Overview
ISO/TR 18228-7:2021 - Design using geosynthetics - Part 7: Reinforcement provides practical guidance for geotechnical and civil engineers on the design of structures that use geotextile reinforcement. The technical report describes key potential failure mechanisms, soil–geosynthetic interaction, and how to select appropriate engineering properties and design strengths for reinforced soil systems. It supports designers in achieving required performance and serviceability over the specified design life (from short-term temporary works to permanent structures up to ~100–120 years as commonly used).
Key topics and requirements
- Scope and applications: Focus on uniaxial reinforcement uses such as retaining walls, bridge abutments, steep slopes, basal reinforcement and veneer layers; excludes pavement stabilization covered in other parts of the ISO 18228 series.
- Soil–geosynthetic interaction: Mechanisms (friction, bearing, pull-out vs. sliding) and the need for large-scale pull-out tests or shear-box tests to derive interface parameters. Emphasis on correct interpretation of test data per the chosen national code.
- Tensile capacity and testing:
- Short-term (index) strength: ISO 10319 test methods for quality control and specification.
- Long-term/creep strength: assessment according to ISO 13431 for design life evaluation.
- Reduction factors and design strength: Guidance to apply factors for
- creep (creep factor),
- installation damage,
- durability (weathering, chemical, biological, environmental),
- extrapolation of test data.
ISO/TR 20432 is referenced for deriving and applying reduction and partial factors.
- Design life and performance: Selection of design strength tied to intended life span and anticipated changes in foundation conditions (e.g., consolidation of soft soils).
- Local design considerations: Summaries of regional guidance (Scandinavia / Nordic guidelines, Germany’s EBGEO, France’s NF P94-270, UK’s BS 8006-1, and U.S. practices) and the expectation that designers follow applicable national documents.
Applications and intended users
Who uses ISO/TR 18228-7:2021:
- Geotechnical and civil engineers
- Design consultants and contractors specifying geosynthetic reinforcement
- Project managers and regulators overseeing earth structures
Practical applications include:
- Reinforced soil walls, vertical and battered faces
- Bridge abutments and load-bearing reinforced fills
- Basal reinforcement for embankments on soft ground or spanning voids
- Veneer reinforcement for slope remediation and landfill closures
Related standards
- ISO 10318-1 - Geosynthetics terms and definitions
- ISO 10319 - Tensile testing of geosynthetics (index tests)
- ISO 13431 - Long-term strength (creep) assessment
- ISO/TR 20432 - Guidance on reduction factors and design strength
- National codes: BS 8006-1 (UK), EN 1997 / Eurocode 7, DIN 1054 (Germany), NF P94-270 (France), and regional guidelines (Nordic, EBGEO)
ISO/TR 18228-7 is a practical reference for selecting geotextile properties, evaluating failure modes and deriving design strengths for safe, durable reinforced soil structures.