Conveyance is the process of transporting things from one place to another by mechanical or physical means. Tunnel Boring Machines (TBM) use a conveyor system to transport rock and soil cuttings from the excavation face to the exterior of the tunnel. TBMs have made it easier to dig tunnels through difficult geology for various purposes such as transportation, mining etc.
Trenchless methods such as horizontal directional drilling (HDD), horizontal auger boring (HAB) and microtunneling all use different types of conveyance systems to transport spoil from the borehole to the surface.
Trenchlesspedia Explains Conveyance
HDD uses bentonite slurry or drilling fluid in order to convey the cuttings in suspension to the slurry separation unit at the surface. HAB utilizes augers or screws conveyors to remove cuttings from the borehole. Microtunneling also utilizes a slurry system to remove the spoil to the surface. TBM use a belt conveyor system that runs from the face of the excavation to the exterior. It is one of the most efficient ways to remove spoil as it is a continuous process and for longer tunnel runs, a belt conveyor storage system is used depending on available space.
Continuous conveyor systems were first utilized in mining operations and their effective muck removal ability has become a great boon to the tunneling industry. Computerized monitoring systems, self-adjusting curve idlers and kilometer long steel cable belt system are some of the advances made in the traditional conveyor system.