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

PPT Presentation

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The Westlink Project is a 6-km commuter rail link through central Gothenburg, including about 4 km of underground tunnels and three new stations. Construction began in 2018, with operations planned to start in 2026. Its rock excavations are mainly in gneiss and granodiorite, beneath soil and clay layers, and contain fracture systems with varying water-bearing characteristics.<br /><br />To meet strict leakage limits—generally 2–5 L/min per 100 m—the project uses three grouting classes (IK1–IK3), tailored to local conditions and required tightness. Grouting fans use boreholes up to 25 m long, with specified overlap. Three cement mixtures address normal conditions, fine fractures under higher groundwater pressure, and larger fractures with high grout take. The most stringent class may also use silica sol. Decisions on supplementary grouting are informed by earlier grouting rounds and water-loss tests.<br /><br />Performance is monitored through water-loss measurements in control boreholes, leakage measurements in excavated areas, and groundwater-level observations at approximately 1,110 monitoring points, alongside other measurements. Leakage forecasts help identify when measures such as post-grouting or infiltration may be needed.<br /><br />Experience to date is promising, though challenges remain, including at Service Tunnel 210. Complex station geometry, large spans, shallow rock cover, and sensitive surroundings make some areas particularly difficult. The project emphasizes adapting the initial design to observed conditions, maintaining reliable monitoring, and ensuring strong communication among contractors, construction management, and designers so that corrective measures can be implemented promptly.

Keywords

Westlink Project

Gothenburg

commuter rail

underground tunnels

new stations

rock excavation

grouting classes

leakage limits

groundwater monitoring

service tunnel