Understanding peatland hydrological processes and phenomena is critical for peatland management. Peat soils have a complex pore structure that affects hydrological processes. However, the micro-scale characteristics of peat pore space and their impact on hydraulic and transport properties have not been deeply investigated. This study characterized the pores in peat soil using 2D/3D X-ray computed tomography images and examined the connection between pore features and the simulated permeability. There were no apparent variations in porosity or pore morphology in different directions for peat soils with different degrees of decomposition at the pore scale. Peat soil with a high degree of decomposition had more numerous smaller pores with lower pore connectivity and higher tortuosity. Spherical pores were the highest proportion of total pores in peat soils, followed by ellipsoidal, long columnar, and branching pores. The diameters of spherical and ellipsoidal pores were small and isolated, and thus water in the peat soil flows preferentially through the more connected columnar and branching pores. The high permeability in peat soils was closely associated with the high porosity and abundance of well-connected and low tortuosity pore networks. The results of this study can provide insights into the underlying hydrological processes and also provide realistic parameters for use in multi-scale 3D digital soil-structure models and numerical simulations.

Calcareous sand is a crucial construction material for island and reef development and reinforcing it using Microbially Induced Calcite Precipitation (MICP) technology is a promising new method. This study employed 3D scanning technology to assess changes in the particle size and morphology of MICP-treated, coated calcareous sand particles. Single-particle crushing tests were conducted to analyze their crushing strength, crushing energy, crushing modes, and fragment fractal dimensions. The results indicated that MICP treatment significantly increased particle size, surface area, and volume, while reducing flatness. At a cementation solution concentration of 1 mol/L, both crushing strength and crushing energy were optimized. The coated particles exhibited three crushing modes: explosive crushing, mixed crushing, and splitting crushing. Thicker coatings led to a tendency for particles to break into larger fragments through the mixed and splitting crushing modes. Fractal analysis revealed that coating thickness directly affects the local crushing characteristics of the particles.