BTS HARDING PRIZE COMPETITION 2025 | MECHANISED TUNNELLING
● The bottom segment was installed back using the erector;
● The segment feeder was pushed forward; ● The remaining segments were installed as per standard procedure;
● WR89 (tailskin grease) was injected; and, ● The erector was repositioned to its normal operational state.
Since this task involved hot works in the TBM, I ensured all safety measures were in place, including obtaining permits. I coordinated with the tunnelling gang and engineering team to manage site operations and liaised with the miners to ensure correct procedures were followed. I also made sure the erector components were covered to prevent grease contamination.
CHALLENGES ENCOUNTERED
TBM Breakthrough Alignment and Portal Transition Challenges After the TBM breakthrough, the machine only had the plinth to mine through, meaning there was no pressure on the top thrust cylinders. As a result, the TBM began to lift, and within two rings, I realised that we were not going to align with the portal. To counteract this issue, the team implemented corrective measures by exerting maximum pressure on the top thrust cylinders while applying minimal pressure on the bottom cylinders. This strategic adjustment aimed to gradually bring the TBM down to the required level for proper alignment with the exit portal. Throughout the mining process within the shaft,
meticulous monitoring was conducted after the completion of each ring build to assess the TBM’s positioning.
As part of this effort, I was stationed at the face of
the TBM, relaying instructions from the engineering manager to the TBM operator. Every 100mm to 200mm of advancement, I coordinated back and forth, ensuring real-time adjustments to the thrust and articulation cylinders. This close communication played a pivotal role in achieving continuous alignment corrections, ultimately enabling the TBM to successfully pass through the portal. Despite the successful breakthrough, an unforeseen
complication arose. The hinge plates, which were installed on the portal to facilitate a smooth transition, had sheared off at the top right corner due to the TBM entering at a higher-than-expected position. While positioned at the TBM face, I observed that these dislodged plates were adhering to the cutterhead and being dragged along with the advancing machine. To prevent damage to the excavation system, the
TBM’s advance speed was reduced to 5mm per minute while the cutterhead rotations were increased. This adjustment allowed the plates to dislodge safely, preventing them from being drawn further into the excavation system. A total of five plates were recovered from the excavation chamber. This precautionary measure was critical, as any of these plates entering the screw conveyor could have caused significant damage to the screw. One of the key sustainability initiatives trialled at
the Kidbrooke intermediate shaft site was the use of Earth Friendly Concrete (EFC). The trial aimed to assess its pumpability and placement characteristics before its planned permanent use at the Hurst shaft site. At Kidbrooke, EFC was used in the construction of the plinth over which the TBM transitioned. The insights gained from this trial directly contributed to the
Below left:
Outbye section of the screw being disconnected from the inbye section
Centre & right:
Considerable wear of the screw; Refurbished screw
July 2025 | 15
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