Abstract:

Porous structure of coral sand has a significant impact on its mechanical properties and permeability characteristics. In this study, computed tomography (CT) was used to scan the coral sand particles, and the three-dimensional pore structure model of the coral sand particles was established in combination with image processing technology. The diameter, volume, compactness, and sphericity of the pores were quantitatively analyzed. Numerical simulation methods were used to examine the permeability characteristics of the pore structure of loosely accumulated coral sand and single-particle coral sand. Experimental results show that the number of pores in the particles decreases significantly with the increase of the pore diameter, which is characterized by a large number of micropores and a small number of macropores. There is a power function relationship between the diameter of the pores and the tightness, and a linear relationship with the sphericity. Seepage analysis results show that the seepage capacity in the Z direction is significantly less than the seepage capacities in the X and Y directions, and the seepage capacity shows anisotropy. Porous seepage velocity in the inner pore of coral sand particles is slow, the seepage capacity gap between different particles is large. In addition, no seepage occurs in some particles, and the absolute permeability of the pores in the particles only accounts for 1.26% of the total absolute permeability.

Key words: coral sand, CT, pore structure, seepage, 3D reconstruction