Would be interesting to see a closeup of the bottom of the pole. The article said it was a failure of the foundation, but is it rather a failure of the connection? The footing doesn't appear to have moved, but then that is impossible to tell with a distant photo.

Found some good construction photos. Looks like typical rock anchored mats.

https://canprojects.com/projects/wind/kent-hills-3...

Doesn't look like the foundation to me. Looks the pole snapped its attachment to the baseplate.

Cheers

Greg Locock


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From the images I've seen, it looks like the anchors ripped out of the concrete base, or at least that's the impression I got. These are the only two images that I could find that shows where the failure occurred. I just wish they had some higher resolution photos so we could zoom in on the relevant area:

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From images linked in above posts



Enlarging the photo of the base hints at what I would expect if the anchor bolts pulled out of the concrete. Better post accident pictures would be nice

The following drawing looks somewhat like the pictures.

Quote (http://getdrawings.com/get-drawing#foundation-draw...)

This is one of the situations where the cost of not fulfilling contract obligations related to delivering power could be larger than the large cost of replacing the foundations.https://thedeepdive.ca/transalta-renewables-forced...

Looks pretty much like that central structure has ripped itself out of the base.

Is there only one set of top bars crossing the failure plane?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

In the photo with the guy in the green hat, it almost looks like there are some cracks on the side face that have already been repaired in some fashion.

If that second picture is accurate it looks like there Sis only on set of top bars across the failure plane in shear?

The base of the anchor bolts for the turbine seem to finish above the level of the bottom bars.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

Yea seems likely it was a breakout cone type failure propagating from the lower anchor ring. I’ve seen other wind turbine foundations where the center area is thickened at the bottom so the ring plate can be set below the bottom mat.

As stated in the original article, the defective foundations are in sections one and two of the wind farm and not in section three. The construction photos are of section three.

Sorry, I missed that. Good catch!

You do wonder how someone got that so wrong?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

It's an interesting foundation design. The pole anchorage tension forces have to transfer over to the deep anchor rods - big shear in that section. I don't see any stirrups in the photo. Does that failure photo show a shear failure? Like a diagonal break?

I've never liked the the double bolt circle arrangement. Usually the larger circle resists a greater amount of tension than the inner circle but I have seen pole designers take the average diameter for the section modulus.

The footing appears to be intact; it's the rest of it that leaned over too far...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

To me at this point, it looks like the break is between the pole anchor rods and the out tie-down anchor rods. An up close would be helpful.

a better picture would help... I thought just above the anchor rods.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

from another source:

https://www.wind-watch.org/news/2021/10/30/transal...

"The company says the discovery of the subsurface cracks means the foundations will likely need repairs, and if replacement is required, costs are estimated at $1.5 million to $2 million per foundation.

The suspended operation includes 50 wind turbines at Kent Hills 1 and Kent Hills 2, where the tower collapsed. Five turbines at Kent Hills 3 continue to operate."

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Thanks, dik. A possible circular ring of cracks might appear before the final failure. I'm good at taking pix's of cracks. It's possible because of a lack of stirrups - say at 4 to 6 inch spacing. Could be wrong. The sketch provided - which may not be from this project shows a stirrup which appears to have a note on spacing. The picture of the steel placement doesn't appear to have any stirrups.

dik: It looks like you have been on Eng-tips one month longer than me. As far as poles go, the Egyptians just finished a 650 foot flag pole. Now tallest in the world.

Quote (I'm good at taking pix's of cracks.)

One of the pre-construction photos, above, appears to show cracks... could be thermal from mass concrete. The references to foundation failure come from the provider of the wind turbine, so I'm not convinced yet. They are the ones making the claims about the foundation failing. It's strange that no one has taken photos of the actual failure surface. If I were on site this would be my main interest... also to see what damage was done the the wind turbine itself.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Quote (As far as poles go, the Egyptians just finished a 650 foot flag pole. Now tallest in the world.)

It's always funny (to me) when a third world country makes that kind of achievement. That and $2.00 will get you a cup of coffee in these environments.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Those cracks are on the sides, not between the pole anchor rods and the tie-down rods. I also wouldn't be happy with those cracks.

Thanks old... but the photo is so poor that I cannot tell the condition at the top and the windmill supplier only talks about cracked foundations. I'd really like to see a close up photo.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

These things always look funny to my eye. Too tall and skinny for their own good. I'm surprised there are not more issues with collapses.

Because there's not more failures, it means it nicely engineered... I really dislike PEMBs, but I do appreciated the engineering that goes into them... just like the old Volkswagons...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

The rock anchored piles actually have pancake shaped voids on the top. So when the anchors are post tensioned the concrete cap and piles can be drawn tight and the anchor bond to the earth can be mobilized. They fill them with grout through tubes afterwards. You can see the tubes in one of the photos above. Pretty neat stuff.

https://www.windpowerengineering.com/foundation-id...