The soil mechanics laboratory of TU Wien is part of the Institute of Geotechnics, Research Unit for Ground Engineering, Soil and Rock Mechanics. The main area of responsibility is mainly teaching and research, but also the supervision of current construction projects.

Until 1928 there were two hydraulic engineering chairs at TU Wien, which were redivided in view of the appointment of K. Terzaghi in hydraulic engineering I, II and III. The new subject of Hydraulic Engineering II - as the later chair of foundation engineering and soil mechanics was called - included the "Construction Elements and Working Methods of Foundation Engineering", "Hydraulic Engineering" and "Earthworks Mechanics".

With the appointment of K. Terzaghi as professor at the Technical University in 1929, his colleague A. Casagrande took over the construction of the soil mechanics laboratory. From that time come numerous important experimental devices and research methods that are now familiar to every soil mechanics institute, such as:

• the liquid limit machine for determining Atterberg's consistency limits,
• the aräometer-analysis (sludge analysis) to determine the grain size distribution of fine-grained soils,
• the compression apparatus for determining the compressibility of fine-grained soils,
• the shear box apparatus.

The research activities at the institute were extraordinarily diverse. K. Terzaghi benefited from his degree in mechanical engineering, which enabled him to manufacture almost all apparatus himself.

For the shearing apparatus manufactured by H. D. Krey in the 1920s for the Berlin Research Institute for Water and Shipbuilding, A. Casagrande - based on ideas by K. Terzaghi - developed an improved shear box. In numerous shear tests, the influences of granularity and serration of the filter stones, as well as the internal changes in the shape of the shear specimens, were investigated before the standard design of Terzaghi's shear bushes was achieved. They already recognized the need to prevent tilting of the shear frame or the loading device as far as possible in order to avoid falsification of the test results due to imprecise application of the normal force. A disadvantage of this shearing device, however, was that preloading and shearing of the sample could not be carried out in the same device.

The poster Schergerät (PDF), opens a file in a new window contains a description of the shear test device according to H.D. Krey with the shear rifles according to A. Casagrande.

A shearing apparatus was also developed by A. Casagrande. This differs from Krey's shearing device essentially in that the lower shear frame is held in place and the upper one is moved (this is the other way around in the Krey shear apparatus). The application of the vertical load is effected - as in the shearing apparatus according to H. D. Krey - by means of a lever, whose own weight is lifted by a counterweight, and the load is applied by lead weights. The shear force is caused by a weight running on a second lever. The advantage is that preloading and shearing can be carried out on the same device.

Both the shearing apparatus according to H. D. Krey and the shearing apparatus according to A. Casagrande have the disadvantages that a reduction in the specimen cross-section occurs as shearing progresses and the soil therefore partially slides onto metal. In contrast to the others, the circular ring shear apparatus developed by J. Hvorslev had a circular ring cross-section and thus enabled long shear paths with a shear surface of the same size.

More details can be found in the poster Kreisringscherapparat (PDF), opens a file in a new window.

In addition to the development work on direct shear devices, the construction of the first triaxial apparatus with facilities for pore water pressure measurement (first carried out by L. Rendulic) began in Vienna at that time. As early as 1934/1935, the device was fully functional and provided the basis for essential findings in soil mechanics.

A description of the test technique can be found in the poster Erstes Triaxialgerät (PDF), opens a file in a new window.

After both A. Casagrande and, in 1938, K. Terzaghi moved from TU Wien to Harvard University (USA), K. Kienzl took over the management of the soil mechanics laboratory and also held the lectures and exercises on an interim basis.

Prof. O. K. Fröhlich, one of Prof. K. Terzaghi's closest collaborators, was entrusted with the management of the chair in 1940 as his successor. He is considered a co-founder of soil mechanics and devoted himself - especially after the war years - to various theoretical problems of this young science, in particular the stability of embankments, the critical boundary load under foundations, the elaboration of pile driving formulas, etc.

The management of the soil mechanics laboratory was the responsibility of K. Kienzl until the end of the war, when it was transferred to W. Tettinek. During the reconstruction phase, extensive soil investigations for large public and private buildings began, as the soil mechanics laboratory of TU Wien is still the only such research institute in Austria.

