Trends of the Highway Tunnel Building in Slovakia
by Alojz Kopáčik
Key words: tunnel building, lay-out, control measurement, 3-D
model building
Abstract
1. Introduction
A multitude of railway tunnels in the Slovak
Republic on the one hand and total absence of road-tunnels on the
other hand is a paradox which is a result of political and
economic development in the post-war period. A comeback to the
market economy in the last decenium of 20th century has
been connected not only with economic and political changes but also
with the decision to eliminate the retardation of traffic
infrastructure development.
2. Structure of the traffic network in Slovakia
In connection with the above fact the necessity has
arisen to update the national traffic routes. The Slovak Road
Administration has elaborated the "Concept of the Traffic Network
Development in the Slovak Republic" which re-evaluates the used
network classification as well as the importance of individual routes
and their classification under new conditions. The most important
traffic routes are included to the network of transeuropean routes, in
a volume of 852,8 km. Particular part of the conception are as
follows: evaluation of the road network capacity reached, evaluation
of traffic safety as well as of ecological conditions and
a proposal for the gradual modernisation, including higway
construction.
Design and construction of highways are in the last
years connected to the more demanding parts of the routes D1 and D18.
The various geological and morphological conditions of the Karpaty
mountains can be not overcome without tunnels. To determination of the
number of tunnels and their situation on the highway, are very
important the results of the multicriterial evaluation of the region.
In connection with this evaluation are designed 17 tunnels, with
common longitude of 39 km, on a new highway parts.
3. Driving methods used for tunnel construction in Slovakia
In present time exist two different groups of
methods for the driving of transport tunnels. The first of them is
conventional tunnelling on the lines of the principles of the new
Austrian tunnelling method (NATM) and the second group is tunnel
driving with using tunnel boring machines (TBM). The NATM use for the
hard rock excavation conventional mining explosive materials. For the
soft rock excavation are used boring machines with cutting head or
excavators. Tunnel driving by TBM is more impalpable to the rock and
the surrounding of the tunnel is fewer affected. The both of
excavation method are know in Slovakia, but the using of TBM for
excavation of tunnels with large profiles (highway tunnels) are to
this time not used.
4. Management of geodetic works connected to the tunnel
construction
The realisation of large building constructions
need the very "hard" participation of surveyors. The
surveyor participate on the all of tunnel construction phases –
geological investigation and preparation, design and realisation. From
the viewpoint of surveyors is very demanding, if the geological
investigation is realised by prospect drift. In case of the both
largest highway tunnels in Slovakia (tunnel Branisko and Višňové)
are driven the prospect drift. For drift excavation were used both of
the named excavation method (NATM, TBM). The design of tunnel required
ortophotomaps, conventional maps or
3-D models of terrain in the surrounding of the designed tunnel
portals. Very important is the preparation of the documents for the
land property.
The basic assumption of successful realisation of
the surveying tasks during the tunnel construction, is the existence
of a reliable control network. The configuration and type of
network are dependent on the required accuracy of measurements,
terrain requirements and lay-out methods, which are used. The largest
amount of surveying tasks is connected to the tunnel construction. The
surveyor groups make "daily service" for the tunnel
(lay-out, deformation measurement, measurement of overbreaks, etc.).
The divergent accuracy requirements, the necessity
of measurements realised in a common system of co-ordinates and
their explicit connection to the tunnel construction, results in using
of new integrated technology of control measurement. This technology
use the modern measurement systems (lasers, electronic theodolites and
totalstations) and conventional surveying methods (polygonal method,
polar method, free station, etc.). Important part of this conception
is the automated storage, transfer and processing of data. To this aim
local computer networks on the site, connected by modems, are build.
Important part of control measurement is the group of measurement they
are oriented to the tunnel surface determination. The aim of this
measurements is the determination of the 3-D model of the tunnel
surface, which is for volume determination of the overbreaks, of the
used materials, etc., used. The model can be the base of the tunnel
information system, after their completion by data from another
systems (signalisation, cameras, phone, ventilation, etc.) and
implementation in a appropriate software. The existence of that
system would be the first step to the efficient daily service and the
high safety of the future tunnel.
5. Conclusion
The base of the successful realisation of tunnel is
the high quality of tunnel lay-out and control measurements. The
quality of geodetic works is given by the quality of the control
network, the measurement technology used and the professionality of
the geodetic personnel.
Assoc.Prof. Alojz Kopáčik, PhD
Department of Surveying
Faculty of Civil Engineering
Slovak University of Technology, Bratislava
Radlinského 11
SK-813 68 Bratislava
SLOVAKIA
E-mail: kopacik@svf.stuba.sk
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