Abstract: Based on 3D printing and fiber Bragg grating (FBG), a strengthening rib geogrid with FBG pressure sensing zones is prepared, and its reliability in soil is verified through experiments. Pull-out tests are conducted to study the pull-out interface characteristics of strengthening rib geogrids under different rib heights, spacings, and numbers, as well as the variation patterns of lateral pressure on the strengthening ribs. Based on the punching shear failure mechanism, the theoretical calculation formula for the passive lateral pressure of the strengthening ribs is established. The results show that strengthening ribs can effectively improve the pull-out resistance of geogrids. The ultimate pull-out force of the geogrid increases with the rib height and the number of ribs, while an excessively small rib spacing reduces the ultimate pull-out force. The passive lateral pressure of the ribs increases gradually with the pull-out displacement and stabilizes after reaching the peak value. The active lateral pressure decreases first and then stabilizes. The passive lateral pressure of the strengthening ribs located on the longitudinal ribs is slightly smaller than that on the mesh. In the case of multiple strengthening ribs, the passive lateral pressure of the strengthening ribs on the rear side in the pull-out direction decreases, and the smaller the rib spacing, the greater the degree of reduction. The theoretical calculation results of the passive lateral pressure of the strengthening ribs are in basic agreement with the experimental results. These results verify the feasibility of embedding FBG sensors into the strengthening ribs of geogrids to monitor lateral pressure and deepen the theoretical understanding of the interaction mechanism between strengthening rib geogrids and backfill.

Key words: flber Bragg grating (FBG), 3D printing, strengthening rib geogrid, pull-out test, pull-out interface characteristics, lateral pressure on strengthening ribs