Simulation of stress field condition during Waller Creek tunnel construction with a 2D finite element model
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Two-dimensional (2D) Finite Element Method (FEM) analyses are widely used as a tunnel design tool. These analyses are used to establish the initial support requirements, to estimate ground displacements and to design support systems to have adequate capacity and stiffness. Due to the complexities of ground characteristics, construction methods and the interactions between the ground and initial support lining systems, it is valuable to compare predictions from design analyses with field measurements. The objective of this thesis is to compare FEM results with field measurements for stresses in an initial support lining system for a tunnel constructed in shale using the Sequential Excavation Method (SEM), the Waller Creek Tunnel in Austin, Texas. The major conclusion is that the predictions of liner stresses from FEM are greater than what was measured in the field, particularly for the thrust in the liner. While assuming that the ground is 20 times stiffer produces predictions closer to the measurements, the predictions are still greater, particularly for the thrust. One possible explanation for the discrepancy between predications and measurements is that the stress cells did not have intimate contact with the liner.