Author Topic: Why are Tunnels Round?  (Read 22295 times)

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Offline KIZUNA

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Re: Why are Tunnels Round/// SURVIVAL TUNNELING ; CU CHI TUNNELS
« Reply #30 on: February 02, 2012, 09:55:30 AM »
Cu Chi Tunnels - Part 4: Tunnels' Defense

This is the fourth installment on the Cu Chi tunnels, a collection of quotations from the book by Mangold & Penycate (1985). This installment focuses on how the tunnels were defended; mostly from Chapter 10: Stop the Americans!

"[The] tunnels did need a defense system; they could not be left unprotected at the mercy of every GI foot patrol that stumbled upon a tunnel entrance or telltale ventilation shaft. The slow development of a tunnel defense strategy eventually owed much to Captain Linh's careful observations of the Americans during Operation Crimp.

"'They marveled at everything they saw,' he said, 'everything seemed strange and new to them - the jungle, the fruits, the water buffalo, even the chickens. Again and again they would stop and stare, even pick things up. Not only were they easy targets for our snipers, but I realized the best way to kill them was with more booby traps. After Crimp, we made more and more of them. I was sure they would work well for us.'

"[The homemade booby-trap business began to boom. Those with access to explosive powder, detonators, and a crude tunnel workshop, produced first and foremost, the DH-5 or DH-10 mine. These were modeled on the successful American claymore mine, and were to be used primarily against the American light armored tracks and half-tracks, and inevitably against unwary infantrymen. They were detonated either by pressure or - and this was a surprise - by command (remote-detonated)." (p. 109)

"The DH-5 and DH-10 were made out of crude steel, shaped like a saucer and containing five or ten pounds of high explosive. The mines stood on bipods pointing directionally, or they would lie buried a few inches underground. They inflicted dreadful injuries. [...]

"Tunnel rat Lieutenant David Sullivan ... recalled a particularly devious Viet Cong booby trap. A tunnel entrance would be exposed to lure the Americans. When a rat tem was sent down to investigate, the guerrillas in the tunnel knew that other GIs would gather round the entrance for communication or on guard. A claymore mine hidden in a nearby bush would then be detonated by wire from inside the tunnel. Sullivan lost several men like that: The VC waited until they heard the rats in the tunnel and then blasted the men still on the surface. In the confusion, the rats aborted the search and the guerrillas escaped into the tunnel system.

"One of the most feared variants of the DH-10 was the notorious Bouncing Betty, conical, with three prongs jutting out of the soil. When a foot struck a prong, a small charge was detonated, which shot the mine into the air about three feet, where it then exploded, showering shrapnel at groin level.
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Offline KIZUNA

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Re: Why are Tunnels Round/// SURVIVAL TUNNELING ; CU CHI TUNNELS
« Reply #31 on: February 02, 2012, 10:11:27 AM »
CONT'N...AND LAST PART OF THE SERIES....

"For sheer ingenuity in adapting to local warfare conditions, a guerrilla farmer from the Cu Chi village of Nhuan Duc was to win the top award. To Van Duc invented a helicopter booby trap. It was known as the cane-pressure mine and for a while it was a successful (and to the Americans, quite baffling) answer to the problem of how to destroy the helicopters that brought troops and supplies into the jungle. [...]

"Mindful of the simple physical principle that the blades of a helicopter create a considerable downdraft, the farmer (To Van Duc) suggested placing DH-10 mines at the TOPS of trees in an area where the helicopters could be expected to fly fairly low, or one to which they could be lured to fly low for surveillance. A highly sophisticated friction fuse was connected to the branches of the tree or fairly tall bush, which bent under the helicopter's downdraft, detonating the mine, which then exploded under the machine. " (p. 110-111)

"At the other end of the evolutionary scale of weapons were those that owed more to the War of the Roses than to the high-tech was in Vietnam. There was the crossbow and arrow ... Historically cotemporaneous was a ... heavy mud ball with spiked bamboo stakes sticking out of it. This was attacked to a tree by a seemingly innocuous jungle vine. When freed by the tripwire, the ball swung hard across the track.

"Then there was the coconut mine, a hollowed-out nut packed with explosive powder and then covered by a rock as the missile - not lethal but scary. Or there was the bamboo mine. This was large bamboo joint, cleaned out and filled with nuts, bolts, broken glass or scrap metal, together with a small amount of plastic explosive or powder explosive. A friction fuse operated by a tripwire detonated this package.

