Standards and References — MADEP CPT Interpreter

Scope

1. Scope, traceability, and reporting boundaries

This chapter is the registry chapter of the public manual. It records the source basis, the unit system, the exact meaning of exported fields, the naming used by the Stage 7 report payload, and the quantity registries used by the engineering modules. Its function is to make the app auditable: a reviewer should be able to identify what a field means, what unit it uses, where it comes from, and whether it is displayed only, report-exported, or exported to an external workflow.

The interpretation chapter documents how the layer model and parameter families are derived from the CPT record.
The Stage 6 chapters document the governing theory and solver behaviour of each engineering analysis.
This chapter defines unit conventions, export semantics, and reference traceability.
The technical specification remains the long-form implementation note for full internal detail.

Reporting boundary. Not every displayed Stage 6 quantity is currently frozen into the Stage 7 payload. Where a quantity is display-only, Stage 7-exported, or exported to an external format such as PLAXIS, that status is stated explicitly below.

Units and conventions

2. Global unit system, sign conventions, and quantity semantics

The app uses a mixed but explicit engineering unit system. Length is expressed in metres, cone resistance in megapascals, stiffness and stress in kilopascals, unit weight in kilonewtons per cubic metre, and hydraulic conductivity internally in metres per second. Public plots sometimes rescale stored quantities for readability; those conversions form part of the declared quantity semantics.

Quantity family	Public unit	Technical note
Depth, layer top, layer base, width, length, displacement, head, water-table elevation, TAW elevation	m	The public documentation uses metres as the base length unit. Displacements are stored internally in metres even when plots convert them to millimetres.
Cone resistance q_c	MPa	The CPT workflow and raw/profile exports use MPa for cone resistance.
Sleeve friction f_s	MPa in the PLAXIS-style simulated CPT export; kPa in report tables and layer summaries	The raw workflow preserves the source quantity, while the report layer tables expose a converted kPa value for readability.
Friction ratio R_f	%	Computed and reported as a percentage ratio.
Unit weight gamma, gamma_sat, gamma_w	kN/m^3	Used across interpretation, seepage-pressure conversion, slope stability, and deformation.
Stress, pore pressure, cohesion, undrained strength, stiffness parameters E, E_oed, E_50, E_ur, E_mc	kPa	The constitutive, reporting, and layer-export routes use kPa consistently.
Angles phi, psi, theta	degrees in the public manual and UI	Internal solver routines may use radians, but the public representation is degrees unless stated otherwise.
K_0,nc, nu, nu_ur, m, alpha_E, r_shear, k_h/k_v, eta_MC, F, lambda	dimensionless [-]	Dimensionless ratios are reported without unit conversion.
Hydraulic conductivity k_h, k_v, k_x, k_y	m/s internally, in CSV export, and in report payloads; m/day in PLAXIS command export	The PLAXIS command export performs an explicit m/s-to-m/day conversion.
Darcy discharge q, q_x, q_y, q_n	m/s	This is Darcy velocity or specific discharge, not pore-water velocity.
Through-flow, inflow, outflow	m^3/s/m	The seepage route is a two-dimensional section model and therefore reports discharge per metre out of plane.
Beam foundation modulus k_s	kN/m^3	Reported as a Winkler bedding modulus.
Pasternak shear parameter G_p	kN/m	Reported as the strip-shear parameter used by the beam/slab annex.
Moment for strip-based structural checks	kNm/m	Per metre strip width.
Steel area A_s,req	mm^2/m	Reported per metre strip width in the reinforcement annex.

Conversion note. The deformation route stores displacement in metres and strain in dimensionless form, but the public plots present displacement in millimetres and strain in percent. The seepage and layer-model routes store conductivity in m/s, while the PLAXIS material export converts conductivity to m/day.

Source families

3. Principal literature and method families used by the app

3.1 CPT classification and interpretation

Robertson (1990) — normalized CPT soil-behaviour framework.
Robertson (2016) — updated iterative normalized SBT formulation.
Robertson and Wride (1998) — normalization background used widely in CPT interpretation practice.
NEN 6740 — stress-corrected Dutch classification route.
NEN Tabel 3 — characteristic subtype catalogue used for engineering parameter mapping.

3.2 Stiffness and constitutive parameter derivation

Sanglerat — q_c-to-stiffness correlation basis.
SB260 — Belgian practice route for characteristic parameters from electrical sounding.
CUR 2003-7 — reference family for Hardening Soil style parameter ratios and stress dependence.
PLAXIS Material Models manuals — constitutive naming, parameter meaning, and export interpretation.

3.3 Stage 6 engineering analyses

Bishop (1955) and Spencer (1967) — slope-stability foundation methods.
Prandtl (1921), Reissner (1924), Brinch Hansen (1970), Meyerhof (1953), Vesić (1973) — slip-line and shape/depth/inclination-factor basis for the bearing-capacity route.
Standard Darcy seepage theory — basis for the seepage route.
Classical small-strain finite-element mechanics, Mohr-Coulomb plasticity, Clausen, Damkilde and Andersen (2007), Simo and Taylor (1985), de Souza Neto, Perić and Owen (2008) — basis for the deformation route's principal-stress active-set return mapping and consistent tangent.
Boussinesq and related elastic half-space solutions — basis for the settlement-route stress integration; oedometric modulus from CPT-derived stiffness.
Sichardt-style radius-of-influence relations — basis for the analytical dewatering screen.
Winkler (1867) and Pasternak (1954) — basis for the beam / slab on elastic-foundation strip analysis.

