ISO 18674-8:2023

Overview

ISO 18674-8:2023 - Geotechnical investigation and testing - Geotechnical monitoring by field instrumentation - Part 8: Measurement of loads: Load cells - specifies how to measure forces in geotechnical monitoring using load cells. It complements ISO 18674-1 (general rules for geotechnical monitoring) and focuses on practical requirements for installing, calibrating and using electric and hydraulic load cells in the field. The standard applies to performance monitoring of anchors, tiebacks, piles, struts, props and steel linings, and for evaluating stability or checking designs during or after construction.

Key Topics and Technical Requirements

• Types of load cells: electric (deforming body with electrical sensors) and hydraulic (liquid-filled compartment with pressure measurement).
• Sensor technologies: strain-gauge, piezoelectric, vibrating wire, capacitive - configured to minimise eccentric loading (multiple sensors evenly spaced).
• Design features: load-bearing element, load distribution plates (spherical plates recommended for alignment), protective covers and cabling.
• Dimensional guidance: for cylindrical electric elements the height-to-diameter ratio H/D should be in the range 0.1 ≤ H/D ≤ 2.
• Range and accuracy: nominal range must exceed the maximum anticipated load plus a 10–30% margin; lower 5–10% of nominal range can be less accurate. Overrange is limited to values that do not damage the cell.
• Environmental effects: temperature influence must be considered and documented; use temperature-compensated sensors and independent temperature measurements.
• Installation & measurement: procedures for installation (anchors, cast-in-place pile bases, struts), instrument checks, on-site calibration and data logging are specified.
• Data handling & reporting: requirements for data processing, evaluation and standardized installation and monitoring reports.

Applications

• Performance monitoring of geotechnical structures (anchors, piles, tiebacks, struts, props, linings).
• Observational method: checking and adjusting geotechnical designs during construction.
• Stability assessment during and after construction to inform remediation or design changes.
• Long-term asset management: structural health monitoring for retaining walls, excavations and deep foundations.

Who should use this standard

• Geotechnical and structural engineers
• Instrumentation and monitoring contractors
• Construction supervisors and site engineers
• Asset owners, consultants and researchers involved in geotechnical monitoring and load measurement

Related Standards

• ISO 18674-1 - Geotechnical monitoring: general rules
• ISO 18674-7 - Measurement of forces by strain or displacement gauges (related methods)
• ISO 7500-1 - Calibration/verification of force-measuring systems (referenced for calibration)

Keywords: ISO 18674-8:2023, geotechnical monitoring, load cells, measurement of loads, electric load cell, hydraulic load cell, anchor load cell, instrumentation, calibration, geotechnical investigation.