This standard provides guidelines for the design and construction of reinforced earth retaining walls. It covers material specifications for backfill and reinforcement, design principles for internal and external stability (including seismic conditions), and detailed construction procedures to ensure performance and safety of these structures.
Provides guidelines for the design and construction of reinforced earth retaining walls using metallic or geosynthetic reinforcements.
Quick Reference Values
Minimum Factor of Safety against sliding (static)1.5
Minimum Factor of Safety against overturning (static)2.0
Minimum Factor of Safety against bearing failure (static)2.5
Maximum percentage of fines in backfill (<0.075mm)15%
Minimum effective friction angle of backfill30 degrees
Minimum reinforcement length0.7 times wall height (H)
Minimum Factor of Safety for reinforcement pullout (static)1.5
Key Formulas
Ka = tan²(45 - φ/2) — Active earth pressure coefficient for level backfill
Ti = Ka * σv * Sv — Tensile force per unit width of reinforcement at level i
L_e = (Ti * FS) / (2 * σv * tan(δ)) — Embedment length required in resisting zone
Pa = 0.5 * γ * H² * Ka — Total active earth thrust on wall
Practical Notes
The quality of backfill material is critical; use of cohesionless, free-draining granular soil as specified is non-negotiable for long-term performance.
Proper compaction in 150-250 mm lifts is essential, paying special attention to the zone immediately behind the facing elements where hand-operated compactors may be needed.
Ensure adequate surface and subsurface drainage systems are incorporated to prevent buildup of hydrostatic pressure within the reinforced mass, which is a common cause of failure.