采动覆岩与水环境协同作用机理及地表沉陷预测模型构建

Large-scale excavating of coal resource damages strata primary structure and disturbs underground water environment. Synergistic interacting of disturbed rock-soil strata, especially alluviums of Cenozoic Era and underground water environment makes surface subsidence, range and position difficult to predict increasingly. In this item comprehensive research methodologies mixing In-situ surveying, theoretical analysis with experimental measurements will be employed. The main destination of the project is to research characteristics and laws of disturbed overburden strata fracture field caused by coal mining under the geological condition of thick water-bearing alluvium. Based on mechanical properties parameters of disturbed strata, prediction model of the height of fractured water-conducting zone will be constructed from the research angle of strain energy balance. Synergistic interacting mechanism between overlying strata and underground water environment (phreatic water and confined water in alluvium) will also be studied. By utilizing simulative experimental equipments of stable loading and descending water pressure, the test of soil mass compression deformation will be carried out, the aim of which is to acquire functional models between compression amount and water-level descendent depth for different granule and different gradation soil mass. Based on above research results, space-time prediction model of surface subsidence coupling overburden strata settlement induced by coal mine with water-bearing alluvium dehydration can be deduced through merging normal distribution time function. This fruitful research can not only afford theoretical support for preventing or relieving disasters for coal mines in North-east, North and East China under the geological condition of thick water-bearing alluvium, but also promote coal industry safe, scientific, sustainable development and optimum ecological cycle.

煤炭资源的大规模开采损伤了岩体的原生结构，扰动了地下赋存的水环境，采动岩土体尤其是新生界松散层与水环境的协同作用使得地表沉陷量、沉陷范围和沉陷位置的预测难度提高。项目拟采用现场实测、理论分析和实验室测试相结合的综合研究手段和方法，主要研究厚松散层条件下采动覆岩裂隙场的发育特征和规律，基于采动围岩的力学属性参数，从应变能平衡的角度构建导水裂隙带发育高度预测模型。研究采动影响下覆岩与水环境（松散层潜水和承压水）的协同作用机制，利用恒载荷降水压模拟实验装置开展岩土体压缩变形实验，研究得出不同颗粒体大小、不同级配的土体压缩变形量与水位降深关系的函数。基于上述研究成果，引入正态分布时间函数，构建采动覆岩沉降与含水松散层固结沉降相耦合的时空预测模型。项目研究成果可为我国东北、华北和华中厚含水松散层煤矿区的矿井防灾、减灾提供理论依据，促进煤炭工业安全、科学和可持续发展以及煤矿区的良性生态循环。

项目采用现场实测、理论分析、物理模拟和实验室仿真计算等综合研究手段和方法，分析了水环境作用下采动地表沉陷的特征和规律，基于多模态时间函数，开展了地表沉陷的动态预测。基于有效应力原理，构建了潜水含水层和承压含水层土体压缩计算模型，研究了水环境变化对土体压缩量的影响，并结合现场实测资料对模型进行了分析和验证。采用应变能平衡理论模型对研究区域导水裂隙带发育高度进行了预测和分析，并把计算结果与经验公式法、“上四带理论法”以及关键层理论法的计算结果进行了对比分析。构建了顾及三维空间及时间效应的地表任意点最大下沉速度表达式，并给出了达到最大下沉速度的时间，建立了利用采动程度系数、覆岩岩性系数、采深等多因子来表达非充分采动地表移动延续时间的计算公式。建立了正态分布时间函数、优化分段Knothe时间函数和Logistic时间函数模型，设计了求参方法，从地表下沉、下沉速度、下沉加速度及空间分布形态等方面论证了时间函数的时空完备性，并将其应用于地表沉陷动态预测中。构建了老采空区地表残余下沉计算函数模型，并在宁夏灵新煤矿开展了工业性实践。采用数值分析方法，建立了巨厚冲积层薄基岩下间歇开采地表沉陷仿真计算模型，揭示了岩层移动的机理，并对煤层间歇开采过程中覆岩的应力应变状态、地表形变和裂隙场发育规律、地质采矿条件对地表形变规律的影响等开展了系统的分析和研究。研究成果提升了矿山开采沉陷预测结果的精准度，避免或减轻了煤矿区地面塌陷和民房受损程度，为煤炭绿色高效开采、矿区生态文明建设提供了理论依据和技术支撑。