el boring machine Wikipedia Tunnel boring machine WikipediaChinese20191020 ensp 0183 enspA tunnel boring machine TBM also known as a quotmole is a machine used to excavate tunnels with a circular cross section through a variety of soil and rock strata They may also be used for microtunneling They can bore through anything from hard rock to sand Tunnel diameters can range from one metre 3 3 ft done with microTBMs to 17 6 metres 58 ft to date History ensp 0183 ensp