How does cohesion affect active earth pressure?

Active pressure with cohesion: σ_a = Kaγz - 2c√Ka. Negative (tension) near surface to depth z_c = 2c/(γ√Ka). Practical approach: ignore tension zone (tension crack fills with water), use KaγH distribution from z_c down.

What Ka value should I use for sand?

Loose sand (φ=30°): Ka = 0.333, Kp = 3.0, K0 = 0.50. Medium sand (φ=35°): Ka = 0.271, Kp = 3.69, K0 = 0.43. Dense sand (φ=40°): Ka = 0.217, Kp = 4.60, K0 = 0.36.

What are Rankine theory limitations?

Rankine assumes: smooth vertical wall (no friction), horizontal backfill, no seismic forces. Fails for sloping walls and sloping backfill without modifications. Use Coulomb for walls with significant friction and sloping surcharge.

Rankine Earth Pressure Calculator

Apply Rankine theory for lateral earth pressures with and without cohesion. Ka = (1-sinφ)/(1+sinφ), Kp = (1+sinφ)/(1-sinφ). Tension crack depth z_c = 2c/(Kaγ) in cohesive soils. Total force on wall.

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. Apply Rankine theory for lateral earth pressures with and without cohesion. Ka = (1-sinφ)/(1+sinφ), Kp = (1+sinφ)/(1-sinφ). Tension crack depth z_c = 2c/(Kaγ) in cohesive soils. Total force on wall. Use the rankine pressure result to inform your clinical assessment.

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Frequently Asked Questions

How does cohesion affect active earth pressure?

What Ka value should I use for sand?

What are Rankine theory limitations?