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D41 Crib walls/ gabions/ drystack masonry

105 DESIGN AND CONSTRUCTION OF EARTH RETAINING STRUCTURE
• Requirement: Obtain from the structure manufacturer:
- A design and details for the retention structure.
- A stability check for the earth mass containing the structure.
• Type of structure: site specific.
• Standard: BS 8002 and BS 8006.
• Design working life category: 25 years.
• Limits on ground movements: None other than those required for the integrity of
the structure.
• Retained condition
- Height: site specific.
- Surcharge loading on upper ground surface: site specific.
- Unplanned general excavation (minimum): Assumed over excavation in front of
retention structure site specific.
- Trenches/ Pits in lower ground surface:
Planned excavations: site specific.
Unplanned excavations/ over excavation: Do not permit.
• Other requirements: site specific.
• Existing subsoil conditions:
- Soil strength and density: site specific.
- Ground water conditions: site specific.
• Fill/ Backfill:
- Material: site specific.
- Compaction: As retaining structure manufacturer's instructions.
• Monitoring of ground conditions during construction:
- Purpose: To identify differences between actual ground conditions and those
assumed in design.
- Geotechnical report: Provide design information and a method statement for
monitoring ground conditions during and, when appropriate, after construction.
- During/ after construction: Monitor ground conditions, immediately notify any
variations from the assumed ground conditions and submit proposals for
necessary changes to the retention structure.
- On completion: Provide a record of the monitoring results and details of any
changes to the retention structure.

109 EUROCODES
• National Annexes: Reference to a Eurocode shall be deemed to include the
appropriate United Kingdom National Annex, and nationally determined
parameters shall apply.
• Substitution of alternative design rules for Application Rules: Permitted when it can
be demonstrated that the alternative rule is in accordance with the relevant
principles and that structural safety, serviceability and durability of the resulting
structure will be at least that required by the Eurocode.

RotF generic (intermediate) NBS 2014 6118-AEW-XX-XX-NBS-A-01