红壤中无定形氧化铁-高岭石胶结体系的结构和抗剪强度OA

[Objective]The key mechanisms by which amorphous iron oxide regulates the mechanical properties of Benggang soil were analyzed from a microscopic perspective in order to provide a theoretical basis for the prevention and control of Benggang erosion.[Methods]Kaolinite,the dominant clay mineral in soil from a typical Benggang area of Fujian Province,was selected as the research object.By incorporating amorphous iron oxide at different concentrations(1,2,3,and 10 g/kg)into kaolinite and utilizing X-ray diffraction(XRD),scanning electron microscopy(SEM),and direct shear tests,this study analyzed its regulatory effects on soil microstructure and shear strength parameters.[Results]XRD analysis revealed that amorphous iron oxide did not undergo a chemical reaction with kaolinite but primarily altered mineral characteristics through physical coating.The concentration of amorphous iron oxide significantly influenced the distribution of cemented aggregates across different particle sizes,demonstrating a pronounced regulatory role in the formation of aggregates within the 2-250 μm range.Among microstructural parameters,only particle long-axis and roundness exhibited significant changes.The long-axis decreased by 22％in samples with the 3 g/kg treatment,while roundness was reduced by 25％in samples with the 2 g/kg treatment.The coefficients of variation for all other parameters remained below 15％.The treatment with 3 g/kg consistently exhibited the highest shear strength across all confining pressure levels.The enhancement in shear strength was closely associated with the observed microstructural alterations.Further analysis indicated that the 3 g/kg treatment resulted in the most substantial improvement in cohesion,which increased by 24.82％compared to pure kaolinite.In contrast,the internal friction angle varied by less than 5.30％.[Conclusion]Amorphous iron oxide enhances soil shear strength by optimizing soil structure through cementation and encapsulation.