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🚧 Under development

This section of the documentation is currently under development. More detailed content and model descriptions will be added soon.

Mechanical models describe the stress-strain behaviour of soils and are a core component of numerical geotechnical analysis. In numgeo, these models are responsible for updating the (effective) stress at time \(t = t_0 + \Delta t\), based on the imposed strain increment \(\Delta \boldsymbol{\varepsilon}\) and the internal state of the material.

In its simplest form, the stress at the current time step is computed as:

\[ \boldsymbol{\sigma}^t = \boldsymbol{\sigma}^{t_0} + \Delta \boldsymbol{\sigma}, \quad \text{with} \quad \Delta \boldsymbol{\sigma} = \Delta \boldsymbol{\sigma}(\Delta \boldsymbol{\varepsilon}) \]

However, many models incorporate additional dependencies on:

  • Void ratio \(e\)
  • Current stress state \(\boldsymbol{\sigma}\)
  • Degree of saturation \(S\)
  • Internal state variables (e.g., plastic strains, fabric tensors, accumulated cycles)

These models enable the simulation of non-linear, inelastic, and path-dependent soil behaviour.

Available Mechanical Models in numgeo

Model Superposition

In addition to stand-alone constitutive models, numgeo supports the superposition of mechanical responses by adding:

  • Viscous stress components, via:

  • Additional elastic contributions, via:

    • Linear Elasticity