Prediction of blast-induced ground vibration and rock fragmentation by statistical and combined finite-discrete element modelling methods for the McGill utility tunnel

The prediction of blast-induced ground vibration and rock fragmentation at the McGill Utility Replacement Tunnel was investigated using two techniques: empirical peak particle velocity prediction formulae and combined finite-discrete element method (FDEM) modelling. A statistical analysis of ten scaled-distance empirical formulae was performed by fitting them to 269 vibration recordings and assessing the quality of fit with seven statistical indices. In the FDEM studies, a transient blast loading function was developed for explosive product gases by idealizing explosive detonation and depressurization as the injection and expansion of gas into a borehole. With calibrated material properties and blast loading functions, stress-wave induced tensile and shear fracturing were replicated for a single blasthole. Moreover, synthetic fragmentation patterns and velocity-time histories were produced in simulations of blasting round BR-T66. The influence of free surface wave reflection and material impedance constrasts on ground motion amplification was investigated by comparing recorded and synthetic velocity-time histories.