Island Builders- ancient and new


(Wilfried Ellmer) #21

you might consider that “sandbank building” is actually big business today and performed on large scale successfully…with interesting consequences in business and politics… but today we can do better than landfill - we can solve the technology bottleneck - and build city sized structures afloat.


(Larry G) #22

Yes, we’re aware of the ramification. But the so-called technology bottleneck would be thread drift in this case, since we’re discussing island building here.

The two are not mutually exclusive. Some people can do one, some people can do the other. But this particular discussion is about island building. Yet another link to your website isn’t very helpful.


(Matias Volco) #23

floating island building included?


(Larry G) #24

I would prefer to focus on building permanent islands or platforms that ground on the bottom in this thread. There are plenty of threads about floaters, and I like to engage in helpful discussion about those as well. But for the purposes of engineering a solution, I would like to keep the discussions separate.

I’m not sure what you mean by this?


#25

pol·der
ˈpōldər/
noun
noun: polder; plural noun: polders

a piece of low-lying land reclaimed from the sea or a river and protected by dikes, especially in the Netherlands.

(Matias Volco) #26

laterally, as in only the “sides” are addressed.


#27

True, if you addressed only the sides, water flow would be from the bottom up when you began pumping the ground water from the top. On the other hand, if you made a watertight bowl in the atoll, and pumped the water out, there would be a tendency for the landmass to float right up. Hmm, might be a way to make huge floaties! :smile:


#28

Certain offshore oil rigs are designed to be floated in, set and ballasted, then emptied to re-float and relocate… ‘Con’… something. The name escapes me, at the moment.


#29

Thank you @KatOnTri

ConDeep.

http://www.offshoreenergytoday.com/removal-of-condeep-platforms-feasible-but-needs-thorough-planning-norway/

It is technically feasible to remove concrete installations resting on the seabed. But this is comprehensive work that requires thorough planning and risk management.

This is the conclusion reached by the consultancy firm Dr. techn. Olav Olsen, which has prepared the report ”Disposal of concrete installations” on assignment for the Norwegian Petroleum Directorate. The report describes the technical challenges associated with raising the concrete substructures from the seabed and making them float again. In addition, it discusses issues related to transport of the installations from the field to land.


(Matias Volco) #30

That is extremely close to what I envision! As always, great contribution @KatOnTri


(Larry G) #31

Well, if that were the goal, you wouldn’t want to start with an atoll with it’s irregularities and grounded connection that could cause suction and uneven lift resulting in cracking or deformation. Nor would you want to start with it full of water and then pump out the interior of the structure.

You would want to start in a dock that could be evacuated of water, shaped as a form/mold, concrete poured consistently, then the dock flooded again to float the whole assembly. That’s what I envisioned for the torus I described above.

(Side cut-away view)

It could be floated to a pre-determined location shallow enough to ground it firmly and then fill your reservoir with fresh water as ballast.


(Matias Volco) #32

Yes I agree


(Larry G) #33

That size/scale looks rather expensive (judging that to be 80-90’ high or about 30 meter based on the number of floors and the average human scale height of a building’s floors or a ship’s deck), but I think a reasonable case could be made for the dimensions I proposed above without too many investors.

Especially submerging past the mid-point. It occurred to me that if the mid-point is in the wave zone (± the average wave height from the average calm waterline) there might be a significantly larger problem with scouring action affecting the sea bed under the structure.

Which means probably no day-lighting for any decks below the mean high tide + wave action point at least on the exterior of the torus.

And lack of fresh water is the flaw of most islands that are unoccupied right now in the world. Rather than sand ballast, I would go with a fresh water reservoir. The nice thing is the ballast to fill it could be towed to the site at the same time in a polymer bag and pumped in once situated.


(Matias Volco) #34

yes so would I, much like sunlight, fresh water can be accumulated from the top down. Imagine a Koi pond in that central atrium. You may half the diameter and still have a pretty stable semi-emerged pod


(Larry G) #38

(Larry G) #39

https://amti.csis.org/island-tracker/


(Larry G) #40

Well, Thor Heyerdahl’s Ra and Ra II were made of reeds and the second one managed an Atlantic passage, even made by amateurs. But the amount of precision hand work and limited timespan don’t seem like worthwhile lines of inquiry to me,