"The most common ... booby trap was the wired grenade, used in tunnel entrances or in the tunnels themselves. [...] On jungle tracks and paths near the tunnels a favorite tactic was to place the grenade, with the safety pin removed, inside an appropriate tin can. A pull on the tripwire extracted the grenade from the can, which then automatically primed itself and exploded. [...]

"And there was the infamous punji stick traps around all the tunnels. Sometimes the Viet Cong dug tiger-trap pits; if a GI fell into one, he became impaled on the spikes. The trap was kept to reasonable size so that it could easily be camouflaged with twigs and foliage. but its depth was sufficient so that the victims foot would descend with enough force for the stakes to pierce ... the GI's jungle boot. A more sophisticated version had stakes buried in the wall of the pit, but facing downward, making extraction of the foot even more painful. Sometimes the sticks were smeared with excrement to aid infection, sometimes with a poison the VC simply called Elephant's Trunk, which they claimed caused death within twenty minutes of entering the bloodstream. " (p. 112-114)

"Inside the tunnels there were occasionally false walls, thinly plastered with clay, on the other side of which waited Viet Cong with bamboo spears. As a tunnel rat (American soldier) made his way slowly forward, the VC would spy through a hole in the false wall and spear [him]. [...]

"Booby traps and ambushes took a disproportionately high toll among infantrymen and remained a source of great anxiety to military tacticians in Vietnam. Throughout the war, booby traps were responsible for 11% of all American deaths, and 17% of all wounds.

"Real damage was often caused by the high rate of wound infection. [...] The ... booby traps inside and just outside the tunnels generated sufficient fear among the ordinary grunts to seriously affect their military effectiveness. A high-tech infantry that usually fought only by day and was helicoptered out by night was not necessarily going to go out of its way to discover long tunnel complexes. Everyone knew about the booby traps. And what the grunt eye did not see on patrol, no officer's heart was going to grieve about.

"In a revealing study conducted by Lt. General Julian J. Ewell, former commander of the II Field Force in Vietnam, it was shown that at least half the booby traps found by the 9th Division's GIs had been found by detonation - in other words, the men had set them off. 46% of the resultant casualties were multiple, caused by the bunching of troops, who just did not know any better. In 1969, booby traps were the single most important casualty source in the 9th Division. [...]

"If the tunnels' outer defenses failed to deter, the next line of defense was the so-called spider hole. Spider holes were superbly camouflaged pits, dug to shoulder depth near each of the three tunnel entrances, and linked by short communications tunnels to the main tunnel. One, sometimes two, Viet Cong snipers stood, perfectly protected, and shot at intruders; when it became too dangerous to stay, they scuttled through the communication tunnel back into the main tunnel complex. No sophisticated detection or weapons system could easily or mechanically find, fix, and destroy the ubiquitous spider-hole sniper. He could be (and frequently was) mortared, shelled by artillery, napalmed, or besieged by tank. But the longer he fought, the more he fulfilled his primary function, which was to engage large numbers of the enemy and keep them busy, distracting them from the real prize, the tunnel complex over which he kept his lonely vigil." (p. 115-116)
Light travels faster than sound. This is why some people appear bright until you hear them speak.

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Offline KIZUNA

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Re: Why are Tunnels Round/// SURVIVAL TUNNELING ; CU CHI TUNNELS
« Reply #32 on: February 02, 2012, 10:18:18 AM »


  NOW, FOR OUR FINAL ANALYSIS;;

  LOOK AT THE DIAGRAM BELOW; (Buddies, Janner and THunter ,can't help spoon feeding them again..)
Light travels faster than sound. This is why some people appear bright until you hear them speak.

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Offline KIZUNA

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Re: Why are Tunnels Round?
« Reply #33 on: February 02, 2012, 10:33:30 AM »
MY NEXT POSTINGS WOULD BE ABOUT JAPANESE TUNNELS, BOTH THEIR OLD AND MODERN TUNNELING TECHNIQUES...
Light travels faster than sound. This is why some people appear bright until you hear them speak.

