Geotechnical Domains
The Geotechnical Domains branch holds the project's rock masses. A domain is made of one rock material. It carries the inputs of the classifications and shows their results: RMR89, Q, GSI, the Hoek-Brown parameters, rock mass strength and modulus, and the equivalent Mohr-Coulomb strength, each strength over a GSI range. The method is on the Rock Mass Classification page.
Context menu
Right-click the Geotechnical Domains branch header or a domain.
- New Geotechnical Domain — Add a domain, named Domain, made of the first rock material. With no material yet, the messages panel suggests adding one first. (
ID_GEOTECHDOMAIN_NEW) - Export Classification (CSV)... — Write every domain's inputs and results to a CSV file (below). (
ID_GEOTECHDOMAIN_EXPORTCSV) - Import Field Sheet (CSV)... — Update domains, or add new ones, from a CSV file of inputs (below). (
ID_GEOTECHDOMAIN_IMPORTCSV) - Add Data Sheet to Report — Add a geotechnical data sheet of every domain to an open report (below). (
ID_GEOTECHDOMAIN_DATASHEET) - Duplicate — (a domain) Add a copy. (
ID_GEOTECHDOMAIN_DUPLICATE) - Rename — (a domain) (
ID_ITEM_RENAME) - Delete — (a domain) (
ID_POPUP_ITEM_DELETE)
Properties
Geotechnical Domain
| Property | Description |
|---|---|
| Name | Name of this domain. |
| Rock Material | The intact rock this rock mass is made of, from Rock Materials: its UCS, mi, Ei and unit weight. |
| Show on Mohr Diagram | Draw this domain's Hoek-Brown envelope (Balmer 1952) on the Mohr diagram. |
| Notes | Where the domain is, and where its inputs come from. |
Block Size and RQD
| Property | Default | Description |
|---|---|---|
| Jv (joints/m3) | 10 | Volumetric joint count, e.g. the median of the Jv layer over the domain (Block Size). |
| RQD Source | Field (logged) | Field (logged), on core or a scanline, or Derived from Jv: 110 − 2.5 Jv (Palmström 2005). Derived RQD is labelled as derived. |
| RQD (%) | 75 | As logged; used when RQD Source is Field. |
RMR89 Inputs
| Property | Default | Description |
|---|---|---|
| Spacing (m) | 0.3 | Spacing of the discontinuities (of the set that rates lowest). |
| Persistence (m) | 3 | Discontinuity length. |
| Aperture (mm) | 0.5 | Separation of the walls. |
| Roughness | Slightly rough | Very rough, Rough, Slightly rough, Smooth or Slickensided. |
| Infilling | None | None; Hard, under 5 mm; Hard, over 5 mm; Soft, under 5 mm; Soft, over 5 mm. |
| Weathering | Slightly weathered | Unweathered, Slightly weathered, Moderately weathered, Highly weathered or Decomposed. |
| Groundwater | Damp | Completely dry, Damp, Wet, Dripping or Flowing. |
Q System Inputs
| Property | Default | Description |
|---|---|---|
| Jn | 9 | Joint set number: 9 for three sets, 12 for three plus random. |
| Jr | 1.5 | Joint roughness number: 1.5 rough or irregular, planar. |
| Ja | 1 | Joint alteration number: 1 unaltered walls, staining only. |
| Jw | 1 | Joint water reduction factor: 1 dry or minor inflow. |
| SRF | 1 | Stress reduction factor: 1 for medium stress. |
Enter these as numbers from Barton's tables. A value outside the tables' ranges (Jn 0.5–20, Jr 0.5–4, Ja 0.75–20, Jw 0.05–1, SRF 0.5–400) is still used, but the messages panel warns which one and the Athos classification carries the note: a 10 for Jw, or Jn's value in Jr, is the usual slip.
