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TUNNEL DESIGNING AND CONSTRUCTION PROCESS IN DIFFICULT GROUND CONDITIONS USING CONTROLLED DEFORMATIONS (ADECO) APPROACH; A CASE STUDY (2018)
The 10.6 km long Sabzkuh water conveyance tunnel is currently under construction in the High Zagros structural zone, located in western
Iran, through conventional (in section T1) and mechanized (in section T2) methods. The section T1 of the tunnel driven through alluvial
geological units with a great complexity in an area of highly potential for sliding and water-bearing fault which has made the excavation
operation encounter many challenges. After excavating 35 m of the tunnel using conventional methods, geological problems and the inappropriate method of the tunnel excavation resulted in the tunnel collapse and failure in the tunnel inlet portal. After the incidence of the collapse, the Design and Construction Process (DCP) of tunnels were revised by using an Analysis of Controlled Deformations in Rocks and Soils (ADECO-RS) in conjunction with the Sequential Excavation Method (SEM). The ground improvement in the portal and tunnel excavation continued in five phases including survey, diagnosis, therapy, operation, and monitoring. The application of this approach into construction of Part T1 of the tunnel increased the safety and minimized risks and costs, despite geological complexities and hazards.
Moreover, the excavation process with appropriate daily advance rate of 1 to 1.5 meters was achieved according to a predicted schedule.
International Journal of Mining and Geo-Engineering - IJMGE 52-2 (2018) 149-160
Young Researchers and Elite Club, South Tehran Branch, Islamic Azad University, Tehran, Iran