SELECTION OF THE OPTIMUM STAGED EXCAVATION METHOD FOR THE YOGYAKARTA-BAWEN TWIN TOLL ROAD TUNNELS

• Main Author: Timothy Motoh, Rexy
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69407
• Institution: Institut Teknologi Bandung

The Yogyakarta-Bawen Twin Toll Road Tunnels will be constructed in Kragan, Losari village, Magelang, Central Java with 490-510 meters in length. The twin tunnels will have large dimensions (20.18 m x 13.7 m and 490-510 meters in length) and be excavated through soft-moderate soil materials. In this study, 3 staged excavation methods are analyzed to obtain the optimum excavation method. The 3 excavation methods are a combination of the top heading and bench method and the side drift method (Method 1), the three-bench seven-step excavation method (Method 2), and the side drift method (Method 3). 2D numerical modeling was carried out on the three methods using a cross-section at STA 20+435 which is the location with the greatest thickness of overburden. The results show that Method 3 has the smallest vertical displacement (3 cm), compared to the others (5 cm). Each method has a minimum plastic zone and an arch effect is formed close to the excavation boundary. In addition, the three excavation methods have a strength factor above 1.5, so they meet the minimum safety factor for tunnel excavation based on KEPMEN ESDM 1827K/MEM/2018. These results show that three excavation methods can be used to excavate Yogyakarta-Bawen Tunnel, but the optimum method is Method 3, which is the side drift method.