Furthermore, during this era, K. Klugar built the first large-frame shear apparatus in the Vienna soil mechanics laboratory: a large frame shear device with hydraulic power transmission, suitable for particularly coarse-grained material (e.g. track ballast, etc.).

In 1957, Prof. H. Borowicka was appointed full professor of foundation engineering and soil mechanics. During his time as a full professor, he focused his scientific attention on theoretical treatises on half-space, on the stability of embankments, and on laboratory investigations of the shear strength of soils. The decisive further development of the "Vienna Routine Shear Test" consisted in the fact that the pore water overpressure caused by volume change is eliminated by keeping the pore volume constant by changing the vertical load accordingly during the shearing process. In addition, a way to determine the residual shear strength was found by "shearing back and forth".

Although the laboratory had suffered relatively minor substantial losses during World War II, the equipment could not be expanded in the war and post-war years due to the shortage of materials and money, so Borowicka sought to modernize the laboratory's existing equipment.

For example, triaxial apparatus with pore water pressure measuring devices and a large number of smaller devices were newly purchased. In 1963 and 1964, a walk-in frost room with groundwater simulation, irrigation and a freezing capacity down to -40°C was set up by H. Brandl (the poster Frostraum (PDF), opens a file in a new window gives an insight into the experiment). In connection with a small spatial expansion of the soil mechanics laboratory, further equipment could be accommodated in the following years, whereby - following the tradition of the institute - these were often manufactured in-house.

From 1945 to 1968 the soil mechanics laboratory was headed by W. Tettinek, then by A. Hondl and from January 1969 to 1972 by H. Brandl. This was followed in February 1972 by M. Fross as head of the laboratory, who held it until 2004.

In 1981, H. Brandl (then full professor at the Graz University of Technology) was appointed as successor to Prof. H. Borowicka emeritus. The focus of his diverse research and developments in connection with laboratory tests and in-situ measurements has contributed, among other things, to the development of the "semi-empirical dimensioning" of retaining structures, slope stabilization, foundations in slopes at risk of slipping, etc. His pioneering achievements in the field of geosynthetics and environmental geotechnics should also be mentioned.

Despite the large equipment capacity at that time (e.g. 55 compression devices, shear devices and triaxial devices of various types), an expansion of the soil mechanics laboratory was unavoidable, with special emphasis on special tests, arrangements for large-scale model tests, etc.

In 2006, a renovation with partial conversion of the laboratory premises took place in order to meet the increased requirements for employee protection regulations (installation of a dust extraction system) and to create space for new equipment. For example, several automated devices were purchased to carry out pressure, compression and permeability tests.

In addition, at the end of 2007, a dynamic triaxial device was purchased, which, in addition to the independent dynamic control of axial and lateral pressure, also enables temperature-controlled test from -25° to +120°. These options opened up a wide range of possible applications and uses, which led, among other things, to participation in the planning of the Lobau tunnel of the Vienna Regional Ring (S1) in 2009 in connection with the ground freezing of the cross-passages.

© TU Wien, Institute of Geotechnics

Dynamic triaxial device with climatic chamber.

Dynamic triaxial device with climatic chamber.

_{Abb. 8: Dynamic triaxial device withe climate chamber.}

In addition to these new acquisitions, the automation of the Viennese routine shear test introduced by Prof. Borowicka was also developed - together with a device manufacturer. Since the beginning of its development, the Vienna routine shear test has been carried out in Krey shear devices by means of stepwise loading. For mylonitic soils, for example, which generally suggest a low residual shear angle - but also contain coarse fractions to a certain extent - the mechanical test procedure showed limits. The automated device now allows a much finer recording of the force and deformation data, which allows a more precise evaluation of the fracture process.

From 2004 to 2006, F. Kopf set up a calibration stand for the calibration of dynamic load plates (Light Falling Weight Device) in the soil mechanics laboratory. This is the only such calibration stand in Austria with which calibrations can be carried out in accordance with RVS 08.03.04; these calibrations must be carried out 1 x per year for each dynamic load plate.

