Multifaceted Bioinspiration for Improving the Shaft Resistance of Deep Foundations

This paper describes the bioinspiration process to derive design concepts for new deep foundation systems that have greater axial capacity per unit volume of pile material compared to conventional deep foundations. The study led to bioinspired ideas that provide greater load capacity by increasing the pile shaft resistance. The bioinspiration approach used problem-solving strategies to define the problem and transfer strategies from biology to geotechnical engineering. The bioinspiration considered the load transfer mechanism of hydroskeletons and the anchorage of the earthworm, razor clam, kelp, and lateral roots of plants. The biostrategies that were transferred to the engineering domain included a flexible but incompressible core, passive behaviour against external loading, a longitudinally split shell that allows expansion for anchorage, and lateral root-type or setae-type anchoring elements. The concepts of three bioinspired deep foundation systems were proposed and described. The advantage of this approach was illustrated with two examples of the new laterally expansive pile in drained sand under axial compression. The finite element analysis of these examples showed that the new laterally expansive pile can provide considerably greater load capacity compared to a conventional cylindrical pile due to the increased lateral confining pressure developed along the expanded pile core.