Mechanical Property of Biomodified Geogrid and Reinforced Calcareous Sand

The strength and deformation properties of maritime geotechnical structures made primarily of calcareous sand are critical for project safety. The geogrid reinforcement is developed as a promising approach to improve the mechanical properties of calcareous sand. This study investigates the mechanical property of biomodified geogrid via a microbially induced calcite precipitation (MICP) process to improve the effectiveness of geogrid for reinforcement of calcareous sand. A series of unconsolidated undrained triaxial experiments were conducted to evaluate the mechanical property and deformation behaviors of biomodified geogrid and reinforced calcareous sand (BGRCS), taking into consideration the impacts of the geogrid layer, times of biotreatment, and confining pressure. Compared to the untreated geogrid, the strength of the BGRCS is distinctly changed due to the increase roughness, and the deviatoric stress-strain curves are evidently hardening. Strength and pseudocohesive force can be further enhanced by raising the geogrid layer of the reinforced specimens, while internal friction angle also increases the amplitude of variation with the times of biotreatment. The geogrid, times of biotreatment, and confining pressure are all intimately related to the strength and the deformation of the reinforced specimens. The interactions of geogrid ribs and calcareous sand particles are analyzed and friction using scanning electron microscope tests that could provide a reference for revealing the mechanical mechanism of BGRCS.