The back faces of gravity-type RW,
and the bottom surfaces of the foundation directly contact with the subsoil, and the back faces of FHR
facings for geogrid-reinforced RW and geocell-reinforced RW were made rough by being covered
with a sheet of sand paper (No. 150). In order to minimize the friction between the edge of RW models
and the side wall of the soil box, a sponge tape and grease were used, and the leakage of sand from the
gap between RW models and the soil container could completely be prevented.