The "Rohr Junction" is part of the high-performance railway track Vienna - Salzburg and
represents the western connection between the St. Pölten freight train by-pass (GZU) and
the existing Western Railway Line in Austria.
The demand of level-free rail crossings required two underpasses. In order to integrate
the construction without a major change of the characteristic landscape, the rails had to
be lowered deep into the ground. Because of the high groundwater level, numerous tunnels
and troughs had to be constructed.
The walls were designed mostly as a combination of bored pile (building pit wall) and
cast-in-place concrete walls. |
In this project, the geotechnical and hydrogeological consulting work was carried out
by BGG during all the design and construction phases. Several subsoil exploration
campaigns were planned and supervised in order to gather the necessary data about
the underground. The results of these examinations were used to compile geotechnical
and geohydrological expert's reports required for the application of a construction permit.
In this context, extensive ground water communication measures were designed.
During construction, BGG was responsible for the following: The geotechnical and
hydrogeological supervision on the site; The evaluation of the project details from a
geotechnical perspective; The dimensioning of retaining structures; And lastly, the
geological documentation during the excavation.
Furthermore, numerous geodetic and 33 inclinometer measuring points (predominantly
inclinometers in bored piles) were supervised. |
Tunnels and trough structures:
Special attention had to be given to the design of the tunnels and the trough structures
due to their considerable heights and the high groundwater level. In some area tension
piles had to be placed for uplift control.
Along the trough structures, where bored piles were used for construction, large zones
of weathered oligocene deposits were found. This constituted a critical situation due to
the high slide susceptibility. Through a continuous comparison of the predicted
displacements with those recorded by the bored pile inclinometers, the actual stability of
the structure could be assessed correctly.
On this basis, the construction progress was managed in an ideal way, critical situations
were avoided and an optimally economic solution was achieved. |