Overview
ISO 22477-2:2023 - "Geotechnical investigation and testing - Testing of geotechnical structures - Part 2: Testing of piles: Static tension load testing" specifies how to perform static axial tension (uplift) load tests on a single pile to determine its load–displacement behaviour and tensile resistance. The standard covers vertical and raking piles of all types and is limited to maintained (static) load tests; cyclic tests are excluded. ISO 22477-2 is intended to be used in conjunction with EN 1997‑1 for design factors and correlations.
Key topics and technical requirements
- Scope and purpose: Defines procedures to check that a pile behaves as designed and to measure pile resistance (tensile resistance at the ultimate limit state).
- Equipment and reaction systems:
- Reaction devices may include shallow foundations or compression piles; embedded jacks (see ISO 22477‑1) are recognized.
- Minimum clear distances between test pile and reaction system are specified to limit interference (e.g., guidance on 5D over‑estimation limit, 10D recommended for serviceability; for piles <300 mm the minimum clear distance may be reduced but not below 1.5 m).
- Force input and jacks:
- Use of one or more hydraulic jacks; multiple jacks must be identical, symmetrically arranged and supplied from a common unit.
- Jack capacity and stroke must exceed the maximum test load and expected deformations.
- Force regulator accuracy: better than 0.5% of the predefined maximum test load or 10 kN, whichever is greater.
- Measurements and instrumentation:
- Pile head displacement measured by dial gauges or transducers supported from reference beams independent of the test pile.
- Reference beams require minimum clearances (e.g., at least 2.5 m or 3.5 D) and secondary control checks (levelling or similar).
- Requirements for measurement of pile load, pile instrumentation and monitoring of reaction piles.
- Test procedure and reporting:
- Specifies test preparation, loading procedures (single-cycle and multiple-cycle load step sequences and durations), measuring intervals, maximum test load, and data/reporting requirements (data report and interpretative report).
- Additional guidance: Annex on critical creep load in tension.
Practical applications
ISO 22477-2 is used to:
- Verify uplift capacity and load–displacement behavior of foundation piles.
- Provide field-measured tensile resistance values for design verification and quality assurance.
- Support performance-based foundation design where uplift, raking or tension loads are critical.
Who should use this standard
- Geotechnical engineers and designers
- Construction and foundation contractors performing pile tests
- Geotechnical testing laboratories and site supervisors
- Structural engineers integrating pile test data into design (in conjunction with EN 1997‑1)
Related standards
- EN 1997‑1 (Eurocode 7 - geotechnical design: partial factors and correlations)
- EN 1997‑2 (Ground investigation and testing)
- ISO 22477‑1 (related pile testing methods)
- ISO 7500‑1 (calibration/verification of testing machine force measurement)
- EN 1990 (basis of structural design)
Keywords: ISO 22477-2, static pile load test, static tension load testing, pile testing, geotechnical testing, pile uplift test, tensile resistance, load–displacement.