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Radoncic N.,Geoconsult Salzburg ZT GmbH | Hein M.,Geoconsult Wien ZT GmbH | Moritz B.,OBB Infrastruktur AG
Geomechanik und Tunnelbau | Year: 2014

Both the technical boundary conditions and the usual advance rates achieved during hard rock TBM shield drives severely limit the ability of the on-site-personnel to document the geological conditions and the system behaviour at appropriate intervals. A systematic and continuous short-term investigation of the rock mass conditions is performed on the construction lot KAT2 of the Koralm Tunnel (obtained by impact drillings and geophysical methods). The difference in scales and the fact that no continuous inspection of the ground conditions can be performed lead to a gap between the prognosis and the observed behaviour and a direct comparison is seldom possible. Based on the daily comparison between the observed behaviour and the analysed machine data, a state-of-the-art interpretation method has been developed. This method allows reliable conclusions regarding the primary aspects of the system behaviour and thus enables deductions on the geological/geotechnical conditions which have been encountered. The identification of the relevant parameters and suitable analysis methods has been performed in a "trial and error" manner: machine parameters deemed relevant in theory have been continuously compared with the observations on site and depending on the results, found usable or discarded. Reliable knowledge about the face stability, qualitative degree of fracturing of the rock mass, occurrence of over excavation in the cutter head area, the state of the annular gap and the blockiness of the rock mass can be deduced by applying this method. The results are used on daily basis by the on-site geologist and geotechnical engineer in order to verify the prognosis and recommend additional/auxiliary construction measures. © 2014 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

Moritz B.,OBB Infrastruktur AG | Radoncic N.,Geoconsult Salzburg ZT GmbH | Helmberger A.,IL Ingenieurburo Laabmayr and Partner ZT GmbH | Uschan R.,Jager Bau GmbH
Geomechanik und Tunnelbau | Year: 2013

The paper deals with the challenge on structural analysis, logistics as well as on geotechnical aspects during sinking of an approximately 60 m deep construction shaft with a cross-sectional area of about 720 m2 at the Koralm Tunnel lot KAT 2. Numerical 3D simulations were used for the structural analysis. The results in terms of level of loading of the support measures and the displacements served as a basis for predicting the system behaviour of the shaft. During sinking, the behaviour of the shaft and surface was continuously monitored within the geotechnical safety management by means of 3D displacement measurements, measurement of strains in the shotcrete lining and measurements of pile inclinometers. Thereby a continuous target-performance comparison was accomplished. Special characteristics in the design and construction phase are illustrated and discussed. © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

Radoncic N.,Geoconsult Salzburg ZT GmbH | Holzl H.,Geoconsult Salzburg ZT GmbH | Moritz B.,OBB Infrastruktur AG | Bacher W.,3G Gruppe Geotechnik Graz
Geomechanik und Tunnelbau | Year: 2013

The Paierdorf ventilation facility is a part and a preparatory contract for the Koralm Tunnel KAT 3 contract, and is situated approximately 3.7 km from the western portal. It consists of a vertical 120 m deep shaft, an 88 m long expanded section of the south tunnel, access tunnel/TBM entry cavern, an approximately 100 m section in the north tunnel and a ventilation tunnel having a length of around 93 m. The shaft, the access tunnel and the top heading of the south tunnel had already been constructed during the extended exploratory programme of the Koralm Tunnel. The TBM entry cavern, the segment of the north tunnel as well as the section in the south tunnel and the ventilation tunnel were then added in 2012. The ventilation tunnel crosses over the south tunnel with a minimal separation of 2.8 m and connects to the vertical shaft. This geometrical arrangement results in complex geometry of the underground structure and complex geotechnical interaction between the parts. This paper concentrates on the prediction of system behaviour in the design phase with 2D and 3D numerical calculations and the comparison of predicted with observed behaviour during construction. © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

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