WHEELER S. J.

A novel image based technique has been developed to measure strains of soil specimens subjected to wetting-drying by using vapor equilibrium with closed-loop ventilation. A digital SLR camera, fitted with a macro telephoto lens, and an advanced photo system type-C (APS-C) sensor have been used to take images of specimens during wetting-drying....

The paper discusses some aspects of the Barcelona Basic Model (BBM), which is one of the most widely used elasto-plastic models for unsaturated soils. In addition to modelling those unsaturated soils where the collapse potential increases with increasing net stress (as envisaged by the original authors), the BBM can also be used to model soils...

An improved relationship for the variation of degree of saturation in an unsaturated soil is presented, incorporating the influence of changes of void ratio. When combined with an elasto-plastic stress-strain model, this is able to represent irreversible changes of degree of saturation and changes of degree of saturation caused by shearing....

The popularity of the Barcelona basic model (BBM) has grown steadily since its publication in 1990, due to its ability to capture key aspects of unsaturated soil behaviour. Nevertheless, the BBM is still rarely employed by practitioners, partly because of the absence of simple and objective methods for selecting parameter values from laboratory...

A 2D lattice approach to describe hydraulic fracturing is presented. The interaction of fluid pressure and mechanical response is described by Biot's theory. The lattice model is applied to the analysis of a thick-walled cylinder, for which an analytical solution for the elastic response is derived. The numerical results obtained with the...

This paper investigates the 'initial' and 'evolving' mechanical anisotropy of a compacted unsaturated soil. A wide campaign of triaxial compression and extension tests, involving different stress and suction paths, has been performed on both isotropically and anisotropically compacted samples of unsaturated Speswhite kaolin. The first objective...

Transport of corrosion products into pores and cracks in concrete must be considered when predicting corrosion induced cracking in reinforced concrete structures, since this transport significantly delays the onset of cracking and spalling by reducing the amount of radial displacement imposed on the concrete at the steel/concrete interface. We...

Spatial variability of material properties is inherent in both natural soil deposits and earth structures, yet it is often ignored during geotechnical design. With the objective of developing novel methods for assessing the effects of soil variability on groundwater flow, this study presents a stochastic finite element model of seepage through...

Seven teams took part in a benchmarking exercise on selection of parameter values for the Barcelona Basic Model (BBM) from experimental data on an unsaturated soil. All teams were provided with experimental results from 9 tests performed on a compacted soil in order to determine values for the ten BBM soil constants and an initial value for the...