STABILITY ANALYSIS AND SUPPORT RECOMMENDATIONS IN THE WEAK ROCK AT CROSS CUT XC 662 CIURUG PT ANTAM UBPE PONGKOR

• Main Author: Cahyaningsih, Bimbi
• Format: Theses
• Language: Indonesia
• Subjects: Pertambangan dan operasi berkaitan
• Online Access: https://digilib.itb.ac.id/gdl/view/37113
• Institution: Institut Teknologi Bandung

Underground mining methods have a high security and safety risk, careful calculations are needed in the underground mining process which aims to reduce the risk caused by production activities so that the safety of mining workers is more guaranteed. PT Antam UBPE Pongkor conducts underground gold mining activities by applying the mechanized cut and fill method, in this method, access to the ore through a cross cut. Cross cut is an opening hole that has a vital function as an access to ore deposits. One of them is the cross cut XC 662 Ciurug Pongkor which is an access to ore at level 600 Ciurug. Convergent monitoring results show that during the period September 14, 2017 to April 18, 2018, this cross cut has sustained with a horizontal displacement of 64 mm so that stability analysis for cross cut XC 662 Ciurug is needed. Numerical modeling was performed using phase 2 software with the finite-element method, the properties of material were obtained from the approach of the rock mass classification (RMR System) and then back analysis was carried out by trial and error adjusted to the results of convergent monitoring. The modeling result shows that cross cut XC 662 experiences instability with factor of Safety 1 and requires an additional support strength of 2 MPa. The modeling results with an additional support strength of 2 MPa showed an increase Factor of Safety at monitoring points A, B and C, with value 1.3, 1.3, and 4. Analytical calculation results of the support strength estimation obtain that shotcrete with a thickness of 14 cm can provide support strength 2 MPa.