Geology Reference
In-Depth Information
Figure 7.21
Anticipated
conditions for
piling in karstic
limestone,
following ground
improvement
contract.
casing through
drift
drift
rock socket
voids that were to be grouted
limestone
improvements was. Of course, other foundation schemes might have
been conceived that would have placed less reliance on the pre-piling
grouting contract, but as things stood there was a valid claim.
Sometimes things go wrong because of some fundamental misunder-
standing of the proper approach to follow or due to some miscommu-
nication or lack of management of the process. Muir Wood (2000)
compares the design of a tunnel to the performance of a symphony.
Whereas in the concert hall, all the players are using the same music
sheets and are watching a conductor, all too often in engineering pro-
jects the control is inadequate and all the players have their own agenda.
The result, as Muir Wood puts it, can end up cacophonic. Often when
things go wrong it is argued that ground conditions were unexpected,
but on analysis it is shown that ground characterisation of the site was
fatally incorrect or there were failings in management of the project.
Regarding the Heathrow Express Tunnel collapse discussed below,
this was described by the Health and Safety Executive, UK (2000), as
an organisational accident with a multiplicity of causes. Other cases
below could be described in similar fashion.
One case from which many lessons can be learned is the well-
documented collapse of a series of tunnels and chambers in London
Clay under construction for the Heathrow Airport Express (HEX) in
October 1994. This case is described in detail, both technically and
regarding management and contractual issues, by Muir Wood (2000),
