[math-fun] 700 foot ice wall ?
The TV series 'Game of Thrones' claims a 700' high ice wall. Game of Thrones uses significant amounts of CGI, so the only place this ice wall exists is inside a computer. Nevertheless, could a real ice wall of its dimensions be built and stand? In various scenes, the ice wall is essentially vertical. I haven't seen the more-or-less vertical ice walls created by 'calving' glaciers personally, so I don't know whether any of them attain 700' in height. However, unlike those glacier ice walls, the Game of Thrones ice wall is 2-sided, and is warmer on one side -- enough to 'weep' under the sun. Sooooo... Based on standard Earth gravity and standard water ice, is a 700' ice wall possible? Note that the GoT ice wall is flat, so it doesn't gain any stability from being curved, and as a result, could probably not stand up to the high winds that its mere presence would generate. Ice is only a tad lighter than water, and 700' is approx. 22x the 32' of water that equals 1 atmosphere. I don't think that WWII *steel* submarines could withstand 700' depths of water, so the pressure at the bottom of such a wall would be quite high and would likely require some reinforcement.
Received wisdom among mountaineers used to be that the maximum depth attained by a crevasse was in the region of 300 feet; at greater depths the ice would flow sideways under vertical stresses to close the gap. Any attempts by myself to verify this limit have until now been frustrated by alert team partners and various quantities of 9-mil nylon rope ... WFL On 11/20/16, Henry Baker <hbaker1@pipeline.com> wrote:
The TV series 'Game of Thrones' claims a 700' high ice wall.
Game of Thrones uses significant amounts of CGI, so the only place this ice wall exists is inside a computer.
Nevertheless, could a real ice wall of its dimensions be built and stand?
In various scenes, the ice wall is essentially vertical.
I haven't seen the more-or-less vertical ice walls created by 'calving' glaciers personally, so I don't know whether any of them attain 700' in height.
However, unlike those glacier ice walls, the Game of Thrones ice wall is 2-sided, and is warmer on one side -- enough to 'weep' under the sun.
Sooooo...
Based on standard Earth gravity and standard water ice, is a 700' ice wall possible?
Note that the GoT ice wall is flat, so it doesn't gain any stability from being curved, and as a result, could probably not stand up to the high winds that its mere presence would generate.
Ice is only a tad lighter than water, and 700' is approx. 22x the 32' of water that equals 1 atmosphere.
I don't think that WWII *steel* submarines could withstand 700' depths of water, so the pressure at the bottom of such a wall would be quite high and would likely require some reinforcement.
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
Here's some visual examples. https://www.youtube.com/embed/hC3VTgIPoGU?rel=0 Brent On 11/20/2016 3:07 PM, Fred Lunnon wrote:
Received wisdom among mountaineers used to be that the maximum depth attained by a crevasse was in the region of 300 feet; at greater depths the ice would flow sideways under vertical stresses to close the gap.
Any attempts by myself to verify this limit have until now been frustrated by alert team partners and various quantities of 9-mil nylon rope ...
WFL
On 11/20/16, Henry Baker <hbaker1@pipeline.com> wrote:
The TV series 'Game of Thrones' claims a 700' high ice wall.
Game of Thrones uses significant amounts of CGI, so the only place this ice wall exists is inside a computer.
Nevertheless, could a real ice wall of its dimensions be built and stand?
In various scenes, the ice wall is essentially vertical.
I haven't seen the more-or-less vertical ice walls created by 'calving' glaciers personally, so I don't know whether any of them attain 700' in height.
However, unlike those glacier ice walls, the Game of Thrones ice wall is 2-sided, and is warmer on one side -- enough to 'weep' under the sun.
Sooooo...
Based on standard Earth gravity and standard water ice, is a 700' ice wall possible?
Note that the GoT ice wall is flat, so it doesn't gain any stability from being curved, and as a result, could probably not stand up to the high winds that its mere presence would generate.
Ice is only a tad lighter than water, and 700' is approx. 22x the 32' of water that equals 1 atmosphere.
I don't think that WWII *steel* submarines could withstand 700' depths of water, so the pressure at the bottom of such a wall would be quite high and would likely require some reinforcement.
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
At 02:30 "The calving face is 300 --- sometimes 400 --- feet tall" WFL On 11/21/16, Brent Meeker <meekerdb@verizon.net> wrote:
Here's some visual examples.
https://www.youtube.com/embed/hC3VTgIPoGU?rel=0
Brent
On 11/20/2016 3:07 PM, Fred Lunnon wrote:
Received wisdom among mountaineers used to be that the maximum depth attained by a crevasse was in the region of 300 feet; at greater depths the ice would flow sideways under vertical stresses to close the gap.
Any attempts by myself to verify this limit have until now been frustrated by alert team partners and various quantities of 9-mil nylon rope ...
WFL
On 11/20/16, Henry Baker <hbaker1@pipeline.com> wrote:
The TV series 'Game of Thrones' claims a 700' high ice wall.
Game of Thrones uses significant amounts of CGI, so the only place this ice wall exists is inside a computer.
Nevertheless, could a real ice wall of its dimensions be built and stand?
In various scenes, the ice wall is essentially vertical.
