脱湿路径下考虑干湿循环和体变影响的膨胀土土水特征  

Soil water characteristics of expansive soil considering the effects of drying and wetting cycles and volume change under dehydration path

作　　者：方瑾瑾[1] 薛同兴 杨小林 于建新[1] 张军[1] 冯以鑫 FANG Jinjin;XUE Tongxing;YANG Xiaolin;YU Jianxin;ZHANG Jun;FENG Yixin(School of Civil Engineering,Henan Polytechnic University,Jiaozuo,Henan 454000,China;Infrastructure Department,Henan Polytechnic University,Jiaozhuo,Henan 454000,China)

机构地区：[1]河南理工大学土木工程学院,河南焦作454000 [2]河南理工大学基建处,河南焦作454000

出　　处：《岩石力学与工程学报》2022年第8期1671-1679,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(42107200);河南省科技攻关项目(212102310293);河南理工大学青年骨干教师培养计划项目(2022XQG-02)。

摘　　要：为了研究干湿循环和体积变化对膨胀土土水特征曲线的影响,利用改进的非饱和土真三轴仪,对经历不同干湿循环后的弱膨胀土进行脱湿试验,测得每级脱湿稳定后的质量含水率和孔隙比。试验结果表明:干湿循环次数越大,饱和后的孔隙比越大,而脱湿后的孔隙比越小。干湿循环后膨胀土的含水率和孔隙比随着吸力的增大而减小;在基质吸力的增大作用下,质量含水率-吸力关系曲线、饱和度-吸力关系曲线出现交叉现象,孔隙比-吸力关系曲线出现交叉聚拢现象;干湿循环次数越大,脱湿完成后膨胀土的体积含水率和饱和度越小,体现了干湿循环后膨胀土的土水特征与体变特性的耦合效应。以Fredlund-Xing模型为基础,构建以质量含水率表达的考虑干湿循环影响的SWCC方程,再建立考虑干湿循环影响的膨胀土的体变方程,最后得出以饱和度表达的考虑干湿循环和体积变化影响的SWCC方程,这3个模型均能够很好地描述不同干湿循环后膨胀土的质量含水率、孔隙比和饱和度的变化规律。A set of dehydration tests of weakly expansive soils experienced different drying and wetting cycles were carried out by using the improved true triaxial apparatus for unsaturated soil to investigate the influence of drying and wetting cycle and volume change on soil water characteristic curve of expansive soil,and the water content and void ratio after each stage of dehydration were measured.The results show that with the increase of drying and wetting cycle,the pore ratio increases after saturation and decreases after dehumidification.The water content and void ratio of expansive soils after drying and wetting decrease with an increase in suction.Under the increasing of matric suction,the curves of the water content and the degree saturation with suction appear cross phenomenon,and the void ratio and suction curves appear cross-convergence phenomenon.With the increase of drying and wetting cycle,the volumetric moisture content and degree of saturation of expansive soils after dehydration decrease,which reflects the coupling effect of soil water characteristics and volume change of expansive soils after drying and wetting cycles.Based on Fredlund-Xing model,a SWCC equation expressed by the water content considering the influence of drying and wetting cycle is constructed,and the volume change equation of expansive soils considering the influence of drying and wetting cycles is established.Finally,the SWCC equation expressed in degree of saturation considering the effects of drying and wetting cycles and volume change is obtained.These three models can well describe the change rules of the water content,the void ratio and the degree of saturation of expansive soils after different drying and wetting cycles.

关 键 词：土力学 脱湿 干湿循环 体积变化 土水特征 真三轴仪 

分 类 号：TU43[建筑科学—岩土工程]