Undrained cyclic responses of biocemented calcareous silty sand

Microbially induced calcium carbonate precipitation (MICP) technology is an emerging and environmentally sustainable method for improving the strength and stiffness of soil. Specifically, this innovative approach has gained favor in marine engineering due to the advantaged compatibility between precipitated calcium carbonate induced by MICP and coral sand. Sand containing fines is susceptible to liquefy. Whereas, the impact of fines contents on cyclic behavior of MICP-treated calcareous sand remains uncertain. Consequently, this technical note aims to investigate the liquefaction behavior of biocemented calcareous silty sand by conducting undrained cyclic triaxial shear tests and microscopic analysis. The results revealed the patterns of the excess pore water pressure curves and cyclic deformation characteristics as the fines contents increased. The liquefaction resistance of biocemented sand initially decreases with the addition of fines but subsequently exhibits an increasing trend. Microscopic analysis showed that at the cementation level with the cementation solution concentration of 1 mol/L, the calcium carbonate crystals are mainly attached to the surface of sand grains and this pattern does not directly affect the force chain.