3.4 Belgian axial pile design

BUtgb-UBAtc Informatieblad 2025/3 (versie van 16 september 2025) — current Belgian transition framework for pile and micropile design factor sources.
Buildwise Dimensioneringsmethode 20 (DM20, 2020) — geotechnical ULS design of axially loaded piles and micropiles from CPTs; the current Belgian reference method.
Huybrechts, De Vos, Bottiau and Maertens — Buildwise / BBRI (2016), Design of piles — Belgian practice — the public source for the η*_p table, ξ₃/ξ₄, γ_Rd, γ_b/γ_s tables, and the F_nk slip method.
BGGG-GBMS — Reference document for the application of the De Beer method (the de Beer scale-effect base-resistance procedure) and De Beer, E., Méthodes de déduction de la capacité portante d'un pieu à partir des résultats des essais de pénétration.
Allani and Huybrechts — Pile settlement under vertical static load: SLS design method based on Belgian experience, ICSMGE 2022 — basis for the load-transfer SLS settlement model with hyperbolic t-z and q-z curves linked to the Belgian 10 % D_b ULS resistance convention.
BCCA — ATG-with-certification framework for foundation piles (publication of 8 May 2023, expanding through CFA and micro-piles in subsequent phases).

3.5 Reinforcement design

EN 1992-1-1 (Eurocode 2) — the source for the strip-based ULS reinforcement screening output (As_req, As_min), durability cover (c_nom) per Table 4.4N, and structural-class adjustment.

Codes and standards

4. Standards and code context within the app

Source family	Main role in the app	Current public relevance
NBN EN 1997-1 + Belgian National Annex (2022)	Eurocode 7 Part 1 — general geotechnical design rules with the Belgian ANB.	Reference basis for the bearing, pile, and Stage 6 design-route factor chains.
NBN EN 1997-2:2007	Eurocode 7 Part 2 — ground investigation and testing; remains the legally applicable Belgian standard during the EN 1997-2:2024 transition (until 30 March 2028).	Cited for CPT-test-result interpretation context.
NEN 6740	Stress-corrected CPT classification.	Available directly in Stage 2 classification.
Standaardbestek 260 (SB260, v3.0, July 2025)	Flemish standard specification for civil-structure and hydraulic-engineering execution.	Used directly in Stage 4 characteristic parameter derivation; project-specification reference for execution and reporting.
Buildwise Dimensioneringsmethode 20 (DM20, 2020)	Geotechnical ULS design of axially loaded piles and micropiles from CPTs — the current Belgian reference method.	Source of the α_b, α_s, γ_Rd, γ_b, γ_s factor tables driving the Stage 6 pile-capacity route.
BUtgb-UBAtc Informatieblad 2025/3	Current transition framework for pile-system factor sources (DM20 vs DM19 vs ATG by pile category and date).	Reference for the pile-type categorization in the Stage 6 pile-capacity route.
BCCA ATG-with-certification (May 2023 onward)	Belgian Approval and Certification framework that links favourable design factors to verified quality systems and instrumented load tests.	Activated through the ATG override block on the pile-capacity panel.
BGGG-GBMS De Beer reference	Algorithmic specification of the De Beer scale-effect transformation from CPT q_c to pile-base unit resistance q_b.	Implemented in the Stage 6 pile-capacity route (see /docs/engineering/pile §3.3).
EN 1992-1-1 (Eurocode 2)	Concrete structural design rules.	Basis of the Stage 6 strip-based ULS reinforcement screening (As_req, As_min, c_nom, structural-class output).
PLAXIS manuals	Material naming, constitutive parameter interpretation, and export compatibility.	Important for Stage 4 exports and Stage 6 constitutive documentation.

Layer-model exports

5. Layer CSV, layer payload, and parameter-field semantics

The layer CSV export is the most direct public export of the interpreted engineering model. The field names below are the exact CSV header names currently written by the app.

