Evaluation of Liquefaction Potential of Fiber-Reinforced Coral Sand: An Energy-Based Method

The influence of fiber reinforcement on the liquefaction behavior of coral sand is investigated from the viewpoint of dissipated energy using undrained cyclic simple shear tests. Five fiber contents and four fiber lengths are considered in this study. The testing results indicate that as fiber content and length increase, the required cumulative dissipated energy to cause coral sand liquefaction, referred to as capacity energy, increases gradually. A capacity energy prediction model is then established to quantitatively evaluate the liquefaction resistance of coral sand under different fiber reinforcement conditions. The cumulative dissipated energy ratio, i.e., the ratio of cumulative dissipated energy to capacity energy, in reinforced coral sand, follows a unique relationship to the pore pressure ratio. Thus, a unified energy-based model for fiber-reinforced coral sand is proposed to assess the pore pressure generation. Moreover, compared with clean coral sand, coral sand with higher fiber content and length necessitates greater dissipated energy to achieve the same pore pressure ratio, shear strain, and stiffness degradation levels. The cumulative dissipated energy ratio ranging from approximately 0.75 to 0.90 is identified as the threshold for initiating large deformation of tested sand. Additionally, a unique relationship between the stiffness degradation index and the cumulative dissipated energy ratio is observed, independent of the inclusion of fibers. Overall, a strong correlation is observed between various cyclic behaviors and dissipated energy, confirming the prospect of dissipated energy as an effective metric for evaluating the liquefaction potential of fiber-reinforced coral sand.