APPLICATION OF PRESPLITTING IN NORTH TUTUPAN PIT BY PT SAPTA INDRA SEJATI JOBSITE ADARO, SOUTH BORNEO

• Main Author: Angsetya, Philip
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/43934
• Institution: Institut Teknologi Bandung

Blasting is a rock breakage method whose one of its negative impacts is damaging the slope that is intended to be formed if the energy used in the blasting is excessive. One of the hazardous effects of blasting to the slope is the formation of backbreaks in the area that will become a slope. To avoid the creation of a backbreak, a controlled blasting method is generally used, in which the energy produced in an explosion of a controlled blasting is made in such a way as to optimize the results of blasting in critical areas, such as the final slope. One of the controlled blasting methods that will be tested is presplitting because the use of the line drill method that has been applied is considered ineffective. The trial is conducted at the Pit North Tutupan of PT Adaro Indonesia which is operated by PT Sapta Indra Sejati. The design of the presplit blasting is made empirically using the equation of Chiappeta (1991) and the radial stress analysis equation by Brady and Brown (1985), then the results of the test are evaluated visually in the field. The first trial was conducted to find out the optimal blasting geometry that can be used for presplitting in final slope. From the results of the trial it was found that in trial 1, backbreaks was found at a distance of 1 to 2.3 meters behind the row of presplit holes eventhough fracture was formed between all holes in trial 1. Which is why in the second trial, a 4 meter spacing between hole was chosen, but the result was not optimal due to wet holes because of holes drilled in sandstone areas that contained high concentration of water. Therefore, in trial 3 the same spacing was carried out with trial 2 with same location and with stronger rock mass so that the presplit holes were dry. From trial 3 it was found that a fracture was formed between holes and no backbreak was found in trial 3. Therefore, blasting presplit for blasting in the final slope can be done with a presplit hole spacing of 4 meters.