Soil stiffness, Plate bearing

[domdem]

Hello Everybody

We are currently looking into producing a class 3 foundation for use on a major highway,(based on IAN 73) at the moment we are trying to correlate the LWD,FWD And dynamic plate on a stony cohesive clayey silt, before and after modification with cement. So if anyone has any experience or comments which may speed up the process i would be grateful for the knowledge.
Traditional design is a cbr of 15 on capping and 30 on a sub-base,(assumed), how does this relate to the stiffness ? figures quoted to me are 150mpa in 800mm, which seems a bit onerus when looking at the previous design regimes ?

 

[iandig]

If you get a copy of IAN 73, on page 8, under section 3.9 is the following equation:
E = 17.6 (CBR)0.64 MPa. you have to raise the CBR to the power of 0.64, can't get the reply to write it as superscrip. For the purposes of IAN 73, E is the stiffness modulus. You can then back calculate E to get CBR.
If you don't have a copy of IAN 73, you can download it free from the Highways Agency website.