5.1 Layer CSV export

CSV field	Meaning	Unit or type	Technical note
`Layer`	1-based layer number in the exported CSV.	[-]	Administrative label only.
`Type`	Broad engineering soil type.	text	Examples include Sand, Clay, and Gravel.
`Subtype`	Final subtype selection carried by the layer model.	text	Usually the NEN Tabel 3 style subtype.
`Top_m`	Layer top depth below ground level.	m	Depth in the CPT reference system.
`Bot_m`	Layer base depth below ground level.	m	Depth in the CPT reference system.
`Top_TAW`	Layer top elevation relative to the site datum.	text containing m TAW	This CSV field is exported as a formatted label, not a bare numeric field.
`Bot_TAW`	Layer base elevation relative to the site datum.	text containing m TAW	This CSV field is exported as a formatted label, not a bare numeric field.
`Thick_m`	Layer thickness.	m	Equal to Bot_m minus Top_m.
`avgQc_MPa`	Average cone resistance of the layer.	MPa	Layer-average value after segmentation.
`avgRf_pct`	Average friction ratio of the layer.	%	May be blank if the source record lacks sleeve friction.
`gamma`	Representative bulk or unsaturated unit weight.	kN/m^3	Exported as the Stage 4 engineering layer value.
`gamma_sat`	Representative saturated unit weight.	kN/m^3	Exported as the Stage 4 engineering layer value.
`phi`	Effective friction angle.	deg	Characteristic or design value according to the selected route.
`c`	Effective cohesion.	kPa	Characteristic or design value according to the selected route.
`cu`	Undrained shear strength proxy.	kPa	Provided for workflows that need undrained interpretation.
`alphaE`	CPT-to-stiffness conversion factor alpha_E.	[-]	Selected by the current Stage 4 alpha method.
`alphaMethod`	Alpha-method identifier.	text	Method A = Sanglerat fixed; Method B = SB260 qc-dependent.
`Eoed_i_kPa`	Current-stress constrained modulus E_oed,i.	kPa	Computed at the representative layer stress state.
`Eoed_ref_kPa`	Reference constrained modulus E_oed,ref.	kPa	Reference-stress form used by the HS-style family.
`E50_ref_kPa`	Reference secant stiffness E_50,ref.	kPa	Derived from the selected stiffness method.
`Eur_ref_kPa`	Reference unload-reload stiffness E_ur,ref.	kPa	Derived from the selected stiffness method.
`E_mc_kPa`	Mohr-Coulomb stiffness exported for the current loading route.	kPa	At present this is taken as E50,i, not an independent stiffness family.
`nu`	Poisson ratio used by the Mohr-Coulomb family.	[-]	Layer default or manual override.
`rShear`	Reduced Stage 1 shear factor.	[-]	Relevant only to the Stage 1 pseudo-plastic route.
`m`	Stress-dependency exponent.	[-]	Manual override or default/tuned value.
`K0nc`	At-rest earth pressure ratio for normally consolidated conditions.	[-]	Used for in-situ confinement interpretation.
`nu_ur`	Unload-reload Poisson ratio.	[-]	Currently fixed by the Stage 4 route unless later extended.
`stiffMethod`	Stiffness-family derivation method identifier.	text	Method A = CUR 2003-7 ratios; Method B = E50 = Eoed.
`kh_ms`	Representative horizontal conductivity.	m/s	Exported in internal hydraulic units.
`kv_ms`	Representative vertical conductivity.	m/s	Exported in internal hydraulic units.
`khkv`	Conductivity anisotropy ratio k_h/k_v.	[-]	Used for hydraulic interpretation and export traceability.
`psi_unsat_m`	Unsaturated suction head proxy psi_unsat.	m	Used for the hydraulic family and PLAXIS-style compatibility.
`Infiltratie_klasse`	Infiltration class label.	text	Design-oriented qualitative classification derived from k_h.

5.2 Stage 7 layer payload additions

The Stage 7 JSON payload carries the final layer model again in camelCase form, together with additional provenance fields that are not present in the CSV export. The entries below are the fields that materially extend the CSV meaning.

Stage 7 field	Meaning	Unit or type	Technical note
`avgFsKPa`	Average sleeve friction of the final layer.	kPa	Report-friendly conversion of the layer-average sleeve friction.
`overrides`	Boolean record of manual parameter overrides.	object of flags	Identifies which layer properties were manually overridden.
`hasAcceptedTuning`	Whether a Stage 5 fit was accepted into the layer.	[-]	Boolean diagnostic.
`manualMOverride`	Whether m was manually overridden without a tuning fit.	[-]	Boolean diagnostic.
`hs.alphaE`	CPT-to-stiffness conversion factor.	[-]	Mirror of alphaE in camelCase JSON form.
`hs.eOedI`	Current-stress constrained modulus.	kPa	Mirror of Eoed_i.
`hs.eOedRef`	Reference constrained modulus.	kPa	Mirror of Eoed_ref.
`hs.e50Ref`	Reference secant stiffness.	kPa	Mirror of E50_ref.
`hs.eurRef`	Reference unload-reload stiffness.	kPa	Mirror of Eur_ref.
`hs.m`	Stress-dependency exponent.	[-]	Current accepted or default value.
`hs.k0nc`	At-rest earth pressure ratio.	[-]	Mirror of K0nc.
`hs.nu`	Poisson ratio.	[-]	Mirror of nu.
`hs.nuUr`	Unload-reload Poisson ratio.	[-]	Mirror of nu_ur.
`hs.rShear`	Stage 1 reduced-shear factor.	[-]	Relevant only to the Stage 1 constitutive route.
`hs.psi`	Dilation angle.	deg	Current Stage 4 derived value.
`hs.eMc`	Current Mohr-Coulomb export stiffness.	kPa	Mirror of E_mc.
`hs.sigmaV`	Representative total vertical stress at the layer reference point.	kPa	Used for parameter derivation traceability.
`hs.porePressure`	Representative pore pressure at the layer reference point.	kPa	Used for parameter derivation traceability.
`hs.sigmaVEff`	Representative effective vertical stress at the layer reference point.	kPa	Used for parameter derivation traceability.
`hydraulic.kh`	Representative horizontal conductivity.	m/s	Mirror of kh_ms.
`hydraulic.kv`	Representative vertical conductivity.	m/s	Mirror of kv_ms.
`hydraulic.khkv`	Conductivity anisotropy ratio.	[-]	Mirror of khkv.
`hydraulic.psiUnsat`	Unsaturated suction head proxy.	m	Mirror of psi_unsat_m.
`hydraulic.infiltrationClass`	Infiltration-class label.	text	Mirror of Infiltratie_klasse.

