Swelling of Compacted Clay as Affected by Quantity of Water Intake and Soil Structure

摘要

Abstract The mathematical description of the water flux and swelling mechanism during wetting of unsaturated, compacted clay, is complex. The number of variables is greater than the number of available equations, and, additional relationships, theoretical or empirical, are required in order to assist in the development of a solvable framework. This paper aims at providing relevant relations based on a series of simple, one-dimensional swelling tests performed on a highly plastic, compacted clay, as well as advancing understanding of the wetting-flow-swelling mechanism. Linear relationships were observed between the percent swell and the quantity of water entering the specimens for a range of initial water contents, initial dry densities, gravity heads and vertical confining stresses. This result is upheld to a degree of saturation of approximately 85%, at which it is expected that air voids become occluded. The slopes of the linear relationships were observed to increase with increasing initial moisture content and dry density (counter-intuitively), and with decreasing gravity head and vertical stress. This observation is discussed in relation to the double porosity structure of compacted clay. The end of the linear relationship appears to coincide closely with the end of primary swelling. The linear relationships may be useful in development of additional equations for describing the water flux—swell process.