Geotechnical insights of mammal burrows in loose desert sand

Loose desert sand poses a constraint for geotechnical engineers to construct tunnels without a lining, which is typically steel, concrete, or slurry shield. Many desert mammals, however, can construct tunnels in loose sand, and the tunnels can remain stable over extended periods of time in harsh desert environments. This study presents the state of knowledge on mammal burrows in loose desert sand and provides insights from a geotechnical engineering perspective with the aim of understanding how desert mammals tackle a geotechnical challenge. The study presents these desert mammals as biogeotechnical engineers and explains their burrow stability using three fundamental soil mechanics principles: (i) unsaturated soil mechanics, (ii) compaction, and (iii) soil cementation. Damara mole-rats, kangaroo rats, pocket gophers, and round-tailed ground squirrels are presented as the desert biogeotechnical engineers. Proof-of-concept experiments conducted with a poorly graded fine sand demonstrate the effects of the fundamental soil mechanics principles used by the animals on soil strength. A limit equilibrium tunnel stability analysis performed using sand from a kangaroo rat habitat in the Sonoran Desert also demonstrated the link between tunnel stability of desert mammals and the three geotechnical principles.