Liquefaction resistance of MICP-treated calcareous sand with different particle size and gradation
Yi Shan, Ziye Liufu, Jie Yuan, Yuanyuan Li, Huawei Tong, Jie Cui
Abstract
Calcareous sand is a type of marine soil with the poor engineering performance and a high potential of liquefaction under seismic or wave action. To address this issue, microbially induced calcium carbonate precipitation (MICP), an eco-friendly bio-grouting technique, has been shown to effectively improve its liquefaction resistance. However, the particle characteristics of sand can influence both its cyclic behavior and effectiveness of MICP treatment. This study investigates the effects of particle size and gradation on the liquefaction resistance of MICP-treated calcareous sand through cyclic triaxial tests and microscopic scanning tests. The results indicate that increasing the median particle size ( d 50 ) enhances the cyclic strength of untreated sand but reduces that of MICP-treated sand. In contrast, increases in the uniformity ( Cu ) coefficient lead to a reduction in cyclic strength for both untreated and MICP-treated sands, while change in the curvature ( Cc ) coefficient initially improve and then reduce the cyclic strength. SEM images reveal that the grading characteristics affect the precipitation of calcium carbonate, which in turn affects the cyclic behavior of MICP-treated sand. Additionally, the study discusses the stiffness degradation of MICP-treated calcareous sand under cyclic loading. These findings offer valuable experimental and theoretical insights for enhancing the liquefaction resistance of the MICP-treated calcareous sand with varying grading characteristics.