Classical Faulting Theory


Classical faulting theory postulates that the maximum compressive stress is oriented approxamately 30 degrees to the failure plane based on the following equations and illustrations.


  • Byerlee's Law

    The coeffient of sliding friction for most rock types was experimetally determined to be ~0.6-0.8. The best fit line in the diagram defines the failure envelope used in Mohr Circle analysis.

    From Davis and Reynolds



  • Mohr Circle equations and the Coulomb equation are used to determine the ideal angle between maximum stress and the failue plane, which is referred to as theta. When a friction coefficient of ~0.7 is used theta equals 30 degrees.



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