Controlling Horizontal Displacement Of Reinforced Soil Wall Constructed Over Stone Column Treated Ground

In recent years, stone columns have been increasingly used to support reinforced soil wall structures when they are constructed on soft foundations. Whilst the installation of stone columns have been considered as an economic solution to increase bearing capacity, reduce settlement and enhance global stability of the reinforced soil walls, they are less effective in limiting the horizontal displacement since stone columns are geotechnical elements without significant bending stiffness. This paper presents a design solution using a dead-man anchor to control the horizontal displacement of the reinforced soil wall (RSW). It is shown that when a dead-man anchor is adopted to tie back the ground beam of the RSW into the retained embankment fill, the horizontal displacement of the RSW facing can be substantially reduced to a tolerable design level. Moreover, the RSW and the anchored ground beam can be considered as a single soil reinforcement unit. The minimum embedment of this unit as required for scour or future trenching can be achieved by embedding the ground beam to below the ground surface without excavating the entire reinforced soil block area. This is particularly advantageous from the construction point of view as soil excavation within stone column treated soft ground may be subject to various constraints including the damages of the stone columns and the disposal of the excavated soft soil. Finally a case study is described where an RSW in conjunction with a dead man anchor were constructed over soft ground treated by stone columns. Comparisons between construction monitoring results and design predictions are provided.