摘要
房柱式及巷式矸石充填开采中,煤柱与矸石两两相隔,破碎矸石充填体处于侧限压缩状态,破碎矸石的密实程度、孔隙特征及渗透特性对于煤层瓦斯流动及地下水渗流的控制具有重要的价值。基于稳态渗透法及轴向位移控制法,利用一套自制的破碎岩体渗透试验系统,测定了破碎矸石在不同混合粒径下承压过程中的非Darcy流渗透特性,得到渗透特性(渗透率k和非Darcy流β因子)随孔隙率的变化规律。研究表明:1)雷诺数计算及孔压梯度与渗流速度关系曲线说明破碎矸石的渗透特征属于非Darcy流;2)孔隙率随着压缩位移的增加而减小,对于混合粒径试样,较小颗粒充填到较大颗粒的孔隙中,是使岩样的初始孔隙率减小的主要原因;3)在侧限压缩下,大颗粒受挤压破碎是产生0~2.5 mm粒径的原因,而渗流造成细小颗粒质量流失;4)侧限压缩下,渗透率总的趋势减小,而非Darcy流β因子增加,但在压缩过程中,渗透特性的变化趋势受颗粒粒径的影响会出现局部波折,说明破碎矸石的渗透特性与侧限压缩位移、颗粒粒径大小、压缩破碎、排列方式及孔隙结构(通道)有关。
In room-pillar and roadway gangue backfill mining, the coal pillar and gangue are interval, and crushed gangue are under confined compression, besides which, the compaction, porosity and seepage properties of crushed gangue play a significant role in the control of coal seam gas and groundwater flow. Based on the steady-state flow measurement and axial displacement control method, a self–designed testing system for water flow in crushed rocks has been used to monitor the non-Darcy seepage properties of mixture particles of crushed gangue under confined water pressure, and the experiment has obtained the relation between seepage properties(permeability k and non-Darcy coefficient β) and porosity. Testing results have indicated that: 1) The Re calculation and the pore pressure gradient and flow velocity curves have shown that the water seepage flow in crushed gangue is a non-Darcy flow. 2) The porosity of crushed gangue is strongly influenced by compaction(axial displacement) and particle mixture. The porosity decreases with the increase of axial displacement and decrease of bigger particle size, respectively. 3) During the compaction, some larger particles being crushed and broken is the main reason that gave birth to particle size of 0-2.5 mm, and small particles have been washed away because of the effect of water seepage. 4) In general, under confined compression, the permeability k decreases while the non-Darcy coefficient β increases. The fluctuation of seepage properties curves has shown that the seepage properties of crushed gangue are not only related to compaction levels, mixture sizes, particle crushing, style of arrangement, but also to the pore channel.
引文
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