A model considering solid-fluid interactions stemming from capillarity and adsorption mechanisms in unsaturated expansive clays  

作　　者：Jian Li Chenggang Zhao Guoqing Cai Yanxin Guo 

机构地区：[1]School of Civil Engineering, Beijing Jiaotong University [2]College of Civil Engineering and Architecture, Guilin University of Technology

出　　处：《Chinese Science Bulletin》2014年第26期3314-3324,共11页

基　　金：supported by the National Natural Science Foundation of China (51278047);Guangxi Science Foundation (2012GXNSFGA060001)

摘　　要：Solid-fluid interactions in unsaturated expansive clays can be divided into capillarity and adsorption effects based on their physical mechanisms. Most constitutive models for unsaturated soils are proposed on the basis of the capillarity mechanism, ignoring the contributions of the adsorption effect to mechanical and hydraulic behaviors. For expansive clays, however, the adsorption effect which leads to more complex behavioral characteristics than that in low plasticity clays cannot be ignored. In the light of this, a new binary-medium model for unsaturated expansive clays is proposed, involving a consideration of the solid-fluid interactions stemming from the capillary and the adsorption mechanisms at the same time.Firstly, we assume that expansive clay is a mixture of two ideal parts, i.e. the ideal capillarity part and the ideal adsorption part, and then an ideal capillarity model and an ideal adsorption model, each of which is available for the corresponding ideal part, are established. Furthermore, a participation function is used to reflect the degrees of capillarity effect and adsorption effect. Finally, predictions are performed on the results of the consolidation tests and the cyclical controlled-suction tests published in literature.After comparing predicted results with test results, it is illustrated that the established model can quantitatively predict mechanical and hydraulic behaviors in expansive clays.Solid-fluid interactions in unsaturated expansive clays can be divided into capillarity and adsorption effects based on their physical mechanisms. Most consti- tutive models for unsaturated soils are proposed on the basis of the capillarity mechanism, ignoring the contributions of the adsorption effect to mechanical and hydraulic behaviors. For expansive clays, however, the adsorption effect which leads to more complex behavioral character- istics than that in low plasticity clays cannot be ignored. In the light of this, a new binary-medium model for unsatu- rated expansive clays is proposed, involving a consider- ation of the solid-fluid interactions stemming from the capillary and the adsorption mechanisms at the same time. Firstly, we assume that expansive clay is a mixture of two ideal parts, i.e. the ideal capillarity part and the ideal adsorption part, and then an ideal capillarity model and an ideal adsorption model, each of which is available for the corresponding ideal part, are established. Furthermore, a participation function is used to reflect the degrees of capillarity effect and adsorption effect. Finally, predictions are performed on the results of the consolidation tests and the cyclical controlled-suction tests published in literature. After comparing predicted results with test results, it is illustrated that the established model can quantitatively predict mechanical and hydraulic behaviors in expansive clays.

关 键 词：非饱和膨胀土 吸附机制 相互作用 毛细现象 e模型 毛细管模型 固结试验 行为特征 

分 类 号：TU411[建筑科学—岩土工程] TU443[建筑科学—土工工程]