080731 6LYG A1 Particular Tunnelling Specification ... - SCATnow

Lee Tunnel, Contract No. 6LYG/A1
PT – Particular Tunnelling Specification - PT200
PT224.5
e) During forward movement of the TBM, the guidance system shall provide as
a minimum the following real-time data for the TBM, with reference to the
designed tunnel alignment at the machine head:
i) Station (chainage)
ii) Horizontal/line displacement
iii) Vertical/level/grade displacement
iv) Left or right lead/yaw at axis level
v) Overhand or look-up/pitch at axis level
Main axis rotation
This information shall be presented in numerical and graphical form, refreshed
every 20 seconds or faster.
PT224.6 The accuracy and the limits of each measurement shall be as stated in Table 1
Accuracy and Limits of Position Measurements.
Table 1 Accuracy and Limits of Position Measurements
Data Accuracy (+/-) Limit (+/-)
Station (chainage) (6mm) (12mm)
Horizontal displacement (6mm) (6mm)
Vertical displacement (6mm) (6mm)
Left or right lead (3mm) (6mm)
Overhang or look-up (3mm) (6mm)
Main axis rotation (3mm) (12mm)
PT224.7
PT224.8
PT224.9
PT224.10
PT224.11
The data shall be presented on displays at the underground Machine Operators
position and at the offices on surface of the Contractor and the Project Manager
(three displays in all). Facilities to download data electronically (for further
transmission) and for paper printout, independently of the current display, shall be
provided at both offices.
Data shall be recorded in a medium unaffected by primary power loss in a store
of sufficient capacity to hold the entire tunnels production records.
The guidance system shall, throughout the forward movement of the TBM,
compute the correct curve which returns the TBM tangentially to the designed
tunnel alignment and compute and display the necessary corrections to attitude
to be applied during the course of the forward movement. This computed data
may be used directly as input into the control mechanism of the TBM body and
the excavation and between the tail skin and lining.
The guidance system should also facilitate construction of the tunnel lining so that
it follows, and does not bind onto, the TBM. The system shall provide data
defining the plane of the circumferential joint of the leading edge of the tunnel
lining with respect to Designed Tunnel Alignment and TBM axis.
Procedural Aspects
The operation of the guidance system shall be a specific feature of the
Contractor’s Quality Assurance Plan. This should clearly address:
a) Definition of responsibility and authority of personnel maintaining and
operating the guidance system.
Thames Water Utilities Limited August 2008
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