Ks value for slab on grade 1

[nebla]

Dear Geo-technical Engineers,
I am following TR34 for slab on grade design,
From plate load test (plate size 600mm) we are getting the value of contact pressure corresponding to settlement = 1.25mm
then Ks = pressure / 1.25mm settlement.

to evaluating Modulus of Subgrade Reaction (Ks) for full sized isolated footing, it is appropriate to adjust the ks value obtained from PLT. Terzaghi..... ks = kp*(B+Bp/2B)^2

My Question -
Shall i use the same approach to calculate the Modulus of Subgrade Reaction under Slab on Grade.

 

[fattdad]

I consider the plate load test for slab-on-grade design a bit wonky. Others may think different. The plate load test is too dependent on moisture content, unsaturated behavior and the like.

I worked for an A/E firm that started in structural engineering. We did a lot of forensic work. We also designed a lot of very large industrial floor slabs. In all cases I based the design subgrade modulus on correlation to soaked CBR. Works/worked for me! That's my advice and I sleep well at night!

Others think otherwise!

f-d

ípapß gordo ainÆt no madre flaca!

 

[Retrograde]

In all cases I based the design subgrade modulus on correlation to soaked CBR.

Could you share those correlations.

 

[geomane]

Retrograde,

See attached from FDOT pavement design manual.

 

[geomane]

Oops, I meant to attach this one.

 

[Retrograde]

Thanks

 

[fattdad]

jmc beat me to it! It's an old correlation. It's pretty useful; however.

f-d

ípapß gordo ainÆt no madre flaca!