17-09-2015, 10:22 AM
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topic:underwater construction
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underwater structures construction ppt
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request post a seminar
topic:underwater construction
17-09-2015, 01:49 PM
underwater structures construction ppt
Building anywhere brings its own set of environmental challenges. Creating skyscrapers in the middle of a bustling hub like Hong Kong or New York can be challenging for any experienced development team. How about creating a skyscraper in the middle of the ocean?
Marine or deep sea construction has a long history dating back to the first century Romans who used underwater cement to build artificial harbors.
Thanks to technological advances, builders have been making their marks on the other two-thirds of the planet. These four underwater construction techniques changed the world we live in.
Pneumatic Caissons
Pneumatic caissons are sunk into the sea floor and have pressurized air pumped in from the surface. These watertight retaining structures allow us to build at great depths and enormous pressure levels. Used for work on bridge piers, dams, and ship repairs, this innovative yet dangerous technique helped to create the Eads Bridge piers in St. Louis. This was the first bridge to use pneumatic caissons in pier construction and these are still some of the deepest caissons ever sunk. The Eads Bridge was completed in 1874 and these caissons inspired John Roeblings’ work on the Brooklyn Bridge, which was completed nearly a decade later.
The term “underwater construction” or “commercial diving” covers a wide array of activities. At the core, underwater construction is simply industrial construction that happens to take place under water. Activities vary greatly but include bridge inspection, building repair, repair of wastewater treatment facilities, and equipment installation.
“Basically, to me, diving’s nothing more than a means of transportation to and from a job,” says Harold Einhorn, vice president of operations at Walker Diving Underwater Construction in Hammonton, New Jersey. “After that, we’re underwater mechanics. We’re jack of all trades.” Walker Diving Underwater Construction provides everything from inspection to turnkey construction of bridges, dams, and piers and works with general contractors, DOTs, environmental firms, power companies, and dam owners, among others.
Dangers and Safety Precautions
According to Einhorn, underwater construction is just like other types of construction, with one exception. “The only difference is we do it under water,” Einhorn says. “We just face a little more hazards. You face pretty much everything that normal construction sites have. When we work on construction sites, not only do we have the topside land dangers, we’re working in an environment in and around the water. You can have drownings, swift currents, air embolisms, etc. The environment itself is a big factor in it.”
Limited visibility is also another huge risk factor for underwater construction workers. “Most of the time – especially inland – you have no visibility or minimal visibility. You may only have a foot or two … maybe three. Three feet is good,” says Einhorn, chuckling. “Guys that stay with it learn to deal with it. It’s like being a blind person. You develop a sixth sense.”
“Basically, to me, diving’s nothing more than a means of transportation to and from a job." – Harold Einhorn, Vice President of Operations, Walker Diving Underwater Construction
According to Workplace Safety and Health, other underwater dangers also include nitrogen narcosis, oxygen toxicity, and decompression sickness. Nitrogen narcosis has effects similar to alcohol intoxication and is caused by breathing in harmful gases from the air supply. The risk of nitrogen narcosis increases as the depth of the dive increases, because these gases are easily absorbed in the body as pressure levels increase. When an excess of oxygen is inhaled, oxygen toxicity can occur, which can lead to vision problems, lung damage, seizures, disorientation, and death. Decompression occurs when divers rise abruptly from the water, not allowing enough time for nitrogen to escape the body. Decompression symptoms include vision and hearing problems, skin irritation, achy joints, paralysis, and death.
Due to the extra dangers those in the underwater construction industry face, they must take special safety precautions. In addition to following naval dive tables, other common safety precautions include diving in teams, closely monitoring air supply, and being aware of how various pieces of equipment react under water. (The laws of physics are altered under water, causing equipment to react differently, because objects weigh less and move slower under water. Chemicals also react differently.)
Breaking into the Industry
Einhorn became “hooked” on the underwater construction industry after watching diver Mike Nelson (played by Lloyd Bridges) in the television show Sea Hunt. At the age of eight he became the youngest person in the state of New Jersey to be certified in scuba diving. He later earned a degree in Oceanography and Marine Biology and received his commercial diving and professional diving certificates.
