mines have been established by tunneling from 
land. None opens to the water column. To 
construct in-bottom habitats or mines far from 
shore or in seamounts and on midocean ridges, 
tunnels driven directly from the sea floor will be 
required. 
There are three different tunneling system 
requirements: in rock, in soft ground, and opencut 
ditches dredged from the surface. In all cases, 
thorough preliminary geological investigation and 
test borings are essential. 
In recent years great advances have occurred in 
boring machines for use in soft rock. Such 
machines have many cutter bits mounted on a 
large cutter head with a diameter equal to that of 
the bore. The largest boring machine in the United 
States has a cutter head 20 feet in diameter with 
43 cutter bits; five 200 hp motors rotate the head 
at 3.5 rpm. The Soviets have developed a 28-foot 
diameter borer. A 10-foot bore has been driven as 
much as 375 feet in one day and 6,713 feet in one 
month. Advances up to 4,000 feet per week may 
be achieved within the next decade. 
b. Future Needs In-bottom installations will be 
constructed where large concentrations of men 
and equipment are to be assembled for extended 
periods. Sites especially suitable for tunneling are 
seamounts, mid-ocean ridges, and large rock out- 
crops on the continental slope. 
To date, boring machines have proved econom- 
ically feasible only in such relatively soft rock as 
sandstone and shale. Studies are under way to 
develop machines to bore harder rocks. Future 
development should be directed at completely 
mechanized and automated tunneling procedures. 
Rapid tunneling at reduced costs depends on 
perfecting boring machines and on such comple- 
mentary technology as instrumentation to probe 
formations for water flows, grouting, guidance and 
control, lining, and material removal. A need also 
exists to develop systems for remote unmanned 
operation at deep ocean sites. 
Work vehicles will be needed to perform such 
functions as foundation preparation, leveling, and 
drilling. Machines analogous to bulldozers, back- 
hoes, cranes, and emplacement systems will be 
able to take advantage of the buoyancy provided 
by water. 
Systems for boring and drilling into the bed or 
side of a seamount and for placing drill pipe or 
other surface powered devices into an exact 
VI-94 
location will be required. These tasks imply 
vehicles with large capacity power sources or 
availability of a power supply submersible or shore 
power source. They also imply the need for 
reliable large-scale external machinery, including 
motors and drives. 
There may be a requirement to establish foun- 
dations by such methods as pile driving on the 
seafloor. More data and prediction methods are 
needed concerning the bearing capacity of large 
diameter piles. 
3. Conclusions 
Dr. Carl F. Austin, of the Naval Weapons 
Center, China Lake, Calif., has said of undersea 
installations: 
The technology to work and live beneath the sea 
floor is in hand at the present time for water 
depths over the entire continental shelves of the 
world excluding areas of permanent ice cover. Let 
us learn to use this technology to our economic 
and national advantage.° 
Deep ocean installations will be required for 
such activities as understanding the environment 
and its processes, study and exploitation of living 
and nonliving resources, surveillance, terminals and 
bases, and underwater power and_ processing 
plants. A capability to utilize the slopes, sea- 
mounts, and deep ocean basins may be the best 
and surest way of preserving freedom of access to 
the land masses under the high seas. Manned 
stations—beginning with portable or emplaced 
types and followed by more permanent in-bottom 
types—can achieve continuous deeply submerged 
operations. 
Prototype ambient pressure habitats have been 
built for continental shelf depths, and one- 
atmosphere habitats could be built for limited 
endurance missions at much greater depths using 
existing submersible technology. Many technolog- 
ical needs of both habitats and submersibles are 
similar. On the other hand, certain technology for 
bottom habitats is in its infancy, such as under- 
®Carl F. Austin, “Manned Undersea Installation,” 
Proceedings of the Conference on Civil Engineering in the 
‘Oceans, American Society of Civil Engineers, September 
1967, p. 83Q. 
