Obituary 26 Mar 2018

Franz Pacher 1919-2018

Austrian civil engineer and a pioneer of rock mechanics Franz Pacher died in March 2018 in Salzburg aged 98. He was internationally recognized as a progressive tunnel construction engineer and especially in the development of the new Austrian tunnel method (NATM).

Franz Pacher 1919-2018

After leaving the Upper Grammar School in Graz, Austria, Pacher began his studies in Civil Engineering at the Technical University of Graz, where he graduated in 1943 and remained as a research assistant in the field of hydraulic engineering until 1945.

In the years from 1946 to 1952 he worked as a design engineer and project manager on hydropower plant construction sites, where he had his first introduction to rock mechanics and tunnelling. In 1952, he joined the Engineering Office for Geotechnics and Tunnel Construction of Leopold Müller.

The following years were marked by the rapid development of rock mechanics science, and the input of Pacher and his closest co-workers, as a partner of Leopold Müller and from 1957, was crucial. In 1966 he became the sole manager of the engineering office. In the years leading up to 1975, his collaboration with Professor Ladislaus Rabcewicz was of crucial importance for the development of tunnel construction and design.

In 1983, Pacher renamed his company Engineering Group for Geotechnics and Tunnel Construction – German acronym IGT. After successively handing over his interests and duties, Pacher retired in 1988.

Pacher at the 2008 Salzburg Geomechanics Colloquium

In his 45 years in the profession he worked as a project engineer, head of an engineering office, a collaborator with researchers and teachers, and was an honorary member of institutions in the field of geomechanics and tunnel construction.

From the beginning of modern tunnel construction operations in the mid-1960s, Pacher was highly active in the planning and design of tunnel construction projects. In particular, these included the Schwaikheimer Tunnel on the railway line from Waiblingen to Schwaebisch Hall-Hessental as the first tunnel in Germany constructed according to the principles of shotcrete construction (NATM). This was followed by planning and consulting services for the construction of the Munich and Vienna subway networks. From 1968 to 1975 Pacher was involved on the Tauern and Katschberg Tunnel projects. From 1981 to 1985 he was engaged on the development of the new Hanover to Würzburg railway line for the German Federal Railways, providing regular and vital advice on site. In addition, Pacher was associated with many power plant construction projects. In the years before his retirement, he was engaged on nearly 90% of all tunnels in Austria.

Particular achievements of Pacher are in the area of fundamental research, for example the definition of planar and volumetric proportions of discontinuities and the ground reaction curve. In a 1964 publication, Pacher demonstrated for the first time a method for prediction and graphical representation of the interaction between ground pressure and tunnel support loading (the Pacher-Fenner curve). This was based on measurements of deformations and led to the development of the convergence-confinement method. In 2009 Pacher extended this representation to a diagram showing the time-dependency of both ground pressure and deformation.

Pacher was a founding member of the International Society for Rock Mechanics (ISRM) in 1962 and the Austrian Society for Geomechanics in 1968, both in Salzburg. During his 45-year career, he delivered countless lectures and was author of numerous papers and publications. In an interview with him on the 50th anniversary of the founding of the ISRM (in German) he explains his work and the advancements in the science of rock mechanics. He was an outstanding engineer and an example to future generations of pioneering engineers.