Author Topic: Why are Tunnels Round?  (Read 21450 times)

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DINDO BAYAUA

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Re: Why are Tunnels Round?
« Reply #15 on: December 11, 2011, 06:50:31 PM »
« Last Edit: December 11, 2011, 06:55:45 PM by DINDO BAYAUA »

Offline Myres

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Re: Why are Tunnels Round?
« Reply #16 on: December 11, 2011, 07:43:30 PM »
He he. That stuff is too technical for me, Sir Dindo. I wouldn't want to overburden my limited mental faculties. Ha ha!

DINDO BAYAUA

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Re: Why are Tunnels Round?
« Reply #17 on: December 11, 2011, 07:59:59 PM »
The point is: the shapes of tunnels thru the engineering designs.

Offline admin

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Re: Why are Tunnels Round?
« Reply #18 on: December 11, 2011, 10:16:05 PM »
Using hand tools - HOW do you dig a round tunnel? Must be quite hard to make it perfectly round.
TW
« Last Edit: December 12, 2011, 08:18:44 PM by admin »

Offline Janner

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Re: Why are Tunnels Round?
« Reply #19 on: December 12, 2011, 12:54:04 PM »
Take a look at modernized cave dwelling in Spain, nearly got one of these, they are brilliant as a temp of 18 degrees
inside all year round...

anyway take a look...

http://cavesspain.com/listing.php?type=3


Regards

t_hunter44

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Re: Why are Tunnels Round?
« Reply #20 on: December 13, 2011, 02:44:08 AM »
        Here are some pictures of Tunnel Boring Machines and they are humongous in size but of course those is not feasible for us Treasure Hunters. The Philippines can use it on road constructions for instead of going up hills and mountains to go to the other side, all they need is to bore a hole though the mountain side all the way to the other side, wishful thinking.
http://www.google.com/search?q=tunnel+boring+machines&hl=en&client=firefox&hs=ntq&rls=com.yahoo:en-US:official&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=QkbmTuD0Eq_gsQLWy5nRBA&ved=0CEAQsAQ&biw=1196&bih=656
       In the use of hand tools, crowbars, pick and shovel and for the more equipped treasure hunters, electric jackhammers, if they can dig squarish tunnels or vertical shafts, with those same tools they can also make it roundish in form, does not have to be a perfect circular hole, on tunnels, the upper portion can be rounded to about 3/4 of the tunnel and the remaining lower portion can be level, or the upper half can be Rounded or Arched as the most Stress is on the overhead or ceiling, see the Link posted by DB. The Romans, the Greeks and other older nations has made use of the Arches for load bearing structures like bridges and big entrances or gateways.

Offline admin

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Re: Why are Tunnels Round?
« Reply #21 on: December 13, 2011, 10:25:39 AM »
Good info, Gents!
Thanks.
TW

Offline Myres

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Re: Why are Tunnels Round?
« Reply #22 on: December 13, 2011, 12:44:43 PM »
Wow! Such awesome boring machines. They would probably turn the gold bars into peelings if they hit them... :o

Offline KIZUNA

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Re: Why are Tunnels Round?
« Reply #23 on: February 02, 2012, 09:13:55 AM »
Anyhow friends, generally tunneling is purposely "survival tunneling"
Let's take a quick review and take lessons to one of the best tunnelers in the world  (aside from the japanese & others), let's focus first to the Vietnamese and the Vietcongs on their;

In light of the emergence of the Tunnels of Gaza, which have been dug and developed as a response to prison conditions imposed on the entire Gaza Strip, it is instructive to study other instances of tunnels used to combat oppression, particularly in anti-colonial/anti-imperialist struggles of the Vietnamese people against the French and later the Americans.

CU CHI TUNNELS


A four-part series of quotations from an educational book, The Tunnels of Cu Chi, (Tom Mangold & John Penycate; 1986); a detailed look at one of the most crucial technical aspects of the Vietnamese liberation movement:

1) Introduction
2) Strategic Import & Structure
3) Resource Management
4) Tunnels' Defense

All the quotes below are from a book by Tom Mangold and John Penycate, titled, The Tunnels of Cu-Chi (1986).

