The 1991 German geoscientific expedition to northem Spitsbergen will take place from May 15 to August 21, 1991. It is supported mainly by the Deutsche Forschungsgemeinschaft (DFG). As in 1990, some 45 geographers, geologists and biologists will visit the Liefdefjorden area and conduct research under the general topic "Land-Sea Sediment Transport in Polar Geosystems." Permafrost-related topics are mainly treated by L. King, Giessen (glacial geomorphology and ground ice), H. Liedtke, Bochum (periglacial geomorphology), and G. Stablein, Bremen (pemafrost mapping). The complete list of working groups was published in Frozen Ground, No. 8. Some working groups intend to continue their permafrost-related research on Svalbard in 1992.
On the engineering side, and with respect to artificial ground freezing, investigation of the properties of frozen soil continued at several university institutes. Deep shafts in frozen ground are under construction; the shaft of Rheinberg especially deserves mention. Artificial ground freezing also is used frequently in tunneling. For a major project the main problems are
thedrillingof roughly 100-meter-long horizontal freeze pipes and the increase of water content needed to achieve the required strength of the frozen ground above the water level.
Another field of research for engineers is investigation of the frost susceptibility of mineral layers within the sealing systems of landfills. In central Europe this problem is serious, especially in the construction phase, when the mineral lining system is not covered.
Prof. Dr. Lorenz King