MSc Students 2010-2011

Stephan Andreas Christian Bolay

Mapping and Analysis of Exfoliation Fracture Spacing in a new Gallery of the Upper Aare Valley, Central Swiss Alps

At present, a new gallery is excavated with drill and blast between Handegg and Gerstenegg in the Central Aar Granite of the Upper Aare Valley. Most of the gallery is unlined. The area is well-known for exfoliation joint sets (Talklüfte), i.e. relatively young joint sets that are parallel to today's or a former landscape surface. These joints can have a major impact on the stability and safety of near-surface excavations, tunnelling performance, and they can decisively influence the stability of slopes. In addition, exfoliation joints are characteristically restricted to the shallow subsurface with a maximum depth of around 100-200 meters and their spacing is thought to increase with depth (e.g. Jahns 1943).

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Burkhard Philipp Cless

Simulation of transport in very shallow open and closed geothermal field sites

Geothermal heat pumps (GHPs) have evolved as an attractive technology for space heating and cooling. Energy transfer between GHPs and the ground is established by circulating either a heat carrier fluid (in closed systems) or groundwater (in open borehole systems). Commonly such boreholes reach shallow depths and do not go below one or a few hundred meters.
The task of this thesis is the simulation of the thermal transport of two well-studied field cases in Southern Germany: (1) An open system in Kilchberg (close to Tübingen) with long-term measurements of very shallow temperature development in the aquifer, (2) A closed system in Bad Wurzach within a layered aquifer, where downgradient temperature development is continuously monitored. The purpose is to compare the performance of the two different systems, and finally interpret the role of thermal and hydraulic transport processes. Both systems will be simulated with FEFLOW, a user-friendly and very versatile coupled modelling suite.

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Matthias Michael Andreas H. Fries

Elena Gollob

Optimizing an In-situ chemical oxidation system - A case study of the "Tanklager Aschaffenburg"

The “Tanklager Aschaffenburg” in southern Germany is used by the “Deutsche Bahn” since 1890. Due to an oil accident in 1982 at the “Tanklager Aschaffenburg”, the groundwater and soil are contaminated with BTEX (Benzene, Toluene, Ethyl benzene, Xylenes) and polychlorinated Hydrocarbons.

Now the area of the “Tanklager Aschaffenburg” should be remediated due to future demands < 3 years. Thus a new ISCO – system (in-situ chemical oxidation – system) should be tested in a case study at this contaminated site. In the case study, the focus is on the remediation of the BTEX. If it is possible to oxidize nearly all contaminants, the system will be performed on the whole area.

The main objective of the case study is to remediate the contaminated site efficient due to costs and time of remediation. This includes a detailed investigation of the contaminated site, the generation of several 2D – groundwater flow models, the installation of the ISCO – system and the optimization of the system due to hydrogeological parameters.

Lorenz Maurus Grämiger

Prehistoric Rockslides of Gemmi Pass

Glacial erosion and retreat are implicit preconditioning factors of rock slope failures in Alpine valleys. Redistribution of in-situ stress fields, together with changing climate and local environment, lead to time-dependent development of persistent failure surfaces. This project will investigate large late- or post-glacial rock slope failures in the Gemmi area, specifically those at the Kl. Rinderhorn and Daubensee. Special focus will be given to rockslide mechanisms and relative chronology. Cosmogenic nuclide dating will be applied as possible to constrain the failure timing. Further work will analyze the slope failures collectively with other nearby published cases, investigating common attributes and failure mechanisms in the context of Lateglacial ice extents and changing climate.

Patrizia Simona Köpfli

Oeschinensee Rockslide

The Kandersteg area is home to some of the most dramatic examples of late- and post-glacial rock slope failures in the Alps; e.g. the Kandertal rock avalanche. Steeply inclined limestone and marl strata favor dip-slope sliding, and a number of large events are evident. Because the failure mode is generally consistent between sites, the area is ideal to study the mechanisms and timing of large rock slope failures in relation to glacial chronology and Holocene climate change. This project will investigate the very large rock slope failure at the Oeschinensee, and use cosmogenic nuclide dating to constrain the failure timing. Special attention will be given to the relationship with the adjacent Kandertal event, generation of the landslide dam, in addition to runout and failure mechanisms.

Orlando Vincenzo Lanfranchi

The Kaerpf rock slope instability (Canton Glarus)

The Kärpf is a mountain ridge complex with a history of small to large rock slope failures located in Canton Glarus. Although the rock slope doesn't directly endanger any built infrastructure, the area is a favorite destination for hiking, as it lays adjacent to a UNESCO world heritage area. The overall goal of studying the Kärpf instability and it’s surrounds is to determine key factors driving the instability and factors that ultimately trigger failure. Of additional interest in this project is the role of permafrost on rockslope stability, since the site occurs above 2400 m.a.s.l. The Kärpf has been the focus of monitoring in recent years, which has included remote sensing and in situ geotechnical methods (e.g. radar interferometry, laser scanning, photogrammetry, crackmetres, temperature sensors). Along with field mapping and investigations, monitoring data forms the basis of two possible projects in the Kärpf region.

Katrin Mirjam Wild

The influence of rock mass characteristics on TBM penetration – a case study in the Nant de Drance access tunnel

The response of an anisotropic rock mass to a tunnel excavation with Tunnel Boring Machines (TBM) is dependent on the strength of the rock mass, on the relative orientation and degree of jointing as well as orientation of the tunnel axis in respect to the in-situ stress field. On the basis of two well documented tunnel excavation in granitic and gneiss rock masses the performance of the TBM should be analysed in terms of geological and geotechnical conditions. The degree of jointing, the strength of the intact rock and rock mass and its influence on penetration should compared to the achieved penetration rates of the TBM. A review of the applicability and possibly improvement of standard penetration models should be performed.