Submerged structures

Platinised-titanium, platinised-niobium, lead and lead-platinum anodes used for submerged structures, ships and power stations. 

Cathodic Protection of Buried and Submerged Structures, CP 1021 1973, British Standards Institution, London... 

The determination of the effects of surface waves on submerged structures has many practical applications, particularly in an ocean environment. Due to the complexity of the problem, analytic results are limited to idealized flows and geometries. 

Fig. 22.6 The giant barnacle Austromegabalanus psittacus from Chile, (a) Small individuals are often found on the thick shells of adults, (b) Where benthic populations are available this species is sold in local seafood markets, (c) Only large and singly grown individuals find their way to the dinner plate. Giant barnacles readily grow on submerged structures but their culture remains as yet largely unexplored, mostly due to unpredictable larval settlement and costly larval culture. Images courtesy of Ivan A. Hinojosa...

Submerged structures. When reinforced-concrete structures are submerged in water, or in any case the moisture content of concrete is near the saturation level, the transport of oxygen to the steel is low and the reinforcement reaches very negative potentials, for example between -400 and -600 mV SCE [1]. In this case, the chloride threshold is much higher, sometimes even reaching values... 

An instant off potential more negative than -720 mV vs. Ag/AgCl/0.5 M KCl - this criterion is the conventional one for buried and submerged structures. 

Reconstruction of submerged structures. Water, particularly salt water, leads to breakdown of submerged concrete structures, piers, piles, foundations, bridge footings, dikes, and dams. The most... 

For vessels and tanks that contain liquids, the effects of sloshing and impulsive loads, including frequency effects, should be considered. The effects of liquid motion or pressure changes on submerged structures should also be considered. These effects may involve hydrodynamic loads from the fluid and a reduction of functional capability (e.g. loss of shielding efficiency of fuel pools or disturbance of instrument signals). 

Low-crested and submerged structures (LCS) as detached breakwaters and artificial reefs are becoming very common coastal protection measures (used alone or in combination with artificial sand nourishment).As an example, a number of systems and typical applications of shore-control structures is shown in Figs. 20.4-20.7. 

K. Black and S. Mead, Submerged structures for coastal protection, ASR, Marine and Freshwater Consultants, New Zealand (1999) (www.asrltd.co.nz). 

K. W. Pilarczyk, Design of low-crested (submerged) structures An overview, 6th COPEDEC, Sri Lanka (2003), www.enwinfo.nl (select English, downloads). 

For rubble mound LCBs, to be able to estimate the transmission coefficient Kt also in presence of submerged structures with very wide crests, the following two formulae are given for design conditions (Briganti et al. van der Meer et... 

A linear interpolation between the two is performed in the range 8 < Be/ Hsi < 12. In Eqs. (22.5) Rc is the structure freeboard (negative for submerged structures), Be is the crest width, and op is the surf similarity parameter based on structure offshore slope and peak wave period. Equations (22.5) were applied in the range —5 < Re/Hsi < 5. 

Not all LCBs are of the rubble mound type. Sometimes smooth and impermeable structures exist, for example, LCBs covered with asphalt or armored with a block revetment. Often the slope angles of these structures are gentler (1 3 or 1 4) than for rubble mound structures, mainly for construction reasons. Wave transmission over smooth LCBs is completely different from rubble mound structures. First of all, the wave transmission is larger for the same crest height, simply because there is less energy dissipation by friction and structure permeabihty. Furthermore, the crest width has less or even no influence on transmission, as also on the crest there is lower energy dissipation. Only for very wide (submerged) structures there could be some influence on the crest width, but this is not a case that will often be present in reality as asphalt and block revetments are mainly constructed in the dry and not under water. The presence of tide makes it possible to construct these structures above water. 

A combination of coating and cathodic protection is required for effective protection of submerged structures. 

Currently, the integrity evaluation of submerged structures is performed with the aid of piezometers, level references, surface landmarks, containment devices, and downstream flow measurements to determine the degree of landfill. Although such devices represent valuable arguments for the maintenance of submerged structures, they do not allow inferences about the existence or characteristics of fractures and the proper localization of them. This assessment procedure is carried out by divers, who face the difficulty of water turbidity, which reduces vis-... 

Epoxy coatings used for marine maintenance, tank finings and underwater super and submerged structures,... 

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