ISO 17892-9:2018

Overview - ISO 17892-9:2018 (Consolidated triaxial compression tests)

ISO 17892-9:2018 specifies a laboratory method for consolidated triaxial compression tests on water-saturated soils. The standard is used to determine triaxial shear strength under compression loading and to measure stress–strain behavior and effective stress paths. Cylindrical specimens (undisturbed, re‑compacted, remoulded or reconstituted) are consolidated isotropically or anisotropically under drained conditions and then sheared under drained or undrained conditions. All stresses and strains are expressed as positive values in compression.

Key technical topics and requirements

• Test types covered: CIU (isotropically consolidated undrained), CAU (anisotropically consolidated undrained), CID (isotropically consolidated drained), CAD (anisotropically consolidated drained).
• Specimen preparation and saturation: Procedures for specimen preparation, back‑pressure saturation and saturation checks are specified to ensure fully saturated test conditions.
• Apparatus and measurements: Requirements and guidance for triaxial cell, confining membrane, porous discs, pressure systems, load frame and measuring devices (load, pressure, vertical displacement, volume change).
• Consolidation and shearing procedures: Steps for isotropic/anisotropic consolidation and subsequent undrained or drained shearing.
• Data and calculations: Determination of shear strength, deviator stress, effective stresses, pore pressure changes, vertical and volumetric strains, corrected specimen area and membrane/filter corrections. Annex B provides procedures for evaluating shear strength parameters.
• Reporting and quality control: Mandatory reporting items and graphical presentation requirements; Annex A addresses calibration, maintenance and checks.
• Limitations: Special procedures (lubricated ends, multi‑stage tests, K0 consolidation, local strain or pore pressure measurement, membraneless tests, extension tests, variable cell pressure shearing) are not fully covered but may refer to general procedures in this document.
• Statistical requirement: At least three relatable tests are normally required to define shear strength parameters.

Practical applications and users

ISO 17892-9:2018 is essential for:

• Geotechnical laboratories performing triaxial shear testing on saturated soils.
• Geotechnical and foundation engineers who need reliable shear strength parameters, stress–strain curves and effective stress paths for design of slopes, foundations, retaining structures and earthworks.
• Consultants, researchers and contractors involved in site investigation, soil characterization and validation of numerical models. The standard supports compliance with design codes by providing reproducible laboratory data used in stability analyses and geotechnical design.

Related standards and references

• Normative ISO references: ISO 17892-1, ISO 17892-2, ISO 17892-3 (water content, bulk density, particle density).
• Conformance: Fulfils requirements for consolidated triaxial testing in EN 1997‑1 and EN 1997‑2 (Eurocode 7 geotechnical design).

Keywords: ISO 17892-9:2018, consolidated triaxial compression tests, water-saturated soils, triaxial shear strength, effective stress paths, geotechnical laboratory testing.