Impact loading of tendon reinforcement systems used for ground control: a critical literature review

The present paper reports on various test methods and techniques which have been developed throughout the last decades. These methods have been used to evaluate both axial and shear performance of tendons under impact loading mode. Based on the literature review conducted on the scientific documents, published between 1992 and 2024, the developed facilities mainly work based on the direct impact and momentum transfer methods. In the direct impact method, which can be done in-situ and in the laboratory, the impact energy is applied by a mass freely falls to the test sample. In the momentum transfer method, the test assembly, consisting of both the mass and test sample free-fall at the beginning of the test until the movement of the assembly is halted by a stopper, and the momentum of the mass is transferred to the test sample. Besides, most of the current facilities are working based on the direct impact method. It was also found that less research have been conducted on dynamic shear testing, especially high-strength cable bolts, as most of the facilities have been designed for pull testing. In addition, it was found that in dynamic pull-out tests of rock bolts, two main mechanisms of energy absorption are identified: steel plastic deformation and bolt sliding within the encapsulation medium. The first impact plays a key role in energy absorption, causing significant permanent displacements, while the energy consumed in displacing the bolt is more indicative of dynamic behavior than the total input energy. According to the results, the tendons that undergo static deformations before dynamic loading are more prone to failure as some parts of their performance have already lost. Meanwhile, differences between dynamic and static shear tests suggest that dynamic tests require less energy for failure, as friction is ineffective in impact loading. Finally, the study highlights gaps in the current understanding of tendon performance under impact loading, with potential research directions aimed at improving safety in underground excavation.

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Opracowanie rekordu ze środków MNiSW, umowa nr POPUL/SP/0154/2024/02 w ramach programu "Społeczna odpowiedzialność nauki II" - moduł: Popularyzacja nauki (2025)