ISO 17892-10:2018

Overview

ISO 17892-10:2018 - "Geotechnical investigation and testing - Laboratory testing of soil - Part 10: Direct shear tests" specifies laboratory methods to determine the effective shear strength of soils under consolidated drained conditions. It covers two direct-shear devices: the shearbox and the ring shear. The standard applies to undisturbed, remoulded, re‑compacted or reconstituted specimens and describes the procedure for shearing a specimen under a single vertical (normal) stress to derive effective shear strength parameters.

Key technical topics and requirements

• Test methods: Two procedures are specified - the shearbox test (typically for peak shear strength) and the ring shear test (commonly used to obtain residual shear strength of fine-grained soils).
• Specimen preparation: Procedures for preparing specimens from undisturbed samples and laboratory-fabricated specimens are defined; staged loading, pre-shearing and interface tests are not covered.
• Loading and consolidation: Specimens are consolidated under a predetermined vertical stress with drainage allowed so excess pore pressures dissipate (consolidated drained testing).
• Measurements and instrumentation: The standard addresses apparatus, including shearbox and ring shear devices, loading devices and measuring equipment (load/torque and displacement measurement). Shear force and horizontal/vertical displacements are recorded during shearing.
• Test matrix: Generally, three or more specimens from the same soil are sheared under three or more different vertical pressures to permit determination of shear strength parameters (see Annex B for additional calculations).
• Quality control: Annex A covers calibration, maintenance and checks for equipment; Annex B provides calculation guidance for effective strength parameters.
• Limitations: Special procedures such as staged loading, pre-shearing and interface tests with other materials are explicitly excluded.

Practical applications

ISO 17892-10 is used to produce reliable effective shear strength parameters that feed into geotechnical design and analysis, including:

• Slope stability assessments and landslide remediation design
• Foundation bearing capacity and settlement analysis
• Design of retaining walls, embankments and earth structures
• Geotechnical site investigations and laboratory testing programs
• Research into peak vs. residual strength behavior of soils

Who should use this standard

• Geotechnical engineers and consultants specifying or interpreting laboratory shear tests
• Soil-testing laboratories implementing standardized direct shear procedures
• Civil engineers and designers who need consistent effective shear strength parameters for design codes
• Researchers comparing shear strength results across studies

Related standards

• ISO 17892 series (laboratory testing of soil) - see other parts for water content, classification and related methods
• EN 1997-1 / EN 1997-2 - the standard fulfills requirements for drained shear strength determination in relation to these Eurocode parts

Keywords: ISO 17892-10, direct shear tests, shearbox, ring shear, effective shear strength, consolidated drained, laboratory testing of soil, geotechnical investigation.