5.3 Stage 7 raw and classified row payloads

The Stage 7 report stores both the raw CPT table and the pointwise classified row set. Their field semantics are defined below.

rawRows
Field	Meaning	Unit or type	Technical note
`depth`	Raw CPT depth.	m	Copied directly from the imported CPT row set.
`taw`	Datum elevation corresponding to the row depth.	m TAW	Only present when surface elevation is known.
`qc`	Cone resistance.	MPa	Raw row value.
`fsMPa`	Sleeve friction in source or raw CPT units converted to MPa.	MPa	May be null if unavailable.
`fsKPa`	Sleeve friction converted for report display.	kPa	Convenience conversion used by the report viewer.
`rf`	Friction ratio.	%	May be null if unavailable.
`u2`	Measured pore pressure column, if present in the source CPT.	source units	The raw report preserves the imported value without forced reinterpretation.

classifiedRows
Field	Meaning	Unit or type	Technical note
`depth`	Depth of the classified point.	m	Matches the row depth.
`taw`	Datum elevation of the classified point.	m TAW	Only present when surface elevation is known.
`qc`	Cone resistance used by the classifier.	MPa	Matches the classified row.
`fsKPa`	Sleeve friction converted for report display.	kPa	Convenience conversion for the report viewer.
`rf`	Friction ratio.	%	Used by several classification routes.
`type`	Classified broad soil type.	text	Result of the active Stage 2 route.
`subtype`	Classified subtype if available.	text	Used where the chosen classification route produces a subtype.
`ic`	Normalized behaviour index I_c.	[-]	Present for Robertson-style routes where calculated.
`qtOrQcNen`	Method-specific auxiliary metric.	MPa or normalized metric depending on route	The report viewer relabels this according to the active classification method.

External engineering exports

6. PLAXIS command export and simulated CPT export

6.1 PLAXIS material command export

The current PLAXIS export writes two material-command lines per layer: one Mohr-Coulomb material and one Hardening Soil material. The tables below document the current field mapping exactly as exported.

Mohr-Coulomb command fields
PLAXIS field	Meaning	Unit or type	Technical note
`Identification`	Material name token for the MC export.	text	Built from CPT id, layer number, subtype token, and suffix _MC.
`SoilModel = 2`	PLAXIS Mohr-Coulomb model selector.	[-]	Hard-coded by the export route.
`DrainageType`	PLAXIS drainage interpretation.	text	Derived from the current layer type and subtype.
`gammaUnsat`	Unsaturated unit weight.	kN/m^3	Mapped from gamma.
`gammaSat`	Saturated unit weight.	kN/m^3	Mapped from gamma_sat.
`ERef`	Exported MC Young modulus.	kPa	Mapped from E_mc.
`nu`	Poisson ratio.	[-]	Mapped directly from the interpreted layer.
`cRef`	Effective cohesion for PLAXIS export.	kPa	The current export enforces a minimum of 0.1 kPa for command generation.
`phi`	Effective friction angle.	deg	Mapped directly from the interpreted layer.
`psi`	Dilation angle.	deg	Derived in Stage 4 and exported if available.
`PermHorizontalPrimary`	Primary horizontal conductivity.	m/day	Converted explicitly from the internal m/s value.
`PermVertical`	Vertical conductivity.	m/day	Converted explicitly from the internal m/s value.

Hardening Soil command fields
PLAXIS field	Meaning	Unit or type	Technical note
`Identification`	Material name token for the HS export.	text	Built from CPT id, layer number, subtype token, and suffix _HS.
`SoilModel = 3`	PLAXIS Hardening Soil model selector.	[-]	Hard-coded by the export route.
`DrainageType`	PLAXIS drainage interpretation.	text	Derived from the current layer type and subtype.
`gammaUnsat`	Unsaturated unit weight.	kN/m^3	Mapped from gamma.
`gammaSat`	Saturated unit weight.	kN/m^3	Mapped from gamma_sat.
`E50Ref`	Reference secant stiffness.	kPa	Mapped from E50_ref.
`EOedRef`	Reference constrained modulus.	kPa	Mapped from Eoed_ref.
`EURRef`	Reference unload-reload stiffness.	kPa	Mapped from Eur_ref.
`PowerM`	Stress-dependency exponent.	[-]	Mapped from m.
`pRef`	Reference pressure used by the export.	kPa	Currently fixed at 100 kPa.
`cRef`	Effective cohesion for PLAXIS export.	kPa	The current export enforces a minimum of 0.1 kPa for command generation.
`phi`	Effective friction angle.	deg	Mapped directly from the interpreted layer.
`psi`	Dilation angle.	deg	Derived in Stage 4 and exported if available.
`PermHorizontalPrimary`	Primary horizontal conductivity.	m/day	Converted explicitly from the internal m/s value.
`PermVertical`	Vertical conductivity.	m/day	Converted explicitly from the internal m/s value.

