ISO 22476-2:2005

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.