Geotechnical Engineering

1
UNIVERSITI MALAYSIA PAHANG Department of Civil
and Environmental Engineering

• Geotechnical Engineering
• BAA 3513
• Chapter 2 Lateral Earth Pressure Part 3

Muzamir bin Hasan, M.Eng. Lecturer
2
The Coulomb Theory

• Rankines equations were based on the premise
  that the wall had no friction with the soil.
• Coulomb had taken this into account when he
  published his theory in 1776.
• Coulomb also took into account the inclination of
  the backfill ß, the inclination of the back-wall
  with respect to the vertical a, and the angle of
  friction d between the wall and the soil being
  retained.

3
The Coulomb Theory

• Taking into account these three new parameters,
  will result in the equilibrium of the forces
  shown by the force polygon of the next slide.
• The solution of the force polygon yields the
  value of Ka, the Coulomb active earth pressure
  coefficient. A similar analysis can yield the Kp
  for the Coulomb passive earth pressure
  coefficient.

4
The Coulomb Theory
5
The Coulomb Theory
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Example 1

• Determine the total active pressure per foot of
  wall, by coulomb theory.

a5
?15kN/m3 f30 d25
?8
10m
Pa
d25
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Solution
8
Solution
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Assignment

• From the case shown in Example 1, determine the
  total PASSIVE pressure per foot of wall, by
  coulomb theory.