<![CDATA[Abstrak. PT Nusa Halmahera Minerals memiliki beberapa tambang bawah tanah. Tambang bawah tanah Kencana menggunakan metode penambangan cut and fill underground. Tujuan penelitian yaitu untuk menganalisis kinerja rockbolt terhadap kelas massa batuan menggunakan RMR dan hubungannya terhadap kestabilan terowongan pada heading kencana link-sub10-under cut 3 pada tambang bawah tanah. Hasil penelitian langsung di lapangan kondisi masaa batuan yang terdapat pada heading dibagi menjadi 4 section face mapping yang memiliki 2 kelas massa batuan berdasarkan nilai RMR dan Q-System. Nilai section A ; RMR 50 (fair rock), B ; RMR 43 (fair rock), C ; RMR 39 (poor rock), D ; RMR 37 (poor rock) dan Q-System section A ; 10 (good), B ; 7,8 (fair), C ; 3,5 (poor), dan D ; 0,2 (very poor). Hubungan kondisi massa batuan terhadap kekuatan rockbolt dapat ditinjau dari nilai hasil pull out test. Nilai Faktor Keamanan section A ; left wall 1,76, right wall 1,80 section B ; wall 1,7 section C ; wall 1,71 section D ; left wall 1,66, right wall 1,69 (Berdasarkan Analisis Balik Kualitas Massa Batuan Berdasarkan Penyanggaan Eksisting yang Terpasang). Abstract. PT Nusa Halmahera Minerals operates several underground mines, including the Kencana Underground Mine which applies the cut and fill underground mining method. This study aims to analyze rockbolt performance based on rock mass classification using the Rock Mass Rating (RMR) method and its relationship to tunnel stability at the Kencana Link Sub-10 Under Cut 3 heading. Field investigations were conducted through face mapping, and the rock mass conditions at the heading were divided into four sections based on RMR and Q-System classifications. The RMR values are 50 (fair rock) for section A, 43 (fair rock) for section B, 39 (poor rock) for section C, and 37 (poor rock) for section D. Q-System values indicate section A as good (Q = 10), section B as fair (Q = 7.8), section C as poor (Q = 3.5), and section D as very poor (Q = 0.2). The relationship between rock mass conditions and rockbolt strength was evaluated using pull-out test results. The Factor of Safety (FoS) values for all sections range from 1.66 to 1.80, indicating that the installed rockbolt support system provides adequate tunnel stability based on back analysis of existing ground support.]]>
