Anchor reinforcement motorway tunnel

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Some of the tie bars in the vicinity of a gravity wall have corrosion problems. These corrosion problems can result in tie bars suddenly fracturing – brittle fracture – and flying into the clearance gage profi le of the adjacent freeway lane. The aim of an elaboration was to brake the tie bars at a relatively short distance, preventing them from penetrating the lane space. Geobrugg’s answer comprises a high-tensile steel wire mesh stretched in front of the 64 tie bar heads and provided with four braking rods, two at the top and two at the bottom. The ingenious interaction of this mesh and the specially designed braking system permitted a reduction in kinetic energy of up to 30 kJ for a defl ection of only 40 cm. Use is made here of the specifi c material properties of the utilized steel (very high dynamic- plastic deformation capability).