基于变截面孔隙模型描述岩土介质的渗透及持水特性  

Variable cross-sectional pore model to describe hydraulic conductivity and water retention behaviors of geotechnical materials

作　　者：张昭[1] 程靖轩 刘奉银[1] 齐吉琳[1,2] 柴军瑞 李会勇[4] ZHANG Zhao;CHENG Jing-xuan;LIU Feng-yin;QI Ji-lin;CHAI Jun-rui;LI Hui-yong(Institute of Geotechnical Engineering,Xi'an University of Technology,Xi'an 710048,China;College of Civil and Transportation Engineering,Beijing University of Civil Engineering and Architecture,Beijing 100044,China;State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China(Xi'an University of Technology),Xi'an 710048,China;Sinohydro Foundation Engineering Co.,Ltd.,Tianjin 301700,China)

机构地区：[1]西安理工大学岩土工程研究所,陕西西安710048 [2]北京建筑大学土木与交通工程学院,北京100044 [3]省部共建西北旱区生态水利国家重点实验室(西安理工大学),陕西西安710048 [4]中国水电基础局有限公司,天津301700

出　　处：《岩土工程学报》2020年第10期1807-1816,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(41877278,51679198);国家留学基金项目(201908610043);陕西省教育厅重点实验室科研计划项目(18JS071);西安理工大学省部共建西北旱区生态水利国家重点实验室项目(QNZX-2019-07,2019KJCXTD-12)。

摘　　要：为研究孔隙变截面特征对岩土介质渗透及持水特性的影响,先构建了圆柱形孔喉–大孔隙联合体组成的变截面孔隙模型。其次,假定孔径分布服从分形分布,基于构建的变截面孔隙模型推得岩土介质的饱和渗透系数函数、相对渗透系数函数及滞回持水曲线的理论表达式。最后,利用已有文献中4种砂岩、8种土的饱和–非饱和渗透试验以及3种土的减、增湿持水试验(含一种黏土的补充持水试验)结果分别验证了理论表达式在表征饱和渗透率与孔隙率关系、相对渗透系数与有效饱和度关系以及滞回持水特性时的有效性,通过计算饱和渗透率及相对渗透系数的预测值与其实测值之间的均方根偏差,发现理论表达式在描述4种砂岩和8种土的饱和–非饱和渗透特性时优于Kozeny-Carman公式和Assouline模型。To investigate the contribution of their non-uniform cross-section to hydraulic conductivity and water retention behaviours for geotechnical materials,the pores can be simplified as variable cross-sectional assembly of cylindrical macro-pores with pore throats.In addition,this variable cross-sectional pore model can provide theoretical expressions for both the saturated-relative hydraulic conductivity functions and the water retention curves based on a fractal pore size distribution.Finally,these theoretical expressions are validated against both the saturated-unsaturated permeability data for four sandstones and eight soils and the hysteretic water retention data(including the supplementary water retention tests on a clay)for three soils in the previous literatures.The results of RMSD between the predicted and the measured values of saturated permeability and relative hydraulic conductivity show that these new expressions are superior to Kozeny–Carman equation and Assouline model for describing the evolution of saturated permeability with porosity and the relation of relative hydraulic conductivity with effective degree of saturation.

关 键 词：岩土介质 渗透系数函数 持水曲线 变截面孔隙 有效饱和度 

分 类 号：TU441[建筑科学—岩土工程]