Bio-inspired energy-efficient strategy for rock abrasion

Abstract

Shield tunnelling was inspired by the burrowing process of bivalve mollusk shipworm. Recent studies have discovered new species of freshwater bivalves capable of burrowing into underwater rock. These bivalves dissolve cementing minerals using organic acid and then trap hard minerals on their shell surfaces via microbial biofilm to promote mechanical abrasion. This study aimed to understand the bioerosion mechanisms, which could inspire future advancements in burrowing technologies. Here we investigated the bioerosion mechanisms by performing a series of direct-shear experiments on intact limestone – smooth steel interface, chemically treated limestone – smooth steel interface, intact limestone – quartz-coated steel interface, and chemically treated limestone – quartz-coated steel interface. By comparing the shear behaviors and the abrasion characteristics of the four interfaces, we found that the chemically treated limestone – quartz-coated steel interface, which simulates the combining acid treatment and quartz coating strategies of the bivalves, promotes rock abrasion while achieving the highest energy efficiency. Our results indicate that acid treatment enhances abrasive wear by enabling deep indentation into fractured rock, while quartz coating improves energy efficiency and maintains it at a high level. This energy-efficient strategy for rock abrasion has significant potential for addressing technical challenges in subsurface engineering, such as improving rock-breaking efficiency and reducing cutting tool wear.