Durability study on glass fiber reinforced polymer soil nail via accelerated aging test and long-term field test

2015 ◽  
Vol 38 (12) ◽  
pp. 2863-2873 ◽  
Author(s):  
Zhi Chen ◽  
Lifei Zheng ◽  
Qingping Jin ◽  
Xiaoqing Li
2015 ◽  
Vol 52 (6) ◽  
pp. 671-681 ◽  
Author(s):  
Cheng-Cheng Zhang ◽  
Hong-Hu Zhu ◽  
Qiang Xu ◽  
Bin Shi ◽  
Guo-Xiong Mei

Glass fiber reinforced polymer (GFRP) materials are gaining increasing use in geotechnical engineering applications in recent years. The long-term performance of reinforced geostructures may be influenced by the rheological properties of GFRP soil nails or anchors. However, a clear understanding of this effect is lacking. This work aims to investigate the interaction between GFRP soil nail and sand under pullout conditions considering the time-dependent effect. A time-dependent model was proposed to describe the load–deformation characteristics of a GFRP soil nail during pullout. Laboratory pullout tests were performed using a load-controlled pullout apparatus to verify the effectiveness of the proposed model. Quasi-distributed fiber Bragg grating (FBG) optical fiber sensors were adhered on the pre-grooved GFRP soil nail to capture the variations of axial strain during testing. The test results are presented, interpreted, and discussed. It is shown that there is good agreement between the simulation results and the experimental data under low stress levels. Additionally, the impacts of model parameters on the predicted time-dependent pullout behavior of a GFRP soil nail were examined through parametric studies. The results indicate that the distributions of tensile force and GFRP–sand interfacial shear stress along the nail length are highly time dependent. The creep displacement of a GFRP soil nail is significantly influenced by the rheological parameters of the proposed model.


2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Pengfei Liu ◽  
Qilin Zhao ◽  
Fei Li ◽  
Jinchun Liu ◽  
Haosen Chen

An assembled plane truss structure used for vehicle loading is designed and manufactured. In the truss, the glass fiber reinforced polymer (GFRP) tube and the steel joint are connected by a new technology featuring a pretightened tooth connection. The detailed description for the rod and node design is introduced in this paper, and a typical truss panel is fabricated. Under natural conditions, the short-term load test and long-term mechanical performance test for one year are performed to analyze its performance and conduct a comparative analysis for a reasonable FEM model. The study shows that the design and fabrication for the node of an assembled truss panel are convenient, safe, and reliable; because of the creep control design of the rods, not only does the short-term structural stiffness meet the design requirement but also the long-term creep deformation tends towards stability. In addition, no significant change is found in the elastic modules, so this structure can be applied in actual engineering. Although the safety factor for the strength of the composite rods is very large, it has a lightweight advantage over the steel truss for the low density of GFRP. In the FEM model, simplifying the node as a hinge connection relatively conforms to the actual status.


2018 ◽  
Vol 52 (24) ◽  
pp. 3309-3323 ◽  
Author(s):  
Brahim Benmokrane ◽  
Hamdy M Mohamed ◽  
Ahmed H Ali

This paper presents the physical, mechanical, and durability characterization of glass fiber-reinforced polymer solid and tubular bars. These bars were subsequently used as rock bolts for ground control of the Jurong Rock Caverns in Singapore. The long-term performance of these bars was assessed under harsh environmental exposure (saline solution) simulating the subsea cavern water. The test parameters were (1) type of bars (solid and tubular), (2) temperature (20, 40, and 50℃), and (3) conditioning time (1000, 3000, and 5000 h). The measured tensile strengths of the bars before and after exposure were considered as a measure of the durability performance of the specimens and were used for long-term properties prediction based on a theoretical model. Moreover, microstructural analyzes using scanning electronic microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry are also conducted to investigate the deterioration of fiber, matrix, and the fiber/matrix interface due to environmental conditioning. The results show the very high long-term durability of solid and tubular glass fiber-reinforced polymer rock bolts exposed to field conditions. The predicted tensile strength retention at a MAT of 32℃, with an RH of 100%, is 0.90 and 0.82 for a service life of 100 years for solid and tubular glass fiber-reinforced polymer bars, respectively. Based on the findings of this research, the tested glass fiber-reinforced polymer rock bolts were recommended as alternatives to stainless-steel rock bolts and successfully used as ground control in the Jurong Rock Caverns in Singapore.


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