Thick mat foundation and Frost depth
Thick mat foundation and Frost depth
(OP)
hello,
I am designing a block foundation for outdoor compressor and H-pumps for Oil companies in North Dakota.
My analysis gives me about 24" thick block foundation (24" thick x 7'-0" wide x 40'-0" long). Do I need to consider the 6'-6" frost depth for this 24" thick block foundation?
We do a lot these foundations in TX where frost depth is not an issue.
Thanks.
I am designing a block foundation for outdoor compressor and H-pumps for Oil companies in North Dakota.
My analysis gives me about 24" thick block foundation (24" thick x 7'-0" wide x 40'-0" long). Do I need to consider the 6'-6" frost depth for this 24" thick block foundation?
We do a lot these foundations in TX where frost depth is not an issue.
Thanks.






RE: Thick mat foundation and Frost depth
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Thick mat foundation and Frost depth
So basically I need to design drilled piers or helical piers to resist the tensile force due to the Frost Heave forces under my 24" bloc foundation.
Thanks.
RE: Thick mat foundation and Frost depth
BA
RE: Thick mat foundation and Frost depth
Typically you would include some kind of void under the mat (or with piling perhaps a two-way slab that isn't as thick). These can be the degradable cardboard carton forms.
The only other issue then is once the cardboard rots away you have a void under the concrete - but potential sluffing of dirt into the void from the perimeter of the slab....thus
some kind of fill retainers around the perimeter. All this adds up to extra cost - compare that with determining if the piping can flex or be designed to flex with anticipated frost heave deflections.
RE: Thick mat foundation and Frost depth
- Perimeter grade beams about 3'-0" deep
- Void form under the 24" thick concrete block.
- Drilled piers to support the perimeter grade beams.
Why this approach? Because, if the void form rots under the concrete block, the 1'-0" extension of the grade beam that extend below the concrete block will act like the fill retainer JAE mentioned. And the drilled piers will control any settlement of the foundation system.
RE: Thick mat foundation and Frost depth
1) Speed (design and construction).
2) Durability.
3) Future flexibility.
4) Ease of construction in remote locations.
My northern O&G clients generally avoid concrete like the plague. If it were me and it were feasible, I'd be looking at a raised steel platform on helical steel piles. Your only frost concern would be upwards drag on the helical piles which they can certainly handle so long as your helices are below frost depth.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Thick mat foundation and Frost depth
Elevated steel platform is an option but I prefer concrete blocks because they absorb vibrations better since I am dealing a H-pump with more than 4,000 rpm.
Seems like you mention helical piers a lot. Are they the preferred pier/pile system in ND?
RE: Thick mat foundation and Frost depth
I didn't realize that your machine base was part of a much larger complex. That may make it more feasible to use other technologies that will be on site for other reasons. With regard to vibration control, is one better off with a pad footing or pile support? My gut tells me pad footing but I really don't know.
O&G clients present some challenges but they're also exceptionally good when it comes to paying their bills. That's more than I can say for some architectural clients.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Thick mat foundation and Frost depth
RE: Thick mat foundation and Frost depth
http://www.pavementinteractive.org/article/frost-a...