“三下”厚煤层长壁逐巷充填采煤围岩变形控制机理研究

In China, about 46% of total coal production comes from thick coal seam mining. However, large amounts of thick coal resource trapped by surface buildings, water bodies and railways (three unders) could not be exploited with a high recovery ratio. In the meantime, solid waste and surface subsidence caused by mining are harmful to the environment. On this basis, longwall-roadway backfilling mining technology (LBMT) in “three under” thick coal seam was proposed in the National Science and Technology Support Program. With this foundation, this research focuses on basic theory and the main objectives as follows: Build up a time-pressure two-parameter model of the cemented backfilled body based upon backfill material’s mechanical and rheological properties; accordingly, the characteristics of surrounding rock deformation and mining stress evolution from the part to the whole could obtained. In addition, the primary factors influencing surrounding rock deformation in all stages and the control principles would be proposed. Establish a mechanical model of multi–layered elastic foundation beam, which would be used to reveal the characteristic behaviors of strata movement and surface subsidence on longwall-roadway backfill mining area. Therefore, a prediction method for surface subsidence predicting in LBMT would be developed. The results of this research may provide a basic theoretical reference for LBMT, and enrich the technical and theoretical system of "three unders" thick coal mining.

我国煤炭产量的46%由厚煤层工作面产出，然而大量的“三下”厚煤层无法高采出率开采严重制约着资源的合理利用，同时，煤炭生产带来的固体废弃物排放、地表沉陷等问题影响矿区生态平衡，有鉴于此，国家科技支撑计划课题提出了“三下”厚煤层长壁逐巷充填采煤技术，并在系统、工艺及装备方面取得了突出的研究成果，本项目在此基础上展开深入的基础理论研究，主要内容和思路为：以胶结充填材料力学及流变特性试验为基础，构建充填体变形的压力和时间双参数本构模型，由局部至整体分段分析开采过程中围岩变形特征及采场应力演化规律，提出各阶段围岩变形的主控因子及控制方法，建立多层叠合弹性地基梁力学模型，揭示长壁逐巷充填采煤工作面岩层移动规律，分析厚煤层分层充填开采的地表变形规律并初步建立地表变形的预计方法。本项目的研究成果将为长壁逐巷充填采煤提供基础理论支撑，并进一步丰富“三下”厚煤层开采的技术及理论体系。

本项目以国家能源科技重大需求为基础，密切围绕“三下”厚煤层安全开采和矿区环境协调发展两大主题，针对“三下”厚煤层长壁逐巷充填采煤围岩变形控制机理，综合采用理论分析、数值模拟、物理模拟、实验室试验和现场实测相结合的研究方法，测试分析了胶结充填材料在不同龄期时的性能，包括坍落度、泌水率、单轴抗压试验、劈裂试验、变角剪切试验、抗压入试验和泊松比的变化规律，研究了关键参数对胶结充填材料的物理力学性能影响，建立胶结充填材料力学模型；揭示了长壁逐巷充填采煤工作面掘巷期、充填体胶结期、充填体稳定期及重复采动影响期等不同阶段围岩变形及应力演化规律，提出了围岩变形的控制关键；建立了多层叠合弹性地基梁力学模型，分析了不同分层开采过程中顶板与充填体之间的相互作用关系，并在试验矿区进行了现场实测验证；建立了基于等价采高的厚煤层分层充填开采地表变形预计模型，并针对试验矿区进行了预计。研究成果获得省部级科技进步一等奖2项、中国专利优秀奖1项，出版学术专著1部，发表学术论文10篇（SCI收录9篇、EI收录1篇），获授权国外发明专利3项、国内发明专利3项，培养硕士研究生2名。本项目的研究为长壁逐巷充填开采技术的应用提供了理论依据，进一步拓展了特厚煤层高采出率安全开采理论与技术。