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Version: 3.4.20 (unreleased)

Sets

The Sets branch holds the project's named sets, most often discontinuity (joint or fracture) sets. A plane measurement belongs to a set through its Set property, a tag that is saved with the project. Where the measurement sits in the Interpretation tree does not matter, so a set can hold planes from many folders, and moving a measurement does not change its set.

  • Auto-cluster Selected Orientations tags the clusters it finds, by k-means, P-maximisation, fuzzy k-means, density or a Fisher mixture, with new sets, J1, J2 and so on for planes, each in a colour of its own. A Fisher mixture with a noise class leaves measurements that fit no set with no Set. See Auto-cluster.
  • To tag by hand, select a measurement and choose its Set in the Properties panel.
  • A new project starts with the sets S0, S1 and S2.

To turn the tags into folders, use Group by Set on an orientation group, or tick Move each set into a group of its own in Auto-cluster.

The sets are used by:

  • the stereonet: Colour by → Set, and Sets From → Project Sets for Set Statistics and the kinematic analysis;
  • Slope Stability, where each set is listed as Set: J1;
  • Create DFN, where each set is listed as Set: J1 and becomes a fracture set when ticked;
  • Block Size, to convert P21 to P32;
  • Tunnel As-built, for each set's rating against the drive and the wedges, and Rockfall Inventory, for the sets that bound the scars. Both, and Slope Stability and Block Size, can read a DFN's fracture sets instead;
  • the Mohr diagram, which draws each set's joint-strength envelope;
  • the geotechnical data sheet and Athos's set statistics.
Earlier projects

Before sets were saved as tags, a Set chosen for a measurement was lost when the project closed, and Auto-cluster copied its clusters into folders. Measurements in a project from then open with no set; the old cluster folders still work as sets wherever folders can be chosen.

Joint strength​

Select a set to give it a shear strength of its own, under Joint Strength in the Properties panel. Without one, each analysis uses its own friction angle for the set.

PropertyDefaultDescription
Own StrengthOffGive this set a shear strength of its own. Off, analyses use their own friction angle for it (Slope Stability's, the stereonet's Friction Angle).
ModelMohr-CoulombMohr-Coulomb: cohesion and friction angle. Barton-Bandis (Barton & Choubey 1977): JRC, JCS and the residual friction angle, whose friction falls as the normal stress rises.
Cohesion (MPa)0Mohr-Coulomb cohesion. Kinematic analysis ignores it.
Friction Angle30Mohr-Coulomb friction angle, degrees.
JRC8Barton-Bandis joint roughness coefficient, 0–20, at the scale of the joint. Scale a laboratory value with Barton & Bandis (1982).
JCS (MPa)50Barton-Bandis joint wall compressive strength, e.g. from Schmidt hammer rebounds.
Residual Friction28Barton-Bandis residual friction angle, degrees: (basic − 20) + 20 r / R from Schmidt rebounds.
Reference Normal Stress (MPa)0.1The effective normal stress at which kinematic analysis takes a Barton-Bandis friction angle: about the unit weight times the thickness of the blocks (0.1 MPa for about 4 m).

Every row is shown whichever model is chosen; only the chosen model's rows are used.

The shear strength at a normal stress σn is:

  • Mohr-Coulomb: τ = c + σn tan φ.
  • Barton-Bandis: τ = σn tan(φr + JRC log₁₀(JCS / σn)), with the angle no more than 70°. Where σn reaches JCS, φr alone is used.

How it is used:

  • Kinematics (Slope Stability and the stereonet's kinematic analysis) takes one friction angle per set: a Mohr-Coulomb set's Friction Angle, or a Barton-Bandis set's angle at the Reference Normal Stress. A line of intersection takes the lower angle of its two sets. The stereonet key shows a set's own angle beside its name, as J1 (34°).
  • Factors of safety use the full strength of each set at the normal stress on its plane.
  • A DFN fracture set read by these tools takes the strength of the Set with its name.
  • The Mohr diagram draws each set's envelope.

Renaming a set​

Rename a set in the tree (edit its label) and its joint strength goes with it, and every orientation tagged with the old name is retagged with the new one. The messages panel says how many measurements were retagged. A name another set already has is refused. Analysis runs that read the set under its old name are marked stale.

Exporting the set table​

Export on the Sets branch header writes a CSV table of every set that holds planes, named set table by default. It is laid out to paste into other discontinuity tools. The columns are:

set, planes, dip, dip_direction, fisher_k, alpha95_deg, strength_model, cohesion_mpa, friction_deg, jrc, jcs_mpa, residual_deg, reference_sn_mpa, kinematic_friction_deg

  • The mean plane is the Fisher mean of the set's poles, unweighted, to 0.1°.
  • Fisher K and α95 are blank for a set of one plane.
  • strength_model is mohr_coulomb or barton_bandis, with only that model's columns filled. The strength columns are blank for a set with no strength of its own.

With no tagged planes, a message asks you to tag orientations with a set first.

Context menus​

Right-click the Sets branch header.

  • New — Add a set; a dialog asks for its name. (ID_GROUPPOPUP_NEW)
  • Import — Read sets from a file. (ID_GROUPPOPUP_IMPORT)
  • Export — Write the set table as CSV (above). (ID_GROUPPOPUP_EXPORT)
  • Empty List — Clear every set from the list. (ID_GROUPPOPUP_EMPTYLIST)

Each set shows the standard item menu, listed on the Standard Item and Group Menus page. Select a set to edit its ID, age, colour, opacity and joint strength in the Properties panel.

See also​