Mat Foundation Design 3

Hello
I have a problem with design mat foundation

I have q(allowable), settlement(allowable), Subgrade Reaction of soil from soil investigation report.
and a finite element model of foundation by shell element and joint spring(that result from subgrade reaction)

The maximum joint displacement is less than the allowable settlement, but for reaction control is it O.K. or not?

(joint displacement)*(subgrade reaction) should be less than q(allowable)

 

[dlew]

Aabedini,

The allowable bearing pressure, q, is based on the entire mat being loaded. What I believe you are finding from the computer analysis is that under a few joints the calculated bearing pressure (displacement times modulus of subgrade reaction) slightly exceeds the "allowable" bearing. If that is the case, in my opinion, to exceed the allowable bearing pressure on a small area of the mat is OK if the concrete mat is designed for those soil pressures.

Regards

AEF

 

dlew,
thank you a lot
but if bearing pressure on a big area of the mat exceeds from the allowable bearing (max displacement is less than allowable settlement), what will i do?

 

[boo1]

increase area or decrease load

 

[Ginger]

Alternatively, you could:

a) Treat the ground in order to increase its strength and stiffness. This could be done using vibro compaction, stone columns, lime/cement stabilisation, jet grouting, etc etc.

b) Founding the mat at a lower level in the ground and making the raft cellular so that the effective increase in vertical stress is reduced.

c) Totally redesign using piled foundations

Regards Andy Machon

 

Mr. Andy Machon and boo1
Thanks a lot for your help
Best regards

Amir Abedini

 

[boo1]

Soils compaction/muck removal or injection grouting and pile foundations are possible solution when building conditions were not ideal. Check on the development of drilled concrete piers, driven piles, and pre-construction helix foundations.

 

What are the pros and cons of using a mat foundation system for a high-rise located on a river bank

 

[boo1]

14Concrete recommend u starting a new thread.