Eden: Technical and reproductive clones, alphas, and "semigods" living underground

About 20 years ago I've read a novel about a civilization of clones. The main part of the population were "technical clones" (TCs), responsible for maintaining the habitat (?). Benefits like a greater choice of food and the permission to copulate were rewarded to them for good performance, and taken away if performance dropped.

There was a hierarchy of clones: At the bottom level were "reproductive clones" (?), only capable of giving birth and fed intravenously. I don't remember if there was something inbetween, but above the TCs were "alphas", living an easy life and essentially doing nothing. Everything was ruled by a small group of "semigods" (?), but they were out of reach to the "normal" clones. I think one was born (or cloned) into one's caste, upgrading or downgrading was not possible (although perhaps visiting the world of alphas was possible as a reward for a TC (???)).

More details: Two TCs fell in love and arranged lovemaking by impersonation.

In the end, a group of TCs managed to escape the (underground?) habitat, just to find an Earth destroyed by a (nuclear?) war.

The words "Eden" or "Garden of Eden" might (?) have appeared in the title or in the text.

Sorry for the incomplete and imprecise description -- but does this ring a bell to anyone?