Capacity of Permanent Caisson Foundation

[Kpaudel]

Simply press some words with your opinion,
is 850 kPa of bearing capacity with FoS of 3, achievable for 10 m dia 20 m deep caisson rest on medium dense sand with SPT N 30?

 

[EireChch]

10m dia? Surely a mistake?

my apologies, I thought caisson referred to a bored pile and I havnt seen a bored pile 10m in dia.

Anywasy - more to the point, i agree, what are you building ?

 

[BUGGAR]

We did some 40 ft x 60 ft floating concrete caissons so why not 10m?

My opinion must first be fed by my curiosity. What are you building?

 

[Kpaudel]

Dear EireChch,

Yes it's 10 m dia well/caisson for bridge foundation.

This one is reference for you

https://en.m.wikipedia.org/wiki/Caisson_(engineering)

Yes Buggar we are going to construct bridge.

 

[oldestguy]

I'd look more at figuring expected settlement as controlling design.

 

[LRJ]

Agreed that settlement is likely to dominate design. Scour is likely to be a further issue.

 

[hokie66]

850 kPa is a lot of load on sand. But I agree with others that settlement is what matters. What do you know about how far down the sand layer goes, and what is underneath? When you say 850 with a FS of 3, do you mean 850 is the service load bearing pressure?

 

[BUGGAR]

Are you excavating overburden soils for the caisson? Caisson details? Yours is large enough that it is likely cellular. Will the cells be weighted? Sounds very interesting but very vague.