KZN

Offline Janner

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Re: Why are Tunnels Round?
« Reply #34 on: February 02, 2012, 12:10:27 PM »
to compliment this narration. here is my pdf file of booby traps to download....

http://www.lexpev.nl/downloads/fm531boobytraps1965.pdf

be wise, or be dead... ;)

Offline Janner

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Re: Why are Tunnels Round?
« Reply #35 on: February 02, 2012, 12:46:51 PM »

Offline Janner

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Re: Why are Tunnels Round?
« Reply #36 on: February 02, 2012, 01:10:06 PM »
last info pack...

The majority of Imperial Japan's munitions are grossly unstable. Wartime Japanese military ordnance manufacturers  also used an acid-based explosive that, with time, degrades into a kind of salt known as "picrates".
These salts are extremely sensitive. The slightest jar or even the abrupt change in altitude caused by picking them up then suddenly can be enough to detonate their explosion.
How not to get caught by Vietnamese boobytraps - US guide dated 1969

http://www.scribd.com/haraoi_conal/d/31754606-navpers-16110-%E2%80%93-BOOBY-TRAPS-1944

regards

t_hunter44

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Re: Why are Tunnels Round/// SURVIVAL TUNNELING ; CU CHI TUNNELS
« Reply #37 on: February 02, 2012, 01:32:11 PM »


  NOW, FOR OUR FINAL ANALYSIS;;

  LOOK AT THE DIAGRAM BELOW; (Buddies, Janner and THunter ,can't help spoon feeding them again..)
Way to go and they get pampered and spoiled but the joy of giving is better than receiving, keep going, you are on the right track.

Offline KIZUNA

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Re: Why are Tunnels Round?/// WORLD WAR TWO JAPANESE TUNNEL
« Reply #38 on: February 03, 2012, 10:17:04 PM »

1ST SERIES

There are very few signs pointing to the tunnels---relatively flat land, it is surrounded by steeply climbing hills when site was selected the steepness of the slopes was the most important consideration because the main threat was air power., a small, totally unimportant. There was nothing in particular to distinguish it from the air. The forests and slopes borders  so camouflaging the entrances of each complex was relatively easy to do.

So apart from being able to hide the facilities easily, from an anti-aircraft perspective it was also a strong defensive position. (radio transmissions were easy to identify and then locate via triangulation). However mid/high altitude bombing would have been completely ineffective due to the amount of overhead cover the mountains provided, probably even against special ordnance, and dive bombing missions suicidal - the aircraft simply not having sufficient room to pull out of the dive before hitting the ridge. Each tunnel complex had multiple entrances, and even direct hits on an entrance would have caused relatively little blast damage to the majority of the tunnels in each complex.

Even if you are of average height, you will need to stoop as you walk down the narrow entranceway - the reason the entrance is narrow is for defense against bomb blasts, and only after 100 meters and several 90 degree turns does the passageway widen and the tunnel become more spacious. It is cold inside even in summer, though the main section is well illuminated. A powerful torch can be useful if they want to have a look down any of the numerous cross tunnels.
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Offline KIZUNA

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Re: Why are Tunnels Round?
« Reply #39 on: February 03, 2012, 10:27:07 PM »

Conditions during the construction were terrible. The pressure and insufficient allocation of resources meant that accidents were frequent. Drilling and other tunnelling equipment was in short supply, so hand drills and dynamite were used. Working with dynamite requires training - but there wasn't enough time, so avoidable accidents were constantly repeated. Overhead supports that should have been completed and checked before tunnels were further extended were often unable to be built due to the materials not being available in sufficient quality or quantity etc, leading to frequent tunnel collapses. Iron and steel were in short supply, Even the extensive tram system developed to move rock out of the tunnels used wooden rails on the sleepers instead of steel. We still do not know how many people died digging the tunnels .Apart from cave-ins, explosions, illness (the food supply was the greatest need was also being affected by the bombings, appropriations, and local decision makers), and physical collapse due to overwork and malnutrition, there were also suicides amongst the workers, as well as executions.
Light travels faster than sound. This is why some people appear bright until you hear them speak.

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Offline KIZUNA

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Re: Why are Tunnels Round?/// WORLD WAR TWO JAPANESE TUNNELS
« Reply #40 on: February 03, 2012, 10:37:12 PM »
DISCOVERED JAPANESE WWII TUNNEL SYSTEM
OPENED
This is in reference to the previous works of the team in Papua New Guinea and for educational purposes letís take a look of how ww2 JIA tunnels look like, here if we are just keen enough we will gather many hints.


