Hmm. There were Inferno pit traps and AC/20 backstabbers, I think in the MacCarron's Armored Cavalry Mechwarrior book - something like this might fit in to that kind of fortress defense.
You know, why not put some styrofoam around the vertical pieces, and paint it to resemble ferrocrete? That way, you could reasonably assign it a Hardened CF, and make a case for turning it into a rubble hex to impede ground vehicles once its shattered to allow mechs to enter. It might make an amusing scenario where the attacker has to get a bridging unit into place, and the defender stop it to avoid being overwhelmed.