Spanglers Area Load of Infinite Length Equation

[UFGeotech]

I am trying to calculate the increase in stress due to a strip load and I have done so using Boussinesq and a method from an US ACOE manual (EM 1110-02). I would also like to calculate it using Spangler's method but I do not know how to use his equation (see the attached). It appears to be some sort of limit but I'm not sure. I can work the equation by plugging in both x1 and x2 but I'm not sure if that's right. It's been quite some time since calculus for me. Can anyone give me some guidance?

Thanks in advance.

 

[Bobby46]

It has also been awhile since calculus for me. I believe the process is:

Step 1. Select a depth=z
Step 2. Calculate Eqn. 21.40 where x=x2
Step 3. Caclulate Eqn. 21.40 where x=x1
Step 4. Subtract Step 3 from Step 2. This is your increase in pressure at a certain depth=z
Step 5. Repeat for various depths until you have enough points to plot a line

 

[aeoliantexan]

"Elastic Solutions for Soil and Rock Mechanics" by Poulos and Davis has tables of influence values. It is available on line for free. I think what you want is on Page 36.

As for doubling the pressure for rigid walls, I'm an old Spangler student, and I believe he did considerable testing to confirm that theory. I suspect, however, that fairly small deflections will lower that pressure considerably.