How much movement is needed to mobilize passive pressure?

Passive pressure requires wall movement toward soil: about 0.02H to 0.05H (2-5% of wall height). This is much more than active pressure (0.001-0.005H). In design, passive is often reduced by a factor of 2-3 due to this uncertainty.

What is passive pressure coefficient Kp for typical soils?

Rankine Kp = tan²(45+φ/2). For φ = 30°: Kp = 3.0. For φ = 35°: Kp = 3.69. For φ = 40°: Kp = 4.60. Kp >> Ka = 1/Kp (active).

When should passive earth pressure be neglected?

Neglect passive when: soil may be removed or excavated in future, frost action causes seasonal movement, soil is weak or disturbed, or movement required is not available. Conservative design often ignores passive for driven walls.

Passive Earth Pressure Calculator

Calculate passive earth pressure: Rankine Kp = tan²(45+φ/2). Passive resultant P_p = KpγH²/2 + 2c√Kp·H. Compare with active pressure. Passive mobilization requires significant wall movement (0.02H).

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How to Use

Enter the values for the patient or scenario you are assessing. Calculate passive earth pressure: Rankine Kp = tan²(45+φ/2). Passive resultant P_p = KpγH²/2 + 2c√Kp·H. Compare with active pressure. Passive mobilization requires significant wall movement (0.02H). Use the passive earth pressure result to inform your clinical assessment.

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Frequently Asked Questions

How much movement is needed to mobilize passive pressure?

What is passive pressure coefficient Kp for typical soils?

When should passive earth pressure be neglected?