分级加载下破碎砂岩渗透特性试验及其稳定性分析  

Permeability characteristics of broken sandstone and its stability analysis under step loading

作　　者：张天军[1] 尚宏波[2] 李树刚[2] 任金虎 包若羽 张磊[1] 

机构地区：[1]西安科技大学理学院,陕西西安710054 [2]西安科技大学能源学院,陕西西安710054

出　　处：《煤炭学报》2016年第5期1129-1136,共8页Journal of China Coal Society

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

摘　　要：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 brokenrock over a long time,its permeability characteristics will change with its porosity variation,and the different ratios ofparticle sizes of broken rock will affect its permeability characteristics. According to the Talbol grading theory,and bythe application of DDL600 electronic universal testing machine and the permeameter test equipment,five level constantaxial load pressures are set. The four different osmotic pressures corresponding to each level constant load pressure aretested to explore the permeability characteristics of broken sandstones with different particle size ratios. The test resultsshow that：① When the axial load increases from the first level to the fifth level,the rate of seepage velocityDvgener-ally shows a tendency of decrease with the increase of effective stress of the broken sandstones in the cylinder;②Within the later period of constant load deformation,the permeability shows a decreasing tendency generally with theporosity decrease of broken sandstones,and the absolute value of non-Darcy flowβfactor increases;③ There exists adifference between the permeability of broken sandstones with different Talbol power exponents and the non-Darcy flowβfactor sizes. Whenn=0. 5,the permeability of broken sandstones is minimum,while the non-Darcy flowβfactor ismaximum. Whenn= 1. 0,the permeability of broken sandstones is maximum,while non-Darcy flowβfactor is smalloverall. The following conclusions can be reached from the above research results：when the particle size of brokensandstones is very small or when the breakage of refinement is very serious,the negative value of the non-Darcy flowβfactor appears easily,the seepage instability of broken sandstones occurs.

关 键 词：破碎砂岩 Talbol幂指数 有效应力 非Darcy流β因子 孔隙率 渗流失稳 

分 类 号：TD315[矿业工程—矿井建设]