Abstract: Particle gradation and morphology are key attributes that influence the mechanical behavior of sandy soils. Due to the intertwined characteristics of gradation and morphology in natural calcareous sand particles, current experimental research has not yet been able to provide insight into the influence of these factors individually. In this study, a mass production of calcareous sand particles with controllable morphology and size was realized based on X-ray computed tomography (X-CT) scanning technology, spherical harmonic analysis, and 3D printing technology. By conducting consolidated drained triaxial tests on simulated calcareous sand samples with different gradations, the influence of particle gradation, as a single variable, on the mechanical properties of calcareous sand was explored. The results show that the mechanical behavior of the simulated calcareous sand samples is highly consistent with the typical characteristics of natural sand. The fractal dimension only has a significant effect on the critical state stress ratio when it changes substantially, and the critical state of calcareous sand with different fractal dimensions can be described using the static unique line method. At the phase transformation state, the axial strain is positively correlated with both the fractal dimension and the effective confining pressure, while the stress ratio increases exponentially with the fractal dimension. The simulated calcareous sand exhibits apparent cohesion, with the peak apparent cohesion decreasing linearly with the increase in fractal dimension, while the residual apparent cohesion is largely unaffected by changes in fractal dimension. Both the peak and residual internal friction angles increase exponentially with the fractal dimension.

Key words: calcareous sand, 3D printing technology, particle gradation, fractal dimension, deformation, shear strength