Thesis (Ph.D.) - Cairo University - Faculty of Engineering - Department of Civil Engineering

With the population increase of the old urban cities, the use of tunnels has become the primary means for the establishment of public facilities and infrastructure. This needs sometimes lead to the need of intersection of tunnels or some other structures such as bridges, which needed a detailed study for the impact new tunnel excavation on the existing tunnel or facilities. This thesis aims to use three-dimensional finite elements in numerical simulation of the tunneling process, and the model takes into account the technique used in shield machine. Also, the study aims to find the most appropriate ways to reduce destructive impacts to neighboring facilities; analyze and identify risks and propose a mitigation procedure. The model was applied to the case study of the intersection between Cairo Metro line 3 tunnel (diameter 9.45m) underneath main sewage tunnel (diameter 5m) at Bab El-Shaaria Square in Cairo, which took place in November 2010. The 3D model succeeded in the simulation of the different tunneling excavation phases and calculates their effects on the existing sewerage tunnel. This model can be used in future works to take the necessary measures to determine the most appropriate tunnel route, level, or implement a soil treatment with limited dimensions in the intersection area to reduce the soil movements to the possible limit. The study includes a parametric study to determine different parameters that control the soil subsidence at the intersection of the tunnels area to be used for the future and to take the appropriate actions at the right time for these vital installations and structures

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