Overview
EN ISO 22476-2:2005 - Geotechnical investigation and testing - Field testing - Part 2: Dynamic probing defines requirements for in‑situ dynamic probing as part of geotechnical site investigation (within the scope of EN 1997). The standard covers procedures for measuring soil and soft rock resistance by driving a cone into the ground with a falling hammer and recording penetration resistance as the number of blows per defined penetration. Dynamic probing provides a continuous profile (no samples recovered) and is intended primarily for qualitative profiling and comparative correlation with other tests.
Key topics and technical requirements
- Four probe classes to cover a wide energy range: DPL (light), DPM (medium), DPH (heavy) and DPSH (super heavy). Specific work per blow spans roughly 50 to 238 kJ/m² depending on apparatus.
- Equipment specifications: cone geometry (90° apex), drive rods (high‑strength steel, straightness limits), hammer mass and fall height, anvil, cushions/dampers, and optional hollow rods for injection.
- Energy control & measurement: distinction between theoretical energy (Etheor = m·g·h) and actual measurable energy (Emeas); an energy ratio (Er = Emeas/Etheor) is used to verify transmitted energy. Annex C gives a recommended method to measure actual energy.
- Test execution rules: continuous driving, nominal blow rate 15–30 blows/min, rotation of rods 1½ turns every 1 m (or after 50 blows during heavy driving), record interruptions >5 minutes, torque measurement on rod connections (device able to read at least 200 Nm).
- Calibration & checks: dimensional checks, rod straightness checks (on new site and periodically), instrument precision and calibration records (at least every six months or after overload/damage).
- Optional systems: blow counters, electronic penetration measurement, mud injection (e.g., bentonite mix ~5–10% by mass) to reduce skin friction or fill annulus, and rod deviation control.
Applications and users
- Practical uses:
- Qualitative soil profiling and correlation with sampling or other in‑situ tests.
- Estimating depth to very dense layers (e.g., pile end bearing length).
- Detecting very loose, voided, back‑filled or infilled ground.
- Providing inputs for empirical correlations to strength and deformation properties (commonly for cohesionless soils; may also support fine‑grained soils).
- Typical users:
- Geotechnical engineers, site investigation contractors, foundation designers, geologists, and regulatory authorities involved in ground engineering and foundation design.
Related standards
- EN 1997 (Eurocode 7) - Geotechnical design / investigation framework
- Other parts of EN ISO 22476 series (examples): Part 1 (cone/piezocone), Part 3 (standard penetration test)
- prEN ISO 22475‑1 (sampling principles) referenced for combined investigations
Keywords: EN ISO 22476-2:2005, dynamic probing, geotechnical investigation, field testing, dynamic penetrometer, penetration resistance, site investigation, cone penetration.
