The use of Geosynthetic reinforced structures working as bridge abutements in Scandinavia and Europe
The main focus of this paper is directed to the geosynthetic reinforced slopes or walls which have already been built with heights up to 41 m. Typically multiple horizontal layers of geosynthetics, mainly geogrids, are filled with compacted granular material and arranged on top of each other with a vertical spacing of 0.4 m – 0.6 m. In order to prevent slope failure the required design strength and length of the single geogrid layers has to be estimated in a geotechnical design. The paper includes a short overview of European guidelines that regulate the design and the construction of structures using geosynthetics e.g. “Nordic Guidelines for Reinforced Soils and Fills” (2005).
With international case studies and a large scale test the development of geosynthetic reinforced structures specifically for bridge abutment applications is demonstrated. In 1991 for example the construction of geosynthetic reinforced walls working as bridge abutments over the Nyborg-Fredericia main railway line in Ullerslev was instructed by the Danish State Railways (DSB). After an almost 25-year service life the design, the construction and the settlement behaviour are described in this paper.
The development of geosynthetic reinforced retaining structures (GRS) and their performance for bridge abutments have been introduced. Due to their multifarious construction and design methods GRS are suitable for many construction projects and can be readily adapted to individually unique project requirements.
The geotechnical design for GRS in Europe is based on EC 7 and regulated in National Guidelines dealing with geosynthetics. An overview of the Nordic Guidelines, EBGEO and BS 8006 with regard to the main applications, the design strength estimation and the basis of the geotechnical design of GRS have been presented.
The high vertical load carrying capacity and the deformation behavior under loads up to 650 kPa have been analysed in a large scale test. The vertical and horizontal deformations of the 4.5 m high test wall under typical bridge loads of approx. 250 kPa was measured in a range of millimeters thus substantiating the suitability of GRS for bridge abutments.
After almost 25 years’ service life the Danish bridge abutment in Ullerslev was highlighted. With regard to the serviceability and stability these bridge abutments have performed soundly. Due to the ductile deformation behavior of the GRS settlements causing from the clayey subsoil have not restricted the use of the bridge.