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Pertemuan 09BANGUNAN AIR

Matakuliah : S0182/Studi Kasus Dalam Teknik Sipil

Tahun : Juli 2005

Versi : 01/01

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Learning Outcomes

Mahasiswa dapat memperhitungkan berbagai kemungkinan dan memilih alternatif yang terbaik bagi penyelesaian masalah. C3, C4

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Outline Materi

• Kasus yang selalu dijumpai di proyek

• Kasus yang mungkin terjadi dengan kondisi khusus

• Analisa pemecahan masalah

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Type of DAM

Arch Dams

•An arch dam is a curved dam which is dependent upon arch action for its strength. •Arch dam are thinner and therefore require less material than any other type of dam. •Arch dams are good for sites that are narrow and have strong abutments.

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Arch Dams - Anatomy

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Arch Dams - History

It is rather astonishing that the Romans only sparcely applied the arch in dam constructions, a design otherwise so masterfully employed in their buildings and bridges. One of the few true arch dams built by the Romans was located in the Vallon de Baume, France in order to supply the nearby city with water. The dam was 12 m high and 18 m long.

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Arch Dams - HistoryKebar and KuritThe Mongolians built the first arch dams since the Romans. The earliest one was built around 1300 near Kebar, Iran. The Kebar dam was 26 m high, 55 m long. The arch did not abut against the canyon walls, instead it passed on both sides into straight wing walls. The second Mongolian arch dam was built around 1350 in Kurit, Iran. The Kurit dam is especially remarkable for its extraordinary height of 60 m -- it was the world's highest dam until the early 1900's. The dam was built in a very narrow canyon and its crest length reached only 44% of the height. It therefore remained erect, despite the fact that a large segment of lower half of the vertical downstream face broke away.

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Arch Dams - History

Postmedieval EuropeElche

The first true arch dam in Europe since the Roman times was built from 1632 to 1640 near Elche, Spain. The Elche dam's main arch was 75 m long

at the crest. The Elche dam was designed by Joanes del Temple.

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Type of DAM

Buttress Dams

•Buttress dams are dams in which the face is held up by a series of supports. •Buttress dams can take many forms -- the face may be flat or curved. •Explore the links below to learn more about buttress dams.

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Buttress Dams - Anatomy

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Buttress Dams - History

Roman Buttress DamsEsparragelejo

Whenever Roman engineers, often erroneously, judged the stability of a dam wall to be inefficient, they backed it up by irregularly spaced buttresses. But some dams were too thin. Buttress could not prevent the failure of the super

thin, 0.9 m dam wall at Ituranduz. By contrast, some dams were over designed. The Olisipo dam was 6.5 m thick and didn't need help from its buttresses. The most remarkable of the Roman buttress dams is the one

near the village of Esparragalejo. The 5.6 m high and 320 m long dam was supported in its central part with 12 buttresses averaging 1.2 m wide, 3.2 m

thick and spaced 8.6 m apart. However, the novel feature was that the downstream face of the 2 m wide dam wall became curved between the

buttresses. Thus, the first multiple arch dam was born!

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Buttress Dams - HistoryRoman Buttress Dams

Esparragelejo

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Buttress Dams - History

Buttress Dams in Postmedieval Europe

CastellarThe Castellar storage dam in

Spain was built around 1500 and had three water wheels to power

its mill house. The sturdy end and walls of the mill house were

actually buttresses ensuring the dam's stability. It is certainly no coincidence that this structural

concept re-emerged in a region in which the Romans had built many

buttress dams.

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Buttress Dams - History

Evolution of the Modern Buttress DamToday we understand buttress dams as derivations from the

massive gravity type with the introduction of intermediate spaces. These spaces allows the discharge of water seeping

through the dam and its foundation, thus greatly reducing uplift pressures. Given the absence of uplift, more substantial savings were possible by inclining the upstream face, thereby

mobilizing the vertical water load on the upstream face for sliding stability.

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Buttress Dams - History

Evolution of the Modern Buttress Dam

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Type of DAM

Gravity Dams Gravity dams are dams which

resist the horizontal thrust of the water entirely by their own

weight. Concrete gravity dams are

typically used to block streams through narrow gorges.

