FLAC3D Theory and Background • Constitutive Models

# Null Model

A null material is used to represent material that is removed or excavated from the model. The stresses within a null zone are automatically set to zero:

(1)$\sigma_{ij}^N = 0$

The null material may be changed to a different material model at a later stage of the simulation. In this way, backfilling an excavation can be simulated, for example.