This paper discusses effects of the combination excavation method, namely bench cut and drift advancing which used together, for tunnel constructions in squeezing ground. A case history of Nikkureyama II tunnel construction is particularly used to illustrate typical concerns. A numerical model of 3D finite difference method (3D-FDM) was carried out to simulate the execution works. A comparison with a full-face method of excavation was included into the analyses. An optimum length for a bench and a drift excavation is proposed in order to achieve the rational tunnel construction method.
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