Civil Engineering Reference
In-Depth Information
apply to all construction sites and thus apply to underground construction. Their applica-
tion means that health and safety has to be considered in the design phase, which can well
affect the selection of a tunnelling process.
The “Code of practice for the planning and implementation of a health and safety plan for
underground construction sites” from DAUB and the national tunnelling associations of
Austria and Switzerland (D-A-CH) is based on the regulations mentioned above among
others and includes detailed requirements for the operation of tunnelling machines. In
order to evaluate safety at work, a risk analysis is to be produced including consideration
of the construction process and local conditions. The results of this risk analysis are then
included in the decision process to select a tunnelling machine with a heavy weighting.
If, for example, the occurrence of gas like methane or argon in the ground is to be expected,
the construction ventilation must be designed to cope with it or firedamp-safe machinery
will have to be used. The presence of asbestos in the rock also demands special attention;
appropriate continuous monitoring measuring devices should be installed permanently in
the machine and in the tunnel and combined with an optical and acoustic alarm, which is
activated automatically in case a critical value is measured. Closed machine types with
active face support (SM-V 5, SM-V4) with closed material transport systems are advanta-
geous, and the requirements for the sealing of segment gaskets should be defined. A two-
layer lining system should be considered for the completed tunnel.
11.9
Scope of application and selection criteria
The recommendations for the scope of application and selection criteria are summarised
for each type of machine in Tables 1 to 11 (Appendix 3).
11.9.1 General notes about the use of the tables
The feasibility of a system is first evaluated based on the key geotechnical parameters and
processes, and economic evaluation criteria remain largely ignored. The tables are suit-
able for a preliminary selection on the exclusion principle. In case more than one type of
machine would be possible, the final overall evaluation of suitability is then undertaken
after an analysis of all project-specific parameters and processes, including consideration
of economic and environmental aspects.
11.9.1.1 Core area of application
The fields marked black (Symbol “+”) denote ranges, in which the type of machine has al-
ready been successfully used without many supplementary measures being required. The
technical performance of the machine can vary among manufacturers, and the experience
of the contracting company is also significant. The main areas of application shown for
one parameter may be extended or restricted by the inclusion of other parameters.
11.9.1.2 Possible areas of application
The use of a tunnelling machine in the fields marked dark grey (Symbol “0”) may require
special technical measures, but the technical feasibility has been demonstrated. The achiev-
able advance rates and cost-effectiveness may be reduced in comparison to the core area.
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