Abstract
Volume change behaviour of expansive clays has been one of the leading causes of damage to civil infrastructures worldwide. Contributing factors that lead to failures relate to changes in water content within the soil. Variations of water content can vary significantly based on an area’s climate regime. Trinidad has two seasons, the dry season (January to June) and the wet season (July to December). This variation leads to volume changes of expansive clay, where they exist mainly within the central and south regions of Trinidad. These areas are densely populated by residential and commercial buildings, which can be susceptible to damages from unsaturated expansive clays. The Soil Water Characteristic Curve (SWCC) for expansive clays is critical to estimate their unsaturated properties for the analysis of water flow movement. This study investigates the SWCCs for two expansive clay soil types in Trinidad. A WP4-T (Water Potential Measurement) is used to measure soil suction. The shrinkage curve (SC) test is conducted to consider the volume change of soil. The Fredlund and Xing (1994) SWCC equation and Fredlund and Zhang (2013) SC equation are used to fit the measured data. The SWCCs in terms of gravimetric and volumetric water contents and degree of saturation are compared. It is found that the normalised degree of saturation SWCC can provide a better display of the SWCC and estimation of the air-entry value.
Highlights
Expansive soils are widely distributed in many arid and semi-arid areas throughout the world
Several researchers recently recognised that the volume change in expansive soils has a considerable influence on the measured Soil Water Characteristics Curve (SWCC) represented in terms of volumetric water content or degree of saturation
It is noted that the initial gravimetric water contents are near 79% and 55% for Ecclesville clay and Brasso clay, respectively
Summary
Expansive soils are widely distributed in many arid and semi-arid areas throughout the world. Expansive clays undergo considerable volume change with changes in soil suction. Several researchers recently recognised that the volume change in expansive soils has a considerable influence on the measured SWCC represented in terms of volumetric water content or degree of saturation. This paper investigates the SWCC for two expansive clay soil types in Trinidad. A WP4-T (Water Potential Measurement) was used to measure soil suction and the corresponding gravimetric water content was obtained. The shrinkage curve (SC) test was conducted to obtain the relationship between the gravimetric water content and the instantaneous void of the soil. The Fredlund and Xing [3] SWCC equation and Fredlund and Zhang [11] SC equation are used to obtain the SWCCs in terms of gravimetric and volumetric water contents, and degree of saturation
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