Mohr–Coulomb theory

Mohr–Coulomb theory predicts material failure when shear stress reaches a limit that increases linearly with normal stress. Its strength is governed by cohesion and the friction angle.

Cohesion: The component of shear strength independent of normal stress in a material-strength model. It sets the failure envelope’s shear-strength intercept when normal stress is zero.
Normal stress: The component of stress acting perpendicular to a surface. The criterion makes allowable shear stress depend on the normal stress across a plane.
Slope stability: The assessment of whether a natural or engineered slope will resist sliding or collapse. The criterion estimates shear resistance along potential slip surfaces in soil and rock.
Tresca yield criterion: A yield criterion in which yielding begins when maximum shear stress reaches a material-specific limit. Unlike Mohr–Coulomb, Tresca predicts a shear-strength limit independent of normal stress.
Anisotropy: The dependence of a material’s properties on direction. Layered or foliated materials can have different strengths on different planes, contrary to a single envelope.
Angle of internal friction: A material parameter describing how shear strength increases with compressive normal stress. Its tangent gives the slope of the linear failure envelope in shear-normal stress space.
Shear stress: The component of stress acting parallel to a surface. Failure is predicted when this component reaches the strength specified by the criterion.
Bearing capacity: The maximum load a foundation soil can support before excessive deformation or failure. Classical bearing-capacity equations use Mohr–Coulomb soil strength parameters.
von Mises yield criterion: A ductile-metal yield criterion based on the distortional energy of the stress state. It is pressure-insensitive, unlike the normal-stress-dependent strength in Mohr–Coulomb theory.
Strain softening: A reduction in material strength as deformation continues beyond its peak resistance. A fixed Mohr–Coulomb envelope does not by itself capture post-peak strength loss.

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