Geology Reference
In-Depth Information
The engineer
'
s design generally concerns the permanent works
-
the
long-term stability and performance of the
finished project. Performance
is measured by criteria speci
c to a project, such as settlement, leakage,
durability and long-term maintenance requirements. During construc-
tion, there will usually be other design considerations including stability
of temporary excavations, disturbance to the groundwater conditions
and water in
ow to the works. Temporary work design is generally the
responsibility of the contractor and his design engineers, perhaps
checked by an independent checking engineer. The design of deep
temporary excavations can be just as demanding as for permanent
works, as illustrated i
n Figure 6.2.
Catastrophic failure of such works
is unfortunately common
le
projects as the International Finance Centre in Seoul, Korea, and the
Nicoll Highway subway works in Singapore (
Chapter 7).
In both cases,
the strutted excavations collapsed. Guidance on the design of such
structures is given in Puller (2003) and GCO (1990).
In tunnels, during construction there may be a need to stabilise the
walls and possibly the working face using rapidly applied techniques,
including shotcrete with mesh or steel
-
in recent years affecting such high-pro
fibres, steel arches or lattice
girders and rock bolts (Hoek
et al
., 1995). Such measures are generally
speci
ed and installed by the contractor, typically agreed with a super-
vising engineer who may well be an engineering geologist. The engi-
neering geologist will probably be involved in identifying the rock
Figure 6.2
Temporary works for an underground station construction in Singapore. Piles to the
the piles have been anchored back into the ground and strutted using systems of waling beams
(horizontal, along the face of the piles) and struts, supported where necessary by additional
king posts.
