November 27th 2020 was the last Friday prior to the day of Saint Barbara, who is the patroness of all tunnellers and miners. Traditionally, our institute combines this day with a conference during the day and a social event in form of a come-together and dinner in the evening. We have waited a long time and hoped that due to the low numbers of infections during the summer, the autumn and early winter 2020 would also be quiet. Eventually, we had to cancel the traditional celebration in the evening and transform the conference into an online event.
The online mini-symposium focused on the challenges of Hard Soil and Soft Rock (HSSR) materials in research and practice.
What is Hard Soil and Soft Rock? One characteristic is that such transition material can no longer be described with rock mechanical classification methods but usually also does not meet soil mechanical classifications. It is a challenge to characterise them and to determine characteristic geotechnical parameters based on in situ and lab test data.
What are typical examples for Hard Soil and Soft Rock? Clay-, marl-, sandstone, slate/schist or phyllite, tuffs and stiff clays. A well-known example is London Clay, one of the most studied materials in the world. In tunnelling in Austria, the so-called Schlier is a prominent HSSR candidate, which is a silty or fine sandy marl. Schlier was present in the construction of the new railway line from Vienna to Salzburg (the so-called western line). Another example is the quartz phyllite and green schist at the Brenner Base Tunnel project.
The Symposium 2020 allowed to identify possibilities and limits in the research and practice of HSSR. In the proceeding book, which you can order from us at the institute, you will find contributions on constitutive modelling and anisotropy, tunnelling in fault zones, characterization of and in situ-, site- and experimental investigations on HSSR materials.
Institute of Rock Mechanics and Tunnelling Rechbauerstraße 12 A-8010 Graz