| Summary: | 博士 === 國立臺灣科技大學 === 營建工程系 === 93 === The traditional processing of tunnel deformation data, such as the time history graphs of the convergence of two monitoring points, could not reflect the complex behavior around the excavation face. A new scheme of data presentation, developed by European scholars, could reflect the deformation behavior of tunnel excavation face approaching geological interface and predict the geological conditions ahead of excavation face according to the characteristics of deformation behavior. The scheme incorporates a series of graphical presentation of the absolute tunnel deformation data, such as the influence lines, the trend lines, the displacement vector orientation trend lines, and etc.
Most of the previous studies on the tunnel deformation behavior are limited to the conditions of continuous and vertical interface which are quite different from the in-situ complex geological conditions. This research utilized a three-dimension discrete element code﹘3DEC, which is suitable for simulating the discontinuous rock mass, to analyze tunnel deformation behavior when the tunnel passing through the discontinuous geological interface with different dip angle. Furthermore, this research performed 3-D optical measurements of the deformations in the Snow Mountain Tunnel of the Taipei-Ilan highway to understand the relationship between the tunnel absolute deformations with the geological conditions.
The results of numerical analysis show that the discontinuous interface will obviously influence the stress transmissions and the deformation behavior. Therefore, it will result in different patterns of the trend lines of displacement vector orientation (at the location 0.5B behind excavation face) when the excavation face passing through different geologic structures. When the interface is inclined at certain angle, the locations and magnitudes of the maximum tunnel deformations, as well as the characteristic lines of deformations, will be affected by the breakthrough position of the excavation face.
According to the results of the in-situ measurements in Snow Mountain Tunnel, the tunnel deformation behavior under different geological structures could be represented by the influence lines and the trend lines, and longitudinal deformations would change accordingly when tunnel passing through weak rock mass. The technique of three-dimensional optical measurements is not familiar to the construction business; therefore, this research also provides some suggestions about the practical experiences in operation and certain aspects to be improved.
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