Finite-sliding contact between coupled pore pressure-displacement elements

Step 1, transient:

A downward pressure of 100 is applied on top of the smaller block. For the two- and three-dimensional tests a pore fluid volume flux of 3 × 10⁻⁴ is applied into the smaller block through its upper surface (area is two units). To create a constant flux through the contact interface, a pore fluid volume flux of 1 × 10⁻⁴ is applied out of the larger block lower surface (area is six units). Results should be symmetric about an axis that is parallel to the line joining the centers of the two blocks, and the total pore fluid volume flux through the contact interface should be 6 × 10⁻⁴.

For the axisymmetric tests a pore fluid volume flux of 1 × 10⁻⁴ is applied into the smaller block through its outer surface (area is 12$\pi$), and a pore fluid volume flux of 1 × 10⁻⁴ is applied out of the larger block inner surface (area is 12$\pi$). The total pore fluid volume flux through the contact interface should be 3.76 × 10⁻³.

Step 2, transient:

The top block is made to slide horizontally (1.5 units) over the bottom block. The total pore fluid volume flux through the contact interface should remain 6 × 10⁻⁴ in the two- and three-dimensional tests and 3.76 × 10⁻³ in the axisymmetric cases.

A downward pressure of 10.0 is applied on top of the upper block. The pore pressure is fixed and equal to 2.0 on the top surface of the upper block. The pore pressure on the bottom surface of the lower block is fixed and equal to 1.0. A coupled pore pressure analysis is conducted, and the pressure on the contact interface should be 1.5 for the two- and three-dimensional tests and 1.375 for the axisymmetric case.