70 ft deep, 8 ft diameter manhole concrete and foundation design
70 ft deep, 8 ft diameter manhole concrete and foundation design
(OP)
Hi,
I'm working on designing the walls, rebars, top and bottom slabs for a 70' deep, 8 ft diameter manhole considering H20 loading (meaning there is a minimum of 32 kips truck load on the top slab). I've never designed a structure like this and i'm wondering if there are major issues to look out for.
I'm working on designing the walls, rebars, top and bottom slabs for a 70' deep, 8 ft diameter manhole considering H20 loading (meaning there is a minimum of 32 kips truck load on the top slab). I've never designed a structure like this and i'm wondering if there are major issues to look out for.






RE: 70 ft deep, 8 ft diameter manhole concrete and foundation design
http://www.concretepipe.org/pipe-box-resources/des...
contact the precast concrete plant near your project to review your design conditions
RE: 70 ft deep, 8 ft diameter manhole concrete and foundation design
RE: 70 ft deep, 8 ft diameter manhole concrete and foundation design
RE: 70 ft deep, 8 ft diameter manhole concrete and foundation design
RE: 70 ft deep, 8 ft diameter manhole concrete and foundation design
Good info on concrete manhole design.
With a 70 foot depth, how is it going to be installed? Pretty deep for digging out & shoring. Possible caisson construction?
Why so deep? Are the collection pipes that deep, or do you just need the volume?
With this depth, you probably won't need to worry about buoyancy as there should be plenty of skin friction from soil to resist.
RE: 70 ft deep, 8 ft diameter manhole concrete and foundation design
BridgeEI: I'm surprised that you're needing to look at AASHTO. I've never had to design a manhole or other buried structure to AASHTO that I can recall. Only ASTM C478 and ACI 318 (maybe ACI 530 on occasion). Only culverts and at-grade structures have ever needed AASHTO design.
Sawbux: Good link. I also agree; why so deep?
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
https://www.facebook.com/AmericanConcrete/
RE: 70 ft deep, 8 ft diameter manhole concrete and foundation design
The pipe has to go through a hill and thats why the manhole is so deep. I have checked precast calculations from manufacturers and their manholes don't work for depths below 50 ft.
I also don't know if caisson would work, I've look at a lot of resources and it doesn't seem like the best option. I couldn't find enough information on method of construction. But if I use cassion for construction the bottom slab can only be as big as the manhole and we have to rely on skin friction. Right now the slab comes off as 16'x16' and 24" thick; I'm probably over designing it a bit...
RE: 70 ft deep, 8 ft diameter manhole concrete and foundation design
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
https://www.facebook.com/AmericanConcrete/