6.2 Simulated PLAXIS CPT text export

The app can also write a simplified CPT text file intended for PLAXIS-style import workflows. The format is deliberately simple and the field semantics are fixed.

Export field	Meaning	Unit or type	Technical note
`X[m], Y[m], Z[m]`	Reference coordinates of the CPT location used in the simulated export.	m	Written as header lines in the text export.
`D[m]`	Depth below ground level.	m	One row per original CPT sample depth.
`Q[MPa]`	Simulated cone resistance.	MPa	Layer-average qc is written back to each row within the layer.
`F[MPa]`	Simulated sleeve friction.	MPa	Uses avgFs if available, otherwise qc x Rf / 100.
`x`	Placeholder final column in the exported text format.	[-]	Currently written as 0; the app does not export Rf into this PLAXIS-style CPT text file.

Stage 7 payload

7. Report-payload structure, annex availability, and field semantics

The Stage 7 export is a structured JSON payload. At top level it contains project and replication metadata, raw and classified CPT rows, final layers, optional tuning results, and optional Stage 6 annexes. The annex set is not fixed; it depends on which analyses were actually solved when the report was opened.

Payload block	Meaning	Technical note
`version`, `stage`, `generatedAt`, `appVersion`	Export-version metadata.	Used for compatibility and audit trace.
`project`, `cpt`, `metadata`	Project identity, CPT identity, and source-file provenance.	Coordinates are in metres; imported metadata are preserved where available.
`replication`	Active methods and settings needed to reproduce the interpretation.	Includes classification method, alpha method, stiffness method, water table, and elevation provenance.
`summary`	High-level counts and report-level diagnostics.	Includes layer count, depth range, and list of attached Stage 6 annexes.
`visuals`, `chartInputs`	Report-rendering helpers.	Not primary engineering quantities, but required to reproduce the report layout.
`rawRows`, `classifiedRows`	Raw CPT data and classified row set.	Field semantics are defined in Section 5.3.
`layers`, `layerWarnings`, `tuning`	Final layer model, warnings, and optional Stage 5 fitting data.	Field semantics are defined in Sections 5.1 and 5.2.
`stage6`	Optional engineering annexes.	Availability depends on which Stage 6 modules were solved.

Stage 6 annex	Current status	Reported field family	Public units	Technical note
`bearing`	exported	Df, B, L, eB, eL, Bprime, Lprime, qdDrained, qdUndrained, layer selection and chart inputs	m and kPa	Frozen only when a bearing analysis exists in the Stage 6 cache.
`pile`	not yet exported as a Stage 7 annex	Pile capacity is solved and cached in S.stage6Cache.pile but not currently frozen into the Stage 7 payload. The full set of solved fields is documented in the pile quantity registry below.	see pile quantity registry	Display and solver state are present in Stage 6; the Stage 7 freeze is a current reporting boundary.
`settlement`	exported	qGross, qNet, totalSettlementMm, sublayer stress and settlement curves, optional time curve	kPa, mm, days where applicable	Frozen only when a settlement analysis exists.
`dewatering`	exported	targetWt, newWtAtCpt, drawdownAtCpt, totalSettlementMm, drawdown and stress curves	m, mm, kPa, days where applicable	Frozen only when a dewatering analysis exists.
`beam`	exported	k_s, G_p, deflection, moment, x-samples, EC2 reinforcement (As_req, As_min, c_nom, structural class), and chart inputs	kN/m^3, kN/m, mm or m, kNm/m, mm^2/m	Frozen only when a beam/slab analysis exists. The reinforcement output is part of the beam annex; there is no separate reinforcement annex.
`bishop`	exported	selected result, top results, lambda, residuals, wall interaction, timing, and frozen canvas view	dimensionless, kN/m, m, ms	Included only when Bishop results exist.
`seepage`	exported	boundary conditions, permeability set, head range, flow rates, gradients, mesh and solver timing, and frozen canvas view	m, m/s, m^3/s/m, -, ms	Included only when seepage results exist.
`deformation`	not yet exported as a Stage 7 annex	Display and solver fields exist in Stage 6 but are not currently frozen into the Stage 7 payload	see deformation quantity registry	This absence is intentional and should be read as a current reporting boundary.

