Abstract

Squeezing phenomenon resulting in the time dependant convergence of tunnel is one of the most important problems in deep tunnel constructions and should be considered in the most modern tunneling operations. Usually at great depths, due to tunnel excavation in soft rocks or near fault zone, the induced stresses may exceed the shear strength of rock mass and squeezing the rock into the excavated areas. Designing a suitable support system is the important factor which could decrease the difficulty of excavation in such difficult ground conditions. The approach advocated in this paper is designed to help engineers to use the available two-dimensional analysis tools to design a realistic tunnel support system, which takes into account the three-dimensional stress environment in the region of support installation.

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