Geotechnical Engineering

1
UNIVERSITI MALAYSIA PAHANG Department of Civil
and Environmental Engineering

• Geotechnical Engineering
• BAA 3513
• Chapter 1 Shear Strength Part 2

Muzamir bin Hasan, M.Eng. Lecturer
2
Mohr Circles Failure Envelope
?
X
?
Y
Soil elements at different locations
X
failure
Y
stable
3
Mohr Circles Failure Envelope
The soil element does not fail if the Mohr circle
is contained within the envelope
GL
Y
?c
?c??
Initially, Mohr circle is a point
4
Mohr Circles Failure Envelope
As loading progresses, Mohr circle becomes larger
GL
Y
?c
.. and finally failure occurs when Mohr circle
touches the envelope
5
Orientation of Failure Plane
Failure plane oriented at 45 ?/2 to horizontal
GL
?
90?
Y
?c
?c??
6
Mohr circles in terms of ? ?


?v
?h
?v
?h
7
Envelopes in terms of ? ?
Identical specimens initially subjected to
different isotropic stresses (?c) and then loaded
axially to failure
??f
uf
Initially
Failure
c, ?
in terms of ?
At failure, ?3 ?c ?1 ?c??f ?3 ?3 uf
?1 ?1 - uf
c, ?
in terms of ?
8
Inclination of the Plane of Failure Due to Shear
9
Inclination of the Plane of Failure Due to Shear
10
Inclination of the Plane of Failure Due to Shear
11
Project Case Study

• Find any case that related to major construction
  failure anywhere in the world.
• Example Highland Tower.
• Produce a presentation (in report format) based
  on your selected case from your geotechnical
  perspective.
• Presentation will be conducted on the final week
  before mid-term break.

12
Homework!!!

• Problems 7.2 (page 210)
• Submit Next Class