Lessons in geomechanics of deep foundations from nature

The field of bio-inspired design has been explored extensively in some engineering disciplines. However, biomimicry remains an area under development for geotechnics. One natural system that has been the focus of recent work is tree roots. Those structures are able to provide compressive and tensile support for substantial loads through an anchorage system that is more efficient than common manmade piles. Roots have been able to adapt and improve according to their environment, resulting in relatively shallow foundation systems if compared to piles, which require the use of more material to extend to greater depths. This study explores different proposed pile designs based on tree roots and their effects on bearing and uplift capacity. The root structure-soil interaction during loading is visualized using a synthetic transparent sand and 3D-printed tree root inspired models. The transparent soil is made of fused quartz and a mixture of mineral oils with matching refractive indices. Spatial displacements within the supporting soils were obtained by tracking the movements of the speckle pattern created by the interaction of the fused quartz and a laser light sheet. Images were captured throughout the experiments and then analyzed using Digital Image Correlation, which also provided strain fields. The results were used to identify potentially more effective configurations for the design of bio-inspired deep foundations.