基于3D打印技术和光纤布拉格光栅(fiber Bragg grating,FBG)制备了一种加强肋中内嵌FBG压力传感区的加强肋土工格栅,通过试验验证了压力传感区在土中工作的可靠性.通过室内拉拔试验研究了加强肋格栅在不同加强肋高度、间距和数量下的拉拔界面特性,以及拉拔过程中加强肋侧压力的变化规律,基于刺入剪切破坏理论提出加强肋被动侧压力理论计算公式.结果表明,加强肋可以有效提高土工格栅的抗拉拔特性,土工格栅的极限拉拔力随着加强肋高度和数量的增加而增大,而加强肋间距过小会使极限拉拔力减小;加强肋被动侧压力先随拉拔位移的增加而逐渐增大,达到峰值后趋于稳定,加强肋主动侧压力则先下降后趋于稳定,纵肋上加强肋被动侧压力略小于网格上加强肋;在多加强肋情况下,拉拔方向后侧加强肋被动侧压力会减小,加强肋间距越小,被动侧压力减小幅度越大;加强肋被动侧压力理论计算结果与试验结果基本吻合.所得结果验证了将FBG传感器嵌入土工格栅加强肋监测侧压力的可行性,深化了加强肋土工格栅与填土间相互作用的机制理论.
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.
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