Abstract
Numerical simulation is a useful tool in investigating the loading performance of rock bolts. The cable structural elements (cableSELs) in FLAC3D are commonly adopted to simulate rock bolts to solve geotechnical issues. In this study, the bonding performance of the interface between the rock bolt and the grout material was simulated with a two-stage shearing coupling model. Furthermore, the FISH language was used to incorporate this two-stage shear coupling model into FLAC3D to modify the current cableSELs. Comparison was performed between numerical and experimental results to confirm that the numerical approach can properly simulate the loading performance of rock bolts. Based on the modified cableSELs, the influence of the bolt diameter on the performance of rock bolts and the shear stress propagation along the interface between the bolt and the grout were studied. The simulation results indicated that the load transfer capacity of rock bolts rose with the rock bolt diameter apparently. With the bolt diameter increasing, the performance of the rock bolting system was likely to change from the ductile behaviour to the brittle behaviour. Moreover, after the rock bolt was loaded, the position where the maximum shear stress occurred was variable. Specifically, with the continuous loading, it shifted from the rock bolt loaded end to the other end.
Highlights
The stability of underground excavations directly influences the safety of underground operators, inducing a threat on the production of mining activities
Numerical simulation is a useful tool in investigating the loading performance of rock bolts
The bonding performance of the interface between the rock bolt and the grout material was simulated with a two-stage shearing coupling model
Summary
The stability of underground excavations directly influences the safety of underground operators, inducing a threat on the production of mining activities. To evaluate the loading performance among rock bolts and rock masses, numerical simulation is becoming more widely used. Based on the EFEM, the displacement and the stress in the rock bolt tendon can be simulated Credibility of this numerical model was successfully validated. Ma et al (2016) studied the shear coupling behaviour of the interface between the bolt and the grout and developed a numerical model to simulate the performance of rock bolts. An approach was proposed to incorporate this two-stage shear coupling model into FLAC3D to modify the current cableSELs. After it, a numerical pulling test was conducted with the modified cableSELs. The numerical pulling results were validated with experimental results, confirming the credibility of the modified cableSELs. Last, based on the modified cableSELs, the influence of bolt diameter and grout shear strength on rock bolt performance was studied. When pulling force increased, the shear stress distribution at the bolt/grout interface along the bolt was investigated
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