Estimating the compression behaviour of metal-rich clays via a Disturbed State Concept (DSC) model

Many studies have been made on the compression behaviour of clay exposed to metal-rich liquids (metal-rich clay) because metal contamination of clay is found worldwide and increasingly poses as an environmental risk. However, the study on predicting the compression behaviour of contaminated clay with various metal concentrations is very limited. In this paper, a general compression model of the metal-rich clays is proposed based on a general Disturbed State Concept (DSC) compression model. A simplified form of the general model is proposed, and validated based on the compression behaviour of metal-rich clays with various metal concentrations in the pore liquid. The following conclusions are obtained in this study: (1) the simplified DSC compression model provides a practical means to estimate the compression behaviour of metal-rich clays, and it can quantify the influence of various metals on the compression behaviour of clay; (2) in the simplified DSC compression model, the influence of metal exposure can be reliably described by one parameter b, which is very useful for geotechnical engineering practice; (3) the ratio of the bulk modulus for metal-rich clays over that of the parent clay (i.e., without metal contamination) is found to be dependent on parameter b only, and that value is usually greater than 1. The highest value for the bulk modulus ratio found in this study is 2.2 for a sea water-exposed clay; and (4) two empirical equations for estimating parameter b are established. Hence the proposed model can be used for engineering estimation.