Mechanistic study on the influence of organic matter on soil compressive strength and nonlinear resistivity

The incorporation of organic matter into loess can promote carbon sequestration while also significantly affecting the soil pore structure and strength properties. To investigate the effects of organic matter on the mechanical and physical properties of soil, as well as their interaction mechanisms, experimental studies were conducted on organic soils with different organic matter contents (0%–6%) and water contents (12%–24%). Meanwhile, the real-time evolution of resistivity during the mechanical tests was monitored. The results indicate that the addition of an appropriate amount of organic matter can improve the mechanical properties of loess, whereas the compressive strength decreases with increasing water content. As stress increased, the resistivity of the specimens decreased rapidly, and then remained relatively stable after the elastic stage until failure. Crack generation during the deformation process altered the conductive pathways within the organic soil and became an important factor influencing resistivity variation. These findings provide important theoretical support for soil remediation and land resource utilization in loess regions.