*The ground water flow equation can be combined with the materi equations.
The solid will deform due to the ground water flow pressure gradient
and ground water flow pressure will change due to solid volume changes.
An example of a input file is given below
*

...

materi_velocity

materi_stress

groundflow_pressure

end_initia

...

groundflow_density...

groundflow_phreaticlevel...

...

type 0 -materi -groundflow

( solid material )

group_materi_elasti_young 0 ...

group_materi_memory -updated

( groundflow )

group_groundflow_capacity 0 ...

...

*The stresses as initialized by materi_stress are effective stresses.
Internally the program calculates with total stresses (effective stress + total pressure)
in the material equilibrium equation.
You can obtain the total stresses for postprocessing by means
of the post_calcul option.
*

*To account for the gravitational stresses,
use a density in the group_materi_density record.
Here is the saturated density of the groundwater-soil mixture
(mass of soil + water per unit volume of the soil-water mixture).
Also specify the gravitation in the force_gravity record and, if required,
also the force_gravity_time record to apply the gravitation slowly.
*