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

1.在课题组研究的盾构运动学模型的基础上，发展了铰接式盾构运动学模型。此外，由于试验场地位于横向与隧道走向相反的倾斜地层中，因此对模型进行了改进，以考虑三维地质结构.采用改进的环剪试验机和改进的直剪试验机对土/管片与盾构之间的动态摩擦特性进行了试验研究。在这里，钢表面粗糙度，外壳，剪切速度和围压作为试验参数。通过这些试验发现，在高围压条件下进行泥浆试验时，由于泥浆会从试验装置的狭缝处泄漏，很难得到动态摩擦特性.利用铰接式盾构进行了弯曲试验，并对管片的位移和变形进行了现场测试.采用考虑三维地质结构的铰接式盾构运动学模型，结合现场试验数据，对盾构工作过程进行了模拟。结果表明，所建立的铰接式盾构运动学模型能够较准确地模拟盾构的实际工作状态.在盾构运动学模型的基础上，建立了地下反力系数、静止土压力系数等地基性状的反分析方法。将该方法应用于现场试验数据，不能得到稳定的结果。它被认为是未知的地面属性有一定的共线性。为了克服这个困难，有必要选择未知的地面属性和平衡方程的组合。作为进一步的研究，将利用现场数据进行地基性质的反分析。

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.