Building anywhere brings its own set of environmental challenges. Creating skyscrapers in the middle of a bustling hub like Hong Kong or New York can be challenging for any experienced development team. How about creating a skyscraper in the middle of the ocean?
Marine or deep sea construction has a long history dating back to the first century Romans who used underwater cement to build artificial harbors.
Thanks to technological advances, builders have been making their marks on the other two-thirds of the planet. These four underwater construction techniques changed the world we live in.
Pneumatic Caissons
Pneumatic caissons are sunk into the sea floor and have pressurized air pumped in from the surface. These watertight retaining structures allow us to build at great depths and enormous pressure levels. Used for work on bridge piers, dams, and ship repairs, this innovative yet dangerous technique helped to create the Eads Bridge piers in St. Louis. This was the first bridge to use pneumatic caissons in pier construction and these are still some of the deepest caissons ever sunk. The Eads Bridge was completed in 1874 and these caissons inspired John Roeblings’ work on the Brooklyn Bridge, which was completed nearly a decade later.
The term “underwater construction” or “commercial diving” covers a wide array of activities. At the core, underwater construction is simply industrial construction that happens to take place under water. Activities vary greatly but include bridge inspection, building repair, repair of wastewater treatment facilities, and equipment installation.
“Basically, to me, diving’s nothing more than a means of transportation to and from a job,” says Harold Einhorn, vice president of operations at Walker Diving Underwater Construction in Hammonton, New Jersey. “After that, we’re underwater mechanics. We’re jack of all trades.” Walker Diving Underwater Construction provides everything from inspection to turnkey construction of bridges, dams, and piers and works with general contractors, DOTs, environmental firms, power companies, and dam owners, among others.
Dangers and Safety Precautions
According to Einhorn, underwater construction is just like other types of construction, with one exception. “The only difference is we do it under water,” Einhorn says. “We just face a little more hazards. You face pretty much everything that normal construction sites have. When we work on construction sites, not only do we have the topside land dangers, we’re working in an environment in and around the water. You can have drownings, swift currents, air embolisms, etc. The environment itself is a big factor in it.”
Limited visibility is also another huge risk factor for underwater construction workers. “Most of the time – especially inland – you have no visibility or minimal visibility. You may only have a foot or two … maybe three. Three feet is good,” says Einhorn, chuckling. “Guys that stay with it learn to deal with it. It’s like being a blind person. You develop a sixth sense.”
“Basically, to me, diving’s nothing more than a means of transportation to and from a job." – Harold Einhorn, Vice President of Operations, Walker Diving Underwater Construction
According to Workplace Safety and Health, other underwater dangers also include nitrogen narcosis, oxygen toxicity, and decompression sickness. Nitrogen narcosis has effects similar to alcohol intoxication and is caused by breathing in harmful gases from the air supply. The risk of nitrogen narcosis increases as the depth of the dive increases, because these gases are easily absorbed in the body as pressure levels increase. When an excess of oxygen is inhaled, oxygen toxicity can occur, which can lead to vision problems, lung damage, seizures, disorientation, and death. Decompression occurs when divers rise abruptly from the water, not allowing enough time for nitrogen to escape the body. Decompression symptoms include vision and hearing problems, skin irritation, achy joints, paralysis, and death.
Due to the extra dangers those in the underwater construction industry face, they must take special safety precautions. In addition to following naval dive tables, other common safety precautions include diving in teams, closely monitoring air supply, and being aware of how various pieces of equipment react under water. (The laws of physics are altered under water, causing equipment to react differently, because objects weigh less and move slower under water. Chemicals also react differently.)
Breaking into the Industry
Einhorn became “hooked” on the underwater construction industry after watching diver Mike Nelson (played by Lloyd Bridges) in the television show Sea Hunt. At the age of eight he became the youngest person in the state of New Jersey to be certified in scuba diving. He later earned a degree in Oceanography and Marine Biology and received his commercial diving and professional diving certificates.
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