Confinement effect of geocells on sand samples under triaxial compression

The confinement effect of geocells improves vastly the shear strength of granular soil. To understand the mechanism better, several tests have been performed on geocell-reinforced-sand samples of two different sizes. The geocells were made of high-density polyethylene sheets, and the influencing factors examined include the shape (circular, rectangular, and hexagonal cross-sections), size and number of cells. The effects of these variables on the compression strength of samples as well as the stress–strain behavior were investigated. It has been found that the apparent cohesion of reinforced samples vary with the shape, size and number of cells, of which the cell size is the most significant factor. Among the cells of all shapes, the circular cells induce the highest apparent cohesion. In addition, the effectiveness of the reinforcement is more significant at low confining pressure. This can be explained by theoretical analysis, which shows that the reinforced samples under low confining pressures tend to expand more and induce higher circumferential strain. When under high confining pressure, the samples undergo lesser dilation leading to lower hoop forces in geocells.