Quantity registries

8. Stage 6 quantity names, symbols, and public units

8.1 Seepage quantity registry

Symbol	Meaning	Public unit	Technical note
h	Total hydraulic head.	m	Primary solved field.
u	Pore-water pressure.	kPa	Derived from head and elevation.
\|grad h\|	Hydraulic-gradient magnitude.	[-]	Element-wise before contour post-processing.
\|q\|	Darcy discharge magnitude.	m/s	Specific discharge magnitude.
q_x, q_y	Darcy discharge components.	m/s	Section-axis components.
q_n	Probe-normal Darcy discharge.	m/s	Line-probe quantity only.
throughFlow, inflow, outflow	Section discharge rates.	m^3/s/m	Reported per metre out of plane.
flowError	Relative flow-balance error.	[-] or % in report display	Displayed as percent in the Stage 7 report.
maxExitGradient	Maximum exit gradient.	[-]	Dimensionless hydraulic-gradient measure.

8.2 Deformation quantity registry

Symbol	Meaning	Public unit	Technical note
settlement	Vertical displacement plotted as settlement.	mm in plots; m internally	Public charts use millimetres.
u_x, u_y	Horizontal and vertical displacement components.	mm in plots; m internally	Public charts use millimetres.
\|u\|	Total displacement magnitude.	mm in plots; m internally	Public charts use millimetres.
epsilon_xx, epsilon_yy, gamma_xy	Strain components.	% in plots; [-] internally	Displayed as percentages for readability.
epsilon_p_acc	Accumulated equivalent plastic strain.	% in plots; [-] internally	Stage 2 elastoplastic route only.
delta sigma_yy	Effective vertical stress increment.	kPa	Incremental stress view.
sigma_yy, sigma_xx families	Initial and final vertical and horizontal effective and total stresses.	kPa	Compression-positive engineering interpretation.
tau_xy	Shear stress.	kPa	Same for total and effective stress under the current pore-pressure interpretation.
eta_MC	Mohr-Coulomb utilization ratio.	[-]	Local indicator, not a global factor of safety. Suppressed in tension-cutoff-active zones.
safetyLoadFactor	C-phi strength-reduction safety factor.	[-]	Output of the safety-cphi staging phase; loadFactorMeaning = "safety-strength-reduction".
phaseKind	Solver staging-phase identifier.	enum: initial-gravity / service-load / safety-cphi	Distinguishes the geostatic predictor, service increment, and safety-reduction passes.
elementType	Element family used in the analysis.	enum: t3 / t6	T6 uses 3 Gauss points and the B-bar projection for near-incompressible flow.
activeBranch	Accepted Mohr-Coulomb branch at each Gauss point.	enum: face / edge / apex / tension / mixed	Diagnostic for the exact active-set return mapping in Stage 2.
gpu (v1 / v2)	GPU pipeline path used.	pipeline tag	v1 = linear-elastic; v2 = full elastoplastic resident pipeline including geostatic, service-load, and c-phi safety phases.

8.3 Slope-stability quantity registry

Symbol	Meaning	Public unit	Technical note
F, F_bishop, F_m, F_f	Global factors of safety from Bishop and Spencer branches.	[-]	Dimensionless stability measures.
lambda	Constant Spencer interslice-force ratio.	[-]	Reported only for Spencer results.
theta	Equivalent Spencer interslice-force angle.	deg	Derived user-facing angle.
W_i, Q_i, V_i	Slice weight, surcharge contribution, and total vertical load.	kN/m	Per metre out of plane.
u_i	Average pore pressure on the slice base.	kPa	Hydrostatic by default or seepage-sampled when enabled.
alpha_i	Signed base inclination.	deg in public tables	Internally handled through trigonometric functions.
m_alpha,i	Bishop denominator term.	[-]	Dimensionless geometry-strength factor.
N_i, T_i	Bishop base normal and mobilized shear forces.	kN/m	Per metre out of plane.
Nprime_i, E_L, E_R, X_L, X_R	Spencer effective normal and interslice forces.	kN/m	Per metre out of plane.
momentResidual, forceResidual	Spencer residual diagnostics.	kN/m in the current normalized implementation	The current circular implementation reports the moment residual after cancellation of the common radius.
wallForceTotal	Resultant retaining-wall contribution on the selected surface.	kN/m	Relevant only when retaining walls are active.

8.4 Bearing-capacity quantity registry

Symbol	Meaning	Public unit	Technical note
q_ult,d	Ultimate drained bearing resistance.	kPa	Brinch Hansen / EC7 Annex D summed over the c'·N_c, q'·N_q, and 0.5·γ'·B'·N_γ terms with shape, depth, and inclination factors.
q_ult,u	Ultimate undrained bearing resistance.	kPa	Prandtl 1921 result q_ult = q + (π+2) c_u with shape / depth / inclination factors.
B', L'	Effective footing dimensions after eccentricity reduction.	m	B' = B − 2 e_B, L' = L − 2 e_L (Meyerhof 1953).
N_c, N_q, N_gamma	Bearing-capacity factors.	[-]	EC7 Annex D rough base; N_gamma = 2(N_q − 1) tan φ'.
s_c, s_q, s_gamma, s_cu	Shape factors evaluated on the effective dimensions.	[-]	Brinch Hansen, with conservative-mode toggle that fixes them at 1.0.
d_c, d_q, d_gamma, d_cu	Depth factors.	[-]	Function of D_f / B' and the bearing-capacity factors.
i_c, i_q, i_gamma, i_cu	Inclination factors for horizontal load on the base.	[-]	Brinch Hansen form with directional exponent m.
gamma'_B	Effective unit weight in the N_gamma term.	kN/m^3	Three-case water-table averaging across the failure wedge depth.
gamma_Rd	Belgian ANB resistance-side factor.	[-]	1.40 for drained shallow-foundation bearing; applied to q_ult to obtain q_d.