"The underground tunnels of Cu Chi were the most complex part of a network that -- at the height of the Vietnam War in the mid sixties -- stretched from the gates of Saigon to the border with Cambodia. There were hundreds of kilometers of tunnels connecting villages, districts, and even provinces. They held living areas, storage depots, ordnance factories, hospitals, headquarters, and almost every other facility that was necessary to the pursuit of the war by the South Vietnam's Communists and that could be accommodated below ground." (p. 15)

"No single military engineer designed this vast labyrinth, nor -- despite Vo Nguyen Giap's overall generalship in Hanoi -- did any one commander order it to be built. The tunnels evolved as the natural response of a poorly equipped and mainly local guerrilla army to mid-twentieth century technological warfare. Aircraft, bombs, artillery and chemicals obliged the Viet Cong to live and fight underground ... [By] becoming an army of moles pitched against armies winged into battle by helicopter, the Viet Cong guerrillas, and later the North Vietnamese army, protracted the war to the point of persuading the United States that it was unwinnable. " (p. 15-16)

"The district of Cu Chi (pronounced ku-chi), in what was South Vietnam, became the the most bombed, shelled, gassed, defoliated and generally devastated area in the history of warfare. For years, most of Cu Chi suffered the fate of being a "free fire zone". That meant random artillery fire, known as "harassment and interdiction" rained upon it ... Bomber pilots were encouraged to offload unused explosives and napalm over Cu Chi before returning to base." (p. 17)

"The strategic significance of this part of South Vietnam is self-evident: It straddled the main land and river routes into Saigon. During the war, these were the Viet Cong's supply routes from Cambodia, where the Ho Chi Minh trail from North Vietnam ended. Secondly, Cu Chi district covers the only sizeable territory in South Vietnam across which troops and vehicles can move easily, even in the monsoon rains that fall on the area in summer months every year." (p. 18)

"The tunnels in Cu Chi were originally dug as hiding places for the Viet Minh, the nationalist guerrillas who fought the colonial power, France, in the 1940s and 1950s." (p. 20)
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?///SURVIVAL TUNNELING: CU CHI TUNNELS
« Reply #24 on: February 02, 2012, 09:17:02 AM »
From the prelude, this poem:

The Mother -- The Native Land
by Duong Huong Ly

When she dug the tunnels, her hair was still brown.
Today her head is white as snow.
Under the reach of the guns she digs and digs.
At night the cries of the partridge record the past.
Twenty years, always the land is at war.
The partridge is the night cries out the love of the native land.
The mother, she digs her galleries, defenses,
Protecting each step of her children.
Immeasurable is our native land.
The enemy must drive his probes in everywhere,
Your unfathomable entrails. Mother,
Hide whole divisions under this land.
The dark tunnels make their own light.
The Yankees have captured her.
Under the vengeful blows she says not a word.
They open their eyes wide but are blind.
Cruelly beaten, the mother collapses.
Her body is no more than injuries and wounds.
Her white hair is like snow.
Night after night
The noise of picks shakes the bosom of the earth.
Columns, divisions, rise up from it.
The enemy, seized by panic, see only
Hostile positions around him.
Immeasurable is our native land.
Your entrails, Mother, are unfathomable.

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?/// SURVIVAL TUNNELING : CU CHI TUNNELS
« Reply #25 on: February 02, 2012, 09:28:00 AM »
In this second installment about the tunnels of Cu Chi district in Vietnam, we will continue to quote from the book, The Tunnels of Cu Chi (Mangold/Penycate, 1985). This installment will focus on the strategic significance and the structure of the Cu Chi tunnels, which were highly instrumental in the Vietnamese guerrilla fight against the American military machine (for a diagram of a typical tunnel system,

 see below, (and hey here's a tip here fellows, there might be a pattern here that you can follow in your T.H cave sites here in the Philippines---so STUDY THIS CLOSELY...

SEE THE DIAGRAMS BELOW
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Offline KIZUNA

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Re: Why are Tunnels Round?/// SURVIVAL TUNNELING : CU CHI TUNNELS
« Reply #26 on: February 02, 2012, 09:32:23 AM »
second installment about the tunnels of Cu Chi district in Vietnam

"On 28 September 1967, a detachment of the Korean 28th Infantry Regiment of the 9th (S. Korean) Division captured a remarkable document during a sweep north of Saigon ... The document appears to be ... the only tunnels manual ever issued by the Communists. It is a ten-page technical and political booklet, revealing many secret details about the tunnels' structure and strategic purpose ...

