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http://dx.doi.org/10.7474/TUS.2018.28.5.442

Evaluation of Reinforcement Effect of Rock Bolts in Anisotropic Rock Mass Using Tunnel Scaled Model Tests  

Kim, Jong-Woo (Dept. of Civil Engineering, Cheongju University)
Publication Information
Tunnel and Underground Space / v.28, no.5, 2018 , pp. 442-456 More about this Journal
Abstract
Scaled model tests were performed to evaluate the reinforcement effect of rock bolts in anisotropic rock mass. For this purpose, two tunnel cases were experimented which had different tunnel sizes, rock strengths, anisotropic angles and coefficients of lateral pressure. The fully grouted rock bolts of the D25 deformed bar were modeled as the basting pins with bead and were systematically installed at the roof and the side wall of the model tunnel. As results of the first case experimentations, the unsupported model showed initial crack at the roof of tunnel, but the supported model with rock bolts showed initial crack at the floor of tunnel where rock bolts were not installed. The crack initiating pressure and the maximum pressure of the supported model with rock bolts were 11% and 7% larger than those of the unsupported model, respectively. Moreover, the effect of the existing discontinuities in anisotropic rock mass on the fracture behavior of tunnel was reduced in the supported model, and so the reinforcement effect of rock bolt turned out to be experimentally verified. As results of the second case experimentations considering different support patterns, the crack initiating pressures of models were larger and the reduction ratios of tunnel area according to applied load were smaller as the length and the quantity of rock bolts were larger. Therefore, it was found that the performance of the rock bolts turned out to be improved as they were larger.
Keywords
Scaled model test; Rock bolt; Reinforcement effect; Anisotropy; Crack initiating pressure;
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