36validation checks covering all tests and calculations
9category A: published examples
5category B: standard or analytical solution
22category C: independent calculation
26 / 26calculations redone by hand, all in agreement
7published slope stability cases
Approach
Every test and calculation of CiviLab 7.1 has been checked: the data are entered in CiviLab and the result is compared with an independently obtained value. Three categories of check:
- A published example: data and result taken from a publication (FHWA manuals, British Geological Survey, ACI, university manuals, ACADS and GeoStudio cases…);
- B standard or analytical solution: values tabulated by the standard or exact solution;
- C independent calculation: no published example found; the result is recalculated by hand, step by step, from the formulas of the standard.
The checks are completed by recalculations in Excel (validation workbook) and by the automated tests of the code (xUnit), run at every change.
Slope stability: published cases
Data of the publication entered in CiviLab, automatic search of the critical surface, factor of safety compared with the reference value and with the GeoStudio SLOPE/W results published in its verification manual. Difference = (CiviLab − GeoStudio) / GeoStudio, same method.
| Case | Method | Published reference | GeoStudio | CiviLab 7.1 | Difference / GeoStudio |
|---|---|---|---|---|---|
| ACADS 1(a) — simple homogeneous slope | Bishop | 1.00 | 0.993 | 0.985 | −0.8 % |
| ACADS 1(a) — simple homogeneous slope | Spencer | 1.00 | – | 0.984 | – |
| ACADS 1(a) — simple homogeneous slope | Morgenstern-Price | 1.00 | 0.993 | 0.985 | −0.8 % |
| ACADS — non-homogeneous slope (3 layers) | Bishop | 1.39 | 1.413 | 1.393 | −1.4 % |
| ACADS — non-homogeneous slope (3 layers) | Spencer | 1.39 | – | 1.365 | – |
| ACADS — non-homogeneous slope (3 layers) | Morgenstern-Price | 1.39 | 1.382 | 1.365 | −1.2 % |
| ACADS — non-homogeneous slope, seismic kh = 0.15 | Bishop | 1.00 | 1.016 | 1.011 | −0.5 % |
| ACADS — non-homogeneous slope, seismic kh = 0.15 | Spencer | 1.00 | – | 0.984 | – |
| ACADS — non-homogeneous slope, seismic kh = 0.15 | Morgenstern-Price | 1.00 | 0.989 | 0.983 | −0.6 % |
| Arai and Tagyo (1985) — homogeneous slope | Bishop | 1.451 | 1.417 | 1.404 | −0.9 % |
| Arai and Tagyo (1985) — homogeneous slope | Spencer | 1.451 | – | 1.401 | – |
| Arai and Tagyo (1985) — homogeneous slope | Morgenstern-Price | 1.451 | 1.414 | 1.400 | −1.0 % |
| Greco (1996), example 4 — multilayer slope | Bishop | 1.40 to 1.42 | 1.405 | 1.440 | +2.5 % |
| Greco (1996), example 4 — multilayer slope | Spencer | 1.40 to 1.42 | – | 1.421 | – |
| Greco (1996), example 4 — multilayer slope | Morgenstern-Price | 1.40 to 1.42 | 1.389 | 1.414 | +1.8 % |
| ACADS — weak layer, specified surface | Spencer | 1.34 | – | 1.276 | – |
| ACADS — weak layer, specified surface | Morgenstern-Price | 1.34 | 1.261 | 1.260 | −0.1 % |
| ACADS — weak layer, three-block search | Spencer | 1.26 | – | 1.253 | – |
| ACADS — weak layer, three-block search | Morgenstern-Price | 1.26 | 1.261 | 1.243 | −1.4 % |
CiviLab's searches generally find an F 0.5 to 1.5 % lower than GeoStudio, i.e. a more unfavourable surface. On the specified surface, where the surface is the same in both programs, the difference is 0.001. Exception: Greco, where Bishop gives 1.440 against 1.405; the search was checked with finer grids (1.440 to 1.443); Spencer (1.421) and Morgenstern-Price (1.414) lie within the range published by Greco (1.40 to 1.42). On the weak-layer slope, circles give 1.506: only the "three-block" search finds the mechanism (1.243).
