Macro-microscopic mechanical behavior of geogrid reinforced calcareous sand subjected to triaxial loads: Effects of aperture size and tensile resistance

Reinforcing calcareous sands with geogrids is a potentially effective method for large-scale geotechnical constructions in coastal lands. The breakable nature of polygonal calcareous sands determines the complex particle-geogrid interactions. A three-dimensional numerical model of geogrid reinforced calcareous sand (GRCS) was established to investigate the potential mechanical laws based on the discrete element method (DEM), and the reasonableness of the numerical model was verified by comparing with the indoor triaxial test. It follows that the macro-microscopic mechanical behavior of GRCS under the influence of aperture size and tensile resistance of geogrids was further investigated via effective DEM simulations. The presented results show that the decreased aperture size and increased tensile resistance are beneficial to enhance the macro-mechanical properties of GRCS, including strength, internal friction angle and pseudo cohesion. Particle crushing is mainly affected by shear strain and confining pressure. The bulging deformation of GRCS is partially suppressed due to the confining effect of geogrids. Besides, the source of strength enhancement of GRCS is revealed based on the microscopic particle-geogrid interactions, and the calculation method of horizontal and vertical additional stresses in the reinforced soil element considering the effects of tensile resistance and aperture size is further established.