ID_PLOT_FC_C   Plot > Strength Factors > SF-C   Strength/Stress

ID_PLOT_FC_C_INV   Plot > Strength Factors > SF/C   Stress/Strength

ID_PLOT_EXCESS_SMAX   Plot > Strength Factors > Δτmax   Excess Stress

ID_PLOT_EXCESS_TOCT   Plot > Strength Factors > Δτoct   Excess Stress

Top  Previous  Next

Contours the excess shear stress or strength factor using method "C".

These components can be accessed via the Strength Factor Components toolbar as follows:

 

clip0304

 

This toolbar can be changed to a vertical orientation by dragging is against either the right or left hand edge of the main window.

It can be changed back to a horizontal orientation by dragging is against either the top or bottom edge of the main window.

 

Selecting the clip0306 button on the Contours toolbar activates the Strength Factor Components toolbar.

 

clip0303

 

In elastic analysis the major and minor principal stresses can be used with the Mohr-Coulomb or Hoek-Brown strength criteria

 

ID_PLOT_MODIFY_FC Plot > Strength Factors > Strength Parameters

 

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 in 3D FF blocks.

 

Method "C" assumes that the stress path to failure takes place by increasing σ1 while loosing confinement. This is representative of an abutment failure where σ1 - σ3 is considered to be the driving force.

 

 

ID_PLOT_FC_c   Plot > Strength Factors > SF-C   Strength/Stress can be determined as [ UCS + ½(σ1+σ3) (q-1) ]/[ ½(σ1 - σ3)(q+1) ]

ID_PLOT_FC_c_INV   Plot > Strength Factors > SF/C   Stress/Strength can be determined as [ ½(σ1 - σ3)(q+1) ]/[ UCS + ½(σ1+σ3) (q-1) ]

ID_PLOT_EXCESS_SMAX   Plot > Strength Factors > Δτmax   excess stress can be determined as

 

 Δτmax = ½(σ1 - σ3) - [ UCS + ½(σ1+σ3) (q-1) ]/(q+1)

                 = [σ1 - ( UCS + q σ3) ]/(q+1)

 

 

 

ID_PLOT_FC_C   Plot > Strength Factors > SF-C   Strength/Stress can be determined as { [ 1/16 m²σc² + ½(σ1 + σ3) mσc + s σc²] - ¼ mσc}/(σ1 - σ3)

ID_PLOT_FC_C_INV   Plot > Strength Factors > SF/C   Stress/Strength can be determined as (σ1 - σ3)/{ [ 1/16 m²σc² + ½(σ1 + σ3) mσc + s σc²] - ¼ mσc }

ID_PLOT_EXCESS_Smax   Plot > Strength Factors > Δτmax   excess stress can be determined as

 

       Δτmax = ½(σ1 - σ3) - ½{ [ 1/16 m²σc² + ½(σ1 + σ3) mσc + s σc²] - ¼ mσc }

 

 

 

 

ID_PLOT_FC_C SF-C Strength/Stress   can be determined as [ UCS + (q–1) σmean ] √(2) /[ τoct (q+2) ]

ID_PLOT_FC_C_INV SF-C Stress/Strength   can be determined as τoct /[ UCS + (q–1) σmean ] √(2) /(q+2)

ID_PLOT_EXCESS_TOCT Dtoct Excess   can be determined as τoct - [ UCS + (q–1) σmean ] √(2) /(q+2)

 

where

 q = tan²(45+φ/2)

 τoct = ¹/3 [( σ1 - σ2 )² + ( σ2 - σ3 )² +( σ3 - σ1 )²]

 σmean = ¹/3 ( σ1 + σ2 + σ3 )

 

Note that the strength parameters have been chosen so that the criterion simplifies to the Mohr-Coulomb criterion when σ2 equals σ3.

 

Strength parameters are setup using

 

ID_PLOT_MODIFY_FC Plot > Strength Factors > Strength Parameters

 

Related topics:

 

ID_PLOT_FC_A ID_PLOT_FC_A_INV Plot > Strength Factor > SF-A - Stress/Strength

ID_PLOT_FC_B ID_PLOT_FC_B_INV Plot > Strength Factors > SF-B - Stress/Strength

ID_PLOT_EXCESS_S1 Plot > Strength Factors > dS1 - Excess Stress

ID_PLOT_MODIFY_IP Plot > Strength Factors > In-plane Parameters

ID_PLOT_MODIFY_UB Plot > Strength Factors > Ubiquitous Parameters