等向应力条件下原状Q_3黄土的渗气特性研究  

Gas permeability of intact Q_3 loess under isotropic stresses

作　　者：陈存礼[1,2] 张登飞[1,2] 张洁[3] 陈惠[1] 杨帆[1] 吴康[1] CHEN Cun-li ZHANG Deng-fei ZHANG Jie CHEN Hui YANG Fan WU Kangl(Institute of Geoteehnieal Engineering, Xi＇an University of Technology, Shaanxi Province, Xi＇an 710048, China Shaanxi Provincial Key Laboratory of Loess Mechanics and Engineering, Xi＇an University of Technology, Xi＇an 710048, China Beijing Leading Sottware Co., Ltd., Beijing 100044, 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]西安理工大学陕西省黄土力学与工程重点实验室,陕西西安710048 [3]北京理正软件股份有限公司,北京100044

出　　处：《岩土工程学报》2017年第2期287-294,共8页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(50878183);陕西省教育厅省级重点实验室重点科研项目(14JS063);西安理工大学博士创新基金项目(310-252071509)

摘　　要：用改装的三轴渗气仪,在不同等向应力条件下对不同含水率的原状Q_3黄土进行渗气试验,分析了含水率、体积含气率及应力对渗气系数的影响,提出了直接及间接地反映含水率与应力变化对渗气系数影响的3种类型渗气函数。研究结果表明:应力对渗气系数与含水率及体积含气率关系皆有明显的影响,增湿时含水率及体积含气率对渗气系数的影响比减湿时稍大;应力变化(含水率不变)和含水率变化(应力不变)时渗气系数与体积含气率的关系不同。不同应力条件下相对渗气系数与相对体积含气率关系,渗气系数与修正体积含气率关系皆可分别用唯一的幂函数描述;不同含水率下渗气系数与规格化应力关系皆可用指数函数描述,且仅一个参数随含水率而变化。用3种类型的渗气函数皆可较好预测含水率及应力变化时的渗气系数,而其中无需引入力水耦合作用引起孔隙比变化的指数型渗气函数更便于工程应用。The tests are performed to study the gas permeability of unsaturated intact Q_3 loess with various water contents under different isotropic stresses using the improved triaxial gas permeability equipment. The influences of water content, volumetric gas content and stress on coefficients of gas permeability are analyzed. Three gas permeability functions are proposed to directly and indirectly reflect the effects of change in water contents and stresses on coefficients of gas permeability. The results show that the stress remarkably affects the coefficient of gas permeability as functions of both water content and volumetric gas content. The water content and volumetric gas content slightly have higher influence on the coefficient of gas permeability during wetting than drying. The relationships between coefficient of gas permeability and volumetric gas content at the same water content but different stresses were different from that at the same stress but different water contents. The relative coefficient of gas permeability versus relative volumetric gas content, coefficient of gas permeability versus modified volumetric gas content for different stresses all can be respectively described by the unique power function. The relationships between coefficient of gas permeability and normalized stress for different water contents can be expressed by the exponential function, in which only one of parameters changes with moisture content. The proposed three functions of gas permeability can well predict the coefficient of gas permeability as water content and stress change. The exponential function of gas permeability which needs not to introduce the change in void ratio caused by hydro-mechanical coupling is more convenient for engineering application.

关 键 词：原状Q3黄土 渗气系数 等向应力 含水率 体积含气率 

分 类 号：TU47[建筑科学—结构工程]