Abstract:
This paper details the use of the LS-DYNA finite element code to numerically simulate a simulated rockburst field test conducted at the LKAB Kiirunavaara underground mine, with the goal of investigating the influence of blast design on the dynamic response of the rock mass. The numerical model, created with Truegrid software, consisted of approximately 15 million hexahedral elements and was solved using a Massively Parallel Processing (MPP) version of LS-DYNA. To accurately represent the blast, the simulation utilized a specialized explosive material model governed by the Jones-Wilkins-Lee (JWL) equation of state (EoS) to model the detonation of the NSP711 explosive. The dynamic response and failure of the rock mass were simulated using the Riedel-Hiermaier-Thoma (RHT) material model, an advanced plasticity model for brittle materials. The model also incorporated the decoupling effect by modeling the air gap between the explosive charges and the borehole wall. Numerical results for particle vibration patterns and crack patterns showed good correlation with field measurements, although the simulated peak particle velocities (PPVs) were lower, which may be attributed to the model not including the pre-existing fractured zone near the tunnel wall. The study further used the validated model to perform a parametric analysis on the effects of the blast initiation point and charge structure, concluding that both factors strongly influence the dynamic response of the rock mass and the resulting PPVs on the tested panel.
