Design of frozen earth structures for shafts, tunnels, and cross passages has evolved since the publication of guidelines in 2002 by the Working Committee of the International Sym-posium on Ground Freezing. This evolution is due to the development and implementation of numerical modeling methods, specifically the finite element method (FEM). The design was previously based on determining a thickness of the frozen earth structure with an av-erage frozen temperature. The factor of safety was incorporated by dividing the unconfined compression strength of the frozen soil by two, and thus F.S. = 2. The finite element model allows more specific analysis of a frozen structure cross section and adjusting strength parameters based on temperature and time-dependent strength reduction. Analyses results permit the evaluation of the internal stress regime of the frozen earth structure. This paper discusses the procedure and reports on key recent projects.
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