Many field problems in underground excavations occur in regions whose geometrical dimensions are very small compared with those of the the surrounding media.
In such cases, finite elements are able to model the region of interest fairly well, but they are unable to model the surrounding media which extend to infinity. Therefore, an appropriate boundary must be introduced in the analysis, and this often leads to inaccuracies in computed results.
Hybrid type idealization, which models the region of interest with finite elements and the surrounding media with infinite elements, is perferable for this type of problem.
Two type of infinite element; i.e. 'Mapped' infinite element and 'Isoparametric' infinite element, are formulated in this paper.
Parametric studies with respect to hybrid model are performed to evaluate the applicability of the formulated infinite element in tunnel stability analysis.
