Pile Assessment: Capacity, Demand and Verification

A pile assessment brings together actions, geotechnical resistance, structural resistance, settlement, group interaction, installation records and verification testing. A single ultimate-capacity number is not a complete assessment.

Note: This is a draft assessment workflow for engineer review. The governing design standard and project basis control acceptance.

Assessment cases

Separate cases may be required for:

• Axial compression
• Axial uplift
• Lateral load and moment
• Combined actions
• Single-pile and group response
• Temporary, construction and completed conditions
• Short-term and long-term ground behaviour

Design action

Where drag load or other geotechnical actions are treated as actions by the approved design method, a transparent total may be recorded as:

$$ E_{total}=E_{structure}+E_{drag}+E_{other} $$

The load combination and factor treatment must be defined by the project design basis.

Governing resistance

For a simplified axial check, the governing design resistance may be represented as the lower of approved geotechnical and structural resistances:

$$ R_{governing}=\min(R_{d,geo},R_{d,struct}) $$

The utilisation ratio is:

$$ \eta=\frac{E_{total}}{R_{governing}} $$

This comparison does not replace settlement, durability, lateral or group checks.

Illustrative example

Assume an approved design case has:

• Structural action \(700\ \text{kN}\)
• Drag load \(150\ \text{kN}\)
• Design geotechnical resistance \(950\ \text{kN}\)
• Design structural resistance \(1100\ \text{kN}\)

Then:

$$ E_{total}=700+150=850\ \text{kN} $$ $$ R_{governing}=\min(950,1100)=950\ \text{kN} $$ $$ \eta=\frac{850}{950}=0.895 $$

The acceptance of this illustrative ratio depends on the approved design framework and completeness of all required checks.

Serviceability and group assessment

Pile-head settlement, differential movement and load transfer should be assessed at the relevant serviceability actions. Groups may require checks for block resistance, group settlement, cap interaction and construction sequence.

Verification record

• Design and as-built pile geometry
• Installation method, date and founding record
• Static analysis method and parameter sources
• Integrity, dynamic or static load testing
• Construction deviations and concessions
• Setup, relaxation or time-dependent assumptions
• Final engineer review and design status

Related resources

• Pile Capacity
• Axial Pile Capacity Calculation
• AS 2159 Strength Reduction Assessment
• Pile Capacity from DCP