From: fhapgood@world.std.com (Fred Hapgood)
Newsgroups: sci.nanotech
Subject: underground space creation and nanotech
Date: 6 Nov 92 04:37:36 GMT



I want to thank everyone for helping me brainstorm about this
complex question.  Your posts have convinced me that highly
energy-efficient underground space creation is one function for
which nanotechnology is no direct application.  It is a good
thing for the enthusiasts here, in which number I include myself,
to remember that the technology is not appropriate for absolutely
everything.

However, nanotech may have indirect applications, as follows.
For most of the last five hundred years hardrock tunnels were
drilled with explosives.  Explosive energies have the great
advantages of travelling through the rock face under their own
steam and concentrating naturally in the weaker planes of the
medium (weaker rock resists transmitting vibration, which
concentrates it).  In theory, paradoxically, explosive energy,
which looks uncontrolled, is actually the most energy-efficient
way to cut rock.

However this technique has been substantially abandoned because
the effects of the explosives, on men, machines, and the tunnel
rock itself, have proved too hard to control.

Perhaps in the future underground space creation will proceed in
these steps: first, a number of microtunnelers will dig
exploratory holes of variable trajectories through the volume to
be extracted.  These machines will have access to a rock
mechanics expert system, or something like it.  They would also
be loaded with sensors -- microwave, resistance, seimic -- that
will generate a very detailed map of the country.  As they travel
they will lay charges calculated (shaped, measured) to break the
target volume into sizes as compatible as possible with the
spoils extraction system without doing anything unpleasant.
Where they decided the rock was a little weak, they could extrude
reinforcing struts.  When they finished they would withdraw and set
off the charges.

The extraction system would obviously have to have its own
rock-fragmenting resources for situations where the fragments left by
the charges are too large.  Maybe minicharges would work here. I
visualize the spoils removal process as some number of self-extending
conveyors of adjustable dimensions with robot arms.

The last step would be to smooth, line, and reinforce the
interior.  It is lot cheaper to take these steps when working
space has been created (rather than by extruding or assembling
the liner when the rock is being cut, as now), but so far the
unpredictability of rock has made it critical to install liner
asap.  When we really have a good map, know a lot more rock
mechanics than we know do, and can install reinforcing struts,
it should possible to do this work much more cheaply.

Nanotechnology's role in this technology would be important
though not primary.  The microtunnelers, reinforcing struts, and
robot arms will all need to be pretty stout pieces of equipment,
so nanotech materials will be useful here.  The sensors and
computers would benefit from the technology.  And possibly some
microtunnelers might even be nanotunnelers.   We could use them
for excavating alcoves and closets ....