摘要
The hysteresis of saturation-capillary pressure （S-p） relations was investigated in a fine sandy medium under consecutive drainage-imbibition cycles, which resulted from scheduled water level fluctuations. A drainage-imbibition cycle starts with a drainage process and ends with an imbibition process in sequence. The saturation and capillary pressure were measured online with time domain reflectometry （TDR） probes and T5 tensiometers, respectively. Results show that the relation between the degree of hysteresis and the number of the drainage-imbibition cycles is not obvious. However, the degree decreases with the increase of the initial water saturation of the imbibition processes in these drainage-imbibition cycles. The air-entry pressure of a sandy medium is also found to be constant, which is independent of the drainage-imbibition cycles and the initial water saturation of the drainage process. In all the imbibition processes, parameter a of the van Genuchten （VG） model decreases with the increase of the initial water saturation, which corresponds positively to the magnitude of the hysteresis.
The hysteresis of saturation-capillary pressure(S-p) relations was investigated in a fine sandy medium under consecutive drainage-imbibition cycles,which resulted from scheduled water level fluctuations.A drainage-imbibition cycle starts with a drainage process and ends with an imbibition process in sequence.The saturation and capillary pressure were measured online with time domain reflectometry(TDR) probes and T5 tensiometers,respectively.Results show that the relation between the degree of hysteresis and the number of the drainage-imbibition cycles is not obvious.However,the degree decreases with the increase of the initial water saturation of the imbibition processes in these drainage-imbibition cycles.The air-entry pressure of a sandy medium is also found to be constant,which is independent of the drainage-imbibition cycles and the initial water saturation of the drainage process.In all the imbibition processes,parameter α of the van Genuchten(VG) model decreases with the increase of the initial water saturation,which corresponds positively to the magnitude of the hysteresis.
作者
XIE Xiao-xi
LI Yan
XIA Bei-cheng
XU Li-min
SU Yu
GU Qing-bao
谢小茜;李雁;夏北成;许丽敏;苏钰;谷庆宝(School of Environmental Science and Engineering,Sun Yat-sen University,Guangzhou 510275,China;School of Marine Sciences,Sun Yat-sen University,Guangzhou 510275,China;Guangdong Huizhou Environmental Protection Agency,Huizhou 516001,China;Guangdong Environmental Protection Engineering Research and Institute,Guangzhou 510635,China;Chinese Research Academy of Environmental Sciences,Beijing 100012,China)
基金
Project(41072182) supported by the National Natural Science Foundation of China
Project(2010Z1-E101) supported by the Science and Technology Program of Guangzhou City,China
Project(200809095) supported by the Special Funds for Environmental Nonprofit Research,China
Project(8151027501000008) supported by the Natural Science Foundation of Guangdong Province,China
