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The soil tunnel in Drammen (Norway), part of Bane NOR's 'New Double Track Drammen–Kobbervikdalen' project, has a length of 290 m; however, the different unfavourable boundary conditions combined with a large excavation cross section (156 m2) make this section the most technically challenging part of the project. The soil tunnel is driven mostly in saturated glaciofluvial sediments, which consist primarily of sand and gravel with a low content of fines, resulting in a low cohesion to cohesionless soil. The groundwater level, always within or above the tunnel section, cannot be lowered during the construction due to project requirements. These geological/hydrogeological conditions together with the large cross section present a high‐risk scenario for any tunnelling project and, in the case of Norway, an unprecedented challenge. Moreover, the tunnel is located in an urban area and has a low overburden of just 8 to 9 m during the first 80 m. For the client it was critical that the design solution was safe, robust, and able to respond to the existing level of uncertainty and potential unexpected occurrences. ILF's design is able to answer these technical challenges while removing many of the typical risks associated to saturated soil tunnelling with a solution that relies mainly on extensive pre‐excavation ground improvement works in the form of jet grouting executed from the surface. [ABSTRACT FROM AUTHOR]

Abstract: The 665 m long, twin‐track Untersammelsdorf Tunnel is being built in the course of the construction of the Koralmbahn line between Graz and Klagenfurt. The tunnel is located in extremely challenging subsoil conditions consisting of silty to fine sandy lacustrine deposits. The developed tunnelling concept provided wide‐ranging special underground engineering measures and represents a unique construction method to date. Accordingly, numerous challenges arose in the design phase, which were verified by carrying out extensive trials and investigations in the preparatory period or for which fallback levels had to be provided for the support system. Now tunnelling work is almost complete, the experience can be reported. [ABSTRACT FROM AUTHOR]

The railway line from Graz to Klagenfurt, section Mittlern-Althofen/Drau, is part of the Austrian high-speed network and a partial section of the trans-European railway network (TEN in the EU, Pan-European corridor in the eastern countries). With the Koralmbahn line from Graz to Klagenfurt, capacity on the north-south connection Vienna-Tarvis will be considerably increased and the journey times noticeably shortened. The St. Kanzian tunnel chain is the most important part of the section Mittlern-Althofen/Drau in southern Carinthia, in the immediate vicinity of the tourist region of Klopeiner See/St. Kanzian. The St. Kanzian tunnel chain consists of six tunnels with lengths between 230 and 2,100 m, which are under construction by various methods. Despite the short distances between the tunnels, the inhomogeneous geological conditions ranging from silty-sandy lacustrine sediments to phyllites are a great challenge. The topography also leads to consistently shallow overburden. The stated conditions lead to the necessity of extensive specialised civil engineering and ground improvement measures. [ABSTRACT FROM AUTHOR]

Built in 1914, the listed Reichsbahn directorate building was formerly used as an administrative building by Deutsche Bahn AG in Stuttgart. The Stuttgart 21 Project requires new tracks from the Feuerbach and Bad Cannstatt Tunnels to be built, which branch off from 4 to 8 tracks in the area beneath the DB directorate. Complete demolition of the directorate building was not possible due to the objection of the listed monument authorities, the city administration, the municipal council of architects and the former building owner Vivico. In view of this the preservation of the main building was specified in the planning decision of 28/01/2005. In order for the new station to be constructed by cut-and-cover, part of the building had to be secured and underpinned. The design should also take into account two single-track underground rail tunnels beneath the building and newly constructed temporary retaining structures. The temporary works required to distribute the building loads extended over an area of 800 m2, around half of the building footprint, and poses particular constraints on the design and construction approach due to the building preservation order and its inner city proximity. [ABSTRACT FROM AUTHOR]

