Performance of three geogrid-reinforced soil walls before and after foundation failure

Abstract

ABSTRACT: This paper reports the results of three 4 m high full-scale instrumented geogrid-reinforced soil walls constructed with different structural facings having a range of stiffness. The walls were seated on a 2 m deep foundation layer that was laterally supported at the base of the wall face by a rigid bulkhead. Following end of construction, the bulkhead was moved outward in stages to simulate loss of foundation support in the vicinity of the wall toe. Bulkhead loads, wall deformations, backfill settlements, reinforcement loads and earth pressures recorded at end of construction and during bulkhead displacement are presented in this paper. Measured reinforcement loads are compared to predicted loads at end of construction using different design methods. The walls demonstrated that there was available reserve load capacity which prevented internal failure mechanisms from developing in the reinforced soil zone even after significant loss of foundation support in the vicinity of the wall toe. At the end of each test the reinforcement layers were shortened in stages by cutting using nichrome heating wires. For the most flexible wall in this programme, the shortening of the reinforcement triggered a composite soil failure mechanism extending from the base of the foundation zone to the surface of the soil backfill. Implications of the analysis results and other observations on wall performance and design are discussed.