Volume 4, Issue 4 (December 1981)
Experiments in Geotechnical Fabric-Reinforced Soil Behavior
Four different geotechnical fabrics were evaluated for use in lateral restraint reinforcement of a cohesionless soil mass. Though considerable increases in strength and load-deformation modulus were obtained for the fabric-reinforced soil systems, no significant difference in behavior was noted among the four fabrics tested, despite variations of an order of magnitude or more in their physical properties. Fabric prestressing had essentially no effect on lateral restraint reinforcement behavior.
Lateral restraint reinforcement was determined to occur as a result of fabric interference with development of soil mass zones of radial shear, underneath and adjacent to the loaded area. The net effect of fabric interference is to produce horizontal restraint and confinement in the zones of radial shear, increasing the deformation modulus and ultimate load capacity of the fabric-reinforced soil.
After initial shear failure and soil yielding, loaded area sinkage again brings the radial shear zones into contact with the fabric and reinitiates soil strength gain. The secondary strength gain phenomenon caused by reinterference of the fabric with radial shear zone development was termed soil strain-hardening.
An optimum depth of placement for fabric was found to occur, and is related to the width of the loaded contact area and frictional properties of the reinforced soil. If fabric is placed at a depth greater than optimum, initial load-deformation behavior is reduced to that of the unreinforced soil system and considerably more soil strain is required to develop the strain-hardening phenomenon.