综放开采覆岩垮裂空间演化及溃砂致灾机理研究

Aiming at the geological and mining conditions in western mining area ,which is fully-mechanized caved with high strength in soft weak-cementation thick strata in Jurassic system , the dynamic deformation evolution process and mechanics characteristics of roof caving and fracturing rock ware taken as objects of the study, some theoretical analysis methods such as damage mechanics, broken rock mechanics and discrete element method numerical calculation, laboratory methods for broken rock sand inrush dynamics test, fracture evolution of overlying strata test, water and sand inrush test, and the comprehensive methods of micro seismic monitoring system, EH4 magneto-telluric system and borehole mining fissure leakage monitoring system were adopted. Based on overlying strata stress transfer theory, research the zonality and zoning feature in strata movement and the space form and dynamic evolution lows in crack zones, analyze the mechanical properties of fractured rock under fully mechanized caving, and the migration state and dynamic characteristics of sand in fractured rock mass, establish dynamic sand inrush model for fractured rock mass, put forward the disaster mechanism of sand inrush and its influencing factors, ensure the security structure thickness of strata. The research achievement has important theoretical signification and practical application value.

针对我国西部矿区侏罗系厚层弱胶结松软结构覆岩高强度综放开采的地质采矿条件，以覆岩体移动变形动态演化过程及顶板垮落、损伤裂隙岩块力学特性为主要研究对象，采用损伤力学、破碎散体力学及离散元数值计算等理论分析手段，破碎岩体溃砂动力学试验及采动覆岩垮裂演化和溃水砂模拟试验等室内实验方法，现场采动覆岩垮裂微地震动态监测、EH4大地电磁系统及钻孔采动裂隙漏失量监测等综合研究方法，基于采动覆岩体应力场转移理论，研究高强度开采覆岩结构运动的分带性和分区性特征、垮裂带空间形态和动态演化规律，分析综放开采破断垮落岩块压密支撑特性、水砂颗粒体在垮裂破碎岩体中的运移状态及动力学特征，建立破碎岩体溃水砂动力学模型，提出井下溃砂灾害的致灾机理及影响因素，确定覆岩层合理安全结构厚度。课题研究具有重要理论意义和实际应用价值。

随着煤矿开采上限的持续提高，上覆松散含水层受采动影响，含砂量较高的水砂混合物溃入井下工作面，导致财产损失甚至人员伤亡的事故时有发生，给矿井的安全生产带来很大威胁。本课题在前期研究基础上，基于研发的试验装备，综合运用力学试验、数值模拟、物理模拟和理论分析等方法，以采动覆岩涌水溃砂为工程背景，研究涌水溃砂灾害发生条件及力学机制，构建涌水溃砂采场覆岩垮裂力学模型，建立考虑水砂耦合作用的涌水溃砂发生判据；考虑水对冒落区破碎岩石承压变形的影响，对不同含水状态下破碎岩石分级加载过程中的变形特性进行研究，获得了破碎岩石承压变形时间相关特性；研制了水砂突涌试验系统，定量化地研究不同水压力和不同水砂通道尺寸条件下水砂突涌试验中水砂运移及突涌的信息，探寻含水层底部水压力变化特性，以及水砂流量与通道尺寸、水压力的关系；研制了采动覆岩涌水溃砂灾害模拟试验系统以及相配套的低强度非亲水相似材料，利用其对煤系地层进行模拟铺设并进行模拟开采，获得工作面开采过程中覆岩变形破坏、裂隙发育扩展、水砂通道形成及水砂突涌特征；提出了采动覆岩涌水溃砂灾害防治技术。