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
| Requirement | Standard | This design | Status |
|---|
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.
EPS geofoam grades — ASTM D6817 Table 1 (minimum values for block EPS)
Every state DOT keys its geofoam spec to these grades. Values are minimums; the grade number is roughly 10× the density in kg/m³. QC by ASTM D1622 (density) and D1621 (compressive resistance).
| EPS grade | Min density (pcf) | Comp. @1% (psi) | @5% (psi) | @10% (psi) | Flexural (psi) |
|---|---|---|---|---|---|
| EPS12 | 0.70 | 2.2 | 5.1 | 5.8 | 10 |
| EPS15 | 0.90 | 3.6 | 8.0 | 10.2 | 25 |
| EPS19 | 1.15 | 5.8 | 13.1 | 16.0 | 30 |
| EPS22 | 1.35 | 7.3 | 16.7 | 19.6 | 40 |
| EPS29 | 1.80 | 10.9 | 24.7 | 29.0 | 50 |
| EPS39 | 2.40 | 15.0 | 35.0 | 40.0 | 60 |
| EPS46 | 2.85 | 18.6 | 43.5 | 50.0 | 75 |
CSF's sprayed products are tested to their own density/strength (shown on the product card): BaseReady ~2.0–2.2 pcf falls near the EPS39 strength class; PaveReady ~5 pcf (≈112 psi @10%) exceeds the standard block-EPS grades. Confirm against the current product data sheet. Note: D6817's buoyancy and fuel/solvent clauses are in non-mandatory Appendix X1 — that is why each DOT adds its own mandatory cover, fuel-barrier and flotation provisions. Source: ASTM D6817-07.
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.
Nomenclature & units — every symbol, term and unit used in the tool
| Symbol / term | Meaning | Unit |
|---|---|---|
| Geometry | ||
| Hf | Foam fill height (thickness of the geofoam) | ft |
| Hc | Cover depth — top of foam to finished surface (Σ layer thicknesses) | ft (layers in) |
| Wtot · L | Foam plan width across · length along the road | ft |
| Water & soil | ||
| γw | Unit weight of water (62.4 fresh / 64.0 brine) | pcf |
| γf | Unit weight of the foam (≈2–5 pcf by grade) | pcf |
| γm / γsat | Soil/cover unit weight: moist (above water) / saturated (below) | pcf |
| γ′ | Buoyant unit weight = γsat − γw | pcf |
| φ · c | Soil friction angle · cohesion | ° · psf |
| HWd · hsub | Design high water (above foam base) · submerged foam height | ft |
| Flotation | ||
| qnet | Net buoyant uplift pressure = (γw − γf)·hsub | psf |
| U | Total uplift on the fill = qnet × plan area | lb |
| Rcover · Qcover | Cover hold-down: pressure · total force (moist above water, buoyant below) | psf · lb |
| FS | Factor of safety = resisting ÷ uplift (target 1.5 design / 1.2 min). "Working" uses derated anchor capacity (the acceptance basis); "ultimate" is best-case. | — |
| Loads & cover | ||
| HS-20 / HL-93 | AASHTO design vehicles; the design wheel is 16 kip (½ of the 32-kip axle) | kip |
| σdead / σlive | Foam-top stress from cover dead load / attenuated wheel | psi |
| D/C | Demand ÷ capacity (≤ 1.0 passes); "sustained D/C" = dead-load only (creep proxy) | — |
| LDS | Load-distribution slab (reinforced PCC over the foam) | in |
| spread coeff. | Screening cover load-spread factor (1.15 granular / 1.0), NOT a codified AASHTO factor | — |
| Anchors & material | ||
| Qu / Qa | Anchor capacity: ultimate / allowable (working) = Qu ÷ FSanchor | lb |
| Atrib | Tributary uplift area per anchor = spacing × row width | ft² |
| EPS-grade | ASTM D6817 grade equivalence (PaveReady ≥ EPS39, BaseReady ≈ EPS22) | — |
Lightweight-fill comparison — where CSF sits vs EPS block, CLSM, LCC & aggregates
| Material | Density (pcf) | Strength (psi) | Water / fuel | Placement | Cost |
|---|
3D system view — drag to orbit · scroll to zoom · the load path from auger to cap plate
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)
Anchor type comparison — per-anchor capacity in the current soil (submerged)
| Anchor type | Ultimate (lb) | Working (lb) | vs. demand | Notes |
|---|
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 path | Capacity / limit | Status |
|---|
Field pull-out (load) test — prove the submerged capacity & calibrate the design (PTI / FHWA / AC358)
| %DL | Verif. (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)
| Case | Computed | Expected |
|---|