Stress Relaxation of Grouted Entirely Large Diameter B-GFRP Soil Nail

• Published in: China ocean engineering 2013-08, Vol.27 (4), p.495-508
• Main Authors: Li, Guo-wei, Ni, Chun, Pei, Hua-fu, Ge, Wan-ming, Ng, Charles Wang Wai
• Format: Article
• Language: English
• Subjects: Bars; Coastal Sciences; Engineering; Fiber reinforced plastics; Fluid- and Aerodynamics; GFRP筋; Glass fiber reinforced plastics; Marine; Marine & Freshwater Sciences; Nails; Numerical and Computational Physics; Oceanography; Offshore Engineering; Simulation; Soil (material); Strain; Stress relaxation; Stresses; 光纤布拉格光栅; 土钉; 大直径; 应力松弛率; 应变传感器; 灌浆; 纤维增强复合材料
• ISSN: 0890-5487; 2191-8945
• DOI: 10.1007/s13344-013-0042-8

One of the potential solutions to steel-corrosion-related problems is the usage of fiber reinforced polymer （FRP） as a replacement of steel bars. In the past few decades, researchers have conducted a large number of experimental and theoretical studies on the behavior of small size glass fiber reinforce polymer （GFRP） bars （diameter smaller than 20 ram）. However, the behavior of large size GFRP bar is still not well understood. Particularly, few studies were conducted on the stress relaxation of grouted entirely large diameter GFRP soil nail. This paper investigates the effect of stress levels on the relaxation behavior of GFRP soil nail under sustained deformation ranging from 30% to 60% of its ultimate strain. In order to study the behavior of stress relaxation, two B-GFRP soil nail element specimens were developed and instrumented with fiber Bragg grating （FBG） strain sensors which were used to measure strains along the B-GFRP bars. The test results reveal that the behavior of stress relaxation of B-GFRP soil nail element subjected to pre-stress is significantly related to the elapsed time and the initial stress of relaxation procedure. The newly proposed model for evaluating stress relaxation ratio can substantially reflect the influences of the nature of B-GFRP bar and the property of grip body. The strain on the nail body can be redistributed automatically. Modulus reduction is not the single reason for the stress degradation.