Comparative effects of twin-stacked tunnel excavation on adjacent structure using different simulation models

The increase in transportation in urban areas has made it inevitable to excavate the twin-stacked tunnels and consequently affect adjacent structures. Therefore, an appropriate evaluation of the impact of tunnel excavation on the nearby building has been necessary to prevent the damage that may occur to the structure. In current engineering practice, there are various methods with different degrees of complexity to assess the impact on the building. This study presents a comparison of the effect caused by twin-stacked tunnel excavation on adjacent pile-supported structures by using three different simplified analysis methods. The results reveal that each method gives different results and the distance between the tunnels and the nearest pile affects the computed results. This study indicated that the tunneling analysis with the loaded pile method (FEM-LP) is more appropriate and conservative for the building impact assessment of the piled supported structures. The tunneling in green field (FEM-GF) conditions is proven to not be the conservative method.