A monitoring campaign to record dynamic pressures generated by detonation of a single blasthole was implemented at Barrick Gold′s Pueblo Viejo Open Pit mine (PVDC), located in the Dominican Republic. Pressure amplitudes beyond the dynamic compressive strength of the electronic detonator′s capsules have the potential to damage these electronic devices, generating misfires along with all the associated risks and entailed safety implications. In most instances, misfires generated from high dynamic pressures are a direct consequence of drilling deviations resulting in blasthole distances smaller than originally designed. Tourmaline Crystal Sensors specifically designed for high dynamic pressure measurements in aqueous media were selected to address the challenge. These sensors are custom-made and require additional instrumentation for proper operation, including signal conditioners and recording equipment capable of capturing simultaneous events, both in their amplitude and frequency components. Field-testing comprised detonation of a single blasthole using current explosive loading practices along with an arrangement of sensors positioned within water-filled drillholes in a spiral configuration. Distances, explosive weights and all 23 dynamic pressure record amplitudes are included along with additional data regarding arrival time and P-Wave velocity estimations. As with typical vibration models, the Scaled Distance concept (D/W1/2) was used to construct an attenuation model relating Dynamic Pressure as a function of Distance (D) and explosive Weight (W). The resulting model, adjusted to a 95% statistical confidence limit (covering 100% of the recorded data) was used to generate a series of curves (Abacus) estimating dynamic pressure as a function of distance for different explosive charges. These curves, in association with permissible pressure limits defined at 50% (FOS = 2) of the dynamic pressure strength reported by manufacturers for both, the 1000bar (Al) and the 1400bar (Cu) capsules; allow for the determination of critical (safe) distances between blastholes. Tests were implemented to cover a variety of field scenarios, accounting for different rock mass types, qualities and water conditions; however, preliminary analysis indicate the convenience of developing a unique trend that considers said variability. This approach allowed construction of a single, simple, unambiguous and operationally applicable design tool to address entailed safety issues.
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