Discovery of Rock Burrowing Strategies Inspired by Bio-Erosion

Underground excavation has a long history of using bio-inspired technologies to tackle engineering challenges, such as tunnel boring machines. Recent studies show amazing discoveries of rock-burrowing bioerosion by smart organisms in the marine and freshwater environments of Southeast Asia countries (e.g., Myanmar and Philippines). The newly discovery of rock burrowing strategies inspired by bio-erosion is based on the concepts of utilizing chemical etching to weaken calcareous substrates by removing dissolvable minerals and subsequently applying the remaining hard mineral grains to break down the weakened rock and accelerate the burrowing operation. A series of direct-shear tests were performed on intact limestone-smooth steel interface, chemically treated limestone-smooth steel interface, intact limestone-quartz-coated steel interface, and chemically treated limestonequartz- coated steel interface. Our results demonstrate that the chemically treated limestone—quartz-coated steel interface has the lowest friction angle and the most serious damage on the limestone surface during the tests. The results confirm the efficiency of bio-inspired burrowing strategies, comparing to the results obtained from the other interfaces, and reveal the combination of chemical etching and mechanical abrasion promotes rock material breakability while maintaining low energy consumption.