DBPapers

VERTICAL ACCURACY OF THE BREAKTHROUGH OF THE TUNNEL

AUTHOR/S: Z. KAPOVIC, G. NOVAKOVIC, A. MARENDIC, R. PAAR
Sunday 1 August 2010 by Libadmin2008

8th International Scientific Conference - SGEM2008, www.sgem.org, SGEM2008 Conference Proceedings/ ISBN: 954-918181-2, June 16-20, 2008, Vol. 2, 517-524 pp

ABSTRACT

Tunnels are the objects of road infrastructure which construction requires very complex,
demanding, and responsible geodetic tasks. In the tunnelling, at first it is necessary to
establish high quality geodetic control that serves as the base for the transfer of the
planned tunnel axis in horizontal and vertical directions, as well as the base for all
geodetic measurements realised before, during and after tunnel construction. The basic
quantity for the planning the completely measuring concept in the tunnelling is the
maximum tolerant error of the breakthrough. In this paper, the analysis of vertical
accuracy of tunnel breakthrough will be presented on the example of the tunnel Sveti
Rok that is one of the longest road tunnels in the Republic of Croatia.

Vertical geodetic control in tunnelling must meet all quality criteria that are requested
for the high accuracy networks. The measurements from "secured" (well-stabilized)
points and precise and reliable data guarantee the obtaining of high quality elements
needed in the construction of the tunnel.

The basic methods in determining vertical elements in such engineering works are
differential and trigonometric levelling. The paper describes all sources of uncertainty
that appear in measurements with these methods. In a practical example, at first, the
accuracy of tunnel breakthrough in vertical direction will be examined obtained as
related to the levelling network adjusted as free network. After that, the accuracy will be
examined by calculating the accuracy of breakthrough referring to the reference bench
marks on one and the other side of the hill (at each portal of the tunnel). In both cases,
the results obtained by means of differential and trigonometric levelling will be
presented and compared.

The research results will be presented numerically and graphically and compared with
the standards prescribed by the Rule Book of Technical Standards and Requirements for
Designing and Construction the Tunnels on the Road of the Republic of
Croatia.description of the study and the methods used.

Keywords: tunnel, vertical geodetic control, accuracy of breakthrough