STABILITY ANALYSIS OF THE COMPOSITE SUPPORT AT NANJUNG WATER TUNNEL USING ANALITYCAL AND NUMERICAL METHOD

• Main Author: Eka Putra Abdillah, M
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/47202
• Institution: Institut Teknologi Bandung

Nanjung Water Tunnel is a twin tunnel located in Nanjung, around Curug Jompong, Margaasih District, Bandung Regency. The construction of the tunnel is a national strategic project intended to reduce the flow of Citarum river water by dividing river flows so that it passes through the water tunnel. The Nanjung Water Tunnel will penetrate a weak layer consisting of Silty Clay, Sandstone, Dacite and Soil-Cement. This tunnel is mostly constructed in the Sandstone type rock layer so it requires a good support system so that the function of this tunnel can be optimal. In accordance with the contractor's plan, the main support system of the Nanjung Water Tunnel is a composite support consisting of steel set coated with shotcrete. This study aims to evaluate the stability of the Nanjung Water Tunnel support system analytically using the convergence-confinement method, and numerically using twodimensional modeling using RS2 software to obtain support capacity diagrams. GRC and SRC graphs created from analytical calculations show that the displacement value when the support system was newly installed is 0.029 m with a maximum capacity of the composite support system of 1,078 MPa so that the SF value is 5.75. Numerical modeling represents the condition of the support system on STA 175 which has been installed for several days but has not yet reached the final lining. The results of the Support Capacity Diagram formed show all the points in the T1 tunnel are in SF > 1 envelope, both seen from the steel set and shotcrete capacity diagrams. Analytical and numerical SF calculation results show values above 1 so that it can be concluded that the support system applied in the Nanjung Water Tunnel is correct and the support system can be said to be stable both when newly installed and when it has been installed for a long period