Plot > Strength Factors > Strength Parameters
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Sets up the strength parameters for generating strength factor contour plots in terms of principal stress components. These components can be accessed via the Strength Factor Components toolbar as follows:
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Selecting the
In elastic analysis the major and minor principal stresses can be used with the Mohr-Coulomb, Hoek-Brown or Drucker-Prager strength criteria to estimate the amount of damage due to over-stressing. Since none of the parameters have any orientation sensitivity, this criterion is representative for homogeneous rock mass stability.
By contrast, in non-linear analysis the stresses can never exceed the strength unless some creep is used. In this latter case, viscous creep can allow stress states above the failure criterion, thus indicating a lack of static equilibrium. Hence for non-linear analysis one normally directly considers the amount of non-linear strain or the strain rate predicted by the model
Mohr-Coulomb
Material # specifies the material number. Material #1 represents the host material. Other material numbers are used to define alternate material zones such as ore, fault gouge, backfill etc.
Standard Deviation specifies the uncertainty you have in the failure criterion measured in the σ1 direction.
Material Type specifies the material type: Mohr-Coulomb, Hoek-Brown, Drucker-Prager or None.
Tension Cutoff, UCS, Friction Angle the Mohr-Coulomb criterion defines strength in terms of principal stresses as follows:
Tension cutoff and UCS are specified in units of stress (MPa or psi). Friction angle is specified in degrees.
Apply – regenerates the contour plot.
Acc Dam – plots accumulated damage. Refer to Accumulated Damage
Hoek-Brown
Material # specifies the material number. Material #1 represents the host material. Other material numbers are used to define alternate material zones such as ore, fault gouge, backfill etc.
Material Type specifies the material type: Mohr-Coulomb, Hoek-Brown, Drucker-Prager or None.
Standard Deviation specifies the uncertainty you have in the failure criterion measured in the σ1 direction (specified in units of stress, MPa or psi).
Tension Cutoff, Sigma:C, m and s the Hoek-Brown criterion defines strength in terms of principal stresses as follows:
Tension cutoff and Sigma:C are specified in units of stress (MPa or psi).
Apply – regenerates the contour plot.
Acc Dam – plots accumulated damage. Refer to Accumulated Damage
Drucker-Prager
Material # specifies the material number. Material #1 represents the host material. Other material numbers are used to define alternate material zones such as ore, fault gouge, backfill etc.
Material Type specifies the material type: Mohr-Coulomb, Hoek-Brown, Drucker-Prager or None.
Standard Deviation specifies the uncertainty you have in the failure criterion measured in the τoct direction.
Tension Cutoff, UCS, Friction Angle the Drucker-Prager criterion defines strength in terms of principal stresses as follows:
where
τoct = ¹/3 [(σ1 - σ2)² + (σ2 - σ3)² +(σ3 - σ1)²]½
σmean = ¹/3 (σ1 + σ2 + σ3)
Tension cutoff and UCS are specified in units of stress (MPa or psi). Friction angle is specified in degrees.
Note that the strength parameters have been chosen so that the criterion simplifies to the Mohr-Coulomb criterion when σ2 equals σ3.
Apply – regenerates the contour plot.
Acc Dam – plots accumulated damage. Refer to Accumulated Damage
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