Retaining-wall stability · workbook and reviewed actions

Input guidance

Choose source comparison to inspect one of the supplied workbook’s 22 cases, or enter an independently reviewed action schedule. Geometry is in metres, soil/water density in kN/m³, pressure in kPa, forces in kN/m and moments in kN·m/m. Source case values are examples, not universal design defaults.

Review groundwater on both sides, construction/excavation conditions, uplift, surcharge, key geometry, passive mobilisation and every factor of safety. The source case diagrams are reservoir/box-culvert schematics. They are not reinforcement details.

Calculation basis and worked example

The supplied workbook uses Hong Kong project references, not Eurocode, despite its storage location. Source mode retains exact cell formulas and saved caches so discrepancies and broken branches remain visible. It never treats a cached OK string as design verification.

For the independent action-schedule example: B = 4 m; downward force 500 kN/m and uplift 100 kN/m both at x = 2 m; driving force 80 kN/m at z = 1.5 m; δ = 25°. N = 400 kN/m, restoring moment = 1,000 kN·m/m, overturning moment = 320 kN·m/m, resultant x = 1.7 m and e = 0.3 m. Full contact applies because |e| < B/6; qmax = 145 kPa. Sliding FOS = 400 tan(25°)/80 = 2.332, overturning FOS = 3.125, supplied-bearing FOS = 600/145 = 4.138 and flotation FOS = 5. These are comparisons to user-entered targets, not approval.

Utilisation is entered required FOS divided by calculated FOS. For example, sliding utilisation = 1.5/2.332 = 64.3%. A value below 100% only means the entered target is met by the entered action schedule; it does not verify omitted actions or soil resistance.

Assumptions and limitations

The source workbook contains missing references, project-specific constants, inconsistent centroids and bearing/contact branches, and incomplete reverse/seismic combinations. A complete wall design also requires independently reviewed global stability, settlement, drainage/seepage, structural concrete and reinforcement, durability, construction stages and applicable standards.

Common mistakes include using allowable pressure as ultimate resistance, applying a factor of safety twice, crediting passive soil that may be excavated, omitting uplift, double-counting a key resistance, and entering a total force without its correct lever. Exact standard clauses are shown only after verification; otherwise rows cite workbook cells or derived equilibrium.