8.5 Pile-capacity quantity registry

Symbol	Meaning	Public unit	Technical note
D_s, D_b	Pile shaft diameter and base diameter.	m	D_b > D_s indicates an enlarged base.
D_b,eq	Equivalent base diameter for non-circular cross-sections.	m	Circular: D_b. Square / rect (b ≤ 1.5 a): √(4 a b / π). Rect (b > 1.5 a): √(6 a^2 / π).
A_b, A_p	Base bearing area and pile axial-stiffness cross-section.	m^2	A_p = A_b for closed concrete piles; differs for open tubes / steel sections.
chi_s	Pile shaft perimeter.	m	π D_s circular, 4 a square, 2 (a + b) rectangular.
z_head, z_toe, L	Pile head depth, toe depth, and length.	m	L = z_toe − z_head. z_head defaults to 0 (ground level) but can be set in an excavation.
q_b	Unit pile-base resistance from De Beer.	kPa	Output of the BGGG four-stage transformation: homogeneous q_h, downward q_d, upward q_u, mixed q_p.
q_h, q_d, q_u, q_p	De Beer transformation chain.	MPa internally; kPa for q_b at toe	Diameter scale-effect smoothing with ratio D_c / D_b,eq, D_c = 0.0357 m.
eta_p* (eta star sub p)	Soil-dependent ratio between cone resistance and unit shaft friction.	[-]	Belgian table by soil category and q_c range (clay 1/30, loam 1/60, sandy clay 1/80, sand 1/90, with caps).
q_s	Unit shaft friction in layer i.	kPa	q_s = eta_p* · q_c,m · 1000, with soil-specific upper-bound caps; layers with q_c,m < 1 MPa excluded.
alpha_b, alpha_s	Installation factors for base and shaft.	[-]	Pile-type and soil-category dependent. Defaults are screening midpoints; production values come from DM20 / ATG via the override block.
e_b, beta, lambda	Tertiary-clay scale, shape, and relaxing-base factors for R_b.	[-]	e_b = 1.0 except tertiary OC clay; β shape for rectangular bases; λ requires user override for relaxing prefab enlarged bases.
R_b, R_s, R_c	Calculated pile base, shaft, and total compression resistance.	kN	R_b = α_b · e_b · β · λ · A_b · q_b. R_s = χ_s · Σ α_s · h · q_s. R_c = R_b + R_s.
gamma_Rd	Pile model factor.	[-]	γ_Rd1 (no SLT) / γ_Rd2 (SLT comparable) / γ_Rd3 (SLT on job site) per pile type.
xi_3, xi_4	Correlation factors on the average and minimum calibrated resistances.	[-]	Public Belgian table by pile count and CPT density. Single-CPT branch uses max(ξ_3, ξ_4).
gamma_b, gamma_s	Partial resistance factors on base and shaft.	[-]	No-QA / QA columns from public Belgian practice tables.
R_c,cal, R_c,k, R_c,d	Calibrated, characteristic, and design pile compression resistance.	kN	R_c,cal = R_c / γ_Rd. R_c,k = R_c,cal / max(ξ_3, ξ_4). R_c,d = R_b,k / γ_b + R_s,k / γ_s.
F_c,d, F_rep	ULS design and SLS representative load on the pile.	kN	Direct entry, with optional Gk / Qk-from-components builder mirroring the settlement and beam apps.
F_nk,slip, F_nk,analogy, F_nk,d	Negative-skin-friction loads.	kN	Slip method (χ_s · Σ h · K_0 · tan(δ) · σ'_v) and analogy method (χ_s · Σ α_s · h · q_s) above the user-entered neutral plane; the larger drives the design value with γ_F = 1.0.
s_head, z_b	Pile-head settlement and pile-base settlement.	mm in plots; m internally	Allani-Huybrechts (2022) load-transfer ODE with bisection on z_b; s_head = z_b + Σ N · Δz / (E_p A_p).
t-z, q-z	Hyperbolic shaft and base springs.	kPa, kPa	t = w / (1/k_s + w/t_max), q = z_b / (1/k_b + z_b/q_max). t_max = t_10% (1 + 10 M_s); q_max ≈ q_b,10% (1 + 4.55/M_b).
M_s, M_b	Dimensionless shaft and base flexibility / stiffness factors.	×10^-3 for M_s; [-] for M_b	Tabulated in [5] by pile type (driven / screw / replacement) and soil group (sand / mixed / clay); midpoints used by default with per-layer override.
E_b, beta_b, k_b	Soil modulus at the base, calibrated coefficient, and base-spring stiffness.	kPa, m, kN/m^3	β_b ≈ 0.455 D_b. E_b defaults to eoedAtStress at z_toe with σ'_v + 0.5 q_b,10%; CPT-correlation fallback E_b ≈ α_E · q_c,b · 1000 when Stage 4 parameters are absent.
k_s,i	Per-layer shaft-spring stiffness.	kN/m^3 (kPa/m)	k_s,i = t_max,i / (M_s,i · D_s).
omega	Mechanical-cone correction factor.	[-]	1.30 for M1/M2 in tertiary clay, 1.15 for M4 in tertiary clay, 1.00 elsewhere; CPT-E (electric cone) is the reference.

