Weida Bridge, Germany

The project is part of the construction for the Göttingen – Halle Süd BAB A 38 located over the Weidatalbrücke, Esperstedt, Germany and consists of a 435m long box girder bridge of seven spans, the longest of which is 158m and is due for completion in April 2007 at a cost of €16.8 million. The bridge is located within a nature reserve and is therefore in an environmentally sensitive area. The design for the bridge foundations required verification and the bi-directional testing method was selected as it provided the most environmentally friendly solution.

Weida install.jpg Tests were performed on two 1200mm diameter piles approximately 27 m deep fitted with a multilevel O-cell® arrangement mounted in a purpose built carrying frame. Two 540 mm diameter O-cells were installed in each carrying frame and a pile-tip pressure cell also mounted at the bottom of each of the two test piles. The lower O-cell was 2.4m above the pile tip and at the start of the limestone strata and the second O-cell level set at 9.4 m above the pile toe.

Using to advantage a feature unique to multi-level bi-directional tests, the load was applied in stages, mobilising different portions of the test pile. The test was successfully performed and provided information on side shear for specific zones along the pile shaft. The load tests were carried out mobilising 32MN and 35.2MN combined side shear and end bearing for the two test piles.

Installation of O-cells and pressure cell on the bottom of the carrying frame The pile-tip pressure cells allowed the end bearing to be separated from the side shear, with values of 4.62MN and 1.15MN for each pile and calculated unit end bearing at the base of 4840 kPa and 1017 kPa respectively.

Bi-directional load testing using the Osterberg Cell proved to be the most environmentally friendly solution for testing in this highly sensitive location.

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Weida Bridge, Germany