Drip sealing of tunnels in hard rock: A new concept for the design and evaluation of permeation grouting

• Published in: Tunnelling and underground space technology Vol. 25; no. 2; pp. 114 - 121
• Main Authors: Butrón, Christian, Gustafson, Gunnar, Fransson, Åsa, Funehag, Johan
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.03.2010; Elsevier
• Subjects: Applied sciences; Building process; Buildings. Public works; Cement; Construction works; Dripping; Exact sciences and technology; Grouting design; Grouting evaluation; Hard rock; Miscellaneous; Silica Sol; Tunnels, galleries; Grouting evaluation; Silica sol; Dripping; Hard rock; Cement; Grouting design; System evaluation; Permeation; Sealing; Silica; Hard material; Design; Excavating; Grouting; Tunnel driving; Construction technology
• DOI: 10.1016/j.tust.2009.09.008
• ISSN: 0886-7798

This paper presents a new pre-excavation grouting concept to prevent dripping and reduce the inflow into a railway tunnel. For this purpose, the tunnel’s roof was drip-sealed using colloidal silica and the walls and invert of the tunnel were grouted with cement. The grouting design process followed a structured approach with pre-investigations of core-drilled boreholes providing parameters for the layout. Water pressure tests and pressure volume time recordings were used for the evaluation. Results showed that the design was successful: the total transmissivity was reduced from 4.9 × 10 −08 m 2/s to the measurement limit (1.6 × 10 −08 m 2/s), and the dripping was reduced to eight spots from the roof. Improved rock characterisation showed that the grout hole separation was within the transmissivity correlation length and that grouting efficiency depends to a large extent on the dimensionality of the flow system of the rock mass.