Geometry

Cover / pavement

Build the section over the foam, surface course first. Each layer: material (unit weight shown) × thickness in inches.
Cover goal — auto-prepare
in
0.50
Cost assumptions — editable
Place granular courses in ≤8–12″ lifts; accept by density (95% max dry) or plate-load — not LWD over the foam (it reads through to the soft foam). The bottom course sets the AASHTO load-spread.

Traffic & surface load

Void span 0 = foam continuously supported (normal). Set >0 only for a real unsupported gap (trench, box-culvert opening).

Water & soil

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Cap plate (foam side)

Ground anchor

/

Off-the-shelf anchors

Pick a real product to load its type, size and submerged capacity into the inputs above. Dry catalog ratings are knocked down (or recomputed) for saturated soil; every choice still needs a site proof test.

Spacing & factors of safety

Thermal / cure

What this means

In-service loads & cover — the traffic load case (no flood): wheel load spread through the cover into foam bearing

State-DOT compliance — check the design against the selected agency standard

RequirementStandardThis designStatus

Standards reference library — what each agency requires · extensible: add a state to the registry to get a page + picker option

View standard:

Calculations report — every computed value, live, with the formula and your current numbers

Reflects the current scenario. Each value's pop-up (the ⓘ on its card) shows the same worked calculation in place. Screening only — confirm against the references and a site pull-out test.

Assumptions & limitations — read before relying on any number; this is a screening tool

This is a design-screening tool, not a substitute for a PE-stamped design. Confirm every value against the current governing specification and a site investigation.

Flotation & water

  • Flotation is checked at the design high water = max(seasonal high groundwater, design flood); net uplift clamps once the foam is fully submerged.
  • Cover counts at moist unit weight above the water line and buoyant (γ_sat − γ_w) below it, per layer in its own depth band.
  • FS targets follow NCHRP 529: 1.5 design, 1.2 minimum. The "FS system (working)" headline includes anchors + cover + foam weight; the flotation chart curves are cover + gravity only.

Anchors

  • Computed capacities use submerged soil (Meyerhof-Adams cylindrical shear / bearing, grout-ground bond); submerged capacity is far below dry catalog ratings.
  • Every anchor requires a saturated-soil pull-out / proof test to ≥ 1.5× the working load. Catalog knock-downs are screening estimates; consumer augers are not engineered anchors.

Loads, cover & bearing

  • Wheel load spreads to the foam by the AASHTO area method with a Boussinesq cross-check (larger governs); dynamic load allowance fades to zero at ~8 ft (LRFD 3.6.2.2 buried).
  • The bottom-course spread coefficient (1.15 granular / 1.0) is a screening convention, NOT a codified AASHTO distribution factor. Layer ORDER follows the NCHRP-529 construction convention; a full stiffness-sequenced spread is not yet modeled.
  • The deformation target is a sustained dead-load stress ratio (a creep proxy), not a measured settlement; there is no time-dependent foam-strain model.
  • The load-distribution slab is sized by a 2:1 foam-protection spread plus a Westergaard slab-flexure check.

Materials & cost

  • Unit weights are typical AASHTO / FHWA / ACI values; the "site soil" course tracks the Water & soil inputs. The v1_backfit preset is a calibration fit (γ_sat = γ_moist), not a real soil.
  • Costs are ±30% screening placeholders (editable), for ranking options — not a bid.

Out of scope — run separately

  • Seismic (Caltrans-mandatory), global slope stability, subgrade settlement / consolidation, lateral earth pressure, and detailed cure-thermal beyond the Thermal view.

Acceptance / QC

  • Verify with ASTM D1621/D1622 coupons, settlement plates, and a saturated pull-out test. The lightweight deflectometer (LWD) is NOT valid over geofoam — its influence depth reads through thin cover into the soft foam.

Lightweight-fill comparison — where CSF sits vs EPS block, CLSM, LCC & aggregates

MaterialDensity
(pcf)		Strength
(psi)		Water / fuelPlacementCost

3D system view — drag to orbit · scroll to zoom · the load path from auger to cap plate

x = across road · z = along road · y = up
Anchor system:

Flotation factor of safety vs. headwater — FS drops as rising water makes the cover soil buoyant

Physics deformation view — static pressure, uplift, foam bow & pull-out as the water rises (drag headwater or Ramp)

the mm scale on the left reads the true deflection at whatever zoom you pick. "fit" auto-zooms so the movement fills the frame.

Anchor type comparison — per-anchor capacity in the current soil (submerged)

Anchor typeUltimate (lb)Working (lb)vs. demandNotes
Demand per anchor at the current spacing is shown in the cards above. "Working" = ultimate ÷ anchor FS. The 3-in×36-in field band (2,500–4,700 lb) is a dry rating and is shown for reference only.

Pull-out path check — the governing (weakest) link sets the design

Failure pathCapacity / limitStatus

Field pull-out (load) test — prove the submerged capacity & calibrate the design (PTI / FHWA / AC358)

%DLVerif. (lb)Proof (lb)Hold

Calibrate from a field result → re-run the design

Thermal / cure — exotherm peak & safe-to-compact time

Validation self-test — the in-browser engine reproduces the documented field numbers

Show validation cases (DES 2301160, helical band, Huber layout, thermal)
CaseComputedExpected
Method basis: Archimedes flotation (NCHRP 529 Ch.6, NYSDOT GEM-24b); Meyerhof–Adams uplift (½-factor, submerged) and torque correlation for ground anchors; 45° punching-shear frustum, foam bearing and slab flexure for the cap plate; 1-D transient conduction (Incropera) for cure thermal. Conservative free-rise / lower-bound strengths used throughout. Confirm soil parameters, the agency flotation-FS convention, and anchor capacity with a site pull-out test before sign-off. See ENGINEERING_BASIS.md.