三维应力下破碎砂岩渗透特性试验研究  

Permeability test of broken sandstones under the three-dimensional stresses

作　　者：张天军[1] 石涛 潘红宇 陈阁[1] ZHANG Tian-jun;SHI Tao;PAN Hong-yu;CHEN Ge(College of Sciences,Xi’an University of Science and Technology,Xi’an 710054,China;College of Safety Science and Engineering,Xi’an University of Science and Technology,Xi’an 710054,China)

机构地区：[1]西安科技大学理学院,陕西西安710054 [2]西安科技大学安全科学与工程学院,陕西西安710054

出　　处：《西安科技大学学报》2018年第2期273-280,共8页Journal of Xi’an University of Science and Technology

基　　金：国家自然科学基金(51374168;51474172;51374236);国家自然科学基金科学仪器基础研究专款(51327007)

摘　　要：承压破碎岩体中非稳态渗流是引起多种动力灾害发生的重要因素之一。利用自主研发的破碎岩石三轴渗透试验系统,考虑围压挤出的渗透液总量对碎石孔隙度的影响,进行了三维应力下5~10 mm粒径破碎砂岩的渗透试验,得到了不同轴向压缩位移、不同围压下试样的渗透特性变化规律。结果表明:不同轴向位移下,试样孔隙度随围压的升高呈对数减小,其渗透率随围压的变化逐渐减小,且各自差异性逐渐缩小;同一围压下,随轴向压缩位移增加,孔隙度、渗透率逐渐趋于一个稳定值,其中渗透率量级在10-11~10-13m2之间,表现为试样的孔隙连通性减弱,整体结构趋于稳定;非Darcy流β因子随围压的增加呈非线性增长,其中非Darcy流β因子的量级在108~1011m-1之间,试样原有级配改变明显,非Darcy流β因子增长趋势受有效毛细管数目及其孔径大小的影响,毛细管孔径减小导致渗透液与毛细管壁的相对接触面积增加。该试验结果为可控围压下破碎岩石中的渗流研究提供参考。The unsteady permeating flows in broken sandstones under pressure is one of the important factors that causes a variety of dynamic disasters.The self-developed triaxial permeability test system is employed to crush the sandstones.The influence of the total amount of permeating fluid extruded by confining pressure on the gravel pores is explored by the permeability tests of broken sandstones 5~10 mm in diameter under the three-dimensional stresses,and the permeability variations of the sample are obtained under different confining pressures and different sinking displacements.The result is as follows.Under different sinking displacements,the porosity of the sample decreases logarithmically with the increases of the confining pressure.Its permeability gradually decreases with the changes of the confining pressures,and their disparities are gradually reduced.Under the same confining pressure,with the increase of the sinking displacement,the porosity and permeability of the sample gradually approach a stable value,and the order of the permeability varies between 10-11~10-13 m 2;simultaneously,the connectivity between the pores is weakened,and the overall structure is moving towards stabilization.The non-Darcy flowβfactor grows nonlinearly with the increases of the sinking pressures;simultaneously,the orders of non-Darcy flowβfactor vary between 10 8~10 11 m-1,and the original grading of the sample changes obviously.The growing trend of the non-Darcy flowβfactor is affected by the numbers of active capillary and pore sizes;the reduction of capillary pore size will result in the fact that the permeation fluid relatively increases the contact area with the capillary wall.The test results will provide some references for the research of permeating flows in crushing rocks under controllable confining pressures.

关 键 词：三维应力 破碎砂岩 渗透特性 非Darcy流β因子 

分 类 号：TD315[矿业工程—矿井建设]