Boundary conditions for soil block

Hello

I am currently working with the automatic remeshing feature in FLAC2D. I want to model a soil block and allow it to fail towards the left. However, I am unsure how to properly define boundary conditions in the absence of soil in that direction. From what i know i can only make boundary conditions on soil?

Is there a way to handle this in FLAC2D without introducing an additional soil domain for the block to fall onto? When I try that approach, the soil behaviour becomes unrealistic. I have also attempted to use a liner, but that does not seem to work effectively either.

Any help would be nice