Terrestrial laser scanning as a key element in the integrated monitoring of tidal influences on a twin-tube concrete tunnel

摘要

In 2012, for the first time in Belgium, integrated monitoring was carried out to assess the deformations of a twin-tube tunnel below the River Scheldt in Antwerp under the influence of estuarine tides. Levelling measurements during a tide cycle showed a variation in the height of levelling bolts of up to 10mm between low and high tide. Simultaneous strain-gauge measurements also showed a significant difference in strains. A deformation of the tunnel section during each twice-daily tide cycle, resulting in an eccentric egg or pumpkin shape, could hold large risks for the strength and durability of the tunnel structure. However, laser scanning results showed that there were no significant deformations of the tunnel's shape during the tide cycle. The laser scanning measurements resulted in a more thorough view of the deformation pattern which was much needed and improved the long-term risk assessment of the tunnel.