Tunnel face mapping for empirical assessment to determine the method and type of tunnel excavation on the outlet side of Budong-Budong Dam diversion tunnel, Central Mamuju, West Sulawesi Provinceple Abstract
J P Wibowo 1.2, H Setiawan 1, and D Karnawati 1

1 Department of Geological Engineering, Faculty of Engineering, Universitas Gadjah Mada, Indonesia
2 Ministry of Public Works and Housing, Jakarta, Indonesia Indonesia

Abstract

Determining the method and type of tunnel excavation is important, especially when the tunnel enters the construction phase where there are differences between design data and field data. Budong-Budong Dam, was designed used a tunnel diversion and now the tunnel enters the construction phase. The face mapping in the outlet side of Budong-Budong Dam diversion tunnel has been done with the rock mass quality parameters of the RMR and GSI classifications as research subjects. The RMR classification was used to determinate the excavation method, while the GSI classification was used to determinate the excavation type. Geological data were collected by geological surface mapping and face mapping. The outlet side of diversion tunnel composed by Tuffaceous Breccia. The rock mass quality categorized as good rock on RMR and GSI classification. Hence, the recommended excavation method is a full face method and the recommended excavation type is blasting.

Keywords: excavation, diversion tunnel, GSI, rock mass rating, face mapping

Topic: Geodynamic and subsurface geology