After the retirement of Prof. H. Brandl in autumn 2008, D. Adam was appointed to the subsequent head of the institute in spring 2009. To date, Prof. Adam is head of the research unit for Ground Engineering, Soil and Rock Mechanics of the Institute of Geotechnics, which has since merged with the Institute of Engineering Geology (former head: Prof. E. Tentschert). As early as 2005, M. Fross handed over the management of the laboratory to S. Blovsky.

Since the appointment of Prof. D. Adam, the soil mechanics laboratory has undergone an ongoing renewal process (while retaining the "classic" laboratory equipment), numerous new automated laboratory equipment (e.g. compression equipment) have been purchased; among other things, a rock testing press and a large-frame shearing device. Furthermore, a data acquisition system for dynamic measurements was installed, which is an indispensable means of verifying the theoretical and numerical soil dynamics research activities at the institute.

A large number of research assignments (basic research and industrial research) were carried out, which required the involvement of the soil mechanics laboratory. Examples include investigations into ground freezing for the Danube-Lobau tunnel, material investigations for new stabilizing materials, developments for the evaluation of the abrasiveness of coarse grained soil material, investigations into maintenance of rail tracks, development of tests to determine the mechanical properties of glass foam aggregates, tests on samples for low-pressure injection, investigation of of embankments and the behaviour of soils under dynamic loading. Another focus in recent years has been in the field of flood protection and in particular in the development and testing of sealing wall materials for deep soil stabilization.

S. Blovsky headed the soil mechanics laboratory until 2018; In autumn 2019, R. Markiewicz took over the management of the soil mechanics laboratory.

In 2018, the TU Wien and the Bundesimmobiliengesellschaft started the construction of the so-called Science Center (Arsenal site) in Vienna's 3rd district. The background to this was that the previous laboratory facilities of the Faculty of Civil and Environmental Engineering were scattered at various locations in Vienna. With the new building, these laboratory facilities – including the soil mechanics laboratory – were ultimately combined at a common location. The opening took place in autumn 2019.

The shared building has a length of approx. 150 m, a width of approx. 30 m, a height of approx. 12 m and was built on the site of the former district heating plant (the remaining chimney reminds of this) of Wien Energie. The building is founded on piles and is divided into a two-storey part of the building: on the ground floor there are the laboratories and on the upper floor there are offices and seminar rooms, which are also used as lecture halls.

The new building also resulted in significant improvements for the soil mechanics laboratory. The spacious and spacious test hall with a height of 9 m offers plenty of space for the various test facilities. For large-scale tests, a 5 m x 5 m large and 3 m deep test pit with an associated test frame was built. The other laboratory facilities are located in the laboratory rooms adjacent to the test hall. Furthermore, it was possible to build a separate walk-in climate room, for example, to be able to carry out soil investigations in frost conditions. The relocation of all laboratory equipment from the old location at Karlsplatz to the new location in the Arsenal was a major challenge. Many devices had to be dismantled and reassembled for transport; this also involved a recalibration of all measuring sensors.

Since then, further improvements have been made to the equipment and the test methodology. For example, the new construction of the calibration stand for the calibration of dynamic load plates or the reconstruction of a pinhole system for measuring the erosion stability of sealing wall materials should be mentioned.

1. Adam, D.: Einführung aus Skriptum Grundbau und Bodenmechanik. Wien, Auflage SS 2023.
2. Brandl, H.: Die Geschichte des Institutes für Grundbau der Technischen Universität Wien. Heft 2 aus Mittelungen für Grundbau, Bodenmechanik und Felsbau, Wien, 1983.
3. Tettinek, W.: Die Scherfestigkeit von bindigen Böden. Dissertation, Technische Hochschule Wien, Institut für Grundbau und Bodenmechanik, 1951.

4. https://www.tuwien.at/tu-wien/aktuelles/news/news/alle-labors-der-fakultaet-fuer-bauingenieurwesen-kuenftig-im-tu-science-center (18.02.2023)

5. https://www.tuwien.at/tu-wien/campus/tu-univercity/tu-univercity-news/news/eroeffnung-des-neuen-laborgebaeudes-der-fakultaet-fuer-bauingenieurwesen (18.02.2023)