Development on high precision articulated shield kinematic model using soil-steel dynamic friction characteristics by ring shear test

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1. The articulated shield kinematic model was newly developed, extending the shield kinematic model developed by our group. Furthermore, since it was found that the test site is located in inclined layers in transverse direction against the tunnel alignment, the model was improved so as to consider 3D geological structure.2. The dinamic friction charactersitics between soil/ segment and shield were investigated using the improved ring shear apparatus and the improved direct shear apparatus. Here, roughness of steel surface, enclosures, shear speed and confining stress were taken as test parameters. Through these tests, it was found that it is difficult to get the dinamic friction charactersitics in case of the tests using slurry under high confining stress, since the leakage of slurry appears through the slit of the test apparatus.3. The bending test using the articulated shield, and the mesurement on displacement and deformation of segment were carried out at the site.4. The shield behavior was simulated applying the articulated shield kinematic model considering 3D geological structure to the site test data. As a result, it was confirmed that the newly developed articulated shield kinematic model can simulate the actual shield behavior with high accuracy.5. The back analysis method on the ground properties, such as coefficient of subground reaction and coefficient of earth pressure at rest was developed, based on the shield kinematic model. Applying this method to the site test data, stable results can not be obtained. It is considered that the unknown ground properties have some co-linearity. To overcome this difficulty, it is necessary to select the combination of the unknown ground properties and the equilibrium equations. As a future research, the back analysis on the ground properties using site data will be carried out.