Assessment of water retention behaviour in compacted fills

This paper presents the water retention behaviour of a fill used to build a flood protection embankment in Scotland. The water retention curve was obtained in the laboratory using three different techniques: high-range psychrometer, contact filter paper, and by interpreting mercury intrusion porosimetry data, to cover a relatively wide suction range. The behaviour of the fill has been studied further in a physical model embankment constructed in the laboratory inside an environmental chamber that allowed full control of the environmental conditions. The well-instrumented scaled embankment was subjected to controlled cycles of wetting and drying, and the evolution of the main variables of the problem (i.e. water content and soil suction) was monitored. The assessment of the water retention behaviour of the fill in ‘as-constructed' state under variable environmental conditions has been made possible by means of tensiometers and ThetaProbe water content probes strategically located in the compacted soil. A good agreement was found between the ‘as-compacted' water retention behaviour obtained in the laboratory and that of the ‘as-constructed' in the environmental chamber.