Because it is there weight holding the water back, concrete gravity dams tend to use a large amount

of concrete. This can be expensive.

But many prefer its solid strength to arch or buttress dams.

Explore the links below to learn more about gravity dams

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Gravity Dams - Anatomy

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Gravity Dams - History

The Roman EmpireEmperor Nero (AD 54-68) had a 40 m high, 13.5 m wide, and 80 m lonldam built for a pleasure lake near his villa at Subiaco, Italy. The dam was one of the earliest Roman dams and remained the highest the Romans ever built. Moreover, the Subiaco dam and two smaller dams nearby are the only Roman dams in Italy. Although the dam was to thin, it remained intact until it failed in 1305. Records blace the blame on two monks who took it upon themselves to remove stones from the dam, apparently in an attempt to lower the level of the lake which was flooding their fields.

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Gravity Dams - History

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Gravity Dams - History

Evolution of the Modern Gravity DamThe Correct Shape

In 1765 and 1800, the first triangular gravity dams were built in Mexico. Unfortunately, it remains unknown who their ingenious builder was. Amazingly, he/she had adopted the modern shape almost one century before it was developed in France. In 1850,

French engineer J. Augustin Tortene de Sazilly (1812-1852) showed in a lecture that the most advantagous profile for a gravity dam is

triagle with a verticle upsteam face. Sazilly also analyzed three recent French navigation dams in a paper published posthumously in 1853. He used the cross sections of these three dams to illustrate the confusion and uncertainty in the design of gravity dams. In fact,

two of the dams were wrongly inclined on the upstream side!

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Gravity Dams - History

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Gravity Dams - History

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Gravity Dams - History

Latest Ideas in Gravity DamsSteel

A relatively new development in the construction of gravity dams is incorporation of post-tensioned steel into the structure. This helped reduce the cross section of Allt Na Lairige Dam in Scotland to only 60 percent of that of a conventional gravity dam of the same height.

A series of vertical steel rods near the upstream water face, stressed by jacks and securely anchored into the rock foundation, resists the overturning tendency of this more slender section. This

system has also been used to raise existing gravity dams to a higher crest level, economically increasing the storage capacity of a reservoir. However, since reaching their prime in the 1960s, gravity dams have become something like a dying species, the dinosaurs

of an era which especially the idustrialized countries with their high labor cost no longer can afford.

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Type of DAM

Embankment Dams

•Embankment dams are massive dams made of earth or rock. •They rely on their weight to resist the flow of water. •Explore the links below to learn more about embankment dams.

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Embankment Dams - Anatomy

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Embankment Dams - History

Ancient TimesSadd-el-KafaraThe ruins of the Sadd-el-Kafara embankment dam were discovered over 100 years ago in the Garawi ravine in Egypt. The dam was built around 2600 BC and was 14 m high and 113 m along the crest. It is the oldest dam of such size known in the world. The of the dam was to retain the water from rare, but violent, floods.

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Embankment Dams - History

The Postmedieval Europe•Saint FerreolThe proposal of a large water supply reservoir turned out to be the key to build the Languedoc canal in France, which connected the Mediterranian Sea with the Atlantic Ocean. The reservoir would be used to conpensate the losses of water in the canal during the dry season. After the approval by King Louis XIV, the designs for the canal and dam were drawn up in 1662. The construction of the Saint Ferreol dam began in 1666 and was completed in 1675. •The dam consisted of a water retaining wall supported by a downstream embankment. In case of a too rapid depletion of the reservoir, the water retaining wall was stabilized by a lower embankment built against the upstream face. The result may be regarded as an earthen dam with a masonry core. With its height of 36 m, the Saint Ferreol dam remained the heightest embankment in the world for 165 years!

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Embankment Dams - History

The Postmedieval Europe

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Embankment Dams - History

Evolution of Modern Embankment DamsEmbankment dams in the U.S. prior to 1930 had a poor track record. Of

those over 490 ft high, almost 10% failed, usually due to overtopping in a flood. Overtopping is when the water level in the reservoir reaches

maximum height and begins to flow over the top of the dam. The South Fork dam in Johnstown,PA was one of the first to use rockfills, or loose

rocks, on the downstream face. This dam failed after being overtopped in 1889, kill over 2000 people.