ISO 22476-8:2018

Overview

ISO 22476-8:2018 - "Geotechnical investigation and testing - Field testing - Part 8: Full displacement pressuremeter test" defines the requirements for performing and reporting full displacement pressuremeter (FDP) tests. The standard covers equipment, installation, execution and documentation for in‑situ measurement of soil and weak rock deformation by expansion and contraction of a cylindrical flexible membrane. ISO 22476-8 also satisfies the FDP testing requirements referenced in EN 1997-1 and EN 1997-2 (geotechnical design).

Key topics and technical requirements

• Equipment requirements: specification of the FDP assembly including the pressuremeter module, cone module, membrane characteristics and the overall pressuremeter system (measuring and control devices). The standard recognises both volume‑displacement and radial‑displacement types.
• Terms and symbols: defined nomenclature (e.g., membrane length, cavity volume, radial/volumetric strain, system compliance) to ensure consistent data interpretation.
• Test procedure: guidance on selection, preparation, installation (FDP is jacked/driven to create its own test hole - no pre-boring), controlled pressure application/recording, optional unload–reload cycles, logging frequency and test completion.
• Calibration and corrections: mandatory calibrations (system compliance, pressure losses) and correction procedures for volume and pressure measurements are addressed in normative annexes.
• Data, results and reporting: requirements for processing pressure–displacement (stress–strain) data, documenting test parameters, uncertainties and drift; includes informative annexes on uncertainty and strain conversions.
• Ancillary considerations: handling of membrane compressibility, membrane pressure loss, measuring system zero‑load and drift.

Practical applications

• In‑situ measurement of soil/weak rock deformation properties for:
  • Foundation design (shallow and deep foundations)
  • Retaining structures and earthworks
  • Tunnel lining and excavation support design
  • Calibration of numerical models and constitutive soil parameters
• Use where precise stress–displacement response of the ground is needed to inform geotechnical design or site characterization.

Who should use this standard

• Geotechnical engineers and site investigation specialists
• Field testing contractors and laboratory personnel conducting FDP tests
• Consultants preparing investigation reports in compliance with EN 1997
• Standards bodies and QA/measurement managers involved in test method validation

Related standards (as referenced)

• ISO 22476-1 (Electrical cone and piezocone penetration test)
• ISO 22476-4 (Ménard pressuremeter test)
• ISO 10012 (Measurement management systems)
• ENV 13005 (Guide to expression of uncertainty)

Keywords: ISO 22476-8, full displacement pressuremeter, FDP test, pressuremeter test, geotechnical investigation, field testing, in situ soil testing, pressure–displacement, membrane, calibration, EN 1997.