Underground working

Today any kind of underground work (especially in hard rock) is very time consuming and energy extensive. With APM technology this may change radically. Astonishing cutting speeds should be possible.

With APM technology one could make cutting saw-blades that:

• are made from superhard refractory diamondoid materials
• are only some micrometers thin giving them high surface area relative to their volume and thus good self cooling properties
• are actively cooled with capsule transport allowing for even faster cutting
• can transport away micro debris also employing capsule transport
• regularely replace their cutting teeth (self repair)
• are driven by shearing drives

With such fancy saw blade system big sized chunks (e.g. liter to cubic meter) of soil could be cut out and transported to the surface in an infinitesimal beared state. For this to work the drill channel must have consistent cross secttion. It could be like a bore hole with low bending radius or a just a bunch of perfect cubes. Obviously threading cut out cubes through a square channel with micrometer sharp 90° turns requires full stops of motion at those turns due to the high inertial mass of the huge blocks.

Assuming a cut width of one micrometer and a core diameter or one meter (in square) the ratio between the preserved drill core volume and destroyed cut volume is
(10⁶)²:1 or 10¹²:1 or 1 000 000 000 000 : 1 meaning that if you excavate one cubic kilometer of material you only irreversibly destroy one liter. The drilling cores can be preserved for later research and stored as structural building material where maximum material strength is not of importance (meaning almost erywhere in big scale construction) if the excavated volume isn't needed anymore the cores could be put back to their origin restoring the natural state of the lithosphere.

A high amount of energy is only required for lifting stuff up from very great depths. a vew hunded kilometers down the necessary energies are like the energies involved in spaceflight to LEO (low earth orbit). One don't has to propell the propellant and one can go slowly though.

[Todo: analyze what could be done if very hard rock like corundum (Al₂O₃) is encountered - Na⁺-ion beams? and slushing with water? see: diamondoid waste incineration ]

Related

• deep drilling
• specifics to tunnel construction (tunelling)
• specifics to near surface excavation work
• specifics to prospective work for mining (deep mining) - mining might decrease due to independence of scarce elements though
• geoengineering - (controlled tectonic tension release cables?)
• mining