Concrete Insitu Testing

The Oroville Dam was built in the '60's.

At that time, their idea of testing was a minimum number of concrete cylinders, and a maximum number of cubic yards poured per day...

Other than personal experience and judgement, they were kinda short on electronic devices for testing purposes...

While they did have some (relatively rudimentary ?) electronic devices at that time, the reason we have electronic calculators, etc., today was because, simplistically, the (Russians) made the political decision to develop big powerful rocket engines, The U.S. chose to miniaturize the electronics, (which still had cathode (?) tubes in that time-frame,) enough to be propelled into space by smaller rocket engines...

The 1960's was relatively recent to be having a concrete dam fail, while some, much older earth-filled dams have not yet failed...

Hmmmmm...?

Sounds like poor engineering occurred at the time.

What more could they do in an era where electronics were limited to using:

- available simplistic integrated circuits;

- relatively crude cathode ray tube screens;

- room-sized computers;

- and vacuum tubes as electronic components;

until miniaturized components became available after the mid-seventies?

Yeah, before compact electronic equipment we were totally incapable of building the Hoover Dam, the Empire State Building and the Golden Gate Bridge.

Excellent!

Some rules-of-thumb were more effective than others, in some kinds of construction, but not always...

...ala the (Verrazono (sp?)) Narrows bridge, assorted earthen-fill dams, etc. ...

Advancing technology can help to avoid repeating past mistakes, but additional complexity invites new mistakes...

Let me correct myself. Read ''Tacoma Narrows'' (also known as ''galloping girdie'', in stead...

It's nice to hear that somebody understood what I meant...

The Verrazano bridge is a fine example a cable-suspension-kind of bridge which was built in about the same time-frame as the Tacoma bridge, but the (increased structural drama) ''edge'' has to go to Tacoma...

Nonsense! Galloping Gertie was opened in 1940, the Verrazano-Narrows Bridge in 1964. If you want drama then you can "watch" the roadways "drop" 12 feet from winter to summer as the cables stretch due to the temperature change. The other drama is the $16.00 toll.

The very reason why I avoid the NYC area like the plague when traveling through. And the fuel prices, and the sales taxes, and the . . . .

Especially since we are usually four axles and a 'large' vehicle. The closest I get to NYC is the Tappan Zee bridge. Preference is for Newburgh-Beacon, but that is quite a bit further out of the way when going to the Boston area from Maryland.

There is something VERY wrong with the toll schedules for the Hudson crossings in and around NYC. There's no way in 'ell it costs that much to build and maintain those bridges. Someone needs to get to the bottom of that money pit and find out where it all goes.

The more progressive elements (you could also call them liberals, I do) tend to concentrate in larger cities. That is why this problem is there to begin with.

I'm glad I don't live in that area.

Maybe my time frames are bigger than your time frames, then...

Correction: it was a fine example when it first opened...

quality of repairs?

from what i read.. or was it on video?.. anyhow. A woman who walks around there mentioned that they routinely pick shrubs and grass from the cracks on the spillway.

penny wise hundred of millions foolish

Maintenance costs money, and it's government (your taxes) money so not much has been done on our infrastructure (be it dams, bridges, roads, etc.).

Amen...

There's no (political glory) in spending money on inspection, or maintenance, but there's lots of (political opportunity) in pointing (fingers of blame) after disasters strike...

they've done the maintenance and repairs.. billed for it and spent the money they 'earned'.. They just did shit work. I'd call on the contractors/design engineers who approved the methods as well as the inspectors who approved the work. at the very least they should be moved to desk jobs where they can hurt no one.

I could have repaired the spillway with a common sense approach.

BS on whatever excuse they give for the repairs failing. total and utter

I beg your pardon sir. common sense! I am sure that is extinct.

I hear on the news that this problem, bad workmanship, was made note of in 2005 by the authorities and they are expecting more rain. And they are now asking if the dam will hold. Huston, you have a sad problem.

It's going to be a nail biter into summer I'm sure. Probably a good time to buy up some real estate from those looking to cut and run from the risk. The weir is scary big.. Can they shore it up enough?!

It was probably the cube test for 7 and 28 day cures. Still used today in fact. As with all slab pours, they are done with an expansion slots which are later grouted, and it is quite easy to remove grout with that water force.

Once the slot is open, it is easy for any water force to lift the slab out in chunks and erode the earth base underneath. Also, a corrosion exists known as concrete cancer and that weakens the slabs. Normally related to rebars and salts in the water used.

http://www.cement.org/docs/default-source/fc_concrete_technology/durability/is536-types-and-causes-of-concrete-deterioration.pdf?sfvrsn=4

Verrrry nice link. Thanks.

GA from me

More likely under designed and under evaluated as it was never expected to be used. The California water situation for the last several decades has been based on so much irrigation and drinking water draw-off that reservoirs throughout the region were falling and plans were for running out of water rather than having too much.

Having an emergency spillway with an expected life of about an hour in actual use speaks volumes about the design quality.

My understanding was that the soil under the spillway slipped, subsided, or does what a lot of the soil in California tends to do. Then the spillway failed due to lack of support for the concrete structure. I don't think the engineers designed the spillway to be a free-standing structure. California Highway 1 just north of San Francisco is on an inexorable march to the sea. Caltrans was always out there propping it up and fixing the gaps in the pavement and so on. California has a geology problem that is exacerbated by drought/deluge cycles. It's one reason why the landscape is so stunningly beautiful.

The emergency spillway, which was next to the collapsing concrete spillway, was compacted earth. Anyone who has ever dealt with earthen dikes knows that as soon as water starts flowing over or through the dike wall, it's gone.

They quickly re-thought the use of the emergency spillway because of the erosion and opted for washing out the lower half of the concrete spillway while attempting to fill/shore up the gap with boulders to slow the damage to the area around the concrete spillway. I believe they made the right decision as the damage to the slope for the concrete spillway is 'further away' from the top of the dam. Thankfully, they seem to have it under control at the moment.

If you are talking about the ''Trutman (sp?) Sink'' area on the north coast portion of PCH (i.e.: Highway 1), very roughly, near Eureka, they have been repairing that area (annually?) which is about 100 feet above the Pacific Ocean. The layers (at about 2 tenths of a foot thickness per layer)of asphalt now go all the way down to below the water surface, unless the Highway has finally been re-routed around it...

I was thinking of the section just north of Mill Valley, prior to Stinson Beach. There were (are?) a number of sections where the land is just sliding down the hill. I used to ride it regularly on Sunday mornings and observe where cracks and gaps in the road would appear as the land very slowly slid down the hill. We usually didn't ride further than Bodega Bay, very rarely to Jenner.

Sounds like a much more (genteel, sophisticated, civilized, and yet, still provocative ?) land slide than the trutman...

Do you get television up there yet?...

Over-The-Air TV in California is spotty at best due to the topology. Haven't lived there for a long time, but I'm sure cable and fiber have found their way into most hamlets and satellite for those with a view of the sky, and good books for everyone else.

No, not when it was built. Common testing was compression of slugs, round examples of a pour, which were compressed until fracture. I have shot concrete using Co 60 on floor to floor to see if any lines (electrical, plumming) would be damaged in a thru bore single floor. Once I found a large wrench cast into the concrete.

Yes you can use UT to detect concrete flaws, but due to the very low frequency sensitivity and resolution are lower. Something like a crack would be undetectable.

If you're looking for flaws in the dam then you're looking in the wrong place. The place to look is the soil/geology/hydraulic studies of the pre-existing soil/rock/underpinnings/surface prep that were(?) performed long before one ft3 of concrete was poured.