Slope stability: analytical solutions, seismic coefficients and Excel recalculation
| Check | Expected | CiviLab 7.1 |
|---|---|---|
| Exact equilibrium φ = 0 (200 slices): Bishop; Spencer; Morgenstern-Price | 1.39264 | 1.39259; 1.39258; 1.39258 (−0.004 %) |
| Infinite slope, static (L = 496 m) | 1.4004 | 1.4012 (+0.06 %) |
| Infinite slope, kh = 0.10 (L = 496 m) | 1.1087 | 1.1093 (+0.05 %) |
| RPA 2024, zone III, group 2, site S3: kh; kv | 0.0775; 0.02583 | identical |
| RPA 2024, zone V, group 1B, site S2, ST = 1.2: kh; kv | 0.1440; 0.0720 | identical |
| RPA 2024 §10.3.6: required F in seismic situation | 1.15 | 1.15 |
| NF P 94-270 I.4, ag/g = 0.2, S = 1.2: kh; kv (avg/ag = 0.9 then 0.5) | 0.12; 0.06; 0.0396 | identical |
| Excel recalculation, ACADS 1(a), Bishop: F; Fd | 0.98508; 0.78806 | 0.98508; 0.78806 |
| Excel recalculation, ACADS 1(a), kh = 0.15: Fellenius; Bishop | 0.68711; 0.71586 | 0.68711; 0.71586 |
| Excel recalculation, ACADS 1(a): Morgenstern-Price (λ); Spencer with kh = 0.15 | 0.98410 (0.529); 0.71711 | 0.98410 (0.529); 0.71711 |
| Excel recalculation, ACADS §2.8 specified surface: Morgenstern-Price; Spencer | 1.26033; 1.27602 | 1.26033; 1.27602 |
All tests and calculations
| Test / calculation | Source | Expected | CiviLab 7.1 | |
|---|---|---|---|---|
| Slope stability | ||||
| A | Bishop, Spencer, Morgenstern-Price, seismic, non-circular surfaces | 7 published cases: ACADS (Giam and Donald 1989) §2.1, 2.3, 2.4, 2.7, 2.8; Arai and Tagyo (1985); Greco (1996), compared with the references and with GeoStudio | see table above | differences 0.1 to 1.8 % (Greco Bishop +2.5 %) |
| B | Exact equilibrium φ = 0; infinite slope, static and seismic | Analytical solutions | 1.39264; 1.4004; 1.1087 | 1.39258; 1.4012; 1.1093 |
| B | Seismic coefficients | RPA 2024 §10.3 (10.22, 10.23); NF P 94-270 annex I.4 | 0.100 / 0.050; 0.120 / 0.060 | identical |
| Triaxial (NF EN ISO 17892-8/9, NF P 94-070) | ||||
| A | CIU — c′, φ′ | British Geological Survey, report IR/06/065: 4 published tests | φ′ 24.45 / 26.7 / 17.56 / 26.44°; c′ 28.78 / 0.36 / 7.4 / 3.76 kPa | identical within 0.01° and 0.01 kPa |
| A | CD — failure, c′, φ′ | University of Waterloo, CIV E 353 (2006), Winnipeg clay: raw readings of 4 specimens; independent calculation (Python, Excel) | φ′ 17.97°; c′ 26.14 kPa | 17.97°; 26.14 kPa |
| B | UU — equations (1) to (6) | NF EN ISO 17892-8: hand calculation of the corrections (piston, membrane, area) | hand calculation | identical |
| Laboratory — soils | ||||
| A | Particle size — percent passing | Kennesaw State University, Geotechnical Engineering Lab Manual (2025), Lab 3, table 3-2 (7 sieves, 304.4 g) | 95.99; 86.63; 57.65; 23.98; 6.01; 0.39 % | identical (to 0.01) |
| A | Atterberg limits — wP, wL (Casagrande) | Same manual, Lab 5, table 5-1 | wP 28 %; wL ≈ 40 % | wP 27.99 %; wL 39.55 % |
| C | Limits — 80 g / 30° cone | NF P 94-052-1: w at 17 mm | 44.6 % | 44.6 % |
| C | Proctor — wOPT, ρd max | NF P 94-093: optimum by 2nd-degree polynomial | 12.78 %; 1.879 | identical |
| C | CBR | NF P 94-078: max(F2.5/13.35; F5/19.93) | 22.2 | 22.2 |
| C | Hydrometer — Stokes diameter | NF P 94-057 | 0.0751 mm | identical |
