Study of Tunnel Support Methods Based on RMR and Q-System Methods at Kerinci Merangin Hydropower Jambi Province

Excavation of tunnel construction at the Kerinci Merangin Hydropower in Jambi Province is a complex job, because it will use the tunnel as a waterway which will always be faced with unstable conditions. One of the way to deal with instability is to classify the mass and determine the type of support on the roof and walls using empirical methods. The parameters in rock mass classification include mapping the structure, physical and mechanical properties of the material. Empirical analysis was carried out using the Rock Mass Rating (RMR) classification and the Q-System to determine the condition of the rock mass in the tunnel and determine the type of support that will be used and in accordance with the rock mass class. The rock mass classes in the study area of STA 8+869, 8+872 and 8+879 based on the RMR classification are included in rock class III, namely rocks that have moderate conditions (fair quality rock mass) and rock class IV, namely rocks that have poor conditions (poor quality rock mass). Meanwhile, the rock mass class based on the Q-System includes very poor rock mass.

The recommendation for supporting the tunnel face according to RMR in the study area is to use a combination of rockbolt, shotcrete and wiremesh supports, while the support recommendation according to the Q-System uses a combination of rockbolt and shotcrete supports.