Macroscopic and microscopic experimental study on fractal fragmentation characteristics of calcareous sand during one-dimensional compression creep

Calcareous sand is a natural foundation material for ports, airports and some civil buildings in ocean areas. Through the one-dimensional compression creep test of calcareous sand and the analysis of its micro-structure, it was found that the surface pore area decreased after creep and showed a dispersed distribution. In addition, the characteristics of instantaneous deformation, rapid deformation and attenuation deformation of the sample during the test were highly correlated with the particle size. The relative particle breakage rate and mass fractal dimension improved based on fractal theory were used to describe the degree of particle breakage after creep. The relationship between the decay of fractal dimension and creep with time, as well as the linear relationship between the fractal dimension of macroscopic mass and the fractal dimension of microscopic surface was obtained. On this basis, the fractal fracture behavior of calcareous sand with a single particle size group during long-term creep was analyzed at multiple scales, and the corresponding macro and micro cross-scale correlation was studied. The development of particle breakage and the variation of microscopic pores during creep were obtained. This study proved the rearrangement, crushing and grinding behavior of calcareous sand particles in the creep process, and revealed the creep mechanism of calcareous sand.