Overview
ISO 22476-2:2005 - Geotechnical investigation and testing - Field testing - Part 2: Dynamic probing specifies requirements for in situ, indirect investigations of soils using dynamic probing. The standard covers the method where a cone is driven into the ground by a falling hammer and the penetration resistance is recorded as the number of blows required to drive the cone over a defined distance. Dynamic probing provides a continuous depth record without recovering soil samples and is intended to support geotechnical investigations in accordance with EN/ISO geotechnical practice.
Key topics and technical requirements
- Scope and purpose
- Indirect measurement of soil and soft rock resistance to dynamic cone penetration.
- Four defined procedures to cover a wide energy range: DPL (light), DPM (medium), DPH (heavy), DPSH (super heavy).
- Equipment and components
- Requirements for the drive-weight assembly (hammer, anvil/drive head, fall guide, release mechanism).
- Cone geometry (90° apex cone), drive rods (high-strength steel, straightness limits), and optional hollow rods for injection.
- Specification of hammer mass, height of fall, cone base area and rod dimensions (see Table 1 in the standard).
- Energy and measurement
- Definitions of theoretical energy, actual energy (E_meas) and energy ratio (Er).
- Specific work per blow (En) as a key parameter for comparing equipment/procedures.
- Instrumentation: blow counters, penetration-length sensors, torque measuring devices and calibration requirements.
- Procedure, calibration and reporting
- Pre-test equipment checks, straightness and calibration intervals, recording methods.
- Test results, continuous logs, and recommended reporting formats (including annexes with data forms).
- Interpretation
- Use for qualitative profiling, correlations to soil strength and deformation (mainly cohesionless soils), detection of dense layers, voids or backfill, and guidance for pile end-bearing depth.
Applications and users
- Who uses it: geotechnical engineers, site investigation contractors, civil/structural designers, foundation specialists, and regulatory bodies.
- Practical uses:
- Rapid site reconnaissance and continuous profiling where sampling is limited.
- Preliminary assessment of bearing capacity, estimation of pile lengths and detection of voids/backfilled zones.
- Comparative in situ correlation with other tests (e.g., SPT, CPT) and input to geotechnical models.
Related standards
- ISO 22476 series (other field tests: CPT, SPT, pressuremeter, dilatometer, etc.)
- prEN ISO 22475-1 (sampling by drilling and excavation methods)
- EN 1997 (Eurocode 7 - geotechnical design)
- EN 10204 (inspection documents for metallic products)
ISO 22476-2 is essential for consistent, repeatable dynamic probing practice and for producing defensible in situ data used in foundation design and geotechnical site characterization.