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Lateral Earth Pressure

Active, passive and at-rest earth pressures by Rankine and Coulomb. Includes surcharge, water table effects, cohesion, and resultant force/point of application.

Inputs

m
degrees
kPa
kN/m³
kPa (uniform)
m (large = none)
degrees (Coulomb)
degrees from horiz. (Coulomb)
degrees (Coulomb)
Method & assumptions
  • Rankine active: Ka = tan²(45 − φ/2). Passive: Kp = 1/Ka.
  • At-rest: K0 = 1 − sin φ (Jaky).
  • Coulomb K_a (Mueller-Breslau form): full geometric factors α, β, δ.
  • Cohesive: σ_a = K_a·σ_v − 2c·√K_a; tensile zone z_c = 2c/(γ·√K_a) — total active force from depth z_c to H.
  • Surcharge: ΔP_q = K·q·H; resultant at H/2.
  • Water: hydrostatic γ_w·z added below GWT; soil γ becomes buoyant.

Results (per metre length)

Coefficient K
Tension Crack Depth zc
σ at top of wall
σ at base of wall
Force from soil Psoil
Force from surcharge Pq
Force from water Pw
Total Resultant P
y̅ (from base)