| Summary: | 碩士 === 中華大學 === 土木工程學系 === 86 === The purpose of this study includes (1) to use the finite element analysis to simulate the tunnel advancing effects as well as the supporting effects during the construction, process; (2) to use the deconfinement ratio λ to simulate the stress changes due to tunnel advancing effects; (3) to apply the convergence - confinement method to stimulate the interaction between the rock mass and the supporting system, which contents the ground response curve, the support reaction curve and the equilibrium point. The result obtained include the ground response curve, the distribution curves of radial displacement, radial stress, and tangential stress, and stress path diagram with and without support system.
For consideration of the advancing effects that can induces the rock mass behavior to present stress dependent, nonlinearity and inelasticity phenomena. The Dancan''s hyperbolic model (1980) was adopted to stimulate the ground reaction behavior. In this study, the comparison of results between the linear elastic model and hyperbolic model, and the parametric studies will be investigated. The result obtained show that the cohesion c and friction angle Φ are the major parameters to influence the distribution of the tangential stress and the radial stress around the excavation. On the other hand, the parameters Kh and n could control the distribution of the radial displacement and ground response curve. Furthermore, the maximum value of the tangential stress may not occur on the excavation face but in a certain distance of the tunnel.
Finally, a real case study was analyzed and stimulated to compare with the in - situ measurements. After these comparison, the satisfactory results were obtained. It showed that the hyperbolic model can be used to stimulate the tunnel construction in the soft rock mass.
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