Ru Coefficient
If the Groundwater Method = Ru Coefficient, then a Ru Coefficient can be specified in order to define pore pressure. The Ru coefficient simply models the pore pressure as a fraction of the vertical earth pressure for each column in the sliding mass.
Ru Value
A Ru coefficient between 0 and 1 must be specified. The Ru coefficient used in Slide3 is the one widely used, which simply models the pore pressure as a fraction of the vertical earth pressure.
The calculation of the vertical earth pressure includes the weight of ponded water if a material is submerged underwater. However, the vertical pressure does NOT include forces due to external loads (e.g. line, distributed or seismic loads).
If one soil type has regions of differing Ru values, then a different material will have to be defined for each different Ru value. Appropriate boundaries will have to be added to the model, in order to define the different soil regions.