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岩溶陷落柱是内部结构杂乱无章的特殊地质构造,易成为隐伏于煤层底板下的垂向导水通道,是华北地区石炭二叠系煤田的重大安全隐患。在采动影响下,底板隐伏陷落柱的突水通道通常由底板破坏带和陷落柱共同组成,为了研究其渗流突变机制,利用自行研制的破碎岩体渗透性试验系统,对不同底板破坏带条件下,隐伏陷落柱的渗流特性进行了试验研究。研究结果表明:渗流突变发生的根本原因是大颗粒流失导致破碎岩体孔隙结构改变;发生渗流突变时,流速随渗流边界孔隙直径的增大而增大,同时试样的初始孔隙度均大于0.21;未发生渗流突变时,渗流边界对渗流无显著影响,并且试样的渗透率随孔隙度的增大而增大,渗透率比和孔隙度比存在幂函数关系;非Darcy流β因子为负是渗流突变发生的充分必要条件,非Darcy流β因子的大小决定渗流突变的剧烈程度。
The karst collapse column is a special geological structure with disorderly internal structure. It is easy to become a vertical aqueduct hidden under the floor of the coal seam and a major safety hazard in the Permian Carboniferous coalfield in North China. Under the influence of mining, the water inrush channel of the hidden subsidence column of the floor is usually composed of the bottom plate destruction zone and the collapse column. In order to study the mechanism of percolation and catastrophic failure, the self-developed broken-in rock permeability test system is used to test the water- , The seepage characteristics of concealed collapse column were studied. The results show that the fundamental cause of seepage mutation is the change of the pore structure of the rock mass caused by the loss of large particles. When the seepage mutation occurs, the flow velocity increases with the increase of the diameter of the boundary of the seepage flow, and the initial porosity of the sample increases more than 0.21 ; When no seepage mutation occurs, the seepage boundary has no significant effect on the seepage, and the permeability of the sample increases with the increase of the porosity. The permeability ratio and the porosity ratio have a power function relationship; the non-Darcy flow β factor is negative Is a sufficient and necessary condition for the occurrence of percolation mutation. The size of non-Darcy flow β factor determines the severity of percolation mutation.