Distinct Element Modeling of the Shimizu Tunnel No.3 in Japan
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The tunnel was excavated in a region consisting mainly of soft sedimentary rocks, such as locally weathered sandstone, underlain by interbedded sandstone and mudstone. Due to observed non symmetric deformations and loads in the tunnel, the distinct element and the convergence-confinement methods were used during the numerical simulations.
A parametric analysis was performed initially in a pseudo-continuum approach to study the behavior of the wide tunnel geometry under various conditions. The effects of rock mass elastic modulus, in situ Ko ratio and boundary conditions are discussed.
More complex parametric studies were performed in a stochastically generated model by using joint spatial data from geotechnical investigations. The Barton-Bandis constitutive law was assumed for the behavior of the joints. The sensitivity of the ground "characteristic curves" was examined by statistical variation of the joint shear strength parameters. A final simulation using the code UDEC and the convergence-confinement method yields interesting results which are comparable to the monitored data.
- Masters Theses