I haven't seen the more-or-less vertical ice walls created by 'calving' glaciers personally, so I don't know whether any of them attain 700' in height.
However, unlike those glacier ice walls, the Game of Thrones ice wall is 2-sided, and is warmer on one side -- enough to 'weep' under the sun.
Sooooo...
Based on standard Earth gravity and standard water ice, is a 700' ice wall possible?
Note that the GoT ice wall is flat, so it doesn't gain any stability from being curved, and as a result, could probably not stand up to the high winds that its mere presence would generate.
Ice is only a tad lighter than water, and 700' is approx. 22x the 32' of water that equals 1 atmosphere.
I don't think that WWII *steel* submarines could withstand 700' depths of water, so the pressure at the bottom of such a wall would be quite high and would likely require some reinforcement.
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
Here's a sanity check: Although ice has a Young's modulus of ~9 GPa when measured by the speed of sound, most practical measurements show it to be more like ~1 GPa in actual structural use. Euler buckling is typically the critical issue in building a tall column (or wall). The critical length of a tall column constrained by Euler buckling is L = .792 * (E/rho)^(1/3) * d^(2/3) where E is Young's modulus, rho is specific weight (density*g), and d is the diameter of the column. If the diameter of the column is ~10 pi feet, then the critical height is ~700 feet. Ice crush strength is ~3.5 MPa, so the pressure at the base of the wall is ~55% of the crush strength. So such an ice wall could barely stand (at least for a little while) on its own. However, I still suspect that it could not resist actual wind loads, and ice has a tendency to creep, and it starts to lose strength above -15 degrees C. So I take my hat off to the Game of Thrones writers -- they either guessed right, or had a structural engineer perform some quick sanity checks. Given that many CGI engineers know a lot about structural mechanics, it's conceivable that the CGI people themselves fed back information to the writers about the max height of the ice wall. At 02:08 PM 11/20/2016, Henry Baker wrote:
The TV series 'Game of Thrones' claims a 700' high ice wall.
Game of Thrones uses significant amounts of CGI, so the only place this ice wall exists is inside a computer.
Nevertheless, could a real ice wall of its dimensions be built and stand?
In various scenes, the ice wall is essentially vertical.
I haven't seen the more-or-less vertical ice walls created by 'calving' glaciers personally, so I don't know whether any of them attain 700' in height.
However, unlike those glacier ice walls, the Game of Thrones ice wall is 2-sided, and is warmer on one side -- enough to 'weep' under the sun.
Sooooo...
Based on standard Earth gravity and standard water ice, is a 700' ice wall possible?
Note that the GoT ice wall is flat, so it doesn't gain any stability from being curved, and as a result, could probably not stand up to the high winds that its mere presence would generate.
Ice is only a tad lighter than water, and 700' is approx. 22x the 32' of water that equals 1 atmosphere.
I don't think that WWII *steel* submarines could withstand 700' depths of water, so the pressure at the bottom of such a wall would be quite high and would likely require some reinforcement.
If anyone ever wants to get serious & build an ice wall -- e.g., on a frozen outer planet/moon/asteroid -- they'd be far better off using *pykrete*. I wonder if the creator of "The Martian" ever considered using pykrete in his story? https://en.wikipedia.org/wiki/Pykrete Pykrete is a frozen *composite* material made of approximately 14 percent sawdust or some other form of wood pulp (such as paper) and 86 percent ice by weight (6 to 1 by weight).* During World War II, *Geoffrey Pyke* proposed it as a candidate material for a huge, unsinkable aircraft carrier for the British Royal Navy. Pykrete has some interesting properties including its relatively slow melting rate (because of low thermal conductivity) and its vastly improved strength and toughness over ice; it is closer in form to concrete. Pykrete is slightly more difficult to form than concrete, as it expands during the freezing process. However, it can be repaired and maintained using seawater. The mixture can be moulded into any shape and frozen, and it will be extremely tough and durable, as long as it is kept at or below freezing. ... [Lord] Mountbatten's reaction to the breakthrough is recorded by Pyke's biographer David Lampe: What happened next was explained several years after the war by Lord Mountbatten in a widely-quoted after-dinner speech. "I was sent to Chequers to see the Prime Minister and was told he was in his *bath*. I said, 'Good, that's exactly where I want him to be.' I nipped up the stairs and called out to him, 'I have a block of a new material which I would like to put in your bath.' After that he suggested that I should take it to the Quebec Conference." The demonstration in Churchill's steaming bath had been most dramatic. After the outer film of ice on the small pykrete cube had melted, *the freshly exposed wood pulp kept the remainder of the block from thawing*. ... [Lord] Mountbatten entered the project meeting with two blocks and placed them on the ground. One was a normal ice block and the other was pykrete. He then drew his service pistol and *shot* at the first block. It shattered and splintered. Next, he fired at the pykrete to give an idea of the resistance of that kind of ice to projectiles. The bullet *ricocheted* off the block, grazing the trouser leg of Admiral Ernest King and ending up in the wall. --- * Not the most novel concept: the ancient Romans included straw in their cement & concrete; the Meso-Americans included straw in their sun-dried adobe bricks. --- Of course, due to global warming, pykrete is now completely impractical on Earth.
participants (3)
-
Brent Meeker -
Fred Lunnon -
Henry Baker