Unsaturated soils gain strength from capillary water suction. When they become saturated they can lose that strength, collapse, or generate huge swelling pressures. This guide explains the simple physics behind these important geotechnical behaviours.

Learn how physical and chemical weathering convert rock into residual soil and saprolite. Understand the gradual transition from soil to rock, the risks of floating boulders, and practical implications for site investigations and foundation design.