MIXTURE THEORY CHARACTERIZATION AND MODELING OF SOIL MIXTURES

摘要

Soil mixtures such as silty-sands, clayey-sands and silty-clays are more commonly found in nature and in earth constructions than pure clays, sands and silts. However, the behavior of soil mixtures is not well understood since soil mechanics has concentrated mainly on pure soils. There is much less data on soil mixtures than pure soils, and the available data often provide inconsistent evidence on the behavior of soil mixtures. The conflicting experimental data on the behavior of soil mixtures is particularly prevalent for liquefiable soils. For instance, experimental results indicate different effects of non-plastic fines content on sands including no change, increase, and reduction of liquefaction resistance with increasing fines content. The conflicting experimental evidence on the behavior of soil mixtures can be attributed mainly to the lack of a unified theoretical framework for characterizing and modeling soil mixtures. There is a need to improve the fundamental understanding of how the constituents of a soil mixture combine and how their properties and behavior influence the overall response of the soil mixture. The paper presents a method which can be used for modeling soil mixtures and possibly for optimizing the properties of soil mixtures for specific applications. A unified framework is proposed for the mechanics of soil mixtures based on mixture theory, which is a well-established framework in continuum mechanics and has been used in many science and engineering fields. A modified version of mixture theory is presented and its potential application to soil mixtures is shown. In order to illustrate its value, the proposed mixture model is used to resolve conflicting experimental results on liquefaction potential of silty sand.