Structural design and strain transfer mechanism of fiber Bragg grating–3D-printed geogrid

This study integrates fiber Bragg grating (FBG) sensing technology with three-dimensional (3D) printing to develop a geogrid with strain-sensing capabilities. Polylactic acid (PLA) was used as the printing material, and the geogrid was fabricated using fused deposition modeling (FDM). FBG sensors were embedded within the printed structure to achieve both reinforcement and real-time deformation monitoring. A theoretical model for strain transfer between the FBG sensors and the geogrid was proposed, considering both fiber grating and adhesive layer parameters. The model was validated through laboratory tensile tests on geogrids. The results indicate that the proposed strain transfer model aligns well with the experimental data, with a maximum relative error of less than 3%, demonstrating its effectiveness in monitoring geogrid deformation. A parametric analysis shows that increasing the grating sensing length enhances strain transfer performance by expanding the distribution range of interfacial shear strain. The shear modulus of the adhesive layer directly regulates interfacial slip resistance, while the Young’s modulus influences strain response indirectly through structural stiffness. The effectiveness of both is constrained by the adhesive layer radius. Based on gray relational analysis (GRA), the mean gray relational grade (GRG) value of geometric parameters is 0.433, significantly higher than that of material parameters (0.381), confirming that optimizing structural design is a priority for improving sensing performance. The study provides theoretical support and technical guidance for the design and application of embedded optical fiber sensors in intelligent geotechnical engineering.