Earthquake Geotechnics · Axiom Platform
Liquefaction Analysis
Assess liquefaction potential from SPT data using two published methods simultaneously — Idriss & Boulanger (2004) and NCEER (1996). Input your earthquake parameters and soil profile once; get side-by-side factor of safety profiles, liquefaction potential index, and settlement estimates with colour-coded risk interpretation.
Two methods, one analysis
Running both methods simultaneously lets you compare results and understand the sensitivity of your assessment to methodological assumptions. Both use the same input data — you enter the profile once.
- Idriss & Boulanger (2004) — iterative overburden correction (CN), Kσ factor, exponential fine-content correction. The more recent and widely-used method.
- NCEER (1996) — two CN calculation variants, piecewise fine-content correction. Well-established in practice and required by some project specifications.
- Both methods compute CSR, CRR, FS, IL, and settlement from the same SPT depth profile.
Inputs
Three categories of input fully describe the problem. Enter them once and both methods run from the same dataset.
-
Earthquake parameters
Earthquake magnitude (Mw) and peak ground acceleration (PGA in g). These drive the cyclic stress ratio and magnitude scaling factor.
-
Soil profile
Unit weight (γ), groundwater depth, fine content (FC%), shear wave velocity (Vs), and atmospheric pressure. These determine the effective stress state and SPT normalisation.
-
SPT depth profile
Arrays of depths (m) and measured SPT blow counts (NSPT) from your borehole log. The analysis computes N160cs at each depth with fine-content correction.
Outputs
Full depth-by-depth results for both methods, plus summary statistics and advanced stress parameters — all in a single response.
-
Factor of Safety
FS against liquefaction triggering at every depth. Colour-coded: FS ≥ 1.5 low risk; 1.0–1.5 moderate; < 1.0 high risk.
-
N160cs
Normalised SPT blow count corrected for overburden, energy, and fine content — the key parameter in both triggering correlations.
-
CSR & CRR
Cyclic Stress Ratio (demand) and Cyclic Resistance Ratio (capacity) at each depth, for both methods.
-
rd coefficient
Shear stress reduction factor accounting for soil column flexibility — computed from depth per both method formulations.
-
MSF
Magnitude Scaling Factor adjusting CRR for earthquake duration relative to Mw 7.5.
-
Liquefaction Index (IL)
Iwasaki et al. (1982) integration of FS over depth. IL ≤ 5 very low; 5–15 moderate; > 15 high to very high.
-
Settlement
Post-liquefaction reconsolidation settlement (mm) per layer and total, interpolated from N1 literature curves for N1 values 3–30.
-
Stress distributions
Total and effective vertical stress (σvc, σ'vc) and pore water pressure (u) at each depth — the full advanced parameters output.
Risk thresholds
Results are colour-coded at every depth using published thresholds.
-
Factor of Safety (FS)
FS ≥ 1.5 — Low risk. 1.0 ≤ FS < 1.5 — Moderate risk. FS < 1.0 — High risk (liquefaction likely).
-
Liquefaction Index (IL)
IL ≤ 5 — Very low to low potential. 5 < IL ≤ 15 — Moderate potential. IL > 15 — High to very high potential.
REST API
Programmatic access to the full dual-method analysis. Submit your profile as JSON and receive complete depth-by-depth results for both methods in a single response.
- POST /app_liquefaction_analysis/api/analyze/ JSON body: mw, pga, w, gamma, patm, fc, vs, z[], nspt[]. Returns full results for both Idriss & Boulanger and NCEER methods.
Part of the AxiomBaseLogic platform
Liquefaction Analysis ships alongside Borehole EDA, Retaining Wall, CPT Processor, Plotter, AGS Parser, and Data Mapper — on a single platform with shared auth, shared data, and REST APIs. Subscribe once, access all apps.
Explore other apps
Jump to other AxiomBaseLogic tools and keep your workflow connected across the platform.