Bio-inspired site characterization -- towards soundings with lightweight equipment

Abstract

Equipment used for site investigation activities like drill rigs are typically large and heavy to provide sufficient reaction mass to overcome the soil's penetration resistance. The need for large and heavy equipment creates challenges for performing site investigations at sites with limited accessibility, such as urban centres, vegetated areas, locations with height restrictions and surficial soft soils, and steep slopes. Also, mobilization of large equipment to the project site is responsible for a significant portion of the carbon footprint of site investigations. Successful development of self burrowing technology can have enormous implications for geotechnical site investigation, ranging from performance of in situ tests to installation of instrumentation without the need of heavy equipment. During the last decade there has been an acceleration of research in the field of bioinspired geotechnics, whose premise is that certain animals and plants have developed efficient strategies to interact with geomaterials in ways that are analogous to those in geotechnical engineering. This paper provides a synthesis of advances in bioinspired site investigation related to the reduction of penetration resistance by means of modifying the tip shape, expanding a shaft section near the probe tip, applying motions to the tip like rotation and oscillation, and injecting fluids and generation of reaction forces with temporary anchors that enable self burrowing. Examples of prototypes that have been tested experimentally are highlighted. However, there are important research gaps associated with testing in a broader range of conditions, interpretation of results, and development of hardware that need to be addressed to develop field ready equipment that can provide useful data for geotechnical design.