Abstract: The geohazards, such as, groundwater rush, collapse and excessive deformation, are frequently encountered in the tunnel excavation by Tunnel Boring Machine (TBM). These hazards might result in jam, burry and even the completely loss of TBM equipment. In order to minimize the potential risks, an advanced prediction system can be introduced in the TBM excavation to predict these adverse geological conditions and to prepare the mitigation measures. As the first application of TBM excavated tunnel in Pakistan, the tunnel for the NeelumJhelum hydroelectricity project is located at southern side of Himalaya Mountains and no previous long distance tunnel was constructed. In order to control the potential risks and geohazards, three independent advanced prediction systems, namely, Integrated Seismic Imaging System (ISIS), Tunnel Seismic Tomography (TST) and a conventional advanced prediction system, were installed in the tunnel excavation. The results demonstrated that these systems provided a large amount of useful information regarding the rock mass conditions and facilitated the tunnel excavation.

Key words: Himalaya Mountains, Tunnel Excavation by TBM, Integrated Seismic Imaging System (ISIS), Tunnel Seismic Tomography (TST), Advanced Drilling