承压颗粒煤逐级加载下渗透特性实验研究

发布时间：2018-03-10 07:56

本文选题：采空区　切入点：应力　出处：《中国矿业大学学报》2017年05期 　论文类型：期刊论文

【摘要】：为了识别覆岩应力及颗粒粒径对破碎煤体渗透的影响效应,通过承压破碎遗煤的渗流实验,得到了应力逐级加载过程中渗透率与加载应力、粒径、渗流梯度间的关系.结果表明:1)承压破碎颗粒煤的应力-应变曲线具有明显的阶段特征,在0~6 MPa区间快速压实,在6~12 MPa区间缓慢压实,12 MPa后压实效应微弱.2)测试过程中煤样的空隙率、渗透率随应力增大逐渐降低;而偏达西因子始终为负值,其绝对值随应力增加而增加.3)在相同轴向应力加载下,空隙率、渗透率随颗粒粒径的增加而降低,而其衰减系数随颗粒粒径的增加而增加.4)在应力加载过程中煤样内部物理结构发生变化,造成煤样的粒级构成变化,致使破碎分形维数增加,颗粒煤出现再次破碎,进而影响其渗透行为.5)通过承压破碎煤体渗流实验,说明采空区应力的逐渐恢复,将造成遗煤堆积区的空隙率、渗透率不断下降;通过降低煤体的破碎度、减少小颗粒比重有助于降低空隙率及渗透率,进而有利于煤自燃防治.
[Abstract]:In order to identify the effect of overburden stress and particle size on the permeability of broken coal, the permeability, loading stress and particle size in the process of stress step by step loading were obtained through the seepage experiments of coal left by pressure crushing. The results show that the stress-strain curve of pressurized granular coal has obvious stage characteristics and is compacted rapidly in the range of 0 ~ 6 MPa. The porosity and permeability of coal samples decreased gradually with the increase of stress in the 6 ~ (12) MPa range of slow compaction after 12 MPa. 2) the partial Darcy factor was always negative, and the porosity of coal samples decreased gradually with the increase of stress. The absolute value increases with the increase of stress. 3) under the same axial stress, the porosity and permeability decrease with the increase of particle size. However, the attenuation coefficient increases with the increase of particle size. 4) during the stress loading process, the physical structure of the coal sample changes, which results in the change of the particle size composition of the coal sample, the increase of the fractal dimension of the broken coal, and the occurrence of the re-breaking of the granular coal. Through the seepage experiment of broken coal body under pressure, it is shown that the gradual recovery of the stress in goaf will result in the porosity of coal deposit area and the continuous decrease of permeability, and by reducing the fragmentation degree of coal body, Reducing the specific gravity of small particles is helpful to reduce the porosity and permeability, and then to prevent the spontaneous combustion of coal.
【作者单位】：重庆大学煤矿灾害动力学与控制国家重点试验室;河南理工大学安全科学与工程学院;
【基金】：国家自然科学基金项目(U1361205,51404090,51574111)
【分类号】：TD752.2

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