8.6 Settlement quantity registry

Symbol	Meaning	Public unit	Technical note
q_gross, q_net	Applied SLS pressure and net pressure after subtracting in-situ overburden at D_f.	kPa	q_gross from the selected SLS combination; q_net = q_gross − σ_v(D_f).
sigma_v0, delta sigma_v	Initial vertical effective stress and stress increment from the loaded area.	kPa	Per sublayer, with Boussinesq / Newmark or 2:1 stress spread.
E_oed,i	Constrained modulus at the sublayer mean stress.	kPa	Hardening-Soil stress-dependent law from Stage 4 parameters.
totalSettlementMm	Cumulative one-dimensional settlement at the centreline.	mm	Σ (Δσ_v / E_oed,i) · h_i over the active influence zone with the selected truncation rule.
truncationRule	Influence-zone truncation criterion.	enum: 10% sigma_eff / 20% q_net / CPT_bottom	Determines the active integration depth.
timeCurve	Optional time-dependent consolidation curve.	mm vs days	Per-layer cv from Eoed and kv; Terzaghi 1D consolidation solution per fine-grained sublayer.

8.7 Dewatering quantity registry

Symbol	Meaning	Public unit	Technical note
targetWt, drawdownAtCpt	Target water-table elevation and drawdown at the active CPT.	m	Drawdown = current WT − target WT.
C (Sichardt)	Sichardt-style proportionality constant for the radius-of-influence relation.	[-]	R_inf = C · drawdown · √k (typical C ≈ 3000 for sand; user-editable).
R_inf	Estimated radius of influence.	m	Analytical screening; not a coupled-flow result.
newWtAtCpt	Reconstructed water-table elevation at the CPT during dewatering.	m	Interpolated from the analytical drawdown curve.
sigmaVMode	Drawdown-induced effective-stress treatment.	enum: conservative / progressive	Conservative routes the entire drawdown into σ'_v gain; progressive uses depth-dependent reduction.
totalSettlementMm	Drawdown-induced consolidation settlement.	mm	Σ (Δσ'_v / E_oed,i) · h_i over the affected depth band.

8.8 Beam / slab on elastic foundation quantity registry

Symbol	Meaning	Public unit	Technical note
k_s	Subgrade reaction modulus (Winkler bedding).	kN/m^3	Derived from the CPT stiffness profile (Vesić-style closed form on the averaged Es over the influence depth).
G_p	Pasternak shear-layer parameter.	kN/m	Inferred from the CPT shear-modulus profile and the user-editable η coupling factor; user override accepted.
lambda, beta·L	Characteristic length of the elastic foundation and dimensionless beam length.	m, [-]	Used by the closed-form Winkler / Pasternak strip solution and by the convergence classification.
w(x), w_max	Strip deflection profile and maximum deflection.	mm in plots; m internally	SLS quantity. w_max is compared against L / allowableDeflectionRatio.
M(x), M_Ed	Bending-moment profile and design-moment magnitude.	kNm/m	ULS quantity per metre strip width; drives the EC2 reinforcement step.
loadPattern	Load-application pattern.	enum: uniform_full / uniform_patch / point_centre / point_at_x	Determines the bending-moment distribution.

8.9 EC2 reinforcement-output quantity registry

Symbol	Meaning	Public unit	Technical note
M_Ed	Design bending moment carried into the reinforcement step.	kNm/m	From the beam ULS analysis (above).
d	Effective depth.	mm	h − c_nom − φ_bar / 2.
f_cd, f_yd	Design concrete and steel strengths.	MPa	f_cd = α_cc f_ck / γ_C, f_yd = f_yk / γ_S, with α_cc and material factors per EC2 / Belgian ANB.
c_nom	Nominal concrete cover.	mm	EC2 Table 4.4N + Δc_dev, with structural-class adjustments and exposure-class drive; user override accepted.
A_s,req	Required steel area per metre strip.	mm^2/m	Computed from M_Ed and the EC2 rectangular concrete stress block.
A_s,min	Minimum steel area per metre strip.	mm^2/m	EC2 §9.2.1.1 minimum reinforcement requirement.
A_s	Governing steel area.	mm^2/m	max(A_s,req, A_s,min).
structuralClass	EC2 structural class S1 to S6.	[-]	Function of design working life, exposure class, fck, slab/plate flag, special-QC flag, and casting conditions.

Reference map

9. Route map to topic-specific technical chapters

Primary

Source basis, quantity definitions, export semantics, and audit traceability.