Small-sliding contact between coupled pore pressure-displacement elements

This test verifies that the initial pore fluid pressure procedure works with a contact pair. All nodes in the model are initialized to a pore pressure of −50.0.

The consolidation test verifies that the contact pair procedure works properly with the transient soils consolidation procedure. The test is essentially a one-dimensional problem where two surfaces are brought together at a constant rate, as shown in Figure 2.

Point A in the figure corresponds to nodes 1, 5, and 2; point B corresponds to nodes 4, 7, and 3; and so on. As points C and B move toward each other, fluid rushes out through points A and D. This gives rise to a compressive stress state in the soil segments AB and CD. A pore pressure field develops to balance out the effective stresses.

The steady-state test verifies that the contact pair procedure works properly with soil consolidation procedure. The problem is the same one that is modeled in the consolidation test. There is zero stress and zero pore pressure at steady state; therefore, it is necessary to use solution controls to avoid convergence difficulties as a result of the fact that both the time average force and the force residuals are practically zero.

The interference test verifies that a combination of interface overclosure and pore pressure gradient is handled correctly by the contact pair procedure. The test is essentially a one-dimensional problem where two surfaces start with an interference fit and a pore pressure gradient exists across the two bodies. The steady-state equilibrium is sought.