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?
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:
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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