• Geotechnical Engineering
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• v.37 no.3
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• pp.37-43
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• 2021

• Tunnel and Underground Space
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• v.24 no.5
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• pp.395-403
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• 2014

In this study, a steel pipe type rockbolt manufactured from special material was developed which has high strength and lightweight characteristics. Achievement of grout filling between rockbolt and hole wall was investigated through grout injection tests. Yield force of the developed rockbolt was also examined through tensile tests, which was compared with that of the deformed bar type rockbolt. In addition, the strength and elongation properties of the developed rockbolt were investigated through pull-out tests at three domestic sites showing different RMR classes. It is finally supposed that the developed rockbolt can be suitable for the permanent tunnel support because it has high strength and high durability rather than deformed bar type rockbolt.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.124-131
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• 2010

Rock Bolt generally utilizes deformed reinforcing bar welded from structural steel of which strength is higher than required for making advantageous use of the support function of ground. In the condition with highly corrosive underground water, however, problem frequently occurs on tunnel and slope stabilization in terms of repair, rehabilitation and maintenance issues due to the destruction of Rock Bolt by corrosion of steel. A structural performance evaluation for GFRP Rock Bolt was conducted for the purpose of resolving the foregoing problem and at the same time developing a permanently-usable support material. This study intended to evaluate the safety factor of GFRP Rock Bolt by implementing the slope stability interpretation via structural analysis on the basis of its structural characteristics derived from both tensile force function test and shear force function test. It is judged based on the results that GFRP Rock Bolt would secure sufficient ground stability as an alternative material for existing Steel Rock Bolt.

• Tunnel and Underground Space
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• v.28 no.5
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• pp.442-456
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• 2018

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.