Demo:
1. Wall Type & Geometry
Top of wall to excavation level
Uniform, on the retained side
2. Soil Layers
Depths are measured from the top of the wall on the retained side. The last layer continues below the toe. For undrained clay, enter φ' = 0 and the undrained shear strength su as c.
| Layer | Bottom (m) | γ (kN/m³) | γsat (kN/m³) | φ' (deg) | c' or su (kPa) |
|---|
3. Groundwater
Seepage: head lost uniformly along the wall; matters only where the water levels differ
Depth below top of wall; blank for dry soil
Depth below top of wall; less than H for free water in front
4. Design Margins & Steel Section
Passive pressure ÷ Fp; 1.5–2.0 is common when no extra embedment is added
Added to D0: typically 20–40% with Fp = 1, less when Fp > 1
Often 0.6–0.65 fy, for the required section modulus
Cross-Section Sketch
Results
Step-by-Step Calculation
Method summary
Pressures (Rankine, smooth wall): \( p_a = K_a\sigma'_v - 2c'\sqrt{K_a} \ge 0 \), \( p_p = (K_p\sigma'_{v,f} + 2c'\sqrt{K_p})/F_p \), plus water pressure on each side.Cantilever (simplified method): \( \sum M_O = \int_0^{H+D_0} p_{net}(H + D_0 - z)\,dz = 0 \); the counter-pressure below the point of rotation O is replaced by a force R, developed by the extra embedment.
Anchored, free earth support: \( \sum M_A = \int_0^{H+D_0} p_{net}(z - a)\,dz = 0 \), \( T = \int_0^{H+D_0} p_{net}\,dz \). Shortest pile, largest moment.
Anchored, fixed earth support (Blum): zero moment at the point of contraflexure \( z_c \), taken at zero net pressure; \( T = \frac{1}{z_c - a}\int_0^{z_c} p_{net}(z_c - z)\,dz \), then \( R_c x + \int_{z_c}^{z_c+x} p_{net}(z_c + x - z)\,dz = 0 \). Longer pile, smaller moment.
Water: hydrostatic pressures carry any difference in water level to the toe. Steady seepage loses the head uniformly along the flow path round the toe, which also lowers the passive effective stress in front; neither model is always conservative.
\( D = (1 + \text{increase})\,D_0 \), \( Z_{req} = M_{max}/\sigma_{all} \).
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