MECHANISED TUNNELLING | TECHNICAL
Above, figure 7: Breakthrough of AVN 1800 in strong rocks on Landivisiau gas pipeline project in Brittany, France PHOTO CREDIT: SADE COMPANIE GÉNÉRALE DE TRAVAUX D´HYDRAULIQUE S.A
forces, needed for its small cutterhead and multi-ring cutters to have sufficient thrust force per cutter to chip the rock. Therefore, in hard rock microtunnelling, the roll must be countered by an anti-roll mechanism. From the technical point of view, the anti-roll
mechanisms can be divided into two types: grippers (located just behind the telescopic station) and roller disc cutters (mounted on hydraulic cylinders inside the shield). These are illustrated in Figure 5.
Jacking and telescopic stations, and pipes The main jacking station is located in the launch shaft
and pushes the slurry MTBM and the product pipes toward the target shaft. The thrust force must be transferred effectively along this linear string, from the launch shaft through the installed pipe and any intermediate equipment forward to the MTBM (see Figure 6). However, thrust capacity is often limited by the design
and loads of the pipes, leading to limited alignment length or the more frequent use of intermediate jacking stations. Intermediate jacking stations are important, able to boost thrust, especially for long drives, to ensure the
Above, figure 8: Installation of probe drill in AVN MTBM on Chile tunnel project near a fault zone PHOTO CREDIT: HERRENKNECHT DRILLING SYSTEMS
January 2024 | 27
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49
