Earthblog

VACUUM MICROTUNNELING METHOD

Vacuum spoil extraction micro-tunneling method is a laser guided trenchless method for installation of pipe sections under obstacles and is the same principle as the pipe jacking methodology, except that it is remote driven and a vacuum borer head (2) replaces the jacking shield. The laser guided vacuum borer head has fully articulated positive steering. Tunnel Boring Australia operates steerable boring heads suitable for nearly all ground conditions, from soft clay and sand, up to 200MPa rock. Prior to any pit excavation for horizontal bore operation can commence, all underground services (1) must be properly located and marked. The bore is formed from a launch pit (usually 9m x 2.4m) where the micro-tunneling machine (4) is placed on heavy duty tracks (5) and the operator ensures accuracy with a four way steering control and CCTV laser guidance system. Spoil from the cased bore is extracted by way of 200HP vacuum extraction unit, which is located at the top of the work area. After set up of the above equipment, the laser (6) is then securely fixed and positioned at the back of the launch pit, so that the laser beam has a clear line to the target located at the front of the boring head. The Micro-tunneling machine & vacuum borer head are driven by a diesel Hydraulic powerpack (3)
Laser guided vacuum spoil extraction micro-tunneled bores are with diameters from 300mm to 1000mm and up to 150m in length.
The retrieval pit is usually with dimensions 4m x 3m. The advantages of this system are that it causes no surface disruption, spoil is removed by vacuum which is a dry method.