Sinkhole protection

Main contractor walter-heilit has used huesker's fortec geosynthetic reinforcement system for road repairs as part of Verkehrsprojekte Deutsche Einheit (VDE) road project No. 13, which includes construction of the A143 Western Relief Road at Halle, and interchanges on the A7 at Göttingen and the A14 at Leipzig, as well as the western by-pass around Halle between the A38 and A14 motorways.

As it approaches the residential suburb of Halle Neustadt, the route crosses an area of former brown coalmine workings, prone to the formation of sinkholes. Protection against this subsidence was provided by a bridging system using a single layer of high-strength geosynthetic reinforcement comprising Huesker's Fortrac-AM (aramid/PVA).

The geogrid was placed in one layer longitudinally with the transfer of tensile force being assured by transverse overlaps, tensioned during installation, by a specially designed ‘laying device'.

A gravel and sand layer was then spread over the reinforcement, this pushed the material forward over the tensioned geogrid and held it in place.

This was followed by further compaction. In total about 160000 m² of geogrid was supplied, sufficient to protect over 2,6 km of the A143 Western Relief Road.