The Team
Pacific Ghosts' founder, Justin Taylan is a professional videographer and webpage designer. He has resources and information on topics related to the Pacific War. Instrumental in the project is New Zealander, John Douglas, a Papua New Guinea resident who has been responsible for countless WWII discoveries in New Guinea for the past decade.

The exploration team also consist of the curator of the Modern History Department, a PNG Self-Defense Force soldier specializing in EOD (Explosive Ordinance Disposal) and videography unit. Their mission will be to explore, document, map and identify the contents of the cave system, and make recommendations about their future to the PNG Museum, and government of Japan.

During WWII, massive tunnel systems were excavated and built by the Japanese forces around Papua New Guinea (PNG) during their years of occupation. In Wewak Township, an equally large, but all together forgotten tunnel systems also exist. Immediately after the war, it was sealed shut, complete with weapons, contents and the remains of its defenders entombed inside.

Permission Granted to Explored These Sealed Tunnels
No serious effort has ever been made to explore and document the tunnel area, Pacific Ghosts, a critically acclaimed historical company, has been granted permission by the Papua New Guinea National Museum to explore and document these tunnels for the first time...
 
Inside the Tunnels
Behind feet of concrete used to seal the two known entrances, are a series of tunnels and a forgotten world yet to be explored. Work included interviews with locals who built the tunnels, and worked in them during the war. Also, the ex-patriot who sealed the tunnels immediately after the war, assisted the team in navigation thru the vast area of tunnels.
 
Found?, an underground hospital, with the remains of its occupants is one location. This tomb have been documented, and relayed to the Japanese government for proper burial and services.
 Also, vast amounts of munition and armaments for the system's large artillery guns and cannons that were emplaced in the area. Also, the team is targeted storage areas for Japanese aircraft, such as the Ki-43 "Oscar" and Ki-61 "Tony" fighters, stored in crates, or component parts. There are hidden caches of gold and other war booty. The real 'treasure' is the undisturbed tunnels themselves, and the mysteries they revealed.
Light travels faster than sound. This is why some people appear bright until you hear them speak.

KZN

Offline KIZUNA

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Re: Why are Tunnels Round?/// WORLD WAR TWO JIA TUNNELS
« Reply #41 on: February 03, 2012, 10:39:35 PM »
Tunnel System

As told by Justin Taylan

Before visiting Rabaul, I doubted that the written claims that there were hundreds of kilometers of tunnels built during the war. After a day of walking some of them, I now fully agree with this figure! With the help of some local kids, I walked kilometers of these infamous tunnels, most dug by POW and slave labor.
Light travels faster than sound. This is why some people appear bright until you hear them speak.

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Offline KIZUNA

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Re: Why are Tunnels Round?///WORLD WAR TWO JIA TUNNELS
« Reply #42 on: February 03, 2012, 10:46:17 PM »
.......WORLD WAR TWO JIA TUNNELS
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Offline KIZUNA

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Re: Why are Tunnels Round?
« Reply #43 on: February 03, 2012, 10:48:53 PM »


Tunnel Construction

The packed volcanic ash makes excavation easy. This seaside cliff face was loose enough to come apart with a hard touch. They have been empty since the war.
Light travels faster than sound. This is why some people appear bright until you hear them speak.

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Offline KIZUNA

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Re: Why are Tunnels Round?
« Reply #44 on: February 03, 2012, 10:52:03 PM »
Local Guides
It was not long before a group of local children came out to see me, and offered to show me some of the tunnel systems near their village. We walked into one of the many gully systems of dried stream beds that lead inland. As we walked, they pointed upward to tunnel entrances that were invisible to me. The impressive part was this was just one of many gullies in this area alone.
 
Determined Defenders
I was imediately struck by the fact that the Japanese defenders here were determined to escape the bombings of Rabaul, and in the event of a landing, would have been impossible to route without severe casualties. Although there were no guns pointed at us, it produced an errie feeling to know that an unknown number of tunnels and troops would have been positioned above and around us.
Light travels faster than sound. This is why some people appear bright until you hear them speak.

KZN