基于雷诺数的级配结构破碎煤样渗流失稳特征研究

Characteristics of seepage and loss of stability in broken coal samples based on gradation structure in Reynolds number

为获得不同级配结构下破碎煤岩体渗流失稳特征,本文采用自主研发的破碎样渗流试验系统,研究了位移与渗透压改变时不同级配结构下破碎煤样的渗流参量及雷诺数变化规律,通过两者变化规律分析得出渗流失稳临界特征值。结果表明:1)试验过程中4组破碎煤样的渗流速度与压力梯度关系均呈现非线性特征,骨架密实结构破碎煤样渗透率最大,非达西因子最小,悬浮密实结构破碎煤样渗透率最小,非达西因子最大,骨架空隙结构破碎煤样渗透参量受孔隙率影响变化较大;2)各组破碎煤样的雷诺数最小为0.1,最大为12.66,其中以悬浮密实结构破碎煤样雷诺数最大,骨架密实结构破碎煤样雷诺数最小,骨架空隙结构破碎煤样雷诺数变化小。研究可见,破碎煤样发生渗流失稳时存在临界特征值,悬浮密实结构以及骨架孔隙结构破碎煤样渗流失稳临界雷诺数为3,骨架密实结构破碎煤样临界雷诺数为5。

In order to obtain the characteristics of seepage and loss of stability in broken coal and rock under different grading structures, in this paper the self-developed fracture-like seepage test system has been used to study the variation of seepage parameters and Reynolds number of broken coal samples under different gradation structures when displacement and osmotic pressure change. Through the analysis of the change law of the two, the critical characteristic value of seepage loss stability has been obtained. The results have shown that:1) The relationship between the seepage velocity and the pressure gradient of the four groups of broken coal samples in the test process presents to be nonlinear. The fractured coal sample with the skeleton compact structure has the highest permeability, with the non-Darcy factor being the smallest, and the broken coal sample with suspended compact structure has the lowest permeability with the non-Darcy factor being the largest, and the permeability parameters of broken coal samples in the skeleton void structure are greatly affected by the porosity;2) The minimum of the Reynolds number among each group of broken coal samples is 0.1 and the maximum is 12.66, with the Reynolds number of broken coal sample with suspension dense structure being the largest, the Reynolds number of the broken coal sample being the smallest in the skeleton compact structure, and the variation of Reynolds number of the broken coal sample in the skeleton void structure is small. It can be seen that there will be a critical characteristic value when the fractured coal sample is instable. The critical Reynolds number of the suspended compact structure and the skeleton pore structure broken coal sample is 3, and the critical Reynolds number of skeleton compact structure broken coal sample is 5.