THE INFLUENCE OF VOID RATIO IN CUT HOLES ON BLASTING ADVANCEMENT FOR VARIOUS DRILLING DEPTHS AND SIZES OF DEVELOPMENT HEADINGS IN UNDERGROUND MINES PT FREEPORT INDONESIA

• Main Author: Archellio Hardios, Jedidjah
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/75208
• Institution: Institut Teknologi Bandung

Blasting in underground mines differs from blasting in open pit mines due to the limited free-face availability that can affect the advancement factor parameters of blasting results. The advancement of underground mine development is vital because it impacts high excavation costs and time, so it is essential to ensure the success of creating a void with cut holes drilling pattern. This study aims to analyze the effect of the void ratio on cut holes by considering the confinement factor ratio of headings to obtain an advancement factor ???? 90% using the logistic regression method. 347 data pairs consisting of primary and secondary data were obtained to build a logistic regression model, namely data on drill hole depth, cut hole geometric design, headings size, and actual advancement of blasting. These data are processed further to determine the value of the confinement factor and void ratio as independent variables and the advancement factor in binary form as the dependent variable. Logistic regression modeling was carried out with SPSS Statistics software and showed promising model fit test results and parameter significance results. The probability equation of a heading succeeding in obtaining an advancement factor > 90% is ????(????????=1)=?????4.891?88.459????????+110.712????????1+?????4.891?88.459????????+110.712????????.. The interpretation of the logistic regression model shows that at the same size headings, shallower boreholes will boost blasting in obtaining an advancement factor ???? 90%. In comparison, a larger void ratio value will result in a high probability of blasting development headings to obtain an advancement factor ???? 90 %. Advancement factor graphs have been made based on specific confinement factors and void ratios to select a drilling design with the best confinement factor and void ratio.