How can I apply water pressure to a liner in RS2?

By default, one can think of RS2 as modeling the liner as being free draining, where water pressure does not build up behind the liner. 

Applying a water pressure to a liner with groundwater is a bit complicated.  You actually need to use a composite liner with a joint element or structural element between the soil and the liner.  You can apply the water pressure through the joint. 

Two sample files are attached to this article, which include a composite liner with a joint that gets pressurized by the groundwater pore pressure.  The axial force increases by about 0.2 MN in Stage 3, which is about right for a thin walled cylinder subjected to a hydrostatic pressure of 0.1 MPa (10m*10kN/m3).  N=PR, where P is the water pressure and R is the tunnel radius (2m). 

The first file (Pressurized Liner.fez) uses a groundwater analysis to compute the pore pressure.  The second file (Pressurized Final Liner piezos.fez) uses piezo lines.

Composite liners are also discussed in Tutorial 15.

Phase2-linerwaterpressure_1.PNGPhase2-linerwaterpressure_2.PNG

Pressurized liner examples using groundwater analysis (left) and piezo lines (right)