Evaluation of in-place wetting using soil suction measurements

An evaluation of water sources and extent of wetting at a collapsible soil site is presented. The field and laboratory data were collected after distress of an existing structure was observed. The underlying soils at the site were highly variable in fines content, density, and degree of saturation. Because of the high variability of soil properties, suction contours were developed for the site to evaluate the extent of soil wetting. A relationship between soil suction and basic soil parameters was developed for use in constructing these contours. The depth of wetting obtained using the suction contours was consistent with other data at the site, including quantity of water introduced and standard penetration test results. Laboratory collapse curves were used to estimate the settlement at the site for the depth of wetting inferred from the suction contours. The computed settlements, taking into consideration partial wetting effect, were consistent with observed settlements of the structure.