The impact of climate change on the integrity of structures built on permafrost has been widely discussed (US Arctic Research Commission 2003; ACIA 2005). The problem is twofold. Firstly, it is a prediction of behavior of existing buildings, and secondly, it concerns approaches to design for future conditions. Both are very difficult for design engineers to solve, because of uncertainties involved in existing climatic models and the wide range of results predicted by different climate change models. To predict climate-change impact on existing buildings, it is necessary to assess the thermal regime of the permafrost beneath the buildings, the factor of safety implemented in the designs, and change in the bearing capacity of foundations during the service life of the buildings.
Design engineers do not operate with definitions like "possible, very likely, likely to" and so on. It would be easier for engineers if the result of climate-change discussion could produce a quantitative method which could be used for design. The discussion of climate-change impact on structures in permafrost regions requires a thorough analysis of existing design approaches and of existing methods of maintenance of conditions expected in design. It also requires an analysis of current causes of existing damage to infrastructure, and understanding of their relevance or irrelevance to climate change. The most extensive engineering studies of permafrost as a base for buildings and structures were accomplished in Russia and Northern America between the 1950s and the 1970s. They led to development of design approaches and supporting engineering means (Zhukov 1958; Saltykov 1959; SN 91-60 1963; Dokuchaev 1963; Long 1966; Tsytovich 1975; Velly et al. 1977; Johnston 1981; Technical Manual 1983). Numerous studies have been performed to understand the causes of building failures on permafrost (Bondarev 1957; Shamshura 1959; Lukin 1966; Voytkovsky 1968; Goncharov et al. 1980; Kronik 2001; ACIA 2005; Alekseeva et al. 2007).
Department of Civil & Environmental Engineering, P.O. Box 755900, University of Alaska Fairbanks, Fairbanks, Alaska 99775-5900, USA e-mail: [email protected]
R. Margesin (ed.) Permafrost Soils, Soil Biology 16,
DOI: 10.1007/978-3-540-69371-0, © Springer-Verlag Berlin Heidelberg 2009
Although engineering means to control permafrost are constantly improving, the main approaches to design for permafrost conditions remain the same. These approaches are shown in Fig. 17.1. The two main approaches, "passive" and "active", bear names given in Russia in the 1930s and were brought to Western knowledge by Muller (1945). In Russia they are known as Principle I (use of soil in the base of structures in its permanently frozen state) and Principle II (use of soil in thawing or thawed state). The Technical Manual (1983) calls them design alternatives. They are not. An alternative implies another choice. Unfortunately, in most cases accommodation of changes associated with soil thawing under structures can not be implemented as an alternative to maintenance of the frozen state of soil.
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