Input data — description of each field¶

Field-by-field reference for the Liquefaction page of LiquiTer NX. For the operational flow see Workflow.

"General data" section¶

Description¶

Free text, max 200 characters. Appears on the cover of the Word report. Example: "4-storey residential building — Versilia, lot B".

Address¶

Optional. If filled in, appears in the report.

Coordinates (lat / lon)¶

WGS84 in decimal degrees (e.g. 41.9028, 12.4964). Used to:

Geolocate the site on the report map
Pre-fill a_g and Mw from Parametri Sismici (if this option is enabled)

Water table depth (Zw)¶

Water table depth in metres from ground level.

If Zw > Zmax (maximum depth of the stratigraphy) → no saturated layer → no liquefaction
If the water table varies seasonally → use the worst case (highest) to be conservative

"Seismic parameters" section¶

Code¶

Option	Reference
NTC 2018	Italian D.M. 17/01/2018, Chap. 7.11.3.4 (liquefaction susceptibility)
EC8 — EN 1998-5	Eurocode 8, Annex F

The choice determines: - Limit safety factors (NTC default 1.25, EC8 default 1.0) - Formulas for CSR and correction factors - Exclusion criteria (NTC: depth < 20 m, soils with > 5% particles < 5 µm, etc.)

Ground category (A · B · C · D · E)¶

From Vs,30. Determines the site parameters (S_S, S_T) for computing a_max.

See workflow.md#categoria-suolo for the full table.

Topographic category (T1 · T2 · T3 · T4)¶

Affects the topographic amplification factor S_T (1.0 – 1.4).

a_max (peak ground acceleration)¶

Peak ground acceleration in g (e.g. 0.15).

Where to get it from:

From parametri-sismici.geostru.ai (free) — enter coordinates + return period and it returns a_g
From the INGV grid (esse1-gis.mi.ingv.it)
From municipal geological reports (for level-3 seismic microzonation)

Magnitude Mw¶

Moment magnitude of the design earthquake. Typical range for Italy: 5.5 – 7.0 depending on the INGV zonation.

For Italian territory, the maximum expected magnitude of the seismogenic zone (INGV DISS database) can be used:

INGV zone	Typical Mw
Calabria/Sicily/Friuli	6.5 – 7.0
Central Apennines	6.0 – 6.7
Po Plain	5.5 – 6.5
Sardinia	< 5.5 (low seismicity)

"Analysis method" section¶

See Calculation methods for details on each.

Clean vs silty sands¶

Clean sands: fines content (< 0.075 mm) < 5%
Silty sands: fines content 5–35%
35% fines: the soil is clayey, not liquefiable (still check with the Boulanger 2014 plasticity criterion)

Affects the N1,60 → N1,60,cs correction formula (clean-sand equivalent).

Loose vs medium-dense sands¶

Affects the K_σ scaling factor for stresses. Loose sands have a larger CRR reduction as σ'_v increases.

Step mode¶

MetaStrato (default): one calculation point per layer change
PassoFisso: one point every Δz (e.g. every 0.5 m)

PassoFisso returns a "cleaner" FSL(z) plot but can overestimate the contributions of thin layers. MetaStrato is more representative.

Limit safety factor¶

Default 1.25 (NTC 2018). Threshold below which a point is considered "liquefiable". The calculation uses this value to:

Colour-code the verdict (green/red) in the table
Include/exclude the layer from LPI and settlement totals

For more conservative analyses use 1.5. For limit analyses (real risk computation, not code-driven) use 1.0.

"Stratigraphy" section¶

Dedicated tab, managed by layer. For each layer:

Field	Unit	Meaning
Top depth	m	top elevation
Bottom depth	m	bottom elevation (the bottom of one layer is the top of the next)
Lithology	—	descriptive, does not enter the calculation
γ	kN/m³	unit weight; total above the water table, saturated below
N-SPT	blows/30cm	from the Standard Penetration Test (UNI EN ISO 22476-3)
qc	MPa	CPT tip resistance (UNI EN ISO 22476-1). Optional.
Vs	m/s	S-wave velocity. Optional.
% clay	%	fraction < 5 µm; > 35% rules out liquefaction (NTC)

Stratigraphy import¶

The Stratigraphy tab has functions for:

Import CSV (stratigraphy exported from other GeoStru software or from Excel)
AI Import (photo of the borehole log, AI extracts the parameters)
Stratigraphy adapter (compatibility with other GeoStru formats)