In tunnel excavation methods that use rock as main suppol1, shotcrete and rockbolt are installed to help the formation of ground arch region as a primary reinforcement. For the evaluation of tunnel stability in hardrock, the ground displacements, convergence and the internal forces of reinforcements have been measured on representative 6 sections of Utility. Also, the numerical modeling is performed. Deficient investigation data and the heterogeneity of rock properties might cause impreciseness of numerical modeling output and measured data analysis. To avoid these problems, the analysis area and overburden loads were corrected to fit more safe criteria, and the properties of shotcrete-rock interface, that were estimated through experiments, were applied to the numerical analysis. The measured data and numerical output analysis showed that ground displacements after excavation reliably converged without introducing plastic zone and the internal forces of reinforcements are under failure limits.


The concept ofrock support in modern tunnel excavation method is to use the rock as structural materials to support itself. Most rocks are considerably stronger, especially in case of hard bedrock, and so the problem conceptually is merely to form ground arch region by assistant support such as shotcrete and rockbolt (Bickel & King, 1996). In these tunnelling methods, concrete lining do not act as structural member except for some cases as follow.

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