Retaining wall solutions from TensarTech

Extensive underground mining in south Poland posed a significant challenge to construction of the A1.

To accommodate potential differential settlement on the approach embankments to bridge structures, TensarTech soil retaining walls were specified.

The retaining walls were designed to support the approach embankments to a series of viaduct and bridge structures along the 16km Piekary Slaskie to Pyrzowice (Katowice Airport) section.

Dr Jacek Kawalec, Tensar Business Manager Europe, said: “The A1 motorway project is highly important for improving the strategic transport infrastructure between South East Europe to the Baltic.

“However, the region south of Piekary has been extensively mined for coal, metal and minerals for centuries, with black coal still being extracted.

“As a result, there are extensive and often unknown tunnels, voids, weak spots, unconsolidated spoil heaps and other unstable sections. Unpredictable movement of the ground could cause great damage to a major road structure, and even threaten life.”

Using conventional techniques, such as piling, to stabilise the ground would have been very costly.

Engineering consortium Transprojekt Krakow and Complex Projekt Katowice specified the TensarTech solution, which also managed to incorporate locally available aggregates, such as colliery spoil.

Local material is less expensive and its use minimises transport costs.

It also reduced the requirements for the costly import of high quality aggregates.

With the TensarTech solutions, there is no requirement for the concrete to cure to full strength before loading the structure, which saves time and therefore cost.

Tensar geogrid reinforcement was laid back into the embankment, over which compacted, aggregate fill was laid to form the soil mass.

The geogrid is securely connected by a polymer connector to a range of different dry laid wall facing components depending on the location and the required aesthetics.

A number of finishes are available, including TensarTech TW1 cast blocks, split face blocks, and octagonal concrete panels.

The retaining structures range from near vertical walls, to 600 sloping faces.

The plan layout included a variety of curved faces which can be easily constructed without cutting the blocks, even on tight radius curves.

The largest structure is 600m in length, ranging from 0.8 to 8m in height.