DAM CUTOFF WALL – SEEPAGE BARRIER CONSTRUCTION – PLASTIC DIAPHRAGM WALL


When constructing a new dam (or remediating an existing one) it is important to ensure that water does not flow below the foundation of the dam If it does, then a barrier must be constructed There are different techniques to create such barriers, and one of the most sophisticated, is the construction of a plastic diaphragm (slurry) wall. The first step to build the wall, is to create what is called a concrete “guide wall” along the axis of the dam Then, excavation begins with a grab to remove the soils from the top, until a pre-determined depth is reached, or until the limit of the tool (normally 70 SPT). Grabs are effective to dig through soils such as clays, silts or sands. The hydraulic grab has verticality sensors and flaps on its body to ensure that the excavation is vertical While digging, bentonite slurry (or mud) is inserted at the top, so that the excavation does not collapse The panel being excavated is called a “primary” panel. At this point, the grab equipment moves to another panel, while a trench cutter (hydromill) system is positioned in the pre-excavated panel. The trench cutter can cut through both the soils and harder materials such as rock up to 200 MPa. And it can reach depths of up to 250 meters. A pump which is located between the cutter wheels, pumps the material through hoses These hoses run all the way to the top The slurry (with cuttings) then flows to a slurry recycler system. Here the material goes through shakers, desanders and desilters, which will then clean/separate the bentonite slurry from the cuttings (rock and soils) in a closed system, so that the clean slurry is then pumped back to the bentonite silos and then pumped back into excavation as the trench cutter advances with the excavation to keep the excavation always full of slurry. This is important as to avoid any collapse of the recently excavated panel Once the target depth has been reached, the trench cutter is removed And the panel is prepared to be backfilled with a cement bentonite mixture which gives it the “plasticity” This is a low permeability and low strength mixture Once the first panel is completed, another “primary panel” is built in the same way. Panel thickness normally varies between 0.6m and 1.5 meters. The grab (also called clamshell) can reach depths of up to 80 meters. Verticality tolerance is normally a function of the depth of the wall and its thickness. to ensure that a continuous wall is built. As a rule of thumb, a verticality of 1% is utilized even though verticalities of less than 0.5% can be achieved with the advance of the technology and controls in the equipment utilized Once the excavation with the grab is finalized, the trench cutter is positioned, and starts excavating As soon as the excavation of the primary panel is finished, it is backfilled with the cement bentonite (CB) mix (also called coulis). The CB mix is tested before the project starts in a laboratory setting on what is called a bench scale test. Here the mix is verified if it obtains the design (or target) criteria for both permeability and strength Once the two primary panels are constructed, the construction of what is called a “secondary” panel begins The trench cutter is utilized to “overcut” the two primary panels so that it guarantees that a quality joint is built Overcuts lengths are also pre-determined, and again depends on thickness and depth of the wall, as to ensure that a continuous wall is built Once excavation of the secondary panel is finished, it is backfilled in a similar manner to the primaries The process is then repeated, primaries being built first, and then secondaries, until the complete wall is finalized. This is just an example, of a cutoff wall build with a plastic diaphragm wall. There is also another video in the Brasfond channel that shows a wall being constructed with another technique called “secant piles”. The two techniques can be combined to create “combi” walls (a secant pile wall within a slurry wall). In critical situations, where severe piping takes place, a grouting campaign precedes the construction of the wall, so that slurry loss is minimized while excavating the panel Whichever technique is chosen, it is important to create a seepage barrier as soon as possible, so that the dam or reservoir can operate safely. Ideally, as shown in this video, seepage barriers are constructed before the construction of the new dam. Thanks for watching this video. For other videos, please subscribe to the Brasfond Channel.

100 thoughts on “DAM CUTOFF WALL – SEEPAGE BARRIER CONSTRUCTION – PLASTIC DIAPHRAGM WALL

  1. this is brilliant. Screen the tailings and mix the cement with the crushed tailings right on site!

  2. There should be a dumpster to catch the rock cuttings from the shakeout tables.

  3. Beginning @0:15 you see the same two guys standing there with no work to do like on every other building site.

  4. Very confusing video. When at the the end you might actually see how all of those channels filled with cement are utilized within the structure of the dam, things are sped up and you only get about two seconds to infer their use.

  5. bluotiyus viuolkoh vu ciy demuro xxdsert gf vcent borok kudo maling ayamos matekuso interikus utik podo wae … good job

  6. We dont need to destroy nature ta make electricity, We have a lot more effective, cleaner and better electricity output from other sources. It is a fact, that we have much too many dams in Europe.

  7. You pick a wrong dam fool
    Hey hey hey Dam smoke is Dam
    DJ?, DAMMMMMMMMMMMM

  8. This is bullshit, what happens to the rock already cut? Itll just get stuck in the machinery

  9. Excellent idea. Process looks great until the end when a dam suddenly appears! Lol!

  10. great video, check ours out and throw me a sub please, got pressure to get them up from bossman ha

  11. Love the "magic" buckets that operate on an arc, and yet achieve a square edged hole 😀 😀

  12. What was the purpose? The wall is some part of the dam? it needs to be shown where its located in the dam….The vid needs some comentary, esp at the end

  13. As usual, one guy (or possibly even machine by itself) is doing all the work while everyone else is getting paid to stand right nearby and in the way, musing at what a wonderful project this is and how work sure is coming along. At one point they even disappear for a lunch break only to reappear shortly after. Wow.

  14. Book this is photeshoped that's the earths crust and you can't do there with out attaching a go pro to that machine

  15. It's a tedious a job, time consuming, laborious and the calculations need to be very precise. It's quite justifying that construction workers are paid so much.

  16. У НАС ТАК РАБОТАТЬ НЕ УМЕЮТ , У НАС НАСРУТ БОЛЬШЕ ЧЕМ ПОЛЕЗНОГО СДЕЛАЮТ

  17. "✓ Науч. Студия ✓ Sergey Kachan": https://www.youtube.com/playlist?list=PLlEX99xZE8qOvEV7vDZf_oAkyCOrS1p-z

  18. But they show them filling with cement alone, no bentonite so the wall will crack and slowly fail, plus it will be much harder to excavate and fix. D-

  19. That’s what Trump needs to use to build his wall. Let’s seen them little Mexicans tunnel there ass under it with there drugs and shit.

  20. Нихуя не понял. Но очень интересно!!!!

  21. El equipo guiado con la almeja
    O cucharon automáticamente
    Después de excavar coloca él material en camiones volteo

  22. Арматурный каркас нету ?долга не служить

  23. Well…ten people standing around while one is working. Looks like a normal job site to me!

  24. Никогда не будет так хорошо, из-за материала на станке и глубины залегания.

  25. Hi, I need support for my new channel by posting a new channel on your channel. Thank you ?

  26. please, how much deep we can go with this method ?? and how much it coast for a digging of a 100m deep for 1 meter linear ? .. thank you

  27. That ending really went 0 to 100 pretty damn fast….. seems they left a few steps out

  28. انا محتاج تلك الماكينه .. عندي شغل لها في السدود الجوفيه بالسعوديه . ارجو التواصل

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