TBM tunnel boring machine
Technical Parameter for tunnel boring machine
Force per cyl/oil pressure
Stroke per cyl.
A tunnel boring machine (TBM) also known as a "mole", is a machine
used to excavate tunnels with a circular cross section through a
variety of soil and rock strata. They can bore through anything
from hard rock to sand. Tunnel diameters can range from a metre
(done with micro-TBMs) to 19.25 m to date. Tunnels of less than a
metre or so in diameter are typically done using trenchless
construction methods or horizontal directional drilling rather than
Tunnel boring machines are used as an alternative to drilling and
blasting (D&B) methods in rock and conventional "hand mining"
in soil. TBMs have the advantages of limiting the disturbance to
the surrounding ground and producing a smooth tunnel wall. This
significantly reduces the cost of lining the tunnel, and makes them
suitable to use in heavily urbanized areas. The major disadvantage
is the upfront cost. TBMs are expensive to construct, and can be
difficult to transport. However, as modern tunnels become longer,
the cost of tunnel boring machines versus drill and blast is
actually less—this is because tunneling with TBMs is much more
efficient and results in a shorter project.
The largest diameter TBM, at 19.25 m (63 ft.), was built by
Herrenknecht AG for a recent project in Orlovski Tunnel,
St.Petersburg. The machine was built to bore through soft ground
including sand and clay. Herrenknecht AG built also the world's
largest diameter hard rock TBM: "Martina" (excavation diameter of
15.62 mt, total length 130 mt; excavation area of 192 square mt,
thrust value 39,485 t, total weight 4,500 tons, total installed
capacity 18 MW; yearly energy consumption about 62,000,000 kWh) is
owned and operated by the Italian construction company Toto S.p.A.
Costruzioni Generali (Toto Group) for the Sparvo gallery of the
Italian Motorway Pass A1 ("Variante di Valico A1"), near Florence.
The former largest diameter hard rock TBM, at 14.4 m, was
manufactured by The Robbins Company for Canada's Niagara Tunnel
Project. The machine was used to bore a hydroelectric tunnel
beneath Niagara Falls. The machine has been named "Big Becky" in
reference to the Sir Adam Beck hydroelectric dams to which it is
tunnelling to provide an additional hydroelectric tunnel.
In 2013, Hitachi Zosen Corporation delivered an earth pressure
balance TBM to Seattle, United States for the Highway 99 tunnel