Automatically tracking and guiding underground Tunnel Boring Machines during microtunneling and pipe jacking operations

Tunnel Boring Machine (TBM) has been extensively implemented in microtunneling and pipe jacking projects for constructing subsurface pipeline infrastructure. Commonly used laser systems for TBM guidance tend to suffer from instable performance and low accuracy, while the high complexity in the system design of some advanced solutions compromises the system reliability while driving up the technology's cost. This paper presents an in-house developed automated and cost-effective TBM guidance system. The TBM's positions are automatically surveyed by a robotic total station and real-time line and level deviations from as-designed tunnel alignment are derived instantaneously. Given the coordinates of three observation points on the TBM, the TBM's three rotation angles in the underground space are determined by a "point-to-angle" computing algorithm. The automated system was assembled in house and tested at a pipe jacking site in Hong Kong. Practical constraints and considerations associated with the system setup and field testing are discussed. The performances of the automated system are evaluated in terms of accuracy and timeliness by comparing the testing results against data sourced from current control practices.