| C | Direct shear — c′, φ′ | NF EN ISO 17892-10: regression of failure τ | 16.6 kPa; 29.9° | identical |
| C | Oedometer — Cc | NF EN ISO 17892-5 | 0.172 | identical |
| C | Los Angeles, Micro-Deval, sand equivalent | NF EN 1097-2, 1097-1, 933-8 | 22.6; 13.8; 77.0 | identical |
| C | Particle size — FM, Cu, Cc | NF EN 12620 annex B; definitions of Cu and Cc | 2.68; 5.26; 0.84 | identical |
| In-situ tests | ||||
| C | Ménard pressuremeter — pl (inverse curve, hyperbola) | NF P 94-110-1 annex D | 2.006 MPa | 2.006 MPa |
| C | Ménard pressuremeter — EM | NF P 94-110-1 § D.2.2 | 8.80 MPa | identical |
| C | Dynamic penetrometer — qd | NF EN ISO 22476-2, Dutch formula | 3.39 MPa | identical |
| C | CPT — qc, fs | NF P 94-113 / NF EN ISO 22476-1: Qc = 2.1 kN, Ac = 10 cm²; Qs = 0.75 kN, As = 150 cm² | 2.100 MPa; 50.000 kPa | 2.100 MPa; 50.000 kPa |
| Foundations (bearing capacity) | ||||
| A | c-φ strip footing — c·Nc and q·Nq terms | FHWA NHI-06-089 (2006), example 8-1: B = 6 ft, D = 5 ft, c = 500 psf, φ = 20°, γ = 125 pcf | 7 400 psf; 4 000 psf; qult 13 425 psf (Nγ Vesic 5.4) | 7 400; 4 000 psf; qu 12 712 psf with Nγ DTU 13.12 = 3.5 (difference due only to the code Nγ) |
| B | Factors Nc, Nq, Nγ | EN 1997-1 annex D; DTU 13.12 § 3.2.1 (table) | 18.40 / 20.09 (φ = 30°); 5.14 (φ = 0); DTU 30 / 18.4 / 18.1 | identical |
| B | Shape and inclination factors | DTU 13.12 § 3.2.1 (B/L = 0.75; δ = 10°) | 1.15 / 0.85 / 0.790 / 0.444 | identical |
| C | qu laboratory, pressuremeter, CPT (DTU 13.12) | DTU 13.12 § 3.2.1, 3.2.2, 3.2.3.1 | 626.6; 928.3; 670.6 kPa | identical |
| C | SPT — Meyerhof (1956) | q = 12·N·Kd (B ≤ 1.2 m), published SI form | 239.1 kPa | identical |
| Settlement | ||||
| A | Oedometric — wide embankment | FHWA NHI-06-088 (2006), example 7-3: NC clay 10 ft, Cc 0.5, e0 1.0, p0 600 psf, Δp 2 400 psf | 1.75 ft (0.53 m) | 1.747 ft (0.5326 m) |
| A | Oedometric — under a footing | FHWA NHI-06-089 (2006), example 8-3: NC clay 10 ft, Cc 0.4, e0 0.75, p0 2 145 psf, Δp 208 psf | 0.09 ft = 1.1 in | 0.0919 ft = 1.10 in |
| C | Ménard pressuremeter — sc, sd | NF P 94-261 annex H | 0.40; 0.85 cm | 0.40; 0.85 cm |
| C | Elastic; modulus of subgrade reaction | s = cf·(1 − ν²)·q·B/E; 1/kv (Ménard) | 1.28 cm | identical |
| Concrete | ||||
| A | ACI mix design | ACI 211.1-91, appendix 1, example 1 | water 181; cement 289.1; coarse aggregate 1 136; sand 774.4 kg/m³; water to add 123 | 181; 289.1; 1 136; 774.4; 122.9 |
| C | Rebound hammer | NF EN 12504-2 § 8 (median); ASTM C805 § 9.1 | 32; 31.33 | identical |
| C | Compression; ultrasonic pulse velocity | NF EN 12390-3; NF EN 12504-4 | 26.2 MPa; 4 161 m/s | identical |
| C | SonReb | Published correlations (Meynink et al. 1979…) | 34.5 MPa | identical |
| C | Dreux-Gorisse, Bolomey, Faury | Published methods (Dreux and Festa; Bolomey 1925; Faury 1941) | YA 46.13 %; P(0.08) 15.1 %; 60.87 % | identical |
| Roads and asphalt | ||||
| C | Bulk density (paraffin-coated) | NF EN 12697-6 method D | 2.341 g/cm³ | 2.341 |
| C | Kumagawa; degree of compaction | Binder content; C = 100·γ/γmax | 5.63 %; 96.6 % | identical |
Hand verification (category C)
The 26 category C calculations were redone by hand, step by step, from the formulas of the standard, and compared with the CiviLab result: all agree.
