界面力对光缆与土壤变形协调性的作用：基于3D离散元数值模拟的视角

The role of interface force on the deformation compatibility of fiber opticcable and soil: Perspective from 3D discrete element numerical simulation

Abstract: In the application of distributed fiber optic sensing technology to obtain soil deformation, the deformation coordination between the sensing fiber optic (FO) cable and the soil medium is crucial. In this study, a three-dimensional numerical model for pullout test of a sensing cable in sand was constructed utilizing the discrete element method. The results indicate that, with the continuous increase in pullout displacement, the interface forces between the FO cable and soil particles steadily rise. After complete interface failure, these forces rapidly decrease. Throughout the pullout process along the distribution of the FO cable, the magnitude of interface forces undergoes significant changes depending on the contact state of the interface. As the confining pressure increases 0 MPa to 0.4 MPa, the effective contact between the FO cable and soil particles increases by approximately 0.4 times. The micro-anchors installed on the FO cable can generate anchoring forces. The anchoring forces initiate only after interface failure at their respective locations, restricting the development of strain at subsequent positions. We suggest defining the critical strain value, which corresponds to the maximum interface forces during the pullout process, and provides a basis for determining the interface strength between the FO cable and the soil.

Keywords: Distributed fiber optic sensing; Interface force; Mechanical coupling; Discrete element method; MatDEM

Fig.4. Structural geometric of two cables and numerical model of cable pullout test in two scenarios.

Fig.5. Schematic of the composition of interface forces.

Fig.8. The result of puout force and interface force in three scenarios and development stages, (a) 0 MPa wanchored cable.(b)0.4 MPa unanchored cable. (c) 0 MPa cylindrical anchored cable. (d) The development stages of pullout force and interface force.

Fig.10. The schematic diagram of the interface forces as the contact state changes and the influence of confining pressure.

Yu Zheng, Kai Gu, Fulin Xiang, Chun Liu, Yi Lu, Bin Shi, The role of interface force on the deformation compatibility of fiber optic cable and soil: Perspective from 3D discrete element numerical simulation, Computers and Geotechnics, Volume 176, 2024, 106723, ISSN 0266-352X.

https://doi.org/10.1016/j.compgeo.2024.106723