Stiffness and Bearing Capacity of Piled Rafts

[bdbd]

Hello,

I am trying to understand a concept. I am working on stiffness of rafts, piles and piled rafts.
Other than those, we have bearing capacity.

So, a raft, lets say with a bearing capacity of 500 kPa. In this manner what does Kp (stiffness of raft) means? I mean, it is Pressure/deflection. So, if we have the K of the raft, we use this to estimate the deflection that will occur on the case of load equal to bearing capacity?

I will start again. We have K -stiffness, and q-bearing capacity. If we calculate bearing capacity, we do not know the settlement. Thus, we use K to calculate that. (But we have settlement prediction formulas, are they same thing?)

Long story short, do you know any resource that will clear my mind about these issues?

 

[Ron]

If the raft is pile supported, why are you concerned about the bearing capacity of the soils immediately beneath the raft? It is difficult to equate mat settlement (unsupported) to a comparable pile settlement. The bearing capacity of the soil beneath the raft is not the same (or even similar) to the bearing capacity of the soil at the tip of a pile.

 

[bdbd]

Because this is the new approach. We should consider the raft's bearing capacity and the pile's bearing capacity. Just thinking the pile for the bearing capacity is overdesign.

 

[BigH]

Look up some recent papers by Poulos . . . he has written on the subject several times in the last few years. I'll see if I can dig up the copies I have to advise of titles, etc.

 

[Retrograde]

Here's one:

H.G. Poulos, J.C. Small and H. Chow
Piled Raft Foundations for Tall Buildings
Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol 42 No.2 June 2011 ISSN 0046-5828

 

[BigH]

and another in a magazine that probably few outside of India see. The paper is by Harry Poulos

http://www.masterbuilder.co.in/challenges-design-tall-building-foundations/

 

[Guest262653]

I recommend watching the following webinar by Prof. Poulos at the website of the ISSMGE:

http://www.issmge.org/en/resources/...enges-of-foundation-design-for-tall-buildings