Horizontal Subgrade Modulus Value Interpretation

[EngDM]

Hey all,

I have a table provided in a geotechnical report that I would like to use in a spring support model for a driven H-pile to get a rough idea on how it would perform. I am having some difficulty determining exactly how to calculate my spring constant per meter strip of height. Here is the table:

As you can see the table does not have any units in it for what D should be.

What I have done, say in the 4-9m region, is take 6.7/0.360m = 18.61MPa/m ----- I'm not sure if the units on this product are correct, but the table header appears to indicate that each cell would have those units.

If I then multiply by my 1m strip, I get 18.61MPa, but the spring constant I need is in N/mm, not mm^2 as is present in MPa.

Where do I cancel out the other mm?

 

[centondollar]

The spring constant is "F/L^2" according to the classical elastic foundation theory, where soil reaction is p = kh*w = F/L^2 * L = F/L, and the spring constant "kh" is modulus "k" multiplied by characteristic width, such as diameter.

If you are using point springs, you multiply the modulus with diameter and distance between point springs to obtain pointwise defined springs with stiffness "F/L".

 

[EngDM]

If you are using point springs, you multiply the modulus with diameter and distance between point springs to obtain pointwise defined springs with stiffness "F/L".

So if I am interpretting what you are saying correctly, 6.7/0.360 (14" diameter) gives me MPa/m, multiply 1m strip gives me MPa, then multiply out diameter to get my spring?