Experimental modeling of collapsible soils under different water infiltration patterns

Collapsible soils are moisture-sensitive soils that may experience sudden and significant settlements upon wetting, posing serious challenges in engineering projects. Conventional laboratory tests, such as the oedometer test, generally simulate soil wetting by full submergence and are therefore unable to represent different real-world water infiltration scenarios. In this study, a new experimental apparatus was designed and constructed to simulate four typical water infiltration patterns based on the direction of water movement (top-down and bottom-up) and the mode of water distribution (point and wide). Two laboratory-prepared collapsible soils with different collapse potentials were tested using single and double oedometer tests as well as the proposed apparatus. The results demonstrate that water infiltration patterns have a significant influence on collapse behavior. The highest collapse potential was observed under the top-point infiltration pattern, representing localized surface water sources such as irrigation, whereas the lowest collapse potential occurred under the bottom-point infiltration pattern, simulating leakage from buried pipes. For the tested soils, collapse potential induced by bottom-point infiltration was up to 35% lower than that measured by the conventional oedometer test. The findings indicate that the direction of water movement has a greater effect on collapse potential than the water distribution mode. The proposed apparatus provides a more realistic assessment of collapsible soil behavior under different infiltration conditions and highlights the limitations of conventional testing methods in predicting field settlements.