Recent Development in the Design of Hard Rock Tunnel Boring Machines for the Mining Industryby Larry L. Snyder, Snyder Engineering, Arvada, United States,
Robert I. Williams, Snyder Engineering, Arvada, United States,
Abstract: Underground development for nuclear waste storage will possibly require tunnels to be excavated in a variety of rock conditions and configurations. Recent innovations in Tunnel Boring Machine (TBM) design have allowed for an evolved style of TBM which has distinct advantages over the standard machines. Present day conventional hard rock TBM's were developed primarily for the long, relatively straight tunnels of the civil construction industry, thereby making them for the most part, unsuitable for the sharp curves, turnouts, declines, inclines and ramps required in many underground environments. The five foot to 36 foot (1.52 to 11 m) diameter machines are capable of boring tunnels with curve radiuses as small as 40 to 90 feet (12.2 to 27.5 m) depending on size. These short turning radiuses can be accomplished while gripping the tunnel walls horizontally in the traditional manner or vertically as required when intersecting existing tunnels, or making turnouts from the tunnel that the machine has just bored. The machine's length is approximately half of a traditional machine's length while still employing a full measure of thrust, horsepower and rock cutting ability. The machine's short length, combined with a patented machine structure allows it to steer while boring without causing harmful eccentric loads on the cutterhead and main bearing assembly. The machine configuration is versatile and can be easily modified to operate in a wide variety of conditions. With the addition of an anti-slip device the machine can bore inclines up to 45 degrees. By adding spacers the distance between the grippers can be increased to accommodate stepping through steel ribs or to gain more room for roof bolting activities. The rear gripper can be oriented to any angle from horizontal to vertical to accommodate turnouts or to avoid clamping on weak seams of rock.
Subject Headings: Construction equipment | Tunnels | Boring | Rocks | Waste storage | Radioactive wastes | Mines and mining
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