2019 Volume 7 Issue 2 Pages 250-255
Foundations on expansive soils pose a unique challenge to geotechnical engineers. Oftentimes they cost more to design and construct than foundations on ordinary soils. Free-field heave is the fundamental parameter on which foundation heave is calculated. A method for prediction of free-field heave using oedometer test data was outlined in Nelson and Miller (1992). A refinement of that method is presented in Nelson et al. (2006). To determine free-field heave, it is necessary to have a measured value of percent swell from a consolidation-swell (CS) test and the swelling pressure, σ'cv, measured in a constant volume (CV) test. Only the CS test is commonly conducted in geotechnical engineering practice. Therefore, it is convenient to have a relationship between the swelling pressure, σ'cs, measured in the CS test and σ'cv, so that heave prediction can be determined from only a single test. Several investigators have proposed relationships between σ'cv and σ'cs (Edil and Alanazy, 1992; Reichler, 1997; Bonner, 1998; Thompson et al., 2006; Nelson et al., 2006 and 2012). Nelson and Chao (2014) proposed a relationship between σ'cv and σ'cs based on the experimental results of expansive soil behavior and facilitated the heave prediction from a single oedometer test for each soil. Their method used the parameter "m" which relies on specific soil property. This paper further investigated the change of parameter "m" for various soil samples. The soil samples used in this study were obtained from two different locations in Myanmar and Thailand. Bentonite and sand mixture was also tested in this study for comparison purposes. Furthermore, the relationship between the "m" parameter and the degree of saturation of the soil samples were evaluated in this study. It was concluded that the linear trendline determined by Nelson and Chao (2014) provides the most simple and accurate equation for determination of the m value and the m value decreases as the degree of saturation of the soil increases.
