Soft interface boundary conditions for EDEM coupling with FEA?

Hi Everyone,

I want to simulate an object penetrating through the two layers of materials: the hard particle layer at the top and the soft particle layer at the bottom.

The soft particle layer has a smaller particle size and is computationally more expensive. Is there a way to replace this soft bottom layer with a special boundary condition that can deform as a continuum block (force-deformation calculated by coupling to FEA)? Or maybe a special interface boundary that is not rigid to allow geometry to go through and give certain predefined resistance? 

Best regards,

Hao