化泥岩，通常可作为防砂安全煤岩柱的有效隔水阻砂保护层。但由于风化作用风化岩体中形成的天然微裂隙较多，在采动和上部含水层渗流的共同作用下风化岩体微裂隙将发生扩展演化，失去原有的阻水阻砂工程特性，采煤方法和安全措施选择不当时，工作面将发生具有突发性、破坏性和灾难性的突水溃砂事故。针对我国华北矿区留设风化岩体保护层的防砂安全煤岩柱后所发生的灾难性突水溃砂事故问题，本项目以松散含水层下厚风化带工作面突水溃砂灾害事故为研究对象，采用室内实验、数值模拟、理论分析及现场应用相结合的方法，开展风化裂隙岩体渗流失稳突水溃砂灾变机理研究。通过测定风化裂隙岩体的矿物质组成成分及物理力学性质，获得了风化裂隙岩体阻水阻砂工程特性及载荷作用下裂隙扩展的路径与演化规律，提出风化带定向—定量综合划分方法；根据应力场特征，设计不同三轴围压和水压力风化岩石渗流试验，研制风化岩石裂隙渗流扩展试验装置，进行水压作用下预制裂隙风化岩石渗流突水溃砂试验，揭示了不同采动状态条件下风化岩体裂隙渗流扩展规律及渗流失稳突水溃砂机理，研究表明水头压力对风化岩石裂隙扩展影响明显，较小时可促进风化泥岩崩解裂隙闭合，根据砂土渗溃试验成果归纳了松散砂土临界水力坡降计算公式；建立基于微裂隙扩展的多场耦合风化裂隙岩体渗流失稳力学模型，提出风化裂隙岩体渗流-管涌突变力学判据，表明风化岩体对上部岩层载荷支撑力弱，引起上部载荷向下方传递明显，造成矿压显现剧烈，导致采动地表裂缝明显增大。 项目研究成果有利于完善突水溃砂致灾理论，对我国松散含水层下煤层安全高效开采和突水溃砂灾害防治具有重要的实际意义和应用前景。