| No. | Family | Calculation | Standard / formula | Hand calculation | CiviLab 7.1 |
|---|---|---|---|---|---|
| 1 | Laboratory | Proctor — wOPT and ρd max | NF P 94-093 | wOPT 12.78 % ; ρd max 1.879 g/cm³ | 12.78 % ; 1.879 g/cm³ |
| 2 | Laboratory | Atterberg limits — Casagrande and cone | NF P 94-051 | wL 45.73 % ; IP 23.33 ; wL cone 44.59 % | 45.7 % ; 23.3 ; 44.6 % |
| 3 | Laboratory | CBR | NF P 94-078 | 22.2 | 22.2 |
| 4 | Laboratory | Hydrometer — Stokes diameter | NF P 94-057 | 0.0751 mm | 0.0751 mm |
| 5 | Laboratory | Direct shear — c′, φ′ | NF EN ISO 17892-10 | c' 16.6 kPa ; φ' 29.9° | 16.6 kPa ; 29.9° |
| 6 | Laboratory | Oedometer — Cc | NF EN ISO 17892-5 | 0.172 | 0.172 |
| 7 | Laboratory | Los Angeles, Micro-Deval, sand equivalent | NF EN 1097-2 | 22.6 ; 13.8 ; 77.0 | 22.6 ; 13.8 ; 77.0 |
| 8 | Laboratory | Particle size — FM, Cu, Cc | NF EN 12620 annex B | 2.68 ; 5.26 ; 0.84 | 2.68 ; 5.26 ; 0.84 |
| 9 | In situ | Dynamic penetrometer — qd | NF EN ISO 22476-2, formule des Hollandais | 3.39 MPa | 3.39 MPa |
| 10 | In situ | Ménard pressuremeter — EM, Vl | NF P 94-110-1 § D.2.2 | EM 8.80 MPa ; Vl 914.84 cm³ | 8.80 MPa ; 914.84 cm³ |
| 11 | In situ | Ménard pressuremeter — pl by the inverse curve | NF P 94-110-1 annex D | 2.006 MPa | 2.006 MPa |
| 12 | In situ | CPT — qc, fs | NF EN ISO 22476-1 | 2.10 MPa ; 50.0 kPa ; 2.38 % | 2.100 MPa ; 50.000 kPa ; 2.381 % |
| 13 | Foundations | Bearing capacity, laboratory (DTU 13.12) | DTU 13.12 § 3.2.1 | 626.6 kPa | 626.6 kPa |
| 14 | Foundations | Bearing capacity, pressuremeter (DTU 13.12) | DTU 13.12 § 3.2.2 | 928.3 kPa | 928.3 kPa |
| 15 | Foundations | Bearing capacity, CPT (DTU 13.12) | DTU 13.12 § 3.2.3.1 | 670.6 kPa | 670.6 kPa |
| 16 | Foundations | SPT — Meyerhof (1956) | q = 12·N·Kd (B ≤ 1.2 m) | 239.1 kPa | 239.1 kPa |
| 17 | Settlement | Ménard pressuremeter settlement | NF P 94-261 annex H | sc 0.40 ; sd 0.85 cm | 0.40 ; 0.85 cm |
| 18 | Settlement | Oedometric (3 layers) and elastic settlement | s = Σ H·Cc/(1 + e0)·log((σ'v0 + Δσ)/σ'v0) (NC) | 48.5 cm ; 1.28 cm | 48.5 cm ; 1.28 cm |
| 19 | Concrete | Compression | NF EN 12390-3 | 26.2 ; 31.9 MPa | 26.2 ; 31.9 MPa |
| 20 | Concrete | Ultrasonic pulse velocity | NF EN 12504-4 | 4 161 m/s | 4 161 m/s |
| 21 | Concrete | Rebound hammer | NF EN 12504-2 § 8 | 32 ; 31.33 | 32 ; 31.33 |
| 22 | Concrete | SonReb — Meynink et al. (1979) correlation | Formule de CiviLab | 34.5 MPa | 34.5 MPa |
| 23 | Concrete | Dreux-Gorisse | YA = 50 − √D + K + Ks + Kp | YA 46.13 % ; water 184.2 L | 46.13 % ; 184.2 L |
| 24 | Concrete | Bolomey | P(d) = A + (100 − A)·√(d/D) | P(0.08) 15.1 % ; water 189.8 L | 15.1 % ; 189.8 L |
| 25 | Concrete | Faury | y(D/2) = A + 17.8·D^(1/5) + B/(R/(1.25·D) − 0.75) | 60.87 % ; 154.5 L | 60.87 % ; 154.5 L |
| 26 | Roads and asphalt | Kumagawa, paraffin bulk density, degree of compaction | TL ext = 100·(M1 − M2)/M2 | 5.63 % ; 2.341 ; 96.6 % | 5.63 % ; 2.341 ; 96.6 % |
Limits
- slope stability: tension cracks, reinforcement (nails, geosynthetics, piles), pore pressures other than hydrostatic (ru) and dynamic analysis are not covered by CiviLab 7.1;
- foundations: CiviLab applies the Nγ of DTU 13.12; the difference with FHWA example 8-1 (Vesic Nγ) comes from this factor only;
- SonReb: CiviLab applies the published correlations as they are; their range of validity is that of each publication.
Documents
- Slope stability validation report (PDF, 6 pages): data, results and critical surfaces of each published case;
- Validation report for all tests (PDF, 4 pages): the 36 checks, with the source of each expected value;
- Hand verification (PDF, 8 pages): the 26 category C calculations, step by step;
- Validation manual (PDF, 4 pages): each result with the CiviLab function that calculates it;
- CiviLab user manual.