The collapse mechanism in partly saturated soil

A study has been made of the metastable structure of partly saturated soilt that collapse when wetted under load. This has been done using the scanning electron microscope on air-dried specimens of collapsing soil representative of various types. These include aeolian sand from South Africa, loess from Europe, clay from America and a range of compacted soils. The nature of the intergranular contacts has been studied at magnifications up to 20,000. It is shown that a common basic collapse mechanism applies to the different types of soil ranging from sand to clay.