During the first few years working as professor in Foundation Engineering and Soil Mechanics at the Faculty of Science, Technology and Communication of the University of Luxembourg, I performed research on pile tip bearing capacity. I noticed that some researchers assume the shape of the failure mechanism around the pile tip, to be like a logarithmic spiral, in the same way as the failure mechanism for shallow foundations. I therefore started to study the bearing capacity of shallow foundations, and became fascinated by the beauty of the analytical solutions made a century ago.

Since the publication of Ludwig Prandtl's article “About the hardness of a plastic body”, in 1920, a lot of extensions have been made, for example with inclination factors and shape factors. In addition, numerous laboratory experiments have been carried out and many numerical calculations have been performed. Furthermore, as mentioned, some researchers have even tried to extrapolate the failure mechanism for shallow foundations to the failure mechanism around the tip of a pile. All this scientific work leads back to the first publication of the so-called “Prandtl-wedge” of 1920.

This book “100 Years of Prandtl's Wedge” has been created for all those who are interested in these fundamentals of foundation engineering and their history.

Stefan Van Baars

Luxembourg, June 2015