Building Response Analysis for a Tunnel in Escarpment Seismic zone of Ethiopia


Wondemagegne Aseffa and Henok F. Gebregziabher


This study is concerned with tunnel induced ground surface settlement under seismic actions using PLAXIS 2D V 8.6 Finite Element software with plane strain modeling concepts. Practical construction phases were adopted during the numerical analyses to simulate the actual conditions on site, including the seismic effects expected in the study area, Karakore. Comparison of the results of the different phases indicates that the invert excavation and lining phase gives the maximum ground surface vertical settlement of 85 mm. The outputs of the numerical analyses have further been taken as inputs for the building damage analysis using the Limiting Tensile Strain Method (LTSM) to categorize buildings’ damage extent above the tunnel on the ground surface. The building response analyzed using LTSM confirms that the damage extent associated with maximum vertical settlement is found to be within the allowable limits; the one associated with relative settlement of the building edges is categorized as negligible and that associated with relative rotation is categorized as slight.