Stability analysis of a tunnel supported by shotcrete-rockbolt system in hard bedrock

摘要

In tunnel excavation methods that use rock as main support, 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 tunnel. 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.