This week: PS #1 due today at beginning of class
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Transcript of This week: PS #1 due today at beginning of class
This week:PS #1 due today at beginning of classPS #2 is on the website, due next Tuesday (use student account to print) www.geology.cwu.edu/facstaff/huerta/g360/Reading: ch. 4- Strain (not 4.8) and Ch 5- Rheology of van der PluijmLab #3: Outcrop patterns, Ch 2 of RD&S
Terminology clarification:Differential stress: difference between maximum and minimum stress: = s1 –s3
Deviatoric stress: difference between mean stress and maximum stress (or minimum stress), which is the radius of the Mohr Circle: =(s1-s3)/2(See deveitis)
These equations hold for systems where we only deal with s1 and s3. This works in most real life cases, when the value of s2 does not affect the shear and normal stresses acting on faults and fractures.
Dilation
x
y
Principal Strain Axes
Finite strain vs. incremental strain
Coaxial strain
Incremental principal strain axes are the same throughout strain history
Non-coaxial strain
Incremental principal strain axes rotate throughout strain history
Quantifying strain
• Longitudinal• Volumetric• Angular
Strain States
(a) General strain
(b) Axially symmetric extension
(c) Axially symmetric shortening
(d) Plane strain
(e) Simple shortening
Strain on the map