Geology Reference
In-Depth Information
Hoek & Moy (1993) and Cheng & Liu (1993) describe different
aspects of the design and construction of the Mingtan pumped storage
project in Taiwan and illustrate the need for an integrated approach of
geological investigation, modelling, design, observation, construction
and instrumentation. An exploration/drainage gallery and two other
galleries were used to install long corrosion-protected permanent cable
anchors to reinforce the roof arch of the main cavern 10m below, prior
to its excavation. Small loads were applied to the cable anchors, which
only took on their full loads as the cavern was excavated.
Underground mining is quite different from the formation of caverns
and tunnels for civil engineering, although many of the skills required
are the same. In mining, the objective is to extract the ore whilst
minimising waste rock production. Safety is a prime concern, as it is
for civil operations, but mining involves the formation of non-
permanent voids, many of which will be allowed to collapse or
packed loosely with waste rock, so the fundamental operational con-
cepts are obviously quite different. Rock mechanics of underground
mining operations are discussed by Brady & Brown (2004). In terms of
geological hazards, of particular concern are
flammable and/or noxious
gases, including radon, and the control of dust and ventilation is very
important. Such matters are generally mandated by national standards
on health and safety but still accidents occur regularly worldwide.
A general concern for construction in mining areas is continuing
ground settlement or sudden collapse of old workings. These are
matters to be considered at the desk study stage of site investigation,
as addressed in
Chapter 4.
underground works
In
Chapter 4,
a system was introduced whereby site investigation is
conducted or reviewed following a checklist approach whereby
firstly
geological hazards are considered, then environmental factors and
c type of project or construc-
tion method. Tunnels are often particularly risky undertakings because
they are so dependent upon geotechnical conditions, which may vary
considerably along their length, and it is seldom feasible to carry out as
comprehensive a ground investigation as it is for other types of project.
Good reviews of tunnel collapse mechanisms and case histories are
given by Maury (1993) and GEO (2009) respectively. Consequently,
industry has developed several approaches whereby hazards are con-
sidered in detail, so that strategies can be prepared to reduce or mitigate
the risks. This can be done at the option assessment and design stages
and then later as part of the management of construction.
finally hazards associated with the speci
