noun
timbering; support (in mining/tunneling)
Technical term used in mining, tunneling, and civil engineering for the structural supports (often timber or steel) that prevent collapse.
坑道には支保工がしっかりと組まれていた。
The mine tunnel was securely timbered.
Compound of 支保 (support, shoring) and 工 (work, construction). The exact historical derivation is uncertain; the spelling is conventionally associated with mining and civil engineering support structures.