NotMoreStress

Help please. After various issues, too many to go into, we determined a previous owner of our house had buried the access to the sewage manhole in our porch. We had determined that there was a metal cover in a hatch in the floor. Covered in concrete over the top. I'm trying to determine what the metal cover and hatchway are called? There is no reference marks on the kit itself. After many hours breaking through the concrete with hammer and chisel today, we managed to unscrew and lift the metal cover. Having lifted it, we discovered the manhole cover, itself then covered in a plastic sheet that had been concreted into place. Having broken through that plastic cover and broken out the concrete keeping the manhole in place and finally loosened the manhole cover we discovered that physics simply prevents us lifting the manhole cover through the hatch opening in the concrete floor.... the manhole cover is bigger than the hatch opening and there isn't enough space between the two to twist and lift it. So I'm now trying to determine what that metal hatch and surround are called so I can Google the dimensions to see how much more effort will be required to remove it completely so that the manhole cover can be removed! Anyone know what these things are called?