1. College of Sciences,Xi’an University of Science and Technology,Xi’an　 710054,China;2. College of Energy Science and Engineering,Xi’an University of Science and Technology,Xi’an　 710054,China

煤岩体的渗透特性与孔压梯度满足渗流失稳条件时,易引发突水和瓦斯突出灾害。破碎岩体长时间缓慢变形过程中,其渗透特性将随孔隙率的变化而发生改变,且破碎岩体不同粒径的配比会影响其渗透特性。采用Talbol级配理论,利用DDL600电子万能试验机、渗透仪等试验设备,设置五级轴向恒载加压,每级恒载加压下对应4种不同渗透压进行试验,探究不同粒径配比下的破碎砂岩渗透特性。试验结果表明:1轴向荷载从第1级加载至第5级,随着缸筒内破碎砂岩有效应力的增大,描述渗流速度变化的参数Dv均呈减小趋势;2恒载变形后期,破碎砂岩随孔隙率减小,其渗透率总体呈减小趋势,而非Darcy流β因子的绝对值增加;3不同Talbol幂指数的破碎砂岩,渗透率与非Darcy流β因子的大小存在差异,n=0.5时,破碎砂岩渗透率最小,非Darcy流β因子最大,n=1.0时,破碎砂岩渗透率最大,非Darcy流β因子整体较小。研究可见,破碎砂岩颗粒粒径很小或颗粒破碎细化非常严重时,非Darcy流β因子较容易出现负值,破碎砂岩发生渗流失稳。

When the permeability characteristics of coal and rock mass and pore pressure gradient meet the seepage in- stability conditions,water inrush and gas outburst disaster will easily occur. In the slow deformation process of broken rock over a long time,its permeability characteristics will change with its porosity variation,and the different ratios of particle sizes of broken rock will affect its permeability characteristics. According to the Talbol grading theory,and by the application of DDL600 electronic universal testing machine and the permeameter test equipment,five level constant axial load pressures are set. The four different osmotic pressures corresponding to each level constant load pressure are tested to explore the permeability characteristics of broken sandstones with different particle size ratios. The test results show that:① When the axial load increases from the first level to the fifth level,the rate of seepage velocity Dv gener- ally shows a tendency of decrease with the increase of effective stress of the broken sandstones in the cylinder;② Within the later period of constant load deformation,the permeability shows a decreasing tendency generally with the porosity decrease of broken sandstones,and the absolute value of non-Darcy flow β factor increases;③ There exists a difference between the permeability of broken sandstones with different Talbol power exponents and the non-Darcy flow β factor sizes. When n = 0. 5,the permeability of broken sandstones is minimum,while the non-Darcy flow β factor is maximum. When n = 1. 0,the permeability of broken sandstones is maximum,while non-Darcy flow β factor is small overall. The following conclusions can be reached from the above research results:when the particle size of broken sandstones is very small or when the breakage of refinement is very serious,the negative value of the non-Darcy flow β factor appears easily,the seepage instability of broken sandstones occurs.

国家自然科学基金资助项目(51174158；51174157；51374168)；

Zhang Tianjun,Shang Hongbo,Li Shugang,et al. Permeability characteristics of broken sandstone and its stability analysis under step load- ing[J]. Journal of China Coal Society,2016,41(5):1129-1136.