1. Stress Distribution and all of its mysteries

2. I. The Bulb of Pressure
Force

3. I. The Bulb of Pressure
Force
“what are the
stresses at this
point?”

4. (boo-sinn-esk)
II. The Boussinesq Equation A. Goal: to determine the vertical and horizontal stresses under a point load in a homogeneous, isotropic medium.
Allows us to determine vertical and horizontal stresses at any point in space
Examine the transmission and distribution of stresses in large, extensive masses
of soil.
Culvert?

5. II. The Boussinesq Equation B. The Equation:

6. II. The Boussinesq Equation B. The Equation:
Where v = Poisson’s
Ratio (0.48)
Also an equation for σy

13. 6.71

14. If Poisson’s ratio is ~0.5, equations simplify to:
σx = 3Px2z
2π R5
σy = 3Py2z
2π R5

15. Your turn:
Vertical load of 2500 lb/ft2
Determine horizontal (x) and vertical (z) stresses
at X= 5, Y= 2, Z = 6