Bendungan: Perbedaan antara revisi

 

 

== Jenis bendungan ==

 

Dam dapat diklasifikasikan menurut struktur, tujuan atau ketinggian.

 

 

Tujuan dibuatnya termasuk menyediakan air untuk [[irigasi]] atau [[penyediaan air]] di perkotaan, meningkatkan navigasi, menghasilkan [[hidroelektrik|tenaga hidroelektrik]], menciptakan tempat rekreasi atau [[habitat (ekologi)|habitat]] untuk ikan dan hewan lainnya, [[pencegahan banjir]] dan menahan pembuangan dari tempat industri seperti [[pertambangan]] atau [[pabrik]]. Hanya beberapa dam yang dibangun untuk semua tujuan di atas.

 

 

Kadang-kadang ada yang namanya ''Bendungan Sadel'' sebenarnya adalah sebuah [[dike (construction)|dike]], yaitu tembok yang dibangun sepanjang sisi danau untuk melindungi tanah di sekelilingnya dari banjir. Ini mirip dengan [[tanggul]], yaitu tembok yang dibuat sepanjang sisi sungai atau air terjun untuk melindungi tanah di sekitarnya dari ke[[banjir]]an.

 

 

 

 

 

=== Embankment dams ===

 

 

==== Rock-fill dams ====

[[Rock (geology)|Rock]]-fill dams are embankments of loose rock with either a watertight upstream face of [[concrete]] slabs or timber or a watertight core. Where suitable rock is at hand, a minimum of transportation of materials can be realized with this type of dam. Like the earth embankment, rock-fill dams usually resist damage from [[earthquake]]s quite well. However, water infiltration may cause [[Earthquake_liquefaction|liquefaction]] at embankment dams during an earthquake. This problem can be eliminated by keeping the susceptible material dry. [[New_Melones_Dam|New Melones Dam]] is a rock-fill dam.

 

==== Earth dams ====

Earth dams, also called earthen and earth-fill dams, are constructed as a simple homogeneous embankment of well-compacted earth, sometimes with a watertight concrete or [[clay]] core or upstream face, or sometimes with a [[hydraulic fill]] to produce a watertight core. A type of temporary earth dam occasionally used in high latitudes is the frozen-core dam, in which a coolant is circulated through pipes inside the dam to maintain a watertight region of [[permafrost]] within it. [[Oroville_dam|Oroville Dam]] is an earth dam.

 

 

====Gravity dams ====

In a gravity dam, stability is secured by making it of such a size and shape that it will resist overturning, sliding and crushing at the toe. The dam will not overturn provided that the [[moment (physics)|moment]] around the turning point, caused by the water pressure is smaller than the moment caused by the weight of the dam. This is the case if the [[resultant force]] of water pressure and weight falls within the base of the dam. However, in order to prevent [[tensile stress]] at the upstream face and excessive [[compressive stress]] at the downstream face, the dam cross section is usually designed so that the resultant falls within the middle third at all elevations of the cross section (the [[core]]). For this type of dam, good impervious foundations are essential.

 

 

====Arch dams ====

 

In the arch dam, stability is obtained by a combination of arch and gravity action. If the upstream face is vertical the entire weight of the dam must be carried to the foundation by gravity, while the distribution of the normal hydrostatic pressure between vertical [[cantilever]] and arch action will depend upon the [[stiffness]] of the dam in a vertical and horizontal direction. When the upstream face is sloped the distribution is more complicated. The [[normal]] component of the weight of the arch ring may be taken by the arch action, while the normal hydrostatic pressure will be distributed as described above. For this type of dam, firm reliable supports at the abutments (either [[buttress]] or [[canyon]] side wall) are more important. The most desirable place for an arch dam is a narrow canyon with steep side walls composed of sound rock. [[Parker_Dam|Parker Dam]] is an arch dam constructed of concrete.

 

== Spillways ==

 

A ''spillway'' is a section of a dam designed to pass water from the upstream side of a dam to the downstream side. Many spillways have gates designed to control the flow through the spillway.

== Other considerations ==

 

 

Significant other [[engineering]] considerations when building a dam include

* removal of toxic materials and buildings from the proposed reservoir area

 

 

Dam failures are generally catastrophic if the structure is breached or significantly damaged. Routine monitoring of seepage from drains in, and around, larger dams is necessary to anticipate any problems and permit remedial action to be taken before structural failure occurs. Most dams incorporate mechanisms to permit the reservoir to be lowered or even drained in the event of such problems. Another solution can be rock grouting - pumping cement slurry into weak fractured rock under pressure.

 

== Contoh bendungan ==

* [[Bendungan Aswan]], [[Mesir]]

* [[Bendungan Benmore]], [[Selandia Baru]]

* [[Bendungan Mactaquac]], [[Kanada]]

* [[Bendungan Inga]], [[Republik Demokratik Kongo]]

 

=== Bendungan gagal ===

* [[Camará Dam]] - [[2004]]

 

{{commons|Dam}}

 

== Pranala luar ==