" The primary role of the tunnels is stressed and re-stressed. 'They are for the strengthening of combat vitality for our villages. They also provide more safety for our political and armed units and for the masses as well. But their sheltering purpose in only significant when they serve our soldiers in combat activities. As mere shelters, their great advantages are wasted.' ... 'There must be combat posts and equipment inside the underground tunnels for providing continuous support to our troops -- even if the enemy occupies the village.' The document [continues]:

    'If the tunnels are dug so as to exploit their effectiveness fully, the villages and hamlets will become extremely strong fortresses. The enemy may be several times superior to us in strength and modern weapons, but he will not chase us from the battle-field, because we will launch surprise attacks from within the underground tunnels. We can see that underground tunnels are very favorable for armed forces as limited as ours, in strength and weaponry.'

"The tunnels would be crucial for launching close-in attacks on the Americans and would also provide opportunities to seize their weapons; they would provide excellent mobility and 'we may attack the enemy right in the center of his formations or keep on fighting from different places.'" (p. 56-57)

"[The tunnel] system was to be simple and effective: 'We must plan for the eventual impossibility of fighting from inside the underground tunnels. A secret passage must then be available from which our troops may escape and fight in the open, or reenter the underground passage if necessary.' The passages of the tunnels were not to be either straight or 'snakelike', but were to zigzag at angles of between 60 and 120 degrees ... Zigzagging ... [made] a straight line of fire inside impossible, and helped deflect explosive blasts.'" (p. 57-58)

"A clever and finely engineered trapdoor system was devised ... to create entrances and exists to secret passages and from one tunnel level to another ... Air, sanitation, water supplies and cooking facilities were sufficient to maintain a primitive but reasonably safe existence. It was crucial to the whole plan that even if the first tunnel level was discovered, the secret trapdoor that led down to the next would remain hidden from the enemy. That meant making trapdoors that were virtually invisible." (p. 58)

"The sides of the trapdoor were usually beveled downward at an angle so that it could take considerable over-pressure. There was no sag. If the trapdoor was inside the tunnel, the VC placed earth on top of it and hid in the earth small finger wires, which allowed a soldier to lift the door. If the trapdoor was outside, then small plants would be encouraged to grow on it, or dead foliage would be ... planted to make it as one with the environment.

"Ventilation holes were simplicity itself. They ran obliquely from the surface to the first level -- obliquely to avoid monsoon rain flooding in. Some always pointed east toward the preferred light of the day. Others, 'must be turned toward the wind.'" (p. 59)

"Entrances to the tunnels were carefully and precisely engineered to cater for various contingencies. The ... manual explained:

    'Because the activities of the militia and the guerrillas require appearing and disappearing quickly, the entrances to the underground tunnel must be located like the corner of a triangle, so that each can support the other in combat. Our troops must also be able to escape from the underground tunnel through a secret opening so they may continue to fight.'
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Offline KIZUNA

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Re: Why are Tunnels Round?/// SURVIVAL TUNNELING ; CU CHI TUNNELS
« Reply #27 on: February 02, 2012, 09:36:40 AM »

"Entrances to the tunnels were carefully and precisely engineered to cater for various contingencies. The ... manual explained:---(Hahaha, so there's a Manual, ;) ;) ;) ;) :D ;D

    'Because the activities of the militia and the guerrillas require appearing and disappearing quickly, the entrances to the underground tunnel must be located like the corner of a triangle, so that each can support the other in combat. Our troops must also be able to escape from the underground tunnel through a secret opening so they may continue to fight.'

"The entrances also had to be able to resist fire, flood, and chemical warfare: 'for this reason, we must locate the entrances to the tunnels in dry, elevated, and well-ventilated areas. Such an entrance will not be blocked by the chemicals that will otherwise kill the occupants. Also rainwater will not stagnate in the entrance so located.'" (p. 59)

"[The] fact remains that the tunnels of Cu Chi were the primary factor in fighting the campaign against the Americans, and if sloppiness or engineering imprecision infected the building of the system, the communists would lose.

