Topic:

Getting Structural Fill Right in Reinforced Soil Structures

Course Overview:

Reinforced soil structures (RSS) are widely used for constructing tall retaining systems in transportation, infrastructure, and commercial developments. A typical RSS consists of four primary components: soil reinforcement, facing elements, internal drainage, and structural fill.

While reinforcement and facing systems often get the most design attention, structural fill represents the largest cost and critically influences performance. Material selection, specification compliance, constructability, durability, and interaction with reinforcement and facing all influence project cost and long-term structural behaviour.

This webinar examines the technical limits and acceptance criteria for structural fill, as defined in published guidelines and standards. It highlights how requirements vary with facing type (small segmental blocks, large concrete blocks, rigid panels, semi-flexible mesh units) and how tolerance limits such as gradation, plasticity, fines content, shear strength, and drainage characteristics impact stability, serviceability, and overall performance.

By reviewing these criteria and their practical implications, this session bridges the gap between prescriptive specifications and performance-based understanding, supporting more informed, cost-effective, and technically sound decisions in reinforced soil design and construction.

Speaker:

Eric Ewe is a specialist engineer with more than 28 years of experience. He is the Slope and Walls Technical BDM for Geofabrics, specialising in the design of reinforced soil slopes and walls, slope reinstatement works, slope stability analysis, embankment over soft ground, pavement stabilisation and rockfall protection structures. Eric has industry experience working in Malaysia, New Zealand and Australia. One of his assignments in New Zealand includes being part of the panel for the “MBIE Rockfall Protection Structures Design Considerations Guideline”. 

Learning Outcomes:

• Understand the functional role and cost significance of  structural fill within RSS
• Assess common fill acceptance criteria in industry guidelines and understand their impact on stability and serviceability limit states
• Explain how different facing systems affects material tolerances and deformation compatibility
• Identify primary cost drivers associated with structural fill selection
• Recognise when engineering judgment is required beyond prescriptive specification limits for site-specific conditions
• Apply performance-based reasoning to select and validate fill materials, achieving cost-effective solutions without compromising safety or serviceability