A study from Purdue University suggests the Moon contains a number of wide underground lava tubes, up to 5000 m wide and about 1500 m high, in which subterranean cities could be constructed. Such tubes would protect potential residents from cosmic radiation and from the extremes of temperature on the surface.
Prior to constructing anything in such tubes the inside of the lava tubes would need to be inspected for integrity of the rock and where localized weaknesses were found these would need to be fixed. The risk of a rock or a wedge of rock dislodging from the backs/roof/ceiling or walls of the tube and falling on people, plant, equipment or buildings would need to be to mitigated.
What would be the best way to stabilize any local weak spots in the internal surface of the lava tubes?
For example, here are some common tools and techniques for adding stability to natural and engineered structures:
- Tensioned cable bolts
- Rock bolts
- Shotcrete, steel mesh and bolts
- Concrete lining via form work, as opposed to shotcrete
- Polymer coatings
- Ceramic coatings