"Some first-hand evidence of the stability and efficiency of the Cu Chi tunnel system fell into American hands when a VC guerrilla, Ngo Van Giang, was captured by the S. Vietnamese on 31 January 1968. In a sixteen page debriefing statement, Giang is quoted at length by his interrogators on the subject of the Cu Chi tunnel network. He told his captors where a tunnel became an open bunker, special roofs had been constructed by using 50-cm-thick layer of 'husks'. Then there was a layer of dirt 50 cm thick. On top of the dirt, they had planted flowers or used fallen trees as camouflage. Incredibly, according to Giang, if a 200-kg bomb fell within just ten meters of the tunnel, no damage would result. The husks and leaves used were excellent protection against bomb blast. Bamboo poles were also employed for their resilience. 'In April 1966,' Giang told his captors, 'an airplane dropped a 200-kg bomb at Chua hamlet, and the bomb hit right on this type of tunnel. The dirt and husks caved in, but the cadre [inside] was not wounded.'" (p. 60-61)

"One of the most important secrets of kept from the Americans during the entire war, according to Major Quot, was that the construction of the tunnels was such that each section could be sealed off. 'The Americans thought that our armed forces were confined to one tunnel and that they were able to kill everybody down there by blowing down gas or pumping down a large quantity of water. But this was not so. It was important that the enemy never understood this.'" (p. 64)

"Although the tunnels were natural shelters against the U.S. bombing attacks, further special protection became necessary when the bombing increased in ferocity. So, the tunnelers dug conical A-shaped shelters that were geometrically designed to resist both artillery shells and bomb blast. More important, their conical shape acted as an amplifier and magnified the distant sound of approaching B-52 strikes. This was the only warning tunnel dwellers might get of an imminent attack." (p, 64-65)
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Offline KIZUNA

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Re: Why are Tunnels Round?/// SURVIVAL TUNNELING ; CU CHI TUNNELS
« Reply #28 on: February 02, 2012, 09:43:38 AM »
[u]Cu Chi Tunnels - Part 3: Resource Management [/u]

In this third installment of quotations from the book, The Tunnels of Cu Chi , we bring you some of the ingenuities employed by the Vietnamese in their fight for liberation.

One of the aspects of any fight against an oppressor throughout history has been the task of adapting elements ready at hand in the effort to gain some comparative advantage over the enemy. One particular form of this, mastered by the Vietnamese liberation fighters, was to use whatever 'garbage' the enemy left behind.

This became clear to some of the people (the Australians) fighting against the Vietnamese, but the lessons were soon overlooked or never fully appreciated by others (the Americans). As an example, the book by Mangold/Peycate points to an episode during the Operation Crimp, one of the first operations carried out by the American and Australian military personnel in the district of Cu Chi, in early January 1966.

"[The Australians] realized the value to the Viet Cong of American combat detritus, after [finding] a small tunnel workshop in which hand grenades had been made. The inner casing was made from a small discarded tomato juice tin, and the outer casing from an old beer can. The fragmentation pieces were blue metal road gravel, and the firing mechanism was from old French or American grenades. 'Because of what we found in the tunnels ... we ordered this policy of burn-bash-bury. We had twenty-four-hour ration packs with little tins on them. You never EVER left your tin around so it could be found; you never left anything the enemy could use. Your spoon, they would even use that for making weapons. We left nothing, absolutely nothing,'" (p. 44). This was the lesson that was learned by the Australians, according to the book, and not adhered to by the American GIs.

"As the war became harder on the Viet Cong, they used the waste so generously left around by the Americans more and more, and in some areas, they became dependent on it." (p. 44)

* * *
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Offline KIZUNA

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Re: Why are Tunnels Round/// SURVIVAL TUNNELING ; CU CHI TUNNELS
« Reply #29 on: February 02, 2012, 09:47:52 AM »
contn...part 3..

"Next to food for survival, the manufacture of ammunition and weapons had priority in the tunnels. In the early days of the American presence, there were serious shortages. 'We hardly received any supply of weapons from the North,' said Captain Linh. 'We received only mine detonators and delay fuses. We needed explosives and fortunately soon found them lying all around us on the ground.'

