Failure of a geogrid-reinforced soil wall

The construction and testing of a large-scale reinforced soil wall 3 m high built within the Royal Military College Retaining Wall Test Facility is discussed. The wall was constructed to retain a sand fill and comprised full-height (propped) panel facings and four layers of a relatively weak geogrid. The weak geogrid was chosen so that the wall could be failed under surcharge. Following construction the wall was stage loaded by applying a series of increasing surcharge loads up to 80 kPa pressure. Each load was sustained for a minimum of 100 hr to observe creep in the composite system. The wall was heavily instrumented to record displacements along the grid layers, grid strains, connection loads, panel deformations, toe forces, and vertical earth pressures. Test results indicated that during the final surcharge increment a well-defined failure plane was generated through the reinforced soil mass and was followed some days later by (creep) rupture of the reinforcement. Large strains in the grid layers were observed in the vicinity of the connections that were comparable in magnitude to the peak strains recorded at the location of the observed failure plane in the reinforced soil mass. Finally, important implications are drawn concerning the design and construction of those systems.