: The yield surface shifts its position in stress space, often used to model the Bauschinger effect in cyclic loading.
Plasticity theory replaces real, particulate materials (like sand or clay) with an idealised continuum that behaves elastically until a specific stress limit is reached. Key elements of this theory include:
: The yield surface expands uniformly, representing an increase in strength. fundamentals of plasticity in geomechanics pdf
: Traditionally used for metals but adapted for certain cohesive soils like undrained clay.
The study of plasticity in geomechanics is essential for understanding how soils and rocks behave under extreme stress, particularly in predicting failure and permanent deformation in civil and petroleum engineering. Unlike linear elasticity, which models reversible deformation, plasticity focuses on the irreversible "flow" of geomaterials once they reach a critical state. Core Concepts of Plasticity in Geomechanics : The yield surface shifts its position in
: Widely used for soils and rocks, based on shear stress, cohesion, and internal friction.
: This describes the direction and relative magnitude of plastic strain increments once yielding occurs. : Traditionally used for metals but adapted for
: These rules describe how the yield surface evolves as the material deforms.
: Used when a material's volume change (dilatancy) does not follow the yield surface, which is a hallmark of many granular soils.
: This is a mathematical boundary—often represented as a surface in stress space—that defines the threshold where elastic behavior ends and plastic deformation begins. Common criteria include: