Civil Engineering Reference
In-Depth Information
Table 2-20
General tunnelling classes (VKL) [59].
VKL
Type of excavation
1
Excavation without support
2
Excavation with support, which can be installed together with the construction process so that
excavation and loading are not obstructed
3
Excavation with support following at a short distance behind the face (for vertical shafts: shaft
floor or crown), for the installation of which excavation and loading have to be interrupted
4
Excavation with immediately following support
4A
Excavation according to tunnelling class 4 with division of the excavated section for reasons of
stability
5
Excavation with immediately following support including support to the face
5A
Excavation according to tunnelling class 5 with division of the excavated section for reasons of
stability
6
Excavation with immediately following support and pre-support
6A
Excavation according to tunnelling class 6 with division of the excavated section for reasons of
stability
7
Excavation with immediately following support including support to the face and pre-
excavation support measures
7A
Excavation according to tunnelling class 7 with division of the excavated cross-section for
reasons of stability
Guideline 853 “Design, construction and maintenance of rail tunnels” of the Deutsche
Bahn AG, Issue 06/02.
The design, construction and maintenance of rail tunnels for Ger-
man Railways have to comply with guideline 853 [193], which specifies that a tunnelling
classification according to DIN 18312 is to be undertaken for the production of tender doc-
uments. Previous experience with similar ground conditions should also be taken into ac-
count for the classification. The support measures necessary for each tunnelling class are
to be stated. Alternative tunnelling classes are also to be tendered for each tunnel section.
The tunnelling classes and tunnelling methods to be used in each case are determined dur-
ing the construction phase, proposed by the contractor in agreement with the client. The
tunnelling classes are determined according to the condition of the “freshly” excavated
rock mass. In order to decide any differences of opinion between the contract parties
concerning the determination of tunnelling classes that cannot be agreed, an accredited
independent expert should be agreed between contractor and client as an arbitrator and
appointed at the conclusion of the contract [193].
Additional technical contract conditions and guidelines for engineered structures,
Part 5: Tunnelling, Section 1: Confined mode,
(ZTV-ING, T.5-A.1), Issue 01/2003
[263]. This guideline also includes the classification of excavation and support in tun-
nelling classes according to DIN 18312. Sub-categories are normally required for each
specific project. Essential points for further sub-division could include:
- the selection of individual support measures and the time of their installation,
- the effect of water ingress and
- the round length.
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