Providing interface to cylindrical volume Deep Mixed column

Hello,

I am doing PLASXIS 3D analysis for the Deep Mixed (DM) column installed in soft soil under the embankment load. DM columns are made by extruding a cylindrical volume and replacing the soft soil material with the DM column material. The soft soil is modeled with Modified Cam Clay Model and DM column as Mohr-Coulomb. I am trying to provide an interface between DM column and soft soil but facing an issue with it. When I right-click on the column under 'create' option, I find only 'create rigid body' option. I don't see an option for providing a positive or negative interface to the cylindrical volume. My question is, can I provide an interface to the cylindrical volume (DM column)? If not, will it affect my result?

Please find the image below for reference.

Waiting for the response.

I really appreciate any help you can provide.