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The effect of back-fill grout characteristics on long-term ground settlement induced by shield tunneling

Mohammad Forooghi, Saeed Delara

In the proceedings of: GeoVirtual 2020: 73rd Canadian Geotechnical Conference

ABSTRACT: A 10 km long tunnel of Tehran Metro Line 7 was excavated by a 9.164 m diameter EPB-TBM through an old congested part of the city where ground settlement is one of the main construction challenges. Among different sources of settlement in shield tunneling, the settlement caused by the closure of the annulus gap behind the shield tail was discussed in this paper. This settlement usually takes place over a relatively short period of time from few hours to few days. To minimize this settlement, this gap should be properly filled with grout. In this project, a two-component grout was considered to fill the gap and the tunnel route was properly instrumented to monitor ground movements and assess the efficiency of grouting on the ground control. The grout mixture was studied by conducting over 40 laboratory tests. Based on the quality control recordings, where the optimized mixture was not properly made during the construction, ground settlement was analyzed that showed relation between the grout characteristics and the ground settlement.


RÉSUMÉ: Un tunnel de 10 km de long de la ligne 7 du métro de Téhéran a été creusé par un EPB-TBM de 9,164 m de diamètre à travers une vieille partie congestionnée de la ville où le tassement au sol est l'un des principaux défis de la construction. Parmi les différentes sources de tassement dans le tunnelier à bouclier, le tassement causé par la fermeture de l'écart de l’anneau derrière la queue du bouclier a été discuté dans cet article. Ce tassement se déroule généralement dans une période de temps relativement courte, de quelques heures à quelques jours.Pour minimiser ce tassement, cet espace doit être correctement rempli de coulis. Dans ce projet, un coulis à deux composants a été considéré pour combler le vide et le tracé du tunnel a été correctement instrumenté afin de surveiller les mouvements du sol et évaluer l'efficacité de l’injection de coulis sur le contrôle au sol. Le mélange de coulis a été étudié en effectuant plus de 40 tests en laboratoire. Sur la base des enregistreurs de contrôle de qualité, où le mélange optimisé n'a pas été correctement fait pendant la construction, le tassement du sol a été analysé qui a montré une relation entre les caractéristiques du coulis et le tassement du sol.


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Cite this article:
Forooghi, Mohammad, Delara, Saeed (2020) The effect of back-fill grout characteristics on long-term ground settlement induced by shield tunneling in GEO2020. Ottawa, Ontario: Canadian Geotechnical Society.

@article{Forooghi_GEO2020_186, author = {Forooghi, Mohammad}, {Delara, Saeed},
title = The effect of back-fill grout characteristics on long-term ground settlement induced by shield tunneling ,
year = 2020
}