For goodness sake - why would the navy develop concrete subs when they can afford proper steel?
Steel is even better at compression than concrete, and infinitely better in every other way. In fact, without steel, you wont be building concrete subs.
I bet you found some "very strange things" on the internet - they would be very strange to think there was an advantage to a concrete sub.
By all means, throw in a few references you think are usefull.
This is my concrete sub prototype - a 18m is almost done...
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Here is what navy is doing...
Corporate Author : CIVIL ENGINEERING LAB (NAVY) PORT HUENEME CA
Personal Author(s) : Haynes,Harvey H. ; Highberg ,Roy S.
Report Date : JAN 1979
Pagination or Media Count : 53
Abstract : In 1971, a long-term, deep-ocean test was started on eighteen concrete spheres, 66 inches (1, 676 mm) in outside diameter by 4,12 inches (105 mm) in wall thickness. The spheres were placed in the ocean at depths from 1,840 to 5,075 feet (560 to 1,547 m). Over a 6.4-year period, yearly inspections of the spheres by submersibles have provided data on time-depedent failure and permeability. After 5.3 years, three of the spheres were retrieved from the ocean for laboratory testing. Data on concrete compressive strength gain, short-term implosion strength of the three retrieved spheres, and permeability and durability of the concrete were obtained. This report summarizes the findings from the laboratory and ocean tests. (Author)
Descriptors : *CONCRETE, *UNDERWATER STRUCTURES, PERMEABILITY, PERFORMANCE(ENGINEERING), LOADS(FORCES), SHELLS(STRUCTURAL FORMS), SPHERES, STRENGTH(MECHANICS), LONG RANGE(TIME), SATURATION, PROTECTIVE COATINGS, WALLS, MARINE ENGINEERING, DEEP OCEANS, COMPRESSIVE PROPERTIES, WATERPROOFING, STRUCTURAL ENGINEERING, SEA TESTING, HYDROSTATIC PRESSURE, IMPLOSIONS.
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Descriptive Note : Technical rept. Jun 68-Jul 71,
Corporate Author : NAVAL CIVIL ENGINEERING LAB PORT HUENEME CALIF
Personal Author(s) : Haynes,H. H. ; Kahn,L. F.
Report Date : SEP 1972
Pagination or Media Count : 93
Abstract : Fourteen unreinforced concrete and mortar spheres, 66 inches in outside diameter (OD) and 4.125 inches in wall thickness, were subjected to simulated deep-ocean loading conditions. The average short-term implosion pressure for wet-concrete spheres was 2,350 psi and for the dry-concrete spheres was 2,810 psi; the average uniaxial compressive strength of the concrete was respectively 7,810 psi and 9,190 psi. Under long-term loading, the concrete spheres failed by static fatigue where the relation between level of sustained pressure and time to implosion was similar to that known for concrete under uniaxial loading. Wet-concrete spehres under seawater pressure as high as 1.670 psi showed an average D'Arcy's permeability coefficient, K sub c, of 10 to the minus 12 power ft/sec; this K sub c value was also similar to that known for concrete under freqhwater pressure as high as 400 psi. Design guides were developed to predict the short- and long-term implosion pressures and permeability rates of concrete spheres. (Author)
Descriptors : (*UNDERWATER VEHICLES, HYDROSTATICS), (*SHELLS(STRUCTURAL FORMS), *CONCRETE), (*SPHERES, CONCRETE), COMPRESSIVE PROPERTIES, PRESSURIZATION, LOADS(FORCES), DEFORMATION, STRAIN(MECHANICS), RUPTURE, DEEP WATER
Subject Categories : MARINE ENGINEERING
MECHANICS
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A Decade of Ocean Testing of Pressure-Resistant Concrete Structures
Rail, R.
Naval Civil Engineering Laboratory, Port Hueneme, CA, USA;
This paper appears in: OCEANS
Publication Date: Aug 1983
Volume: 15, On page(s): 593- 597
Current Version Published: 2003-01-06
Abstract
By means of long-term deep-ocean exposure and laboratory testing, experimental data have been obtained on compressive strength behavior, permeability, and durability of pressure-resistant concrete structural models (concrete spheres 66-inch O.D. by 4-1/8-inch wall thickness) subjected to continuously sustained hydrostatic pressure loading. After 10-1/2 years of ocean exposure at water depths of 1,840 to 5,075 feet, the major findings include: (a) The implosion (failure) strength and stiffness of the concrete spheres and the uniaxial compressive strength of concrete specimens increased during the first 5-1/2 years exposure in the ocean and remained essentially constant during the next 5 years; (b) There has been no evidence of seawater permeating through the walls into the interior of ocean-exposed spheres externally coated with a waterproofing material; uncoated (bare concrete) spheres have a very low rate of water ingress, i.e., a permeability coefficient of about10^{-14}ft/ sec; and (c) Visual inspection and microstructure examination of retrieved specimens have not revealed any significant deterioration of the concrete matrix; no corrosion was visible on steel reinforcing bars which had as little as one inch clear cover. This program has been a decade-long demonstration of the effective use of concrete in the ocean; it has been shown that concrete is a durable, reliable material for pressure-resistant structures for long-term deep-ocean applications.
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looks some navies DO concrete... i do it too...
some civil engineers do it too...
Image 1
Statoil's massive concrete based Heidrun platform. The legs of this platform reach over 100m down into the sea. Basicly this floating city is based on the fact that a concrete hull can withstand the ocean pressure stroms and waves all the way from surface to 100m depth during decades - without any alteration.
Image2
Inside the concrete leg of a drilling platform. (Troll Platform) Those engineers at the moment of the photo are tecnically "dived at 300 m protected from water pressure by a submarine concrete hull" of collosal dimension that stands vertically instead of horizontally - just flip that platformleg (in your mind) 90 degrees and add a propeller - you have a giant submarine of 24m diameter with 1m wall thickness and 300m length. This is not a new horizon tecnically speaking - it is just to see things from a slightly different angle. By the way my prototype submarine had a wall diameter ratio of almost exactly the double of troll - so it is good for water pressure at 600m including a similar security factor.
Image3
Grande Dixence, on the river Dixence in Switzerland, concrete dam. It was built between 1953 and 1961 to a height of 285 m (935 ft). Concrete at the foot of this dam holds a watercolumn of 285m - equivalent of 285m dive depth in a submarine.
Image 4
HIBERNIA CANADA, drilling platfrom 105.5m deep diving concrete submarine hull...
Image 5
Golf of Corinth Greece, the legs of this bridge go 70m down to the ocean floor. They where built at sea in floating status and do rest on ocean floor with very little force to enable the bridge to move in case of earthquakes - so this bridge is founded on 70m deep dived submarine concrete hulls.
Image 6
Seikan Tunnel - This train emerges from the depth of 240 m below the sea of japan where ist was protected during his passage by nothing else than a submarine concrete hull - horizontally in this case...
Cheers,
Wil
concretesubmarine.com
