The objective motorway section with a length of
25 km is part of the east-west motorway connection of Slovakia
planned already since 1930. The project, which is conducted as a PPP (Public-Private-Partnership) undertaking, extends
over topographically demanding terrain. For this reason,
10.6 kilometres of the section run in tunnels and 7.6
kilometres over bridges.
In February 2010, the contracted "Early Works" have been resumed. These comprise, among others, a part of the
project design, the clearing of the building area, the establishment of access roads to bridges and tunnels and
the construc-
tion of three tunnel portals.
|
BGG Consult has been com-
missioned by the successful consortium during tendering and execution of the "Early Works"
with the geotechnical and hydrogeological consul-
ting.
In this connection, subsoil explorations in form of core drillings, dynamic probings and cone penetration tests
have been conducted initi-
ally. Based on the results, the foundations of the struc-
tures and the securing mea-
sures
at the three portal cuts were optimised.
Additionally, the geotechnical monitoring has been planned and supervised, and inclino-
meter measurements were
carried out.
|
Optimising of building pit securing at the portal cuts:
For two tunnel portals, mul-
tiple-anchored bored pile walls were planned as secu-
ring measures during tende-
ring.
Furthermore, a drai-
nage shaft with a diameter of several metres (by means of bored piles) was allowed for at one
location.
In the process of the work of BGG Consult, the securing concepts could be changed to anchored shotcrete walls.
Additionally, the anchoring and dewatering measures were reduced. This optimi-
sation was possible because of the
continuing adjust-
ment of the securing and dewatering elements based on the results of the geo-
technical monitoring
(obser-
vational method) by means of inclinometers, anchor load cells and geodetic measuring points.
In this way, a cost reduc-
tion as well as a reduction of the construction period were achieved.
|