By E Schumacher and C Veder
This paper was first published in Bauingenieur in 1976 and was translated for publication in GE’s January 1978 issue.
The Austrian Federal Railways are building a new freight depot and switching yard between Bregenz and Dornbirn. For this they acquired an area of approximately 350000m2 which was, however, completely unsuitable for building. This land lies at the edge of the alluvial cone of the Bregenz River, the densely packed and load-carrying river deposits there being overlain by soft, sandy-clayey silt up to a depth of 11m. The silt, in some places, contains significant peat seams. Ground water was found in the gravel to be between 3.5m and 4.5m, and in the soft layers between 1.0m and 2.2m below the surface of the ground.
Based on a recommendation by C Veder, it was decided to consolidate the soil sufficiently to enable the site to be used for rails and switches (which are very sensitive to settlements) by means of a vertical and horizontal drainage system as well as by surcharge loading. This represented an ideal opportunity to compare the results of basic laboratory experiments with field measurements in order to prove the validity of the Terzaghi and Frohlich theory of consolidation for very inhomogenous soils. Thanks go to the Austrian Federal Railways, and especially to Kurt Nahler and Kurt Fechtner for their support in carrying out these experiments.