Pile Testing at Friedetal

A viaduct is required where the new Göttingen to Halle Autobahn BAB A38 crosses the Peace Valley (Friedetal) near Sollstedt in the state of Thüringen, Germany. The viaduct will have a total span of 485 m and be formed in 6 sections with the largest having a span of 130 m.

At the location of the viaduct piers, some gypsum layers exist which were a cause for concern with respect to the long-term performance of the pile foundations. Additionally, local mining subsidence and consequential settlement of the upper soils necessitated a means for minimizing the negative skin friction which may result in the pier piles.

The proposed solution was to found the piled foundations in the stable lower soil layers and employ a skin friction-reducing mechanism at the upper level.

To verify the design, Multilevel bi-directional testing was performed using Osterberg cells; three at the lower level to determine the skin friction and end bearing and three in the upper level to evaluate the effectiveness of the friction reducing mechanism. On completion of the bi-directional testing, a lateral load test was performed to measure horizontal pressures and pile deflection.

Instrumentation consisted of 4911 sister bars and 4450 displacement transducers for the bi-directional testing and 4810 pressure cells and 6300 vibrating wire in-place inclinometers for the lateral testing.

Despite the complexity of the pile instrumentation, the testing proved to be a great success with all phases completed satisfactorily. The redesigned foundation allowed for a significant reduction in the number of piles compared to the original specification.

For more information, please contact: www.scanrock.de
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