State Key Laboratory of Coal Resources and Safe Mining, School of Mines, China University of Mining & Technology, Xuzhou 221116, Jiangsu, China; Key Laboratory of Deep Coal Resource Mining of Ministry of Education, China University of Mining & Technology, Xuzhou 221116, Jiangsu, China.
State Key Laboratory of Coal Resources and Safe Mining, School of Mines, China University of Mining & Technology, Xuzhou 221116, Jiangsu, China; Key Laboratory of Deep Coal Resource Mining of Ministry of Education, China University of Mining & Technology, Xuzhou 221116, Jiangsu, China.
Sci Total Environ. 2019 Nov 25;693:133607. doi: 10.1016/j.scitotenv.2019.133607. Epub 2019 Jul 27.
Underground coal mining leads to environmental problems such as gangue pollution, surface subsidence and soil erosion, etc. Solid backfilling coal mining (SBCM) can control the strata movement, reducing gangue discharge and environmental pollution in mining areas. Gangue solid wastes (GSW) are backfilled into the goaf space as the supports for the overburden strata in solid backfilling coal mining. In this case, GSW are under triaxial compression. The deformation characteristics of the GSW under this loading condition are the key factors determining the control efficiency of strata movement and surface subsidence. The influence of the particle size grade and the confining pressure condition on the deformation and breakage characteristics of the GSW is studied based on large-scale triaxial compression tests in this paper. Also, the effect of particle breakage on the deformation of the GSW is revealed. The results indicate that in the triaxial compression process, the GSW exhibits strain hardening characteristics and volume decrease under compressive loading. The maximum load-bearing stress is more sensitive to the confining pressure condition but less sensitive to the particle size grade. The maximum load-bearing stress increases linearly with the confining pressure. Particle breakage of the GSW is notably influenced by the particle size grade but almost independent of the confining pressure condition. The S1 specimen with a reasonable proportion has the minimum relative breakage index, while the S3 specimen that mainly contains large particles has the maximum relative breakage index. The research outcomes are significant to the understanding of the mechanical characteristics of GSW, the selection and preparation of the backfilling materials in the field practices and the ensurence of the backfilling efficiency.
地下采煤会导致矸石污染、地表沉降和水土流失等环境问题。矸石充填采煤（SBCM）可以控制地层移动，减少采煤区的矸石排放和环境污染。矸石固体废物（GSW）被回填到采空区作为固体充填采煤中覆岩的支撑。在这种情况下，GSW 处于三轴压缩状态。在这种加载条件下，GSW 的变形特征是决定地层移动和地表沉降控制效率的关键因素。本文通过大型三轴压缩试验研究了粒径级配和围压条件对 GSW 变形和破碎特征的影响，揭示了颗粒破碎对 GSW 变形的影响。结果表明，在三轴压缩过程中，GSW 在受压时表现出应变硬化特征和体积减小。最大承载应力对围压条件更敏感，对粒径级配不敏感。最大承载应力随围压线性增加。GSW 的颗粒破碎明显受粒径级配影响，但几乎独立于围压条件。具有合理比例的 S1 试样具有最小的相对破碎指数，而主要含有大颗粒的 S3 试样具有最大的相对破碎指数。研究结果对了解 GSW 的力学特性、现场实践中充填材料的选择和制备以及保证充填效率具有重要意义。
