Development and Application of Smart Geogrid Embedded with Fiber Bragg Grating Sensors

Zheng-fang Wang 1, Jing Wang** 1,Qing-mei Sui 1,4, Xun-mei Liang 4, Lei Jia 1, Shu-cai Li 3, Shao-shuai Shi 3, Shi-de Lu 4, Qing-lin Ye 1, and Chao Liang 1

1 College of Control Science and Engineering, ShandongUniversity, Jingshi Road 17923, Jinan 250061, China

2 TAIAN Road Engineering Materials co. Ltd, Taiwen Road, Taian 271000, China

3 Geotechnical Engineering Center, Shandong University, Jingshi Road17923, Jinan250061, China

4 ShandongUniversitySuzhouGraduateSchool, Lingquan Street377, Suzhou215123, China

Journal of Sensors    http://www.hindawi.com/journals/js/aip/108209/

Smart geogrids embedded within fiber Bragg grating (FBG) for reinforcement as well as real-time monitoring of geotechnical structures have been developed. After the fabricating process of the geogrids is introduced in detail, the finite element (FE) simulations are carried out to analyze the strain distribution of geogrids and the strain transfer rate from geogrids to fiber optic. Results indicate that FBG should better be deployed in the middle of the geogrids rib so that the strain distribution on the FBG is uniform. Also, the PVC protective sleeves, which are used to protect the fiber optic when integrated with geogrids, have smaller strain transfer loss than nylon sleeves. To test the feasibility of proposed geogrids for strain measurement, tensile experiments are conducted on both geogrids with one FBG and that with multiple FBGs, and the results demonstrate that the proposed smart geogrids exhibit good linearity and consistency. Temperature experiments show that FBG embedded in geogrids has higher temperature sensitivity, and the temperature induced error can be compensated by an extra FBG strain-independent sensor. Furthermore, the designed smart geogrids are used in a geotechnical model test to monitor strain variation during tunnel excavation. The strain tendency measured by smart geogrids and traditional strain sensor agree very well. The results indicate that smart geogrids embedded with FBGs can be an effective method to measure strains for geological engineering related applications.