三轴剪切应力条件下非饱和原状黄土的土水特征  

Soil-water characteristics of unsaturated undisturbed loess under triaxial shear stress condition

作　　者：褚峰 罗静波 邵生俊 Chu Feng;Luo Jingbo;Shao Shengjun(School of Urban Planning and Municipal Engineering,Xi’an Polytechnic University,Xi’an 710048,China;China Jikan Research Institute of Engineering Investigations and Design,Co,Ltd,Xi’an 710043,China)

机构地区：[1]西安工程大学城市规划与市政工程学院,西安710048 [2]机械工业勘察设计研究院有限公司,西安710043

出　　处：《工程勘察》2020年第1期7-13,共7页Geotechnical Investigation & Surveying

基　　金：国家自然科学基金资助项目(No41272320);西安工程大学博士科研启动基金项目(BS1705);陕西省教育厅项目(18JK0332)

摘　　要：采用非饱和土三轴仪,对不同含水率的西安非饱和原状黄土在不同静围压下进行了常含水率三轴剪切试验。用轴平移技术量测了无应力和有应力条件下黄土的基质吸力,分析了不同含水率、不同静围压条件下偏应力变化对基质吸力的影响规律,提出了常含水率三轴剪切条件下非饱和原状黄土土水特征曲线的表达式。研究结果表明:含水率一定时,偏应力变化对非饱和原状黄土基质吸力的影响与含水率的大小有关,对于不同的净围压,含水率小于等于23%时,基质吸力随偏应力的增大先基本不变后增大;含水率大于等于28%时,基质吸力随偏应力的增大先基本不变后减小;不同的含水率与不同的净围压条件下,偏应力变化对基质吸力的影响较小。应力对原状黄土基质吸力的影响规律与应力路径有关。在偏应力变化(含水率一定)及含水率变化(干密度一定)所对应的2种饱和度变化条件下,2类黄土的基质吸力与饱和度关系具有不同的变化特性,含水率变化对应的饱和度变化明显比偏应力变化对应的饱和度变化对基质吸力的影响要大。净围压小于等于400kPa时,偏应力变化对饱和度与基质吸力关系的影响皆较大,对含水率与基质吸力关系的影响皆较小。不同静围压及偏应力作用下,原状黄土的土水特征皆可用无应力条件下呈对数函数的含水率与基质吸力关系来近似地描述。The triaxial shear tests at constant moisture content on unsaturated undisturbed loess in Xi’an under different moisture contents and static confining pressure are conducted using triaxial apparatus for unsaturated soils.Matric suction is measured with pressure and without pressure.The influences of deviator stress on matric suction are analyzed under different moisture content and confining pressure.The formula of soil-water characteristics of unsaturated undisturbed loess is obtained to determine the matric suction of triaxial shear at constant moisture content.Experimental results show that the influence of deviator stress on matrix suction is related to moisture content.For different confining pressure,the matric suction is stable firstly and then increase with increase of deviator stress when moisture content is smaller than 23%;the matric suction is stable firstly and then decrease with increase of deviator stress when moisture content is equal or greater than 28%;The influence of deviator stress on matric suction is small under different moisture contents and confining pressures.The influence of applied stress on matric suction is related to the stress path.The relation between matric suction and saturation related to deviator stress is different from that related to moisture content.The influence of saturation related to deviator stress on matric suction is much smaller than that related to moisture content.When confining pressure is equal to or smaller than 400kPa,deviator stress has relatively great influence on the relation between saturation and matric suction,and it has negligible influence on the relation between moisture content and matric suction.The soil-water characteristics of undisturbed loess under the action of different confining pressure and deviator stress can be illustrated approximately by the logarithm function relation between moisture content and matric suction without stress applied.

关 键 词：非饱和原状黄土 基质吸力 饱和度 常含水率各向均等试验 净围压 

分 类 号：TU411[建筑科学—岩土工程]