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The 100 year old earthen dam that failed in Michigan, washed out part of a dam downstream (but didn't destroy it) had inadequate sluices. They didn't open high enough. Part of the problem was design, and part deterioration of the valves. The dam filled almost to the top but never overtopped, but the earthen portions were too stressed to hold.

SImilarly the 3G dam probably has a maximum fill above which some portion, perhaps earthen beside the dam, would get too stressed and fail. There may be a spillway in addition to the sluices. My definition is the sluices open and close and the spillway simply spills. The Wikipedia article does not give a reference for spillway capacity. It does say

"Days after the first filling of the reservoir, around 80 hairline cracks were observed in the dam's structure.[145][146][147] The submerged spillway gates of the dam might pose a risk of cavitation, similar to that which severely damaged the poorly designed and cavitating spillways of the Glen Canyon Dam in the US state of Arizona, which was unable to properly withstand the Colorado river floods of 1983.[148]"

They are loose with terminology but they mean sluices. You can see the tremendous pressure as the water ejects from those sluices. A cavitation flaw would promote turbulence within the sluices and subject some portion to excess force. We don't really know if the sluices open fully (they knew in Michigan but ignored the problem). We don't know if they are all functional.

The Michigan dam had a spillway along with the sluices but it was inadequate (they knew that too). It would be very interesting if we saw actual spillway action at 3G. I think as long as the water is coming through the sluices, and not over the top of the center portion (which might be spillway), I believe the dam is acting as designed. Doesn't mean the design is safe or it was built properly. The main unknown besides the corruption you pointed out, is if Wikipedia (which lies all the time) is referring to total spillway including over-the-top or just sluices. If just sluices, their number is almost double in the inflow. That seems adequate to me.

I think,from what I have read, the pressure on the dam may increase over the next week to ten days. After that who knows it will most likely depend on rain events until the rainy season ends in Oct as to the fate of the dam. If more sluices are opened up it has to effect downstream flooding. Flooding has already been a huge problem.To make it worse is almost unthinkable but there may not be an alternative.

The bigger question is will the Three Gorges Dam absorb the added pressure as more water accumulates? I doubt anyone knows the answer to that. Also, if the dam does go I was told that there will be all kinds of indications as much as a day or even day and a half before it goes.Lots of strange noises and other indications its about to go.

You gotta also wonder if there is any cavitation going on since from the time the dam was built there were at least 80 cracks in the concrete.

https://www.youtube.com/watch?v=v98omCq1kRA

This short video explains what can happen with to much cavitation.

The CCP is blowing up other dams in the region to lower the pressure on the three gorges,accd. to Breitbart that could save the day but it's hard to say,so much is going on all at once. 6 quakes hit China in 2 days; Three Gorges Dam hit its limit: experts; up to 5.1 could really screw up the dam. Is there a link between dams and earthquakes,hard to say:

https://www.smithsonianmag.com/science-nature/a-link-between-dams-and-earthquakes-4305816/

The earth is big, and so are the tectonic plates—it doesn’t seem possible that anything humans could do to the earth would have an effect on those immense plates. But evidence is mounting that we cause earthquakes.

I listened in fascination to a presentation from earthquake scientist Christian Klose at the 2006 American Geophysical Union fall meeting in which he showed how coal mining was responsible for earthquakes, including the most-damaging ever in Australia. (The 5.6-magnitude Newcastle earthquake of 1989, though relatively small by international comparison, killed 13 people.) The removal of coal, rock and, especially, water from underground can cause enough stress to trigger an earthquake, Klose said. Other potential earthquake triggers he mentioned were oil and gas extraction, creation of reservoirs behind dams and, he conjectured, sequestering carbon dioxide underground.

Now Science reports that Klose is one of several scientists who are pondering the possibility that last May’s 7.9-magnitude earthquake in China’s Sichuan Province, which left 80,000 dead, could also have had a man-made trigger, this time in the form of the Zipingpu Dam. Then the magnitude-7.9 Wenchuan earthquake struck, many scientists wondered if a reservoir was to blame. Ruling out the much-maligned Three Gorges Dam as too distant.