Grouting at the Westlink Project –Gothenburg, Sweden. The Challenges and How These Are Met-Paper

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The West Link is an approximately 8 km railway project beneath central Gothenburg, including 6 km of tunnel and three new stations. About 4 km is excavated in crystalline rock, mainly gneiss and granodiorite. Because nearby buildings and infrastructure are vulnerable to groundwater drawdown, allowable tunnel leakage is generally limited to 2–5 litres per minute per 100 metres.<br /><br />The grouting design addresses variable fracture conditions through three classes, IK1–IK3, with differing numbers of grouting rounds, hole layouts and cement mixes. Fine grout is used where small fractures and higher groundwater pressures demand it; stiffer grout is used for larger fractures and high grout takes. Water-loss tests in control holes, tunnel leakage measurements and groundwater monitoring guide decisions on supplementary grouting.<br /><br />Experience from service tunnel ST210 in the Haga contract led to the development of IKX, a faster alternative to IK3 for less sensitive sections. IKX reduced the need for repeated grouting while maintaining leakage below the legal limit and close to the project’s more ambitious target. Groundwater levels showed no negative effects.<br /><br />In the Korsvägen contract, service tunnels generally had low grout consumption. Measured leakage was below requirements in ST207 and ST209, while ST206 was close to its limit, with inflows concentrated in two areas associated with fracture structures. Monitoring and post-grouting were used to manage these locations.<br /><br />Results from the service tunnels are promising, but the larger stations remain the main challenge because of their complex geometry, large excavation volumes, limited rock cover and sensitive surroundings. The project emphasizes ongoing measurement, adaptation of the grouting design and close communication among contractors, construction management and designers.

Keywords

West Link

Gothenburg railway

tunnel grouting

groundwater leakage

crystalline rock

gneiss

granodiorite

service tunnels

IK1 IK3 IKX

post-grouting