Numerical modelling of the dynamic response of threadbar under laboratory-scale conditions

Abstract

The development of mining and underground excavations under high stress conditions, where the occurrence of seismic events may induce sudden energy release, has generated new challenges and additional research related to the dynamic response of reinforcement systems. To ensure safety of underground excavations, the development of new reinforcement elements able to resist dynamic events and yielding during the loading process has advanced in the last 30 years as a result of research studies and testing programs carried out by recognized institutions. The execution of these testing programs involves a considerable time and requires validation. In Chile, the development of a new laboratory-scale dynamic test facility has required several studies in which numerical modelling is considered as an important part of the design process. This paper presents the implementation and results of a numerical model used to simulate the dynamic response of threadbar under laboratory-scale test conditions. A comprehensive calibration of the numerical model using the results of laboratory-scale dynamic tests available from the literature is presented. The continuous and split configurations for the encapsulating tube are tested and compared. A parametric analysis is performed with the calibrated model. The verification of the model is established with an additional laboratory-scale result not considered in the calibration process. A summary of the results in terms of the dissipated energy and the maximum displacement is presented. The results indicates a linear trend between the dissipated energy and the maximum displacement, and a significant improvement of the dynamic response of threadbar when the steel grade or the diameter of the rockbolt is increased.