煤层底板高承压水疏降多目标时空动态优化模型及方法研究

Groundwater drainage for depressurization is a major measure to prevent water-inrush from coal mine floor. With exploitation depth increasing, water-inrush risk becomes higher and more groundwater would be discharged. In many coal mines of northern China, over-pumping groundwater destroyed the hydrologic cycle and water resources and increased mining cost. Groundwater drainage for depressurization should be optimized in urgent need. Previous researches of multi-objective optimization of drainage, without considering mining plan, usually have single stage and the dewatering region remains unchanged, which do not conform to mining practice. Therefore, based on working faces layout and succeeding plans, that proposal takes the whole single coal seam mined-out period as optimal stage and studies dynamic changing features of dewatering region in different sub-stages. Using GIS spatial analysis, a planning method of drainage borehole layout is to be constructed. Introducing time and space variables and considering several time-space factors, a multi-objective optimization model with space-time dynamics is supposed to be built. Coupling simulation with intelligent searching algorithms, a method for solving the optimization model under varying conditions is to be researched and aims at fully-coupled computation of groundwater flow numerical simulation with automated searching program. The outcome of that proposal will provide a novel way for groundwater management in mining areas and coordinate the drainage engineering and mining activity on space-time dynamics.

疏水降压是防治煤矿突水的主要措施，随着开采深度的不断延伸，高承压水的突水威胁增大，需要疏排的水量更高。在华北许多矿井，过量疏排地下水破坏了区域水循环与水资源，使得生产成本居高不下，疏降工程亟需优化。以往研究矿井高承压水疏降优化，不考虑井下采掘接替规划，优化阶段单一，疏降范围基本不变，不符合矿井生产实际。本课题针对矿井回采工作面的空间分布及时间接替，以单个煤层开采完毕为优化期，研究不同开采阶段疏降范围动态变化特征，利用GIS空间分析方法，研究顾及多开采阶段的疏降钻孔布局规划方法；引入空间与时间变量，统筹多种时空要素，构建煤层底板高承压水疏降多目标时空优化模型；基于模拟-优化耦合与智能寻优算法，研究含变化条件的多目标优化模型求解方法，实现地下水流数值模拟与自动搜索算法全耦合求解。课题成果将为矿区地下水资源管理提供新的思路与方法，实现疏降工程与煤炭开采时空动态相协调。

项目针对煤层底板承压水井下钻孔疏降工程，提出了一种疏降钻孔位置优化方法，该方法将巷道概化为直线，以巷道直线方程、工作面安全水位、钻孔最大水位降深等为约束条件，以排水量最小为目标函数，建立了包含二维坐标的疏降钻孔位置与流量优化数学模型。以单一长壁采煤法为例，基于突水系数与GIS多元信息复合，首次提出了一种顾及采煤工作面空间布置、开采顺序、煤层底板高程与隔水层厚度空间分布等时空要素的井下群孔疏降工程多阶段优化方法，建立了安全-环保双目标优化数学模型；基于数值模拟与遗传算法耦合，设计了模型求解方法；利用地下水有限元数值模拟软件Feflow的编程接口，开发了数值模拟与遗传算法耦合优化程序包（插件），可设置遗传算法参数与优化阶段，自动搜索最佳疏降方案。实际算例结果表明，应用本方法优化后的群孔疏降工程可减少36%～69%的排水量，实现既保证安全开采，又显著降低对地下水资源的破坏，为煤矿节约排水成本与能耗，提高企业经济效益。项目研究成果充实了现有的矿井水排-供-环保三位一体理论，为矿区地下水资源保护与管理提供了新思路与新方法。