Static enthalpy equilibrium and the energetic stability of saturated granular systems (Version 2)

Instabilities and liquefaction phenomena in saturated sands are commonly described in terms of stress and strain, but the underlying energy balance between the granular framework and the pore water remains undefined. This study introduces a static enthalpy equilibrium as a physical condition governing the energetic stability of saturated granular systems. Equilibrium is expressed as the equality between the structural enthalpy released by the granular framework and the hydraulic work capacity of the pore water, providing a single energetic criterion that unifies spontaneous and induced liquefaction within one framework. The condition applies to all saturated granular systems where pore water forms a continuous phase, and the mechanical behaviour is governed by particle contacts. The formulation offers a concise energetic basis for interpreting stability, metastability and collapse in saturated soils.