Is the 3 Gorges Dam Structurally Secure Without Bedrock Anchoring?

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The discussion centers on the structural integrity of the Three Gorges Dam, questioning whether it is adequately anchored to bedrock since no piles were driven into it. Participants express concerns about the dam's design, noting that while gravity holds the structure in place, the lack of bedrock anchoring could pose risks, especially given its location on major fault lines. There is debate over whether the dam's sections are connected by rebar and if this is necessary for stability. Concerns are raised about potential failure modes, including tipping and hydrostatic pressure, emphasizing the importance of drainage and compressive resistance. The conversation highlights the complexity of maintaining and inspecting such a massive structure, underscoring the need for robust engineering practices.
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not sure Mech Eng is proper forum for this. The 3 Gorges dam in China has very high flooding up river and more rains coming. Will the lack of piling driven to bedrock matter?
The dam is a series of massive re-bar and concrete wide base tapering to narrower top. Does anyone know if these structures are " tied" togeather via connecting rebar sections? I researched and apparently no piles were drive into bedrock so only the shear weight is anchoring the massive structures. My thinking is the whole dam is tied togeather making one huge concrete chain acros the river and should be impossibel to fail if materials are to standard. Is this correct or fuzzy thinking?
 
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Someone had posted online sat photos showing the dam has bowed:

https://www.reuters.com/article/us-...re Three Gorges,landslide risks in the region.

However, China said it was the photo imaging that had the problem not the dam.

https://www.britannica.com/topic/Th...Gorges Dam, dam on,dam structure in the world.

More recently, a Chinese Hydrologist has questioned the Dam's safety:

https://www.taiwannews.com.tw/en/news/3951673

https://7news.com.au/news/disaster-...flooding-threatens-three-gorges-dam-c-1119460
 
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yes i saw the photos and looks like pixelation problem stiching photos togeather..concrete can not bow that much i think.
 
https://www.publications.usace.army.mil/Portals/76/Publications/EngineerManuals/EM_1110-2-2200.pdf

Ranger Mike said:
Summary:: not sure Mech Eng is proper forum for this. The 3 Gorges dam in China has very high flooding up river and more rains coming. Will the lack of piling driven to bedrock matter?

Does anyone know if these structures are " tied" togeather via connecting rebar sections? I researched and apparently no piles were drive into bedrock so only the shear weight is anchoring the massive structures
Gravity dam = the weight of the concrete holds the dam in place, which in turn holds back the water.
Piles - not needed to hold the weight of the dam, as the dam would be constructed right on top of the bedrock formation.
Structures connected together = not sure what you mean, what structures?

Since the dam can be several meters wide ( or long, definition wise ) - the 3 gorge is over 2000 meters, some sort of expansion joints would have to in place, every several meters, to accommodate the changing temperatures over the year. Each section should be designed to be structurally stable. One whole solid piece of concrete ...?
 
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Ifin you got all that water building up behind you, one would think you would want to put a stake in the ground to anchor your dam. Drill intor bedrock and tie in the dam so lateral movement isnot going to happen. Especially since you decided to buildon unstable ground to begin with . Three Gorges Dam sits on two major fault lines -- Jiuwanxi and Zigui-Badong. i would have connected each concrete poured portion to the other with re-bar for tension and tied the whole thing togeather... now did this happen?
tell me this is not needed and i am full of beans?? does concrete flex and distort? we are only talkingh about 40% of chinas GDP going out when it brakes..
 
Ranger Mike said:
does concrete flex and distort
It doesn't do well in tension.
Gravity keeps it in compression.

Another failure mode would be tipping.
The hydro static pressure underneath the structure has to be controlled so as to not make the upstream part begin to uplift, or the whole structure begin to attempt to float. Drainage, or no drainage condition, would have to be taken into account. Again, a suitable mass of concrete helps in this regard.
 
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Ranger Mike said:
tell me this is not needed
Not needed for a gravity dam.

The interior of the dam is just filler - say a low grade 10 to 1 mixture, to add compressive resistance and the weight.
The exterior is of higher strength concrete.

Concrete keys are what hold the sections from moving relative to one another, not metal that could corrode, expand and destroy the integrity of the structure. And how would anyone test for that. One would have to add interior walkways and inspection points.
To repair one would then have to drain the "lake" and dig through meters of material.
Out of service for years and years.

It's not like a road that can be ripped up and replaced in suitable time frame.
These things are massive.
 
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excellent info. this is why this forum is so valued! Thank you!
 

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