Transcript Faults and stress - GLG510--Advanced Structural Geology, Spring

Faults and stress
10 April 2015
GLG510 Advanced Structural Geology
Relationship between traction and stress
10 April 2015
GLG510 Advanced Structural Geology
s3
syy
syx = syx
sxx
s1
10 April 2015
GLG510 Advanced Structural Geology
10 April 2015
GLG510 Advanced Structural Geology
10 April 2015
GLG510 Advanced Structural Geology
10 April 2015
GLG510 Advanced Structural Geology
Faults and stress:
traction and stress
Mohr Circle
Graphical construction that lets us visualize the relationship between
the principal stresses and tractions on a boundary (like a fault).
 measured positive clockwise from s1 direction clockwise to plane of interest
2 measure positive clockwise from –sn direction on Mohr circle
10 April 2015
GLG510 Advanced Structural Geology
Faults and stress:
traction and stress
Equations of the Mohr Circle (also “Cauchy’s equations”)
10 April 2015
GLG510 Advanced Structural Geology
Faults and stress:
traction and stress
90
10 April 2015
GLG510 Advanced Structural Geology
Faults and stress:
traction and stress
10 April 2015
GLG510 Advanced Structural Geology
Faults and stress:
traction and stress
10 April 2015
GLG510 Advanced Structural Geology
Faults and stress:
traction and stress
10 April 2015
GLG510 Advanced Structural Geology
Faults and stress:
traction and stress
35
10 April 2015
GLG510 Advanced Structural Geology
Faults and stress:
traction and stress
t = ss
10 April 2015
-Davis and Reynolds
GLG510 Advanced Structural Geology
-Engelder, 1993,
Stress regimes in
the lithosphere,
Princeton Univ.
Press
10 April 2015
GLG510 Advanced Structural Geology
Pollard and Fletcher
10 April 2015
GLG510 Advanced Structural Geology
Coulomb Law of Failure
Coulomb equation
tc = c + tan f sn
Where
tc = critical shear stress
required for faulting (shear
strength)
c = cohesive strength
tan f = coefficient of internal
friction = m
10 April 2015
GLG510 Advanced Structural Geology
10 April 2015
GLG510 Advanced Structural Geology
Faults and stress:
traction and stress
10 April 2015
GLG510 Advanced Structural Geology
10 April 2015
-D+R
GLG510 Advanced Structural Geology
10 April 2015
GLG510 Advanced Structural Geology
10 April 2015
GLG510 Advanced Structural Geology
Practice
10 April 2015
GLG510 Advanced Structural Geology
10 April 2015
GLG510 Advanced Structural Geology