Located in Tagikistanmore specifically in Pamirone of the main mountainous chains of Central Asia near the vakhsh riverthe future Rogun dam (or Roghun) aims to become one of the works most important geotechnical-hydraulics ever: we are talking about the construction of the artificial barrier on the highest land in the worldabout 335 meters. The project, which originated around the 70s, has been interrupted in its development in the past due to the collapse of the USSR and then subsequently re-concreteized in recent times, due to agreements between the company of the government of Tagikistan which coordinates the realization of the project and some important sector companies (also Italian, such as webuild) which are already dealing with some realization phases. To date, a date of end of work in about 10 yearswhile part of the dam is already active and functioning for the production of electricity.
The project: between numbers and construction phases
Rogun’s dam acts as electricity generator For Tagikistan. The heart of the project lies in its dizzying numbers, which we can summarize with the following data:
- About 3600 MW of installed power supplied with a final regime by 6 turbineswhich would double the energy production of Tagikistan currently in progress.
- 74 million cubic meters of dam detected: To get an idea is as if we made a cube of land on the side about 8.6 km!
- 100 thousand cubic meters of excavation in underground e About 2.6 million cubic meters of open -air excavation.
- Height of the barrier of 335 meterswhich exceed those of the current damper in the highest ground in the world (305 m), the Jinping-I, located in China.
The project includes (and has already foreseen in part) several realization phases:
- In a first phase, already performed, An artificial deviation of the Vakhsh river has been created. This artificial deviation guaranteed the possibility of carrying out all the processes on the dam front without the hydraulic interference produced by the river, which will then be the source of water supply of the pelvis.
- After this phase, and also built the first stretch of dam in height (about 70 meters), it was possible recently Start the first turbine (in 2018)therefore starting to produce electricity and consequently generate proceeds that will act as self -financing of the work in progress.
- A second turbine of the 6 was instead started a year later. According to estimates, this start -up strategy in parallel to the completion of the works will allow READY THE DAM within about 25 years.
- The works now continue at full capacity for the realization of the upper strata of the barrier up to the projects of the project outlined.
How a dam on the ground is made
As the same word says, The dams on the ground are made through the creation of a wall of land which blocks the flow of a river, allowing its reservoir. Subsequently, due to the objectives for which the reservoir is carried out, the works relating to the possible production of electricity through the transformation of potential energy that has water at altitude.
Energy production is obtained through turbineWhile The wall on the ground must guarantee a requirement of resistance and stability to the containment of the water accumulated on the valley. What do they have different from the equally widespread, certainly more common, concrete dams? Both the constructive methods and the functioning of the barrier change radically:
- The dams on the ground are made up of material that does not require much processing to be positioned on the siteTherefore they are preferable works to the classic concrete dams when the materials for the construction of the containment wall can be easily found near the construction site. In the specific case, mixed material is used ranging from sand and stones in the outermost part, up to a clay heart.
- The concrete dams, however, exploit the properties of resistance to compression of the material and the possible help of the armor cages, with the aim of obtaining high containment heights by reducing the thicknesses in play or working the form of the barrier (as happens, for example, in the arched dams).
How a dam on the ground works
According to the stratigraphies of material that we find from Monte to the valley, can be distinguished:
- Dams in homogeneous land;
- dams with internal estate core;
- dams with external estate structure.
What changes, among the various cases, is the material that regulates the hydraulic seal of the dam. In the case of the Rogun dam, we can speak of an internal estate nucleus, as it is precisely the heart of clay to guarantee the hydraulic hold of the dismissal.
Therefore, the wall of land must represent, all or in part, one waterproof barrier towards the natural flow of water, which otherwise would have happened undisturbed. The dams on the ground have trapezoidal shape, and the slopes of the sides of Monte and Valle depend on the mechanical characteristics of the land that make the barrier. The minor base of the trapeze, the upper one, is called crowningwhile the oblique sides are called vestments.
It should be emphasized that, in general, a land is a porous vehicle: the propensity that the ground has to be crossed by a fluid is measured through the permeability. Clayey soils have low permeability And for this reason they are ideal candidates for the realization of barrier that can be considered waterproof, because of the fact that the filtration times are so long that they appear infinite! Nevertheless, the fact that the water will begin to find alternative filtration paths (the water will be considered (more permeable), and it is for this reason that The barrier and its outline require appropriate checks and technological precautions that limit symphonment problems or unwanted filters.
An equally important aspect of design is the correct realization/sizing and maintenance of the surface exhausts. The dams on the ground are very sensitive to Tracimation problems: the excess of water compared to the height of the wall paramento would cause a quick deterioration of the valley paramentowhich comes progressively dilated by the water that flows superficially. In Cascata, the resistant section of the wall weakens and a failure of the front follows and the progressive collapse of the whole work.
