Sandbox Foundations
Sandbox Foundations
(OP)
Does anyone have experience designing sandbox foundations?
I've inherited a job when I took a new position replacing a now retired engineer. Some vibrating equipment (1200 rpm/150 hp) is supposed to be "temporary". So the client tends to put these on sandboxes. Literally, a box made of 4x12 (6" in the ground, 5.25" above ground) and filled with sand.
I understand how this would work with low or non-vibrating equipment. But at 1200 rpm I'd think that it would eventually dig itself down.
I've never heard of this method before. So, I'm just going off of my general engineering knowledge.
Help?
I've inherited a job when I took a new position replacing a now retired engineer. Some vibrating equipment (1200 rpm/150 hp) is supposed to be "temporary". So the client tends to put these on sandboxes. Literally, a box made of 4x12 (6" in the ground, 5.25" above ground) and filled with sand.
I understand how this would work with low or non-vibrating equipment. But at 1200 rpm I'd think that it would eventually dig itself down.
I've never heard of this method before. So, I'm just going off of my general engineering knowledge.
Help?






RE: Sandbox Foundations
BA
RE: Sandbox Foundations
RE: Sandbox Foundations
I feel that when I'm supposed to put my stamp on it, then I've got to feel comfortable with it. It isn't enough to simply be told. I've got to see it, understand it, feel it, etc. This is something I've never even heard of before. I've only seen a couple pictures of recent designs. I have no idea how it works over a longer term.
The thoughts about it being self-leveling is a good point. That helps. It is supposed to absorb some of the vibration because it is loose. That is specifically why we can NOT have a binder/stabilizer.
No one else in the office knows much about this. I'm supposed to be the expert on this matter and I've never heard of this particular design.
I've got some questions into the retired engineer who designed most of the previous ones. One of them is about the soil specification for the sand. I had a similar question about the "dry powder sand". But I fear the message will just be "nothing special, just sand."
I'm just trying to get ideas on what physical movement/action will be governing the sitting loosely on the sand and the movement of the sand. If I get enough ideas, I can let it float around in my head until I'm comfortable with it enough to put my stamp on it.
Any other thoughts?
RE: Sandbox Foundations
Mike Halloran
Pembroke Pines, FL, USA
RE: Sandbox Foundations
BA
RE: Sandbox Foundations
RE: Sandbox Foundations
RE: Sandbox Foundations
Apparently, this is only valid for non-vibrating or very low amplitude vibration machinery. And for the size of the machine (over 20k) 150 hp is not going to vibrate much. We obviously can't anchor it much because... HELLO! Sand!
I asked about the sand. There is no spec -- just sand. He said it is no different than simply placing something on native soil or structural fill (w/o concrete pad). The purpose of the box is simply to raise it above a certain flood level. We use sand because it consolidates & compacts immediately and drains well.
Then I got another bomb dropped on me. The client never asked for it. It was all being pushed by the previous engineer. But what's worse is that the client just wants to set this on the gravel fill. Still no concrete. I guess it will be fine as long as it doesn't flood.
RE: Sandbox Foundations
BA
RE: Sandbox Foundations
You may have a different scenario if there's reasonable risk of the thing walking on you (and that's unacceptable to the client), or if you're in a significant seismic zone and there's a risk of it tipping or something else.
Rule out any safety things that bother you, and then just make sure any serviceability issues are communicated to the relevant parties. This sort of thing happens a lot in the construction and resource industries where you aren't going to bother building concrete pads for all your temporary facilities that you plan to move every couple of months.
RE: Sandbox Foundations