Experimental investigation of collapsible soils under oedometric loading: effect of internal erosion

Collapsible soils, geological formations characterized by pronounced structural instability upon saturation, present a significant challenge in geotechnical engineering. This experimental study aims to deepen our understanding of the mechanisms governing the behavior of these soils, which are particularly prevalent in arid and semi-arid regions subject to extreme hydrological cycles. Collapsible soils, sensitive to climatic variability, undergo profound alterations in their hydromechanical properties due to alternating periods of prolonged drought and intense rainfall events. These fluctuations induce significant modifications in the soil's pore structure, promoting the development of internal erosion phenomena such as suffusion. The results obtained from this experimental investigation on reconstituted samples highlight the combined influence of various factors, such as water content, dry density, particle size, and flow rate, on the collapse potential. It appears that fine particles play a predominant role in the formation of fragile structures, susceptible to collapse upon saturation. Moreover, the intensity and duration of infiltration significantly influence the propagation velocity of ultrasonic waves, thus offering a promising tool for monitoring the evolution of damage within the soil mass. Furthermore, this study provides essential insights for assessing the risks associated with collapsible soils and contributes to the development of more reliable characterization and modeling methods. It emphasizes the need to consider the complex interactions between the physical, chemical, and mechanical properties of the soil, as well as the influence of environmental conditions, for better control of the risks associated with these materials.