YES-27-D-10: No Bad Vibrations – Characterising the full seismic wavefield to better control ground vibrations in large-scale rock blasting

No Bad Vibrations – Characterising the full seismic wavefield to better control ground vibrations in large-scale rock blasting

Blasting in rock naturally causes seismic waves and potentially large ground vibrations. Nevertheless, drilling and blasting is an essential tool in both mining and quarrying as it remains a most efficient method of rock excavation. This negative impact needs to be mitigated against by predicting and controlling ground vibrations to be within acceptable limits. These seismic waves are not just undesirable they can potentially trigger more serious failures. Surprisingly, while in many engineering fields mechanistic numerical modelling has replaced or at least reinforced empirical design criteria, this has not occurred in blasting where empirical methods still dominate. The key difficulty for modelling accurate vibrations in rock blasting is scale. Complex models of the actual gas explosion are successfully used at small scales. However, large-scale blasting can include tens of thousands of individual blastholes with complex timing patterns. Researchers have therefore used intermediate scale elastodynamic models to model seismic waves at distances of tens and hundreds of metres by simplifying the individual blast sources. For example, Hildyard and Milev (2001, SAIMM, “Simulated rockburst experiment … ”) took the code WAVE developed for modelling seismic events and implemented a simplified blast model which directly captured some aspects such as each individual detonation, charge length, velocity of detonation, detonation direction, mass, and timings while avoiding the complex gas explosion and fragmentation processes. It was able to model these seismic waves over distances of tens and hundreds of metres. Such models have recently been applied to very large-scale blasting (Linzer, 2023). The hypothesis in this project is that the key limitation has not really been the models. Rather it is the sparseness of the sampled wavefield. Typically having very few recordings to constrain the wavefield from a complex source and complex medium, hence limiting validated effective models. The primary aim of this project therefore is to design field experiments which massively change the scale and quality of data available. Through University of Leeds and partners you will have access to new technologies like distributed acoustic sensing (DAS) using fibre optic cables as well as large numbers of Mems-based seismic sensors, cableless triaxial seismic nodes, along with traditional geophones to design field experiments which provide a leap in the type of data available in this field. You would then characterise the complex seismic wavefield from blasting providing important and unique datasets. Using WAVE (Hildyard, 2005) you will also make the first modelling attempts to reproduce this seismic wavefield and will reach more robust assessments of the potential for direct seismic wave modelling in the field of blast vibrations and design.