Chemistry: An essential key to understanding high-sensitivity and quick clays and to addressing landslide risk

Abstract

The property of silty-clay to clayey-silt quick clays, whereby apparently solid soil transforms to the liquid state when subjected to sufficient stress, derives from chemical factors: mineralogy (low activity); depositional environment (marine-to-brackish conditions causing flocculation and high water content); and post-depositional chemical changes (development of cementation and displacement of marine-to-brackish water by infiltrating rainwater). The stability of slopes developed by river incision is affected (negatively) by physical factors (drainage and fluctuating water tables) and chemical weathering reactions that have led to weak, fissured, blocky, nodular structures. Immediate causes of quick clay landslides are commonly the physical factors of: river erosion; high water contents in the fissured slopes; and human actions. Regardless, the characteristics of the resulting landslides are primarily determined by the chemical factors.