In the course of the building of the new Koralmbahn railway line between Graz and Klagenfurt in Austria, six tunnels have to be built in a sensitive landscape on the Carithian side. The tunnels have lengths of between 230 and 2,100 m. All the tunnels are designed to resist water under pressure and have a two-track standard cross-section. Except for the 495 m long Kühnsdorf Green Tunnel, which has already been completed, all the tunnels are currently under construction. The Srejach and Untersammelsdorf Tunnels with lengths of 620 and 665 m respectively are being driven in very challenging ground conditions consisting of silty to fine sandy lacustrine sediments, and extensive specialised civil engineering works had to be carried out in advance of both these tunnels. The performance of extensive tests and investigations during the tendering phase turned out to be very valuable for the planning of the project. The longest tunnel, the Stein Tunnel with a length of 2,100 m, is characterised by its location in soft ground with shallow overburden and the sensitive hydrogeological and ecological conditions. The driving of the Lind Tunnel in phyllite required special measures due to the lacustrine sediments above the tunnel, which reached down to the tunnel crown. Im Zuge der Errichtung der Koralmbahn zwischen Graz und Klagenfurt sind auf Kärntner Seite in einem sensiblen Landschaftsraum sechs Tunnelbauwerke zu errichten. Die Tunnellängen liegen zwischen 230 und 2.100 m. Sämtliche Tunnelbauwerke werden druckwasserhaltend mit einem zweigleisigen Regelquerschnitt ausgeführt. Bis auf den 495 m langen Grüntunnel Kühnsdorf, der bereits fertig gestellt ist, befinden sich derzeit alle Tunnelbauwerke in der Ausführungsphase. Die Tunnel Srejach und Untersammelsdorf mit einer Länge von 620 und 665 m sind in extrem herausfordernden Untergrundbedingungen, bestehend aus schluffigen bis feinsandigen Stillwassersedimenten, herzustellen. Für diese beiden Tunnelbauwerke werden vorab Spezialtiefbaumaßnahmen in großem Umfang durchgeführt. Für die Planung dieser Arbeiten war die Durchführung von umfangreichen Versuchen und Untersuchungen in der Ausschreibungsphase sehr wertvoll. Der Tunnel Stein, mit 2.100 m der längste Tunnel in der Kette, ist durch seine Lage im Lockermaterial mit geringer Überlagerung und durch sensible hydrogeologische und ökologische Verhältnisse gekennzeichnet. Der Vortrieb des Tunnels Lind im Phyllit erfordert infolge der darüber liegenden Stillwassersedimente, die bis in die Tunnelfirste reichen, besondere Maßnahmen. [ABSTRACT FROM AUTHOR]

The St. Kanzian tunnel chain lies near the Völkermarkt reservoir and is part of the Mittlern-Althofen approval section of the Koralmbahn line in Carinthia. Of the six tunnels in the St. Kanzian tunnel chain, the 495 m long Kühnsdorf green tunnel (cut-and-cover) has already been completed. The construction of the 230 m long Peratschitzen green tunnel (a cut-and-cover noise protection tunnel) and the 620 m long Srejach Tunnel (top-down construction) started in summer 2015. Work should start on the Untersammelsdorf, Stein and Lind Tunnels (all mined tunnels), in spring/summer 2016. The tunnels lie partially in challenging geological conditions (lacustrine sediments), all with shallow overburden, and require special measures for support and ground improvement (bored piles, jet grouting). Particular attention has been paid to later maintenance costs, which have to be considered in the course of the design work. Die Tunnelkette St. Kanzian liegt im Bereich des Völkermarkter Stausees und ist Bestandteil des Einreichabschnitts Mittlern-Althofen im Westteil der Koralmbahn in Kärnten. Von den sechs Tunneln der Tunnelkette St. Kanzian ist der 495 m lange Grüntunnel Kühnsdorf (offene Bauweise) bereits fertiggestellt. Die Herstellung des 230 m langen Grüntunnels Peratschitzen (offene Bauweise) und des 620 m langen Tunnels Srejach (Deckelbauweise) hat im Sommer 2015 begonnen. Mit den Tunneln Untersammelsdorf, Stein und Lind (alle geschlossene Bauweise) soll im Frühjahr/Sommer 2016 begonnen werden. Die Tunnelbauwerke liegen teilweise in herausfordernden geologischen Verhältnissen (Stillwassersedimente) mit durchwegs geringer Überlagerung und erfordern besondere Maßnahmen zur Stützung und Baugrundverbesserung (Bohrpfähle, Düsenstrahlverfahren). Besonderes Augenmerk wurde auf die späteren Erhaltungskosten gelegt, die in den Planungsentscheidungen berücksichtigt wurden. [ABSTRACT FROM AUTHOR]

The new metro line in Thessaloniki includes, besides the excavation of two twin tunnels, the construction of 13 stations with central platform in settlement-reducing top-to-down construction method. Due to restrictions in available space, it was necessary to dispense with the construction of an inner shell. Further constraints were the soft and highly inhomogeneous soil, the large excavation depths in groundwater, and the earthquake-resistant design of the structures. The special foundation works executed for permanent uplift safety as well for the soil strengthening in front of the excavation walls are described for representative stations. Die neue U-Bahn in Thessaloniki umfasst, neben dem Schildvortrieb zweier Röhren, die Errichtung von 13 Bahnhöfen mit zentralem Bahnsteig in verformungsarmer Deckelbauweise. Wegen der engen Platzverhältnisse musste dabei auf eine Innenschale verzichtet werden. Weitere erschwerende Randbedingungen sind der weiche, stark inhomogene Untergrund, die große Aushubtiefe im Grundwasser und die erdbebengerechte Auslegung der Tragkonstruktion. Für typische Bahnhöfe werden die Spezialtiefbaumaßnahmen zur dauerhaften Auftriebssicherung sowie zur Verstärkung des Fußwiderlagers der tiefen Baugruben vorgestellt. [ABSTRACT FROM AUTHOR]

