Post-earthquake rapid resealing of bedrock flow-paths by concretion-forming resin

Abstract

AbstractMany underground activities may require reducing or preventing fluid flows through bedrock, e.g., sealing of site investigation boreholes, underground tunneling, hydrocarbon field abandonment, and nuclear waste disposal. Cementitious materials such as grout are commonly used for bedrock flow-path sealing, however conventionally used these materials unavoidably undergo physical and chemical degradation, therefore potentially decreasing seal durability. Here, we report a more durable sealing method for concretion-forming resin developed by learning from natural calcite, CaCO3, and spheroidal concretion formation. The method was tested by sealing flow paths next to a tunnel in an underground research laboratory at 350 m depth, in Hokkaido, Japan. The flow paths were initially sealed rapidly, then resealed after disturbance by repeated earthquakes with foci below the underground research laboratory at depths of 2–7 km and maximum magnitude Mw 5.4. The treated rock mass rapidly recovered its very low natural permeability, demonstrating robust self-sealing and healing.