Laboratorial Tests and Numerical Modeling of Rock Bolts Bonded by Different Materials

• Published in: Rock mechanics and rock engineering 2023-04, Vol.56 (4), p.2589-2606
• Main Authors: Małkowski, Piotr, Feng, Xiaowei, Niedbalski, Zbigniew, Żelichowski, Mateusz
• Format: Article
• Language: English
• Subjects: Adhesion; Bolting; Bonding strength; Boreholes; Civil Engineering; Coal mining; Computer simulation; Concrete; Curing; Curing (processing); Deformation; Earth and Environmental Science; Earth Sciences; Finite element method; Geophysics/Geodesy; Investigations; Laboratories; Mathematical models; Mechanical analysis; Mechanical properties; Mines; Mining engineering; Numerical models; Optimization; Original Paper; Pull out tests; Rock; Rock bolting; Rock bolts; Rocks; Simulation; Stiffness; Tests
• ISSN: 0723-2632; 1434-453X
• DOI: 10.1007/s00603-022-03191-1

The interaction between bolt and rock is crucial to its reinforcing efficacy. Effective bolt installation depends on the bonding/coupling type and its ability to adhere to the rock in a drilled borehole. In this study, three bond types were considered for rock bolting: resin, Fasloc , and an organic mineral glue, Verpensin T , both of which were provided by DSI Underground and a CEM I 42.5R cement bond. The bonds were tested in the laboratory. The bonding properties were checked and then pull-out tests on bolts installed in concrete were carried out. During the investigations, both bond strength and bond stiffness were determined. Based on the experiment data, ABAQUS numerical models were established based on a Fasloc-bonded specimen to investigate the mechanical behavior of the three bond types. The results indicated that the numerical model could favorably support the pull-out test results. Afterward, a series of numerical simulations were carried out by a finite element program RS2 from Rocscience. The simulations were based on two fictitious engineering scenarios with different geologies. The results indicated a weak relationship with the bonding materials and this was suitable for all models. It seemed that the strata selected for simulation played a decisive role. In addition, interesting results such as stress/displacement distribution zones were established. Finally, the Rocscience results were compared to FLAC results for calibration and optimization. The results of this study can deepen our understanding of the interaction between bolts and rock, especially when their mutual mechanical response is transmitted by different types of materials. Highlights Three kinds of bonding materials for rock bolts were tested considering different curing times. Pull-out tests of rock bolts bonded by different bonds indicated a favorable impact of curing time on mechanical performance. Multiple numerical approaches including ABAQUS, Rocscience, and FLAC were employed to better understand the inner mechanism.