ISO 22476-6:2018

Overview

ISO 22476-6:2018 - Geotechnical investigation and testing - Field testing - Part 6: Self-boring pressuremeter test (SBP) specifies the equipment requirements, execution and reporting for self-boring pressuremeter tests. The standard covers in situ measurement of soil and weak rock deformation by expanding and contracting a cylindrical flexible membrane, and it fulfils requirements for geotechnical investigation services referenced in EN 1997-1 and EN 1997-2.

Key technical topics and requirements

• Equipment and probe design
  • Composition and function of the self-boring pressuremeter probe, including the central measuring cell, membrane, core, fluid lines and protective “Chinese lantern”.
  • Minimum volumetric expansion capability (≥ 25% of initial volume) and a minimum slenderness ratio (expanding length/diameter ≥ 4.0).
  • Use of at least three displacement transducers to monitor mean radial expansion and non‑circular deformation.
  • Pressure transducer locations (above ground or inside probe, <1 m above cell centre).
• Self-boring head and insertion
  • Description of the cutting shoe and self-boring head used to advance the probe while minimizing disturbance.
  • Requirement that the deflated probe outside diameter normally matches the cutting shoe diameter; oversize usage must be reported.
• Measurement, control and data acquisition
  • Control Unit (CU) functions: pressurization, automatic recording of time, pressure and volume or radial displacement, depth measurement and data logging.
  • Options for fluid (liquid assumed incompressible or gas) to inflate the measuring cell; pore pressure transducers may be integrated.
• Test procedure and quality control
  • Selection of equipment and procedures, calibration and correction of readings, probe placing, relaxation, loading program (including end-of-test criteria) and borehole backfilling.
  • Reporting requirements and interpretation of pressure–displacement (SBP) curves.
• Supportive material
  • Annexes cover calibration and corrections, probe placement guidance, accuracy, and strain conversions.

Practical applications

• In situ characterisation of soil and weak rock stiffness and deformability for:
  • Foundation design and settlement analysis
  • Retaining structures and slope stability assessments
  • Ground improvement evaluation and verification
  • Specialized site investigations where minimizing disturbance is critical
• Provides pressure–displacement data useful for constitutive modelling and design checks under Eurocode geotechnical frameworks.

Who should use this standard

• Geotechnical engineers and consultants
• Site investigation contractors and instrument manufacturers
• Laboratory and field-testing teams responsible for SBP execution and data interpretation
• Designers requiring in situ parameters for foundations, earthworks and ground improvement

Related standards

• ISO 22475-1 (sampling methods and groundwater measurements)
• ISO 10012 (measurement management systems)
• EN 1997-1 / EN 1997-2 (Eurocode 7 geotechnical design and investigation)

Keywords: ISO 22476-6:2018, self-boring pressuremeter, SBP, pressuremeter test, geotechnical investigation, in situ testing, pressure–displacement curve, EN 1997.