machine used to excavate circular tunnels through a variety of soil and rock strata
One of the boring machines used for the Channel Tunnel between France and the United Kingdom
A tunnel boring machine (TBM), also known as a "mole" or a "worm", is a machine used to excavate tunnels. TBMs are an alternative to drilling and blasting methods and "hand mining", allowing more rapid excavation through hard rock, wet or dry soil, or sand (although each requires specialized TBM technologies). TBM-bored tunnel cross-sections extend up to 17.6 meters (58 ft) (through June 2023). TBM tunnels are typically circular in cross-section, but may also be square or rectangular or U- or horseshoe-shaped. Much narrower tunnels are typically bored using trenchless construction methods or horizontal directional drilling rather than by TBMs.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).