STABILITY ANALYSIS IN NANJUNG DIVERSION TUNNEL CAUSED BY EXPLOSIVE VIBRATION BY USING 2D NUMERICAL MODELING WITH FINITE ELEMENT METHOD

• Main Author: Laurenzha, Luna
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/40372
• Institution: Institut Teknologi Bandung

Nanjung Diversion Tunnel is one example of a twin civil tunnel used to increase the water flow rate of the Citarum River in the Curug Jompong area to reduce the area and time of inundation during a flood in Bandung.This Final Project Report discusses stability analysis in Nanjung Diversion Twin Tunnel in T2 due to blasting vibrations in the other tunnel(T1). The analysis was carried out using the two dimensional numerical model of finite element method using Rocscience Phase2 8.0 by input load parameters due to blasting event ie seismic load and blast load. Modeling is done in plain strains using Mohr-Coulomb collapse criteria. Some assumptions are used, such as isotropic material, hydrostatic, etc.The modeling is divided into 3 conditions; static condition, given a seismic load, and given a maximum blast load 0.57 MPa. Modeling is done in STA 75 when T2 excavated and supported, and than blasting is carried out in T1. Stability analysis in T2 by determining 12 observation points during T1 is being blasted. The modeling results shows that T2 is stable when T1 is being blasted as indicated by the strength factor values obtained by each condition, strength factor ? 1. This analysis compare strength factor with seismic load and strength factor with maximum blast load. Modeling results generally shows that strength factor in seismic load is lower than with blast load condition and graphic trend is similar from both condition. Blast load calculation is important when planning blasting design to estimate tunnel stability, measurement of seismic load is also important for monitoring actual conditions in the field.