Civil Engineering Reference
In-Depth Information
Controlling the tunnel boring machine
General
The control system of the TBM consisted of software and a few hardware
components. The system made it possible for the operator to determine
the position, to chart a course and to steer theTBM at any time desired. If the
TBM therefore deviated for whatever reason from the theoretical alignment
(DTA
Designed Tunnel Axis), the limited steering possibilities of the TBM
had to be taken into account when calculating the correction course. The
correction course therefore had to be geared to the use of the left and right
hand rings (tapered segments) and the steering possibilities of the TBM.
Operating system
A laser total station - a servo-controlled laser theodolite - and the target plate
(ELS) formed the basic components of the total control system. A target
plate (ELS
electronic laser system) is a small box with a light-sensitive
plate built up of a large number of light-sensitive cells and a prism attached
onto the box.This device is used to make the distance measurements: the laser
theodolite aims a beam at the prism which gives the distance in respect of
the theodolite.
The ELS also contains a rotation meter and an inclinometer. By determining
the angle between the laser beam and the light-sensitive plate, the degree
of yaw (movement in the horizontal plane on the vertical axis) was calcu-
lated. The exact spot where the laser located the target plate was recorded
by means of the light-sensitive plate. The software contained programmes
for processing the measurement data as well as a programme for fitting in
the tunnel rings.
The total system roughly worked according to the method in which first of
all the position and direction of theTBM was determined and then the actual
position (X,Y, Z) was compared with the theoretical alignment (DTA). Three
co-ordinate systems were of importance here:
- the RD system (X,Y, Z), this is the Dutch co-ordinate system;
- a local system;
- a system in theTBM which described factors including the inclination and
the degree of circumferential rotation and yaw.
Fig. 10.12
Diagrammatic
representation of the
operating system for
determining the
direction
Ellewoutsdijk
Terneuzen
Circumferential
rotation
Laser
beam
La
ser t
heo
dolit
e
ELS
Ya w
X
TBM
Y
max. 80 m
Z
Determining direction of tunnel-boring maching (TBM)
ELS Electronic Laser System Laser target plate
DTA
Designed Tunnel Axis
Inclination Y-axis rotation
Circumferential rotation X-axis rotation
Yaw
Z-axis rotation
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