Due to the inhomogeneity and anisotropy of mine rock bodies, ionic rare earth ore bodies exhibit varying pore structures at different depths. This research focuses on an ionic rare earth mine in Fujian Province, where in situ ore samples rather than remodeled soil samples were studied. Samples from the fully weathered layer at depths of 1 m, 12 m, and 21 m, both before and after leaching, were collected for onsite analysis. Microscopic pore characteristics were evaluated using scanning electron microscopy, and digital image processing was utilized to study the evolution of the pore scale, distribution, and shape in rare earth ore samples at various depths pre- and post-leaching. The results indicate an increase in the ore body's porosity with the depth of the ore samples both before and after leaching. The variation in pore scale is predominantly dictated by the ratio of macropore and large pores. Pre-leaching, the middle ore sample showcased the highest uniformity, with the upper part being the most irregular. Post-leaching, the highest uniformity was observed in the lower ore samples, with the upper part remaining irregular. Pre-leaching, as depth increased, the pore distribution in ore samples became more dispersed, with decreasing orderliness. Post-leaching, the orderliness was most improved in upper ore samples, while middle ore samples became the least orderly. Additionally, before leaching, pore-shape roughness increased with depth; after leaching, the pore shape became more rounded as depth increased, simplifying the pore-shape structure of the ore samples both before and after leaching.

This article studied the biomechanical properties of salix root sampled from arid and semi-arid regions of China. The damage law of root in the process of stretching was analyzed by acoustic emission technique. The fractal dimension of root failure was calculated by digital image processing technology. The results show that salix root tensile strength and ultimate elongation decreases with the diameter increasing, while ultimate tensile resistance and diameter are positively correlated. Damage variable characterized by cumulative AE energy can not only help research the rule of root damage quantitatively, but also allows determining the critical elongation when root became inactive. The optimal mining depth values are proposed, which enable reduction of ground surface deformation, elimination of root system damage, protection of planting on ground surface and, thus, decrease of possibility of bench convergence.