Effect of contact angle hysteresis on measuring matric suction in unsaturated sandy soil

Abstract

The contact angle plays an important role in matric suction of unsaturated soils, but few studies consider the effect of contact angle hysteresis on matric suction. In this paper, taking sandy soil as an example, the influence of contact angle hysteresis on the suction of unsaturated soil matric is studied by soil particle model calculation and experimental method. The results show under the same water content condition, the smaller the contact angle is, the larger the matric suction is and the phenomenon of water repellency appears. Under the low water content of unsaturated soil, when the contact angle is less than 90°, it will also produce water repulsion phenomenon, which is different from the hydrophilic characteristics of the contact angle is less than 90° in the capillary law. When the water content is the same, with the increase of contact angle, matric suction will decrease. With the increase of water content, matric suction is not affected by soil contact angle. In the process of dehumidification, the apparent contact angle of the sandy soil with the same water content less than receding contact Angle; there is a difference in matric suction between continuous measurement method and discontinuous measurement method, and continuous measurement’ matric suction greater than discontinuous measurement’ matric suction. This study provides some theoretical basis and reference for the study of matric suction of unsaturated soil.

Keywords:

• Unsaturated soil
• matric suction
• soil-water characteristic curve (SWCC)
• contact angle hysteresis
• sandy soil

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available on request from the corresponding author, Song Yang and Xiaoshun Li.

Additional information

Funding

This research is jointly supported by the Natural Science Foundation of China [grant numbers 41867038 and 41662021], and Open Fund of ‘Technical Innovation Team for land allocation and ecological consolidation in Southwest diversified regions’ of the Ministry of Natural Resources of China [grant number YNTD2018KF05], Major projects of water conservancy science and technology in Yunnan Province, China [Grant No. 2023BG204001]. Major application research project federation of social sciences of Jiangsu Province,China [23WTA-001]. For help with the collection data and revise this article, we would like to thanks Professor Jianxin Yu of Yunnan Agricultural University and Associate professor Yongjun Yang of China University of Mining and Technology.