Instability Phenomena in Geomechanics- A Review from a Multi-Physics Point of View
In situ and laboratory evidence of instabilities, strain localization, bifurcation in landslides, borehole instability in nuclear waste disposal, drying cracking are dis-cussed considering the multi-physical nature of the complex phenomena involved. The multi-physics include: the effect of heat generated during pre-cursor creep in development of landslides, as well as the effect of geo-chemical reactions, the effect of heat on inducing possible failure through pressurization of pore water, the effect of evaporation induced suction and air entry during drying and subsequent cracking of soils. The phenomena illustrated with specific natural or engineered events are interpreted as scenarios of processes either simultaneous or sequential, that are either coupled, or rely on accumulation of dissipative variables. As pointed out by Terzaghi, the causes of the instabilities are often long-term phenomena rather than single events, such as major rainfalls, which are contributing factors. The need for a proper description of these long-term phenomena and their coupling to variable mechanical properties of soil and rock is emphasized.
