The Rossio railway tunnel was built in 1890 crossing several formations involving limestones, basalts and also sandy and clayey formations. Due to the fact that it is an old underground structure rehabilitation and repair works were performed, namely at Km 0,900 and in a zone crossed by a new tunnel from the Lisbon Metro. Reinforcement support systems were designed in the Rossio tunnel in order to prevent its stability. In this paper, repair works and anchor tests performed at km 0,900 are presented, as well as the monitoring system implemented in order to observe the structural effects induced by the construction of the works. For the interpretation of the obtained information complex 3D models was built, permitting the simulation of the sequential excavation scheme used, non-linear behaviour of the different formations, and the support systems used.

Der 1890 erbaute Rossio Eisenbahntunnel durchoertert mehrere Formationen, einschliesslich einer Kalkstein-, Basalt- sowie einer sandigen und tonigen Formation. Auf Grund des Alters des unterirdischen Bauwerks wurden Instandsetzungs- und Reparaturarbeiten im Bereich km 0,900 sowie im Kreuzungsbereich mit einem neuen Tunnel der Lissabonner U-Bahn durchgefuehrt. Aussteifungssysteme wurden entworfen, um die Stabilitat des Rossio Tunnels zu gewahrleisten. Im Folgenden werden die Instandsetzungsarbeiten und Anker Tests im Bereich km 0,900 sowie das Messystem zur Ueberwachung der strukturellen Auswirkungen der Bauarbeiten dargestellt. Zur Interpretation der gewonnenen Informationen wurden komplexe 3D Modelle entwickelt, die eine Simulation des Bauablaufs und die Anwendung nichtlinearer Stoffgesetze fuer die verschiedenen Formationen und Aussteifungssysteme ermöglichten.

Le Tunnel ferroviaire du Rossio a ete construit en 1890, traversant des differents terrains comme des calcaires, des basaltes et aussi des formations limoneuses et sableuses. Dû à l'anciennete de l'ouvrage, des travaux de rehabilitation et reparation ont ete faits, nomment au km 0,900 et dans la zone traversee par le nouveau tunnel du Metro de Lisbonne. Des systèmes de support renforce ont ete conçus pour le Tunnel du Rossio de façon à rassurer sa stabilite. Dans ce papier, on presente les travaux de reparation et les essais d'ancrage realises au km 0,900, et aussi, le système d'auscultation mise au point pour l'observation des effets structuraux induits par les travaux. De façon à interpreter l'information resultant de l'observation, des modèles 3D complexes ont ete utilises, permettant la simulation de la methode sequentielle de l'excavation, du comportement non - lineaire du terrain et, aussi les systèmes de support utilises.

Introduction

The Rossio railway tunnel was built in 1890, with a brick masonry vault, 80cm thick, and walls in stone or brick masonry. The tunnel, with a length of about 2600m, is located in a hill between the valleys of Avenida da Liberdade and São Bento, in Lisbon. The initial stretch, from the Rossio station to km 0.780, crosses, at a shallow depth, clayey-sandy strata, some of them with significant permeability. In the intermediate stretch, it goes through limestones and marls, with important flow of water through the rock mass discontinuities. In the final stretch, the geological formations include basalts, marls and highly fractured limestones (Choffat, 1889, Sousa, 1998, Lemos et al., 2001).

The internal tunnel cross-section was designed with a maximum width of 8m, formed by a circular vault of 4m radius, and maximum height of about 6.5m (Figure 1). The tunnel was constructed according the well-known Belgian method, that considered the following phases (Cabral, 1987):

  • excavation of a pilot gallery in the centre of the upper part of the section;

  • lateral enlargements of the upper part;

  • construction of the brick masonry vault, and subsequent filling of the void between the ground and the vault with stones.

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