Behavior of a welded wire wall with poor quality, cohesive–friction backfills on soft Bangkok clay: a case study

Abstract

A full-scale and extensively instrumented experimental mechanically stabilized earth (MSE) wall with steel grid reinforcements was built on soft clay foundation. Three different locally available poor to marginal quality backfills were used in each of three sections along its length. The soft Bangkok clay in the subsoil is about 6 m thick, overlain by a surficial 2 m thick weathered clay crust and underlain by a layer of stiff clay. It was observed that the amount of subsoil movement greatly influenced the variation in the vertical pressure beneath the wall, as well as the tension in the reinforcement. Pullout resistances in the field were also found to be very much affected by the arching effects due to the presence of inextensible reinforcement in combination with the subsoil movements. The wall showed no signs of instability both during construction and in the postconstruction phases, despite the large settlements and lateral movements. Its overall performance has been satisfactory. It was concluded that the steel grid reinforcement can be effectively used to reinforce poor to marginal quality backfill in walls and embankments on soft clay foundations. Key words: mechanically stabilized earth, inextensible reinforcements, soft clay foundation, poor quality backfills, base pressures, settlements, lateral movements, lateral pressures, compaction, arching.