GSI
| Property | Default | Description |
|---|---|---|
| GSI Source | Chart (your pick) | Chart (your pick): the Chart GSI. From Jv and joint condition: 1.5 JCond89 + RQD / 2 (Hoek, Carter & Diederichs 2013). From RMR89: RMR89 with a dry groundwater rating, less 5 (Hoek 1995). |
| Chart GSI | 50 | Your pick from the GSI chart; used when GSI Source is Chart. |
| GSI Spread | 5 | Results are reported over GSI plus and minus this: a classification is a range. |
Hoek-Brown
| Property | Default | Description |
|---|---|---|
| Disturbance D | 0 | 0 undisturbed, 0.7 good production blasting, 1 heavily blasted (Hoek et al. 2002). |
| Application | Slope | Slope or Tunnel: sets the stress range of the equivalent Mohr-Coulomb fit. |
| Height or Depth (m) | 30 | Slope height, or tunnel depth below surface. |
Tunnel Support (Q)
| Property | Default | Description |
|---|---|---|
| Span (m) | 10 | Span (or height) of the opening. Used when Application is Tunnel. |
| ESR | 1.0 | Excavation support ratio (Barton 2002): 0.8 underground power stations, 1.0 major road and rail tunnels, 1.3 minor road tunnels and storage caverns, 1.6 water tunnels and permanent mine openings, 3–5 temporary mine openings. |
Results (read-only)
| Result | What it is |
|---|---|
| RQD (%) | The RQD the classifications use, marked (derived from Jv) when it was. |
| RMR89 | Basic RMR89 (Bieniawski 1989), without the orientation adjustment, with its class (I Very good to V Very poor). |
| RMR89 Ratings | The five ratings: strength, RQD, spacing, condition and groundwater. |
| Q | Barton, Lien & Lunde (1974), with its class. |
| GSI | At the GSI, and over GSI ± spread. |
| mb, s, a | Generalised Hoek-Brown (Hoek, Carranza-Torres & Corkum 2002), at the GSI. |
| Rock Mass UCS (MPa) | σci s^a. |
| Global Strength (MPa) | σcm (Hoek et al. 2002, eq. 18). |
| Tensile Strength (MPa) | −s σci / mb. |
| Erm (MPa) | Rock mass modulus (Hoek & Diederichs 2006). |
| Sigma 3 max (MPa) | Top of the stress range of the Mohr-Coulomb fit (Hoek et al. 2002, eqs. 20–21). |
| Cohesion c' (MPa) | Equivalent Mohr-Coulomb cohesion over the stress range. |
| Friction phi' | Equivalent Mohr-Coulomb friction angle over the stress range. |
| Max Unsupported Span (m) | (tunnel only) 2 ESR Q^0.4 (Barton 2002), followed by support needed when the span is wider than that, or self-supporting. |
| Bolt Length (m) | (tunnel only) 2 + 0.15 span / ESR (Barton 2002). |
| Roof Support Pressure (MPa) | (tunnel only) 2 √Jn Q^(−1/3) / (3 Jr) (Barton et al. 1974). The Q support chart's category is not drawn. |
A value with a range reads value (low to high). A domain that cannot be evaluated shows Status: Not evaluated: with the reason instead; choose a rock material and check the inputs.
Exporting the classification
Export Classification (CSV)... writes one row per domain, named geotechnical domains by default. The columns are:
name,material,notes;- the inputs:
jv,rqd_source,rqd,spacing_m,persistence_m,aperture_mm,roughness,infilling,weathering,groundwater,jn,jr,ja,jw,srf,gsi_source,gsi_chart,gsi_spread,disturbance,application,height_m,span_m,esr; - the results:
rqd_used,rmr89,rmr_class,q,q_class,gsi,gsi_low,gsi_high,mb,s,a,sigma_c_mpa,sigma_cm_mpa,tensile_mpa,erm_mpa,erm_low_mpa,erm_high_mpa,sigma3_max_mpa,cohesion_mpa,cohesion_low_mpa,cohesion_high_mpa,friction_deg,friction_low_deg,friction_high_deg,max_unsupported_span_m,bolt_length_m,roof_pressure_mpa,status. The three support columns are empty for a slope domain.
Choices are written as short tokens — field or jv; very_rough, rough,
slightly_rough, smooth, slickensided; none, hard_under_5mm, hard_over_5mm,
soft_under_5mm, soft_over_5mm; unweathered, slightly, moderately, highly,
decomposed; completely_dry, damp, wet, dripping, flowing; chart,
jv_and_condition, rmr89; slope, tunnel. rqd_used ends in (derived) when it came from
Jv. status is evaluated, or not evaluated: and the reason, with the result cells blank.
Importing a field sheet
Import Field Sheet (CSV)... reads a CSV file with a header row and fills domains from it, so inputs logged in the field can be brought in at once.
- A name (or domain) column is required: each row is one domain. A row updates the domain of that name, or adds a new one.
- material (or rock material) and notes are optional, as is any of the input
columns of the export, in any order. Headers are matched ignoring case, spaces and
punctuation, so Spacing m matches
spacing_m; a unit in brackets is dropped, and the property page's own labels are accepted (Jv (joints/m3), Chart GSI, Disturbance D, Height or Depth (m)), so a sheet laid out like the page reads straight in. - A file saved with semicolons between the fields (a European Excel), with decimal commas in its numbers, is read as such; a tab-separated file too.
- Choices can be given as the token or as the label on the property page, such as Slightly rough.
- A blank cell keeps the domain's current value. A value a column does not take is reported, and the old one is kept.
- Result columns are ignored, so an exported file can be edited and read back. Any other column is reported as ignored.
- A material the project does not have is reported; add it under Rock Materials.
The messages panel ends with how many domains were updated and added.
Adding a data sheet to a report
Open an analysis report first. Add Data Sheet to Report then adds a section, Geotechnical data sheet, to it:
- for each domain, its rock material and notes, and a table of RQD, RMR89, Q, GSI, mb, s and a, rock mass UCS, global strength, tensile strength, Erm, c′ and φ′ with the value and the basis of each — its source, the inputs it came from, and whether it was derived — and, for a tunnel domain, a Q support row (unsupported span, bolt length and roof pressure, from the span and ESR);
- a table of the discontinuity sets, with each set's planes, mean plane, Fisher K, α95 and joint strength.
See also
- Rock Mass Classification — how each result is worked out.
- Rock Materials
- Block Size — Jv from the outcrop.
- Mohr Diagram