Seepage Analysis (Steady State)-Slurry Trench

Question

I can perform a steady state seepage analysis by defining a non porous element (plate) on a low permeability soil. But If I define non poros element as a lower permeability soil layer (solid), plaxis does not perform the analysis. How can I solve this problem? And which one is better? Defining the slurry trench as plate or solid?

Micha van der Sloot · Answer

Hi, 
 I am not sure what the problem is with your model why it cannot calculate. You can define the solid elements as non-porous so no water will pass through it. 
 There are a few pointers: 
 
 check your hydraulic conductivity. When the ratio of the highest an lowest permeability values becomes larger that 100,000 (1E5), the matrix for the flow calculation does not smoothly converge in all cases. So limiting this ratio, or switch to a non-porous medium, will help this. 
 Have a look at the boundary conditions. If there is no flow path available, the calculation might not run. 
 
 Note that plate elements are not non-porous by themselves: you would need interface elements along the plate to set this up. The reason is that we would need nodes at both sides of the impermeable "line" to calculate different groundwater head and groundwater flow at both sides of this line. 
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