Rock Mechanics NX¶

Processing of the geostructural survey of rock masses carried out on site with compass and clinometer according to ISRM recommendations — geomechanical classifications, characteristic rock-mass parameters and stability checks for planar and wedge sliding.

Open the app 5-minute quickstart

At a glance¶

What it does: it represents and processes the discontinuity survey of a rock mass, runs the main geomechanical classifications (Barton, Bieniawski/Romana, Jašarević, Sen, Robertson, Singh & Goel), derives the characteristic parameters (cohesion, friction angle, deformation modulus) and checks stability for the kinematic mechanisms of planar sliding and wedge sliding (Sliding 3D).
For whom: geologists and geotechnical engineers who characterise a rock mass, classify the quality of the rock and produce the geomechanical report.
How many minutes: 5 (first classification on a survey that is already prepared) → 45 (real case with several joint sets, multiple classifications and a stability check).

The survey follows the procedure described in the ISRM recommendations "Suggested Methods for the Quantitative Description of Discontinuities in Rock Masses".

Typical workflow¶

Open the app: nx.geostru.ai/rockmechanics/
Enter the geostructural survey data: discontinuity sets, attitude (dip direction/dip), spacing, persistence, aperture, roughness, weathering, infilling, hydraulic conditions.
Determine the intact rock strength \(S_u\) (Point Load, Schmidt hammer or ISRM estimate) and the RQD.
Choose one or more geomechanical classifications: the app computes the quality index and the rock-mass class.
Read the derived characteristic parameters (cohesion \(c\), friction angle \(\varphi\), modulus \(E\), GSI).
If needed, run the stability check for planar or wedge sliding, including water, seismic action and external forces.
Use the utilities for the impact force of a boulder or for the seismic susceptibility to collapse.
Export the calculation report and the graphical outputs.

See the full workflow →

Manual chapters¶

Getting started¶

Quickstart — from joint attitude to your first classification in 5 minutes
Full workflow — the ISRM survey and the input → calculation → export sequence

Geomechanical classifications¶

Overview and common parameters — \(S_u\), RQD, spacing, \(J_n/J_r/J_a/J_w\)/SRF
Barton (Q index) — underground works and general characterisation
Bieniawski & Romana (RMR · SMR) — tunnels, foundations and slopes
Jašarević & Kovačević (n index) — carbonate rock masses
Modified RMR (Sen) — simplified continuous formulation
SRMR (Robertson) — slopes in weak rock
Singh & Goel (N index) — tunnels, derivation from Q

Stability checks¶

Planar sliding — limit equilibrium on a single plane
Sliding 3D — sliding of a tetrahedral wedge

Utilities¶

Impact force · seismic collapse — Paronuzzi and Harp & Noble

Output and reference¶

Export and report — calculation report and outputs
File formats — project and survey data
Resources — downloadable figures and sample files
Glossary — geomechanical symbols and terminology
Bibliography — scientific references
Geoapp — complementary online calculations
FAQ — frequently asked questions

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