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 Current Projects / Basel Tunnel Luzernerring
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The Luzernerring tunnel links the French highway A35 with the Swiss national road N2, "Osttangente". The tunnel is only 320 meters long but imposes a number of geotechnical challenges because it passes beneath the existing St. Johan railway station, the railway tracks and the Luzernerring Bridge. The tunnel is partially or fully below the groundwater table. A 25-meter deep excavation, measuring 30-meters in diameter, serves as the starting point for the tunnel. The tunnel is advanced using the crown drivage and the full-face excavation methods. Construction work is being done by the consortium ARGE Tunnel Luzernerring (Walo Bertschinger AG, Murer AG, Brunner Erben AG). Solexperts AG, together with the local partners Aegerter & Bosshardt AG and the Geotechnical Institute AG, was awarded the contract for geotechnical measurements.
Solexperts monitors settlements around the St. Johann railway station, the railway track, the Luzernerrring bridge and the nearby streets. The streets remain open to traffic during the construction work. Most of the geodetic measurements are done using two motorized total stations (robotic theodolites) which are controlled by the Solexperts GeoMonitor data acquisition system. The system automatically surveys 118 mini-prisms, 35 of which are installed in the pavement and have road traffic passing over them. The advanced monitoring system is able to re-measure targets that are momentarily blocked by the passing traffic. Inside the railway station 7 measuring points are continuously surveyed using a high precision digital optical level (Nivellmeter). Additionally 9 multi=extensometers, 3 piezometers and vibrations are continuously monitored.
Manual measurements are made on inclinometer measuring tubes that are installed in 13 boreholes (8 are vertically orientated and located within a wall of drill-piles and the remaining 5 are along the horizontal pipe umbrella). Inclinations are manually controlled at 23 locations using the BL200 portable inclination measuring device and level measurements are manually made at 7 points. Data loggers are used to record water levels in 4 piezometers.
The purpose of the measurements is:- Safety control for personal and equipment
- Monitoring of building in the excavation and nearby areas
- Control of building stability
- Detection of cross-sectional deformation and control of deformation tolerance
- Early detection of deformation and movements
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