Retaining Wall Design

Retaining wall design combines geotechnical actions, foundation behaviour, structural capacity, drainage and construction sequencing. A wall should be assessed for the conditions that may occur during construction and throughout its design life.

The sliding, overturning, resultant and base-pressure equations are on the separate Retaining Wall Stability Calculation page.

Establish the wall system

The design approach depends on whether the system is a gravity wall, reinforced-soil wall, cantilever wall, embedded wall, anchored system, crib wall or another form. Geometry, stiffness, movement and load transfer affect the appropriate ground-pressure model.

Define actions and conditions

The design model may include:

• Soil self-weight and lateral earth pressure
• Groundwater and hydrostatic pressure
• Uniform, strip, line and point surcharges
• Traffic, compaction and construction plant
• Seismic actions where required
• Wall and foundation self-weight
• Anchor, prop or reinforcement forces
• Excavation stages and temporary conditions

Actions and resistance should use a consistent serviceability or ultimate design framework.

External stability

Common external checks include sliding, overturning or resultant position, bearing resistance, base contact pressure and settlement. Passive resistance, base adhesion and interface friction should not be assumed without confirming that they can be reliably mobilised and maintained.

Global and internal stability

External stability calculations do not demonstrate global stability of the wall and surrounding ground. Reinforced-soil systems also require internal stability checks. Embedded and anchored walls require suitable structural and soil-structure interaction analysis.

Drainage and groundwater

Water pressure can govern wall performance. Drainage should include filter compatibility, discharge routes, blockage risk, inspection and maintenance. Where drainage reliability cannot be demonstrated, appropriate water-pressure conditions should be included.

Foundation and serviceability

Bearing resistance, total settlement, differential movement and rotation should be checked using the actual foundation geometry and ground profile. A compressive base-pressure distribution does not by itself demonstrate acceptable performance.

Calculation resources

• Retaining Wall Stability Calculation
• Lateral Earth Pressure
• Rankine Earth Pressure Calculation
• Bearing Capacity of Soil and Foundations
• Footing Pressure and Eccentricity Calculations

Engineering note

The calculation methods, load combinations, resistance factors and acceptance criteria must be selected for the wall system, project conditions and applicable design requirements.