The tunneling robot would probably mine a much more elaborate tunnel than a single shaft. Branching shafts, both horizontal and vertical, could have extra space for things like a water cistern, so that harvested and purified ice could be kept liquid in quantity. . . . Purity Of Essence.
Finally there would be a niche for the reactor, so it could power the habitat when the astronauts arrived. Having robots do the work prior to arrival of humans would save an enormous amount of time and money, and the humans could bring far more supplies and equipment with them, extending their mission and allowing them to conduct much more detail operations at much lower risk.
"I would guess that, ah, dwelling space for several hundred thousands of our people could easily be provided. A computer could be set and programmed to accept factors from youth, health, sexual fertility, intelligence, and a cross section of necessary skills. Naturally, they would breed prodigiously, eh? There would be much time and little to do. The prevailing emotion will be one of nostalgia for those left behind, combined with a spirit of bold curiosity for the adventure ahead!"
You know, of course, that both the US, the Soviet Union, and China did go ahead and build enormous underground cities?
One of the ones in the US is for Washington pols and bureaucrats and their families. It included all sorts of amenities, including shopping malls, fast food restaurants, churches, schools, etc., all maintained by a skeleton maintenance crew.
http://pakalert.wordpress.com/2009/11/10/list-of-underground-bases-in-the-us/
The underground cities in the USSR tended to be ball shaped, and were rather spare and military oriented. Mao built a huge underground city beneath Beijing, which has mostly been converted to active retail and residential over the years, which keeps the real estate prices low, unlike in Shanghai and Hong Kong, were they can get nonsensically expensive.