Browsing by Author "Nyakana, Ivan"

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    Numerical Simulation and Analysis of Railway Tunnel Deformation and Supporting System A Case of Awash-Kombolcha-Hara Gebeya Railway Project (Tunnel T-07)
    (Addis Ababa University, 2019-06) Nyakana, Ivan; Been, Im Soo
    Analysis of tunneling requires proper estimation and prediction of deformations and tunnel supporting system forces in both the shotcrete and lining. In most recent years there has been a rapid increase in the calculation power and improvements of most analysis software that allow the use of complex numerical analyses in tunnel design. Tunneling rock mass has demanded a better understanding of the behavior of tunnel excavation and supporting system for stability purposes. A study on tunnel analysis using numerical finite element method using Structure Medium Analysis Program was explored in this dissertation. Numerical simulation by finite element analysis using SMAP provides an alternative to answer ground settlement, displacements and lining forces since tunneling induces, ground deformation and shows influence of rock mass overburden and geological conditions on the tunnel deformations and supporting system forces. Thus, the problem of stability requires an independent study for each tunnel rock mass zone. The study revealed analysis by numerical simulation by SMAP reported high values in the result compared to the analytical formulation used. From the results of the maximum displacment predicted at the tunnel crown recorded displacement of 50.23 mm and safety factor 2.19. For tunnel excavation stability, the Saftey Factor greater than 1 was computed. In addition, the ground surface dispalacments varies depending on rock mass condition and is higher in lower over burden rock mass. Using numerical solution by FEM for computed maximum displacements around the tunnel revealed higher values in maximum rock mass overburden but also varied depending on the rock mass conditions. In this study, an ultimate compressive major principal stress of was comuputed for the main tunnel and the corresonding supporting system design forces in the final lining i.e liner bending moment of , thrust/axial force of and Shear force of was simulate for Tunnel T07 rock mass and the rock bolt pattern for each rock bolt with an ultimate load capacity of , for diameter diameter and fully grouted rock bolts was estimated numerically.