Rocks

In the subnode you define the properties for modeling materials with failure criteria representative of rocks. This material model can be used together with Linear Elastic Material and Nonlinear Elastic Material. It is available with the Geomechanics Module. The subnode is available for 3D, 2D, and 2D axisymmetry.

The failure criteria are described in the theory section:

Select the — or . The default values for the material parameters are taken . For choices, enter other values or expressions.

The defaults for the σcs, m, and s are taken .

The defaults for the σcs, GSI, D, and mi are taken .

If required, select either or .

When is selected from the list, enter a value or expression for the σt. Use this to constrain the rock model with an extra yield surface, which limits the maximum principal tensile stress.

	See also Tension Cutoff in the Structural Mechanics Theory chapter.

It is possible to specify the maximum number of iterations and the relative tolerance used to solve the plastic flow rule. Enter the following settings:

•

. To determine the maximum number of iteration in the Newton loop when solving the local plasticity equations. The default value is 25 iterations.

•

. To check the convergence of the local plasticity equations based on the step size in the Newton loop. The final tolerance is computed based on the current solution of the local variable and the entered value. The default value is 1e-6.

To display this section, click the button (

) and select in the dialog box.

	See also Numerical Solution of the Elastoplastic Conditions in the Structural Mechanics Theory chapter.

Physics tab with or node selected in the model tree: