Static liquefaction behavior of short discrete carbon fiber reinforced silty sand

Abstract

Saturated silty sand is more likely to cause landslide due to static liquefaction behavior. In this study, easily dispersible short synthetic carbon fibers (CF), with larger aspect ratio and smaller diameter (7 μm) compared with conventional polypropylene fibers, were used to improve the liquefaction resistance behavior of silty sand. A series of triaxial tests under different confining pressures were carried out on reinforced samples with different fiber contents (0.2, 0.5, 1.0%) and lengths (3, 6, 10 mm). The properties of stress and strain relationships, development of pore water pressure, effective stress path, liquefaction brittleness index, critical state line and volumetric strain were examined. The results from undrained tests showed that both the peak and post-peak deviator stresses of CF reinforced samples did not show a regular increase with fiber length. The 6 mm CF fiber showed the best reinforcement effect at a confining pressure of 100 kPa while 3 mm CF fiber achieved the best results at a confining pressure of 200 kPa. CF-reinforced sand was confirmed to be an effective liquefaction mitigation method compared with the method using conventional polypropylene fibers. This study provides an effective improvement method in particular to prevent a geological hazard in backfilling engineering projects.