Robert M. Koerner, Ph.D., P.E. H. L. Bowman Professor of Civil Engineering and Director GRl Geosynthetic Research Institute Drexel University West Wing - Rush Building 10 Philadelphia, PA 19104USA. Dr.-Ing. Erwin GartungLGA-GrundbauinstitutTillystraBe 2D - 90431 Nuremberg Germany. Dipl.-Ing. Helmut ZanzingerLGA-Grundbau institut TillystraBe 2D - 90431 Nuremberg Germany.