Drag Load on Piles in Partially Saturated Collapsible Soils

Collapsible soils possess a considerable strength when dry, and experience a significant and sudden loss in its strength and excessive settlement upon wetting. In the field, wetting may take place due to the rise of the groundwater level or flooding on the ground surface. End-bearing piles are widely used to penetrate these collapsible layers, in order to transfer the building load to a stronger deeper soil layer. While in the literature, reports can be found dealing with evaluating the interaction between piles and collapsible soil when fully inundated (full saturation), the research on the behavior of this soil when partially saturated is lagging behind. This is due to the complexity of modeling and the lack of field data. This paper presents the results of experimental modeling of an end-bearing pile penetrating collapsible soil subjected to partial inundation due to surface running water. The objective is to determine the drag load acting on the pile’s shaft when the degree of saturation increases along the collapsible soil layer surrounding the pile shaft. The measured drag load is presented as function of the degree of saturation, the collapse potential of the soil layer and pressure acting on the soil.