For a safe and efficient construction of underground structures (e.g., tunnels, galleries, caverns, etc.) it is essential to be provided with a most detailed exploration of the subsurface. Direct observations from boreholes can be ideally complemented with geophysical investigations. Seismic measurements have proven to be particularly appropriate. They are being applied successfully from the surface for shallow structures.
Giese, R., Klose, C., and Borm, G. (2005): In situ seismic investigations of fault zones in the Leventina Gneiss Complex of the Swiss Central Alps. In: Harvey, P. K., Brewer, T. S., Pezard, P. & Petrov, V. A. (eds). Petrophysical Properties of Crystalline Rocks. Geological Society, London, Special Publications, 240, 15 - 24.
Lüth, S., Buske, S., Giese, R., Goertz, A., 2005. Fresnel volume migration of multicomponent data. Geophysics 70(6), 121-129. Borm, G. & Giese, R. (2004): Hochauflösende seismische Gebirgserkundung beim Tunnelbau im Festgestein. Geotechnik 27, Nr. 2, 164 - 167.
Giese, R., Dickmann, Th., Eppler, Th. and Lüth, S., 2006, Seismic tomography to investigate the tunnel surroundings of the Side Gallery West of the multifunctional station Faido. In: Geologie und Geotechnik der Basistunnels am Gotthard und Lötschberg, vdf Hochschulverlag AG an der ETH Zürich, 145 -154.
The project COSC (Collisional Orogeny in the Scandinavian Caledonides) focuses on the mid Paleozoic Caledonide Orogen in Scandinavia in order to better understand orogenic processes, both in the past and in recent active mountain belts. The Scandinavian Caledonides provide a well preserved example of Paleozoic plate collision, where the surface geology in combination with geophysical data supply control of the geometry of the Caledonian structure, both of the allochthon and the underlying autochthon, including a shallow W-dipping décollement surface on a thin skin of Cambrian black shales beneath the Caledonian thrust sheets. The COSC project will examine the structure and physical conditions of these units, in particular the Caledonian nappes ("hot" allochthon) and the underlying basement, with two approximately 2.5 km deep drillholes, located near Åre and Mörsil in western Jämtland/Sweden (http://www.ssdp.se/projects/cosc/).
The DFG-funded project is dedicated to complement the surface seismic measurements by drillhole-based investigations to better resolve and define the small-scale structures (including lithological boundaries, steeply dipping fault segments, fracture sets, etc.) around the drillhole COSC-1. This will be achieved by a combination of seismic transmission and reflection experiments using a 3C borehole geophone system complemented by 3C geophones at the surface.Therefore, sources and surface receivers will be aligned at different azimuths starlike around the borehole location. The data processing will employ recently developed advanced imaging techniques and will focus on, amongst other things, the analysis of anisotropic effects caused by aligned fractures and faults and their relation to the stress regime.
Project period: 01.03.2013 - 28.02.2015 Project Partner: TU Bergakademie Freiberg, Institute for Geophysics and Geoinformatics
The Centre for Scientific Drilling contributes with high-resolution seismic exploration in the underground to the project ProSalz. A natural cavernous structure will be examined along different profiles in the underground mining setting. Furthermore, measurements will be done to monitor an artificial cavity which will be created in a salt pillar. Consequently, cavern-like processes can be observed under in situ conditions.
Core-log-seismic integration (CLSI) is an interdisciplinary strategy, integrating core logging, downhole logging and seismic data, to reduce the key uncertainties associated with formation evaluation. The combination of core, log and seismic measurements merges lab data on samples with in situ logging information and bridges scales from the sub millimetre-scale of core investigations to the decimetre scale of logging data and ultimately the metre to kilometre scale of seismic data. The project aims to investigate the geophysical properties of the rocks from Seve Nappe Complex at the COSC-1 borehole (Sweden) and nearby areas and to establish a high-resolution seismic stratigraphy using a cross-disciplinary approach.
This project is seeking for perspectives of further developments of the Drilling Information System (DIS) toward modern technologies and system architectures. A questionnaire early 2016 among previous and current DIS users shows that the product DIS proved itself quite good, but it has deficits with regard to professionality and state-of the-art technology, platform independence, costs and licensing. In consequence to that a survey has been performed in 2017 to specify the existing or future technological developments for a re-design or even new build of a mobile DIS. The development phase will start in 2018.