Lythos Rock

Rock engineering

Rock mass strength after Hoek–Brown

mb, s and a by the generalised Hoek–Brown criterion; the equivalent c′ and φ′ of a tunnel, a slope or a general case; the rock mass modulus; GSI from five classifications; σci and mi fitted to triaxial tests; residual strength.

$ pip install lythosrock

Run

lythos-rock

Default port

8784

Python

3.10+

Version

0.1.0

Licence

AGPL-3.0

See the examples →ReferenceSource ↗

What is known about a rock mass — the strength of the intact rock, the Geological Strength Index, how much the excavation disturbed it — is turned into the parameters an analysis needs, after the generalised Hoek–Brown criterion (Hoek, Carranza-Torres & Corkum 2002). Every application and every estimate is reported side by side, so the effect of each choice is in plain view.

What it computes

1. Intact rock — σ_ci and m_i entered, or picked from typical values (m_i and the modulus ratio MR for 41 rock types, σ_ci from the ISRM field strength grades R0–R6), or fitted to triaxial tests (Hoek & Brown 1980) with r² and a check on the range of confinement.
2. GSI — entered, read from the chart's classes, or converted from JCond₈₉ and RQD, RMR₈₉, Q′, or block volume and joint condition (Cai et al. 2004).
3. Hoek–Brown — m_b, s and a; the tensile, uniaxial and global strength of the rock mass; the disturbance factor D with Hoek's guidance for tunnels, slopes and open pits.
4. Equivalent Mohr–Coulomb — c′ and φ′ fitted over σ_t < σ₃ < σ_3max for a general case, a tunnel, a slope or a custom range — every application side by side.
5. Instantaneous strength — φ_i and c_i of the tangent to the envelope at any σ₃ (Balmer 1952).
6. Deformability — the rock mass modulus by Hoek & Diederichs (2006), generalised and simplified, and by Hoek et al. (2002).
7. Residual strength — GSI_r, the residual constants and c′, φ′ (Cai et al. 2007).

On top of it, a parametric or probabilistic study sweeps any input as a range or a distribution and reports the statistics of every output, the characteristic values (5 % fractiles) of c′, φ′, σ_cm and E_rm, and Spearman sensitivities.

Screenshots

Results summary

Laboratory fit, tunnel — dark theme, Turkish

Failure envelopes, σ1–σ3 and τ–σn

The quantified GSI chart

Deformation modulus against GSI

Triaxial tests and the fitted envelope

Probabilistic study: sensitivity of φ′

Quick start

pip install lythosrock
lythos-rock                                   # interface: http://127.0.0.1:8784/

In the 1 · Rock mass tab enter the intact rock, the GSI, the disturbance and the application, and press Analyse. Results appear under Summary, Results and Figures; the 2 · Study tab runs parametric and probabilistic studies. The report menu in the header writes PDF, HTML or Word.

The same from the command line:

lythos-rock example -o project.rock           # a starter project
lythos-rock run project.rock -o report.pdf
lythos-rock study project.rock -o samples.csv

Figures

The failure envelopes, σ₁–σ₃ and τ–σ_n side by side (Hoek–Brown, the fitted Mohr–Coulomb line, the residual envelope, σ_3max, σ_t and the tangent at the chosen σ₃) · the quantified GSI chart with the rock mass on it · m_b/m_i, s and a against GSI · c′ and φ′ against GSI · E_rm against GSI by every estimate · the effect of D · the triaxial tests with the fitted envelope. Study figures: one-at-a-time sweep, histogram with the 5 % fractile, scatter, tornado.

Next steps

• Examples — the starter project, a blasted tunnel, GSI five ways, a triaxial fit and a probabilistic study.
• Reference — the expressions, inputs, modules and limits.
• Where one discontinuity governs rather than the rock mass as a whole, use Lythos Kinematic. The c′ and φ′ found here go straight into LythosFEA, Lythos LE and the rock methods of Lythos Bearing.