Contract B-9528 - Södermalm Tunnel is a good example of urban tunnelling, where tunnel alignments cannot be chosen freely due to existing buildings and subsurface structures. Around ten tunnel crossings and a number of difficult situations underpassing existing buildings were in the scope of Södermalm Tunnel with the main focus on the Maria Magdalena Church. A NATM approach enabled tunnelling of the first double track tunnel in Stockholm's Esker to succeed in very close vicinity of the church. Hauptbaulos B-9528 - Södermalmstunnel ist ein Beispiel für innerstädtische Randbedingungen, wo die Linienführung des Tunnels von existierenden Bauwerken beeinflusst ist und nicht mehr frei wählbar ist. Neben rund zehn Tunnelkreuzungen war eine Reihe von schwierigen Gebäudeunterfahrungen im Auftragsumfang des Projekts B5-9528 - Södermalmstunnel, wobei die Maria-Magdalena-Kirche im Fokus der Bemühungen stand. Ein NÖT-Vortrieb ermöglichte im Nahbereich der Kirche die erste Durchörterung von Stockholms Esker (Oser) mit einem Großquerschnitt. [ABSTRACT FROM AUTHOR]

The Visp bypass is an important link on the Swiss national road A9 from Lausanne to Brig-Glis in the Canton of Valais, which is being improved to provide continuous dual carriageway. About 7 km of the alignment of this 8.8 km long section of the A9 will run through tunnels, with the core structures being the 4.2 km Eyholz Tunnel and the 3.2 km Visp Tunnel. Altogether five underground junction structures have to be constructed for the Visp bypass, of which three will be newly excavated and two are enlargements of the existing Vispertal Tunnel. The following report only deals with the Eyholz Tunnel, which has already been largely excavated. Construction of the main contract of the Visp Tunnel is planned to start in 2012. Die Umfahrung Visp stellt ein wichtiges Teilstück der zukünftig von Lausanne bis Brig-Glis durchgehenden richtungsgetrennten Nationalstraße A9 im Kanton Wallis dar. Die Linienführung des rund 8,8 km langen Teilstücks der A9 verläuft zu rund 7 km in Tunnelbauwerken. Kernstücke sind der 4,2 km lange Tunnel Eyholz und der 3,2 km lange Tunnel Visp. Insgesamt sind für die Umfahrung Visp fünf unterirdische Verzweigungsbauwerke zu erstellen, von denen drei komplett neu auszubrechen sind und zwei aus einer Ausweitung des bestehenden Vispertaltunnels hervorgehen. Die nachfolgenden Erläuterungen beschränken sich auf den Tunnel Eyholz, der bereits zu einem großen Teil ausgebrochen ist. Der Baubeginn des Hauptloses des Tunnels Visp ist für 2012 geplant. [ABSTRACT FROM AUTHOR]

In the western part of the Koralmbahn railway line, tests were carried out as part of planned specialised civil engineering works in silty to sandy still water sediments in order to find out about the interaction of jet grouting and dewatering measures with this ground, which is considered to be as geotechnically relatively unfavourable. Small-scale tunnelling work was also carried out to gain experience for the later tunnel construction work in this area. The most important discoveries were: that the jet grouting trials achieved jet grout columns with a diameter of 1.5 m within the still water sediments; and the simulation of a tunnel drive was able to demonstrate that stable conditions at the face can be achieved with the chosen advance support measures. The evaluated results made it possible to optimise the design of the tunnel structures and the forecast performance rates for the grouting works. Im westlichen Bereich der Koralmbahn sind im Rahmen geplanter Spezialtiefbaumaßnahmen in schluffigen bis sandigen Stillwassersedimenten Versuche durchgeführt worden, um Erkenntnisse über die Interaktion von DSV- und Entwässerungsmaßnahmen mit diesem geotechnisch als relativ ungünstig geltenden Gebirge zu erlangen. Zusätzlich wurden durch kleinmaßstäbliche Vortriebsarbeiten Erfahrungen für die späteren Tunnelbauarbeiten in diesem Bereich gewonnen. Als wichtigste Erkenntnisse können genannt werden: Bei den Versuchen zu DSV-Arbeiten waren in den Stillwassersedimenten DSV-Säulen mit einem Durchmesser von 1,5 m zu erreichen; durch die Simulation eines Tunnelvortriebs konnte demonstriert werden, dass mit den gewählten Vorraussicherungsmaßnahmen stabile Verhältnisse im Bereich der Ortsbrust erzielbar sind. Basierend auf den ermittelten Ergebnissen können die bisherige Planung der Tunnelbauwerke sowie die prognostizierten Leistungsansätze bei den DSV-Maßnahmen optimiert werden. [ABSTRACT FROM AUTHOR]