Field Investigation of Blast-Induced Damage of the Sedimentary Strata Rock Mass at PT Kaltim Prima Coal, Indonesia

摘要

Five blasting operations at two different pits within PT Kaltim Prima Coal (KPC) were carefully investigated. The areas of interest were Harapan South Pit and Melawan Thiess Pit. The field investigation was carried out to measure the significance of the blast induces fractures within a rock mass. First of all, investigation holes were made and drilled relatively perpendicular with blasting row at near distance behind the last blasting row. To quantitatively determine rock mass fractures, a borehole camera was applied to investigate cracks before and after the blast. A vibration geophone was arranged close to the collar of each investigation hole to monitor peak particle velocity (PPV) of the ground surface. Plotting the PPV as a function of distance divided by cube root or square root of the explosive weight was employed to predict attenuation or decay the PPV. From the data obtained, it was found that the cracks increase proportionally with the PPV.