Analysis On Pullout Load Transfer Mechanism Of Geotechnical Anchor And Its Validating Monitor With Smart FRP Anchor

China is one of the countries influenced by geological disasters most seriously. With the advantages of strengthening soil, lightening structure, saving material and shortening period, geotechnical anchor, which has been becoming the major technology to prevent and deal with geological disasters, has been widely applied in geotechnical engineering such as slope, foundation pit and tunnel in recent years. However, due to the complexity of surrounding soil and environment, the principles of geotechnical anchor have not yet common and completely understood. Thus geotechnical anchor need more study on the stress distribution and transfer mechanism as well as the detecting and monitoring technologies under complex soil and environment. This study has focused on the pullout load transfer mechanism of geotechnical anchor under tension as well as its full-scale monitoring technology and validation based on optical fiber sensors by means of theoretical analysis, experimental measurement and engineering practice. The content of this study mainly contains:Firstly, a novel curvilinear shear stress-slip model is developed from exponential load-displacement relationship curve in consideration of interfacial nonlinearity. Adopting load transfer function method, load-transfer solution of the anchor is derived, which is verified by measuring result from both laboratory and field tests subsequently. Based on this solution, the pullout mechanical behavior of the anchor is analysis.Secondly, the developed curvilinear shear stress-slip model is expanded in consideration of interfacial residual strength. Subsequently, load-transfer solution of the anchor under the expanded model is derived by means of Chebyshev polynomial approximation. Then measuring results are applied to verify this model as well as solution and the pullout mechanical behavior of the anchor with different residual shear strengths are discussed.Thirdly, adopting the above method and curvilinear shear stress-slip models, load-transfer solutions of the anchors in imperfect soils are derived expandly considering the imperfect characteristics. Then the pullout mechanical behavior of the anchors in imperfect soils is discussed as well as the influences from the imperfect parameters.Finally, aiming at the full-scale monitoring requirement of the anchorage engineering, series of smart FRP anchors with built-in optical fiber sensor are developed after discussing the sensing principle of optical fiber sensor. The fabricating processes of these smart anchors are also discussed. Adopting these smart anchors, experiments on pullout load transfer mechanism of the anchors in homogeneous and imperfect soils are carried out in laboratory. The stress distributed and interfacial damage characteristics of the anchors in above cases are studied in sequence to test the performance of the smart FRP anchor on monitoring stress distributed and interfacial damage characteristics. The results from full-scale monitoring and theoretical calculation are compared to verify the effectiveness of both smart FRP anchor and developed solutions. Then the smart anchors are applied in one slope project to verify the effectiveness and reliability. The stress distribution and long-term evolution of the slope anchors are monitored and discussed.