"One single battalion of the newly arrived 25th Infantry Division in Cu Chi fired, in the course of one month, no less than 180,000 shells into the Cu Chi district, averaging 4,500 daily. In one month, throughout South Vietnam, the Americans fired about a trillion bullets, 10 million mortar rounds, and 4.8 million rockets. And this was just the beginning of the war.

"As Captain Linh noted, a great deal of this ordnance fell on Cu Chi. And considerable numbers, as is the nature of these things, failed to explode. For once it was the Viet Cong that began a course of on-the-job training. 'We tried to understand the American science,' explained Captain Linh. 'We would have teams of watchers during a bombing strike, looking for the bombs that did not explode. They would try to mark the location. Then after the raid we would hurry to the spot and try to retrieve the TNT ... [Of] a thousand shells the enemy fired at us, only about a hundred caused casualties; a percentage of the nine hundred that did not hurt [anyone] did not explode either. The Americans used their weapons to fight us and we used their weapons to fight back.'

"Captain Linh's cottage industry began to grow. 'There were unexploded shells everywhere in the Cu Chi area. We organized special workshop chambers in the tunnels and we learned to take the ordnance in there. We dismantled their detonators, fitted our own, and changed the shells into powerful weapons, of which the Americans were very afraid. We exploded them with batteries or made booby traps with them. We also found claymore or directional mines, which did not explode because the bombers did not drop them from the proper height or at the right angle. Sometimes we even had more of these mines than we could use. With each claymore mine, suitably adapted in our tunnel workshops, we could inflict casualties of up to seven American soldiers. We did not need any great technical skill. They were very dangerous to the Americans, but harmless against us when we were in the tunnels.'

"Coca-Cola cans, in an act of ironic cultural inversion, were carefully turned into hand grenades for use against the Americans by the artisans who worked by candlelight and paraffin lamp in the special tunnel workshops. First they poured used bomb fragments into the tin, then TNT was poured into the middle, and finally a homemade detonator was placed on the top. Major Quot recalled: 'At every hamlet underground in the Cu Chi tunnels we had a productive team making mines and hand grenades and repairing firearms. [...] We even organized a little assembly line -- one person specialized in taking the explosive out of the 'dud' American shells, another prepared it, and a third fitted the detonator into the mine itself.' This underground arms industry was to be far more than just a nuisance to the Americans. It was to become the primary means for denying the GIs access to the tunnels complex.

"The electrical power to run the workshops came principally from small hand or foot generators. 'The signals unit had a small gasoline-driven generator,' said Captain Linh, 'but these were rare. Usually there were pedal generators, some hand generators from China, and batteries. We were never short of electricity in Cu Chi; we even threw away dim torch batteries and used only bright ones. We were 'presented' with batteries by the Americans; they were easy to pick up.'"(p. 72-74)

"Only a few GIs ever penetrated the second or third tunnel levels. Jan Shrader ... explored one second-level section and recalled finding chambers over five meters high. 'It was incredible, all that space ... the thing we found more than anything else was arms and materiel, but in very good storage." [...] Shrader also found tunnel workshops where fairly sophisticated armaments were being copied. 'There were these workshops set up where they actually made small arms, Chinese copies of Thompson submachine guns and different French designs. They'd take a French machine gun which they'd captured ... and set up a little tunnel workshop and start turning out copies by hand. They made hand grenades, ammunition, and lots of mines.'

"Sergeant Arnie Gutierrez did discover what some of the largest underground store rooms were for. 'In the chambers, which were fifteen feet high, they were assembling artillery pieces and big mortars. They would be stripped down outside the tunnels, carried through, assembled during the night inside the tunnel, for maintenance or whatever, stripped, and then taken back through the tunnel and out again, reassembled and used. No wonder we never found their guns outside. In one set of underground chambers we found two 105 field guns. These two 105s were over forty years old and they were still in perfect condition. Can you imagine it, putting damn great field howitzers to bed every night in a tunnel?" (p. 74-75)

"In 1966, the Viet Cong managed to steal an M-48 tank from the ARVN (South Vietnam army) unit north of Lai Khe, an event which caused understandable consternation on the government side. Three years later, the Americans found it -- in a tunnel. It had been buried about six feet down and tunnels had been dug around it. The tank itself was used by the VC as a command center; the batteries, the lights and the radio were still working." (p. 75)
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