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Qingbiao W.,Shandong University of Science and Technology | Qingbiao W.,CAS Wuhan Institute of Rock and Soil Mechanics | Qingbiao W.,TAIAN Road Engineering Materials Co. | Cong Z.,Shandong University of Science and Technology | And 6 more authors.
Open Materials Science Journal | Year: 2015

In the paper, we study the high strength geocell development technology route, analyze the rules of the tensile properties and creep properties of geocell, establish the relationship between elongation and stress and time, thus provide theoretical foundation for the development and engineering application of the new material. Through theoretical analysis, experimental research and numerical simulation, the characteristics, raw materials and craftsmanship of the geocell are studied. The research is given on its stress and deformation rules based on elongation test and creep test. The rationality of the experiment is verified through numerical simulation and the conclusions are as follows: (1) With the research on the geocell traditional craftsmanship, combined with new technologies as special ultrasonic welding technology, intelligent optical fiber technology and fixed locking plate technology, new-type safety forewarning high strength geocell can be developed. (2) Based on the geocell material characteristics, the elongation test and creep test are carried on and the tensile yield strength exceeds 250Mpa; the joint is welded by special crafts and the tensile strength ≥2000N/cm.(3) With FLAC3D numerical simulation, simulation study is performed on the mechanical properties of the new cell, analyze the relationship between stress and strain, time and displacement, and guide the safety design and management construction of the new-type geocell based on the actual situation of simulation.(4) The innovation points of the new-type geocell include the optimization technique of whole tensile yield strength, falling proof technique of lock parts, positioning and effective monitoring technique, which effectively solves the geological problems of special projects as ecological afforestation, sand fixation and high slope soft subgrade, ensures the quality of the project and has high economic benefits. © Qingbiao et al.

Wang Z.-F.,Shandong University | Wang Z.-F.,Nanyang Technological University | Wang J.,Shandong University | Sui Q.-M.,Shandong University | And 4 more authors.
Measurement Science and Technology | Year: 2015

Due to the disadvantages of the current smart Geogrid for geotechnical use only being able measure strain and evaluate load location, a smart Geogrid embedded with fiber Bragg grating (FBG) sensors has been developed. Also, a deformation reconstruction technique has been investigated, which enables the newly designed smart Geogrid to evaluate the deformation fields of the key areas in geotechnical structures. After the fabricating process of the FBG embedded smart Geogrid was briefly introduced, a curvature information based deformation reconstruction method for the smart Geogrid was detailed. In order to optimize the distribution of the FBG nodes in the smart Geogrid, the finite element (FE) simulation data of the three possible causes of deformation were extracted, and the reconstruction results of the four distributions were compared. The results indicated that equidistantly distributed FBG sensors at the ribs of the smart Geogrid were the optimal distribution for the newly designed smart Geogrid. In addition, a modified deformation reconstruction technique was proposed to reduce reconstruction errors due to the stress concentration on the junctions of the smart Geogrid. The modified method, which employs FBG measured strains for calculating the deformation of the ribs and weighted strains to compute the coordinates of the two junctions, was validated by FE simulations. The simulation results illustrated that the modified method can improve the deformation reconstruction accuracy for both a Geogrid embedded with one fiber optic cable into one warp thread and a Geogrid embedded with multiple fiber optic cables in different warp threads. For the purpose of verifying the feasibility of the deformation measurements for the designed smart Geogrid using the proposed reconstruction techniques, experiments for the smart Geogrid embedded with one fiber optic cable were conducted in constant temperature environments. The curvatures of the smart Geogrid were calibrated prior to the deformation experiments in order to remove the errors induced by the strain measurement. The experimental results demonstrated that the reconstruction technique for the newly designed smart Geogrid was capable of evaluating the deformation field, and the modified reconstruction technique was able to effectively improve the reconstruction accuracy in order to fulfill the requirements of geotechnical usages. The newly developed smart Geogrid with deformation reconstruction techniques can be a promising smart Geosynthetic for the reinforcement as well as the monitoring of geotechnical engineering-related applications. © 2015 IOP Publishing Ltd.

Wang Q.,Shandong University of Science and Technology | Wang Q.,Shandong Hualian Mining Co. | Wang Q.,TAIAN Road Engineering Materials Co. | Zhang C.,Shandong University of Science and Technology | And 4 more authors.
Journal Wuhan University of Technology, Materials Science Edition | Year: 2015

Glass fiber reinforced plastics geogrid has a wide application in the field of soil reinforcement because of its high strength, good toughness, and resistance to environmental stress, creep resistance and strong stability. In order to get high-powered glass fiber reinforced plastics geogrid and its mechanical characteristics, the properties and physical mechanical index of geogrid have been got through the study of its raw material, production process and important quality index. The analysis and study have been made to the geogrid’s mechanical properties with loading speed, three-axial compression, temperature tensile test and FLAC3D numerical simulation, thus obtain the mechanical parameters of its displacement time curve, breaking strength and elongation at break. Some conclusions can be drawn as follows: (a) Using glass fiber materials, knurling and coated projection process, the fracture strength and corrosion resistance of geogrid are greatly improved and the interlocking bite capability of soil is enhanced. (b) The fracture strength of geogrid is related to temperature and loading rate. When the surrounding rock pressure is fixed, the strength and anti-deformation ability of reinforced soil are significantly enhanced with increasing reinforced layers. (c) The pullout test shows the positive correlation between geogrid displacement and action time. (d) As a new reinforced material, the glass fiber reinforced plastics geogrid is not mature enough in theoretical research and practical experience, so it has become an urgent problem both in theoretical study and practical innovation. © 2015, Wuhan University of Technology and Springer-Verlag Berlin Heidelberg.

Wang Z.-F.,Shandong University | Wang J.,Shandong University | Sui Q.-M.,Shandong University | Liang X.-M.,TAIAN Road Engineering Materials Co. | And 3 more authors.
Journal of Sensors | Year: 2015

Smart geogrids embedded with fiber Bragg grating (FBG) for reinforcement as well as measurement of geotechnical structures have been developed. After the fabricating process of the geogrids is detailed, finite element (FE) simulations are conducted to analyze the strain distribution of geogrids and the strain transfer characteristics from geogrids to fiber optic. Results indicate that FBG should be deployed in the middle of the geogrids rib to make sure that uniform strain distribution along the FBG. Also, PVC protective sleeves, which are used to protect fiber optic when integrated with geogrids, have smaller strain transfer loss than nylon sleeves. Tensile experiments are conducted to test strain measurement performance of proposed geogrids, and the results demonstrate that proposed smart geogrids have 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, designed smart geogrids are used in a geotechnical model test to monitor strain 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. © 2015 Zheng-fang Wang et al.

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