|
Geological engineering characteristics in diversion tunnel Bagong Dam Area, Trenggalek District, East Java Province a) Graduate Student in Underground Geological Structure, Departement of Geological Engineering, Faculty of Engineering, Gadjah Mada University, Yogyakarta 55281, Indonesia Abstract Knowing engineering geological characteristics is very important to prevent tunnel construction failure. The Bagong Dam inversion tunnel is 480 meters long with a trajectory under the main dam body. During the construction phase, new information was found regarding the lithology and geological structure, so it was necessary to update the engineering geological characteristics of the tunnel area. This paper aims to identify the tunnel area^s engineering geological characteristics, including morphological units, lithology, geological structure, XRD testing, and identification of rock mass quality using the Rock Mass Rating (RMR) method. The research area consists of steeply sloping hills morphology and sloping hills. The tunnel site comprises two main lithologies: slightly weathered calcipulverite limestone and moderately weathered andesite breccia with interbedded claystone. XRD testing shows that the clay is dominated by mineral smectite at 15.66 A. Alteration of limestone and breccia was also found in surface and subsurface observations. The tunnel trajectory will pass through limestone with a fair RMR value (41-58) and andesite breccia with interbedded claystone with a poor to fair RMR value (20-58). In the project implementation method, paying attention to the interbedded claystone area is necessary because it has a lower rock mass quality value. Keywords: Tunnel, engineering geological, lithology, XRD, RMR Topic: Hydrology, hydrogeology, and geology engineering |
| ICPMGET 2024 Conference | Conference Management System |