Interfaces forming a new contact

If I have multiple seams separated by coplanar interfaces, and I excavate one of the seams (e.g. longwall mining), would the interfaces automatically detect the new contact once the gap between them closes (running in large strain)? Or is there something specific that needs to be defined/specified for this to happen?

Yes, this can be done, but some notes:
(1) The interface “master” nodes should be in the side where zones will not be nulled or deleted later. In other words, the interface “target” zones can be nulled or deleted, but the “host” zones should not. Otherwise, the interface will be lost once host zones are nulled or deleted;
(2) It should be in “large-strain” mode.
(3) If the interface node velocity is big when contacting and the first penetration is beyond the limit, a contact will not be considered detected. In this case, increasing penetration tolerance may help.
(4) It is also possible that the grid may be too distorted when approaching contact due to the large strain mode.

A simple example is here: