Oxford University
Civil Engineering
Department of Engineering Science
Unsaturated and Gassy Soils
Many soils are unsaturated, with the void spaces occupied by a mixture of liquid (typically water) and gas (typically air or methane). These unsaturated soils occur in both the onshore environment, in the form of compacted fills and natural soils above the water table, and in the offshore environment, where gassy soils result from thermogenic or biogenic formation of natural gases within seabed sediments. A distinction can be drawn between those cases where the gas is held in isolated voids and the pore water pressure is positive, and those where the gas voids are connected through the soil and the pore water is under suction. Equipment available for testing such soils includes specialised triaxial and oedometer cells, with facilities to separate gas and water volume changes and to control pore water and pore air pressure differences on the sample boundaries. Current and recent projects in this category include:
EPSRC: CONSOLIDATION OF GASSY SOILS;
Airflow through unsaturated soils;
Cyclic behaviour of gassy seabed soils; and
The effect of gas production on the consolidation of soft soils
These research programmes and have been carried out by Gilliane Sills' group, based in the Jenkin Building, where research is also conducted on soft soils and seabed soils.
