In memoriam Ioannis Vardoulakis

摘要

Recommended by his former classmate Dimitrios Kolymbas, Ioannis Vardoulakis joined us in Karlsruhe in 1973. He was evidently brilliant, so I advised him to investigate the shear localization of sand by combining Mandel's (Conditions de Stabilite et Postulat de Drucker rheology and soil mechanics, Springer, Berlin, 1966) loss of shear wave propagation with Cornforth's (Geotechnique 14(2): 143-167, 1964) biaxial tests. This turned out to be impossible. Instead, together with Goldscheider, he developed a novel biaxial device and established a theory of localized bifurcation (Goldscheider and Gudehus, in Int J Numer Anal Meth Geo-mech 2(2):99-l 28,1978). In doing so, he pioneered the bifurcation theory for soils, and replaced the conventional concept of shear strength by a sound theory that was validated against experiments. This was the beginning of an exceptional scientific career.