ABSTRACT:

The tunnelling work for the tunnel at the Äspö Hard Rock Laboratory, Oskarshamn, Sweden, is completed. The tunnel has passed rock of different quality and several zones of difficult water conditions. Grouting technology has been developed in order to deal with the difficult conditions, high permeable zones with high water pressure and limited penetration of the grout into the rock. Grout properties have been tested for different types of grout. The grout properties vary depending on concentration and type of admixture. The theory of grouting has also been developed in order to better predict grout take and penetration. The theory indicates that there are three main groups of factors: grouting technology, hydrogeology and geology. Comparison of theoretical grout take and penetration with measured values has been carried out with promising results.

RESUME:

Le percement en lui même du tunnel du Äspö Hard Rock Laboratory à Oskarshamn en Suède est maintenant termine. Le tunnel traverse des roches de differentes qualites et plusieures zones de problèmes hydrauliques delicats. Des techniques d'injection ont ete developpees pour faire face à des difficultes comme des zones très permeables à haute pression hydraulique et à faible capacite d'injection dans la roche. Les proprietes de differents types de coulis ont ete testees, Ces proprietes dependent de la concentration et du type d'adjuvant utilise. Les recherches ont aussi ete orientees en vue d'obtenir une meilleure prediction theorique de la penetration et de la prise du coulis. Ces recherches font apparaître trois facteurs determinants: la composition du coulis, l'hydro-geologie et la geologie du milieu. Les conclusions obtenues après la comparaison des resultats theoriques de la penetration et de la prise du coulis avec des valeurs mesurees sur Ie terrain sont prometteuses.

ZUSAMMENFASSUNG:

Die Tunnelarbeiten fuer das Äspö Hard Rock Laboratory in Schweden sind abgeschlossen. Der Tunnel lauft durch durch Fels mit unterschiedlicher Qualitat und mehrere Zonen mit schwierigen Grundwasserverhaltnissen, Injizierungstechnik wurde entwickelt, um die schwierigen Felsbedingungen mit durchlassigen Zonen unter hohem Wasserdruck und geringer Eindringtiefe des Injiziermaterials zu beherrschen. Die Mörteleigenschaften anderten sich mit deren Konzentration und Zusammensetzung. Ein theoretisches Modell wurde entwickelt, um besser die Eindringtiefe und den Mörtelverbrauch vorhersehen zu können. Die Theorie zeigt, dass drei Faktoren hauptsachlich von Bedeutung sind: das Injizierverfahren, die Hydorlogie und die Geologie. Ein Vergleich des theoretisch ermittelten Mörtelvolumens und der Eindringtiefe mit gemessenen Werten is vielversprechend.

1
INTRODUCTION

The purpose of grouting is to create a watertight zone around a tunnel. This watertight zone should fulfill a tightness requirement which corresponds to a certain penetration length and a filling of the aperture of the fractures. Research into the fundamental mechanics of grouting has been going on at the Dept of Soil and Rock Mechanics, Royal Institute of Technology Stockholm, since 1983, sponsored by the Swedish Rock Engineering Research (SveBeFo). This has led to two doctoral theses on theory of grout flow (Hassler, 1991) and grout properties (Håkansson, 1993). Some theoretical developments have shown that the penetration length is dependent on the pressure, grout mix and the fracture aperture while the grout volume is dependent on the penetration length and the rock porosity for used mix. Particularly difficult and comprehensive grouting work have been carried out for the tunnelling project at the Äspö Hard Rock Laboratory, Oskarshamn Sweden, (Stille et al, 1993, 1994). The grout mix has been developed and investigated in order to find suitable combinations which deal with difficult conditions, highly conductive zones with high water pressure. A particular requirement of this project is that a limited grout penetration is desired in order to avoid excessive ground water contamination around the tunnel.

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