Abstract. Gold Mining Business Unit (UBPE) Pongkor, PT Aneka Tambang is one of the mines in Indonesia under the auspices of PT. Aneka Tambang, Tbk, which applies underground mining system with cut and fill method. The underground mine is a complex activity mainly related to the unloaded rock force for tunnel making. Underground mining methods are closely related to the stability of openings. This is also due to the presence of different rock characteristics and allows the emergence of weak areas of rock that will lead to rock instability.Classification of rock mass is useful to provide an initial estimate of the need for buffers, as well as to estimate the strength and shifting mass of rocks. There are two methods of rock mass classification are often used, namely Q-System and Rock Mass Rating (RMR).The Research location at mine haulage level l-500, is an underground mine access which is very important for production activity in PT. Antam, Tbk, UBPE, Pongkor. Almost all mining activities pass through the access. Then, the evaluation of factor of safety in this area is so important, to prevent the decrease in the stability of the tunnel and to reduce probability of failure. The research process is based on Rock Mass Rating and Q-System methods, which will be used as input data in RocSupport 3.0 software.Classification of rock mass with RMR method obtained average rating of 59,889 (class III) required support in the form of rockbolts, wiremesh and shotcrete and with method of Q-System obtained average rating equal to 13.01 belonging to medium mass rock group, support needed with using rockbolts. This is evidenced by the results of security factors obtained from GSI (Geological Strength Index) data of> 2.Keywords:RMR, Q-System, GSI, and Factor of SafetyAbstrak. PT Aneka Tambang merupakan salah satu tambang di Indonesia yang berada di bawah naungan PT. Aneka Tambang, Tbk, yang menerapkan sistem penambangan bawah tanah dengan metode cut and fill. Tambang bawah tanah merupakan kegiatan yang kompleks terutama terkait dengan kekuatan batuan yang dibongkar untuk pembuatan terowongan. Metode penambangan bawah tanah sangat erat kaitannya dengan kestabilan lubang bukaan. Hal ini juga dikarenakan adanya karakteristik batuan yang berbeda-beda dan memungkinkan munculnya bidang lemah batuan yang akan menyebabkan terjadinya ketidakstabilan batuan.Klasifikasi massa batuan bermanfaat untuk memberikan perkiraan awal kebutuhan penyangga, serta untuk memperkirakan kekuatan dan perubahan bentuk massa batuan. Terdapat dua metode klasifikasi massa batuan yang sering digunakan, yaitu Q-System dan Rock Mass Rating (RMR).Lokasi penelitian yang berada di mine haulage level l-500, merupakan suatu akses lubang bukaan tambang bawah tanah yang sangat penting bagi berjalannya kegiatan operasi produksi di PT Antam, Tbk, UBPE, Pongkor. Hampir keseluruhan kegiatan melewati akses tersebut. Maka, dilakukannya pengevaluasian faktor keamanan pada akses tersebut, untuk mencegah terjadinya penurunan kestabilan lubang bukaan hingga terjadinya ambrukan. Proses penelitian ini dilakukan berdasarkan klasifikasi massa batuan (Rock Mass Rating & Q-System) yang nantinya digunakan untuk dijadikan sebagai data masukan pada perangkat lunak RocSupport 3.0.Klasifikasi massa batuan dengan metode RMR diperoleh rating rata-rata sebesar 59,889 (kelas III) dibutuhkan penyanggaan berupa rockbolts, wiremesh dan shotcrete dan dengan metode Q-System diperoleh rating rata-rata sebesar 13.01 yang termasuk ke dalam kelompok massa batuan sedang, dibutuhkan penyanggaan dengan menggunakan rockbolts. Hal ini dibuktikan pada hasil faktor keamanan yang didapatkan dari data GSI (Geological Strength Index) sebesar >2.Kata Kunci: RMR, Q-System, GSI, dan Faktor Keamanan
Gold Mining Business Unit (UBPE) Pongkor, PT Aneka Tambang is one of the mines in Indonesia under the auspices of PT. Aneka Tambang, Tbk, which applies underground mining system with cut and fill method. The underground mine is a complex activity mainly related to the unloaded rock force for tunnel making. Underground mining methods are closely related to the stability of openings. This is also due to the presence of different rock characteristics and allows the emergence of weak areas of rock that will lead to rock instability.The mass classification of rocks is the grouping of rock masses over the assessments given based on various information about rocks. Information in the form of characteristics of rocks, stresses, hydrological conditions, and rock composition. Classification of rock mass is useful to provide an initial estimate of the need for buffers, as well as to estimate the strength and shifting mass of rocks. There are two methods of rock mass classification are often used, namely Q-System and Rock Mass Rating (RMR).The Research location at mine haulage level l-500, is an underground mine access which is very important for production activity in PT. Antam, Tbk, UBPE, Pongkor. Almost all mining activities pass through the access. Then, the evaluation of factor of safety in this area is so important, to prevent the decrease in the stability of the tunnel and to reduce probability of failure. The research process is based on Rock Mass Rating and Q-System methods, which will be used as input data in RocSupport 3.0 software.Classification of rock mass with RMR method obtained average rating of 59,889 (class III) required support in the form of rockbolts, wiremesh and shotcrete and with method of Q-System obtained average rating equal to 13.01 belonging to medium mass rock group, support needed with using rockbolts. This is evidenced by the results of security factors obtained from GSI (Geological Strength Index) data of> 2.Keywords: RMR, Q-System, GSI, and Factor of safety