Retaining Wall — Rankine Active/Passive Earth Pressure implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t5-139

Effect

Computation or source lookup only

Input and validation requirements

The phi=90 degree input causes tan(90 degrees) to divide by zero, making Kp, passive pressure, and passive resultant undefined. The branch-switch vector also exposes arithmetic consistency requirements: the correct passive base pressure for phi=30 degrees, gamma=18 kN/m^3, and H=6 m is 324 kPa, and the correct passive resultant is 972 kN/m.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "phi_deg": 30,
    "gamma_kN_per_m3": 18,
    "H_m": 6,
    "surcharge_kPa": 0
  },
  "expected_outputs": {
    "Ka": 0.3333333333,
    "Kp": 3,
    "active_base_pressure_kPa": 36,
    "passive_base_pressure_kPa": 324,
    "active_resultant_kN_per_m": 108,
    "passive_resultant_kN_per_m": 972,
    "active_location_m_above_base": 2,
    "passive_location_m_above_base": 2
  },
  "working": "φ/2=15°. Ka=tan²(45°−15°)=tan²30°=(1/√3)²=1/3. Kp=tan²(45°+15°)=tan²60°=3. Active base pressure=KaγH=(1/3)(18)(6)=36 kPa. Passive base pressure=KpγH=(3)(18)(6)=324 kPa. Active resultant=½KaγH²=½(1/3)(18)(6²)=½(1/3)(18)(36)=108 kN/m. Passive resultant=½(3)(18)(36)=972 kN/m. Each soil-pressure diagram is triangular, so location=H/3=6/3=2 m above the base."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche5/tranche5-results.json