Aggregate Stockpile Separation/Containment Wall (Retaining Wall???)

[Northern Engineer]

Hello folks, first time poster here, and appreciate your patience if anything is amiss. I'll get right to the point:

Concrete supplier in BC, Canada has approached me about designing aggregate stockpile containment/separation walls. He would like to construct the wall using concrete lock blocks stacked 4 blocks high (approximately 2.8 m high). The walls would primarily act to contain stockpiled material, and there would be some active pressure against the walls, depending on stockpile height.

My questions:
1) Would engineering even be required for such a structure? I'm hesitant to classify this as a "retaining wall" given that its primary purpose would be more for general "containment" of soil vs. "retention". The risk and consequence of catastrophic collapse would fairly minimal given the location (concrete supply yard), and I don't see public health and safety being a major driving factor.
2) If engineering is required, would seismic design be required? Again, this would seem overkill to me, given the low risk and consequence of failure of the wall.

I have looked through EGBC's Retaining Wall Design Guidelines as well as the OH&S Code/Regulations/Guidelines without much luck. Dr. Google and a search through old forum's haven't yielded much either. Does anyone have experience with something similar, or can point me in the right direction?

Many thanks!

Northern Engineer

 

[EireChch]

I dont see any reason why it should not be designed as if it was a 'normal' retaining wall with seismic etc considered. Ok the most likely outcome of failure of the wall only means some spillage of aggregate but there is potential loss of life if there is a failure. There is still people working around the wall regularly.

Also, these interlocking block walls are generally designed and built by specialist manufactures. Not saying you cant do it but that's my general understanding of these types of walls.

 

[JedClampett]

I've seen cases where these walls needed to be specially braced due to the forces of the front-end loaders pushing the stockpile against the wall. I wouldn't approach this design too casually.
And if you ask how to approximate the front-end loader load, that's a good question.

 

[TigerGuy]

Most of these large blocks are molded at the plant with what leftovers come back to the plant in the trucks. Even with the interlocking features molded into them, I wouldn't count on that much more than friction between the blocks.

Second point, the different materials "bins" will fill and empty at different rates. The walls will need to be designed for full and empty bins on each side.

On the positive side, the static load of gravel and sand against a 2.8m high wall isn't going to amount to much. Seismic will be the challenge.

 

[BridgeSmith]

Seismic loading would be difficult to design for, and likely require additional components to make the block walls adequate for that loading. However, in a private yard, I believe it would be up to the owner to decide whether seismic loading is to be considered in the design. I suspect the owner will not want to spend the money for you to design, and for them to build, the walls to handle seismic loading. If that's their decision, make sure it's documented in the scope of work, etc., and in your design, that seismic loading was not considered.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[PEinc]

Good luck designing these stacked blocks for an unbalanced gravel load that is 2.8m high. These blocks are generally only 2 feet wide. Therefore, when being designed, the stacked blocks usually do not have enough dead load weight to prevent wall sliding or overturning. That being said, I see these blocks being used for this all the time. They may not work "on paper," but they seem to work when constructed. However, your design will need to show the block wall works "on paper." I agree with JedClampett about the extra lateral force from a loader pushing into the stockpile.

http://www.PeirceEngineering.com

 

[EireChch]

PEinc-I was imagining blocks up to 1m wide. I think thats the kind of size you would need to make it work....

 

[PEinc]

EireChch, most of the concrete bin blocks I see are 2'w x 2'h x 4' to 6' long. Even at 1m wide, I would expect problems with sliding and overturning.

Link to a bin block supplier: actionsupplynj.com/products/bin-block/
Block weight / Block volume = ~137 pcf, not 150 pcf.

http://www.PeirceEngineering.com

 

[Northern Engineer]

I appreciate the responses! You've given me lots of helpful things to consider. Thanks!