Civil Engineering Reference
In-Depth Information
Figure 5.72
Top anti-drag system as
used in the proprietary
Ropkins
TM
system
(Ropkins and Allenby
2000, courtesy of BAM
Nuttall Ltd and John
Ropkins Ltd)
the ropes prior to installation and to keep them well lubricated during box
installation using strategically positioned injection points. At the end of the
jacking process, the anti-drag ropes are left
in situ
because their removal
would cause voids and induce additional unnecessary settlement. Grouting
of the box/ground interfaces subsequently takes place using cement based
grouts commencing at the invert, gradually working up the sidewalls and
finally over the roof. Further details of the ADS used on the vehicular
under-bridge in the UK are described in the example in section 5.10.3.1.
5.10.3 Examples of jacked box tunnels
Table 5.3 shows a list of jacked box tunnel projects using the Ropkins
TM
system. The Boston, USA and M1 Junction 15A, UK jacked box tunnel
projects are described in more detail in the following sections.
5.10.3.1 Vehicular under-bridge, M1 motorway, J15A,
Northamptonshire, UK
The vehicular under-bridge, M1 motorway, J15A was constructed by BAM
Nuttall Limited in association with John Ropkins Limited and opened in
2003 (details from Allenby and Ropkins 2004).
This project involved jacking a 45.0 m long, 14.0 m wide, 8.5 m high
reinforced concrete monolithic box under a live motorway (Figure 5.73).
The ground conditions of the original motorway embankment consist of
an engineered clay fill overlying a natural boulder clay. The cover depth
for the box section was 2.2 m under the main carriageway and 1.6 m under
the hard shoulders.
