Study on Dynamic Mesoscopic Damage Evolution of Raw Soil Materials Mixed with Iron Tailings Sand and Cement under Axial Compression

To study the damage evolution performance of iron tailings-modified rammed earth-based materials under dynamic loading, CT technology was used to analyze binary images of the material's interior under different stress states. Cross-sectional images were digitized by threshold segmentation at a microscopic level in each stress state. This research focused on the fractal dimension, porosity, and ε-σ curve evolution of the material, elucidating the microscopic mechanisms of materials from loading to failure. The results indicated that the fractal dimension increased significantly with increasing strength of material, reaching its maximum at σ=2.38 MPa. The irregularity, roughness, and development of cracks and pores in the scanned cross-sections during compression could be characterized by the changing trend of the fractal dimension indirectly. The porosity of the composite increased noticeably as the material undergoes failure and stress increases. The change trend of the material damage factor with porosity as index had same rules of the change of porosity, effectively reflecting the development of damage under axial compression and serving as a quantitative parameter for studying the damage evolution of modified rammed earth specimens.