Design Guidelines For Glass Fiber-reinforced Polymers(GFRP) For Reinfored Concrete Structures And Application In Subway TBM Project

Based on safety and advanced technology, Tunnel Boring Machine(TBM) is widely used in the construction of city metro. The construction experience in China showed that:the safety of the shield launching and breakthrough are the important parts of the construction of tunnel. Based on the construction and research in the domestic and abroad and the methods of newly developed GFRP rebar in the pit retaining structure, the many key technologys are resolved in this research. For example, the most significant issues when designing a concrete member, such as a diaphragm wall or a drilled pile, which is to be reinforced with this material, as well as the construction methods are discussed;The safety and deformation law when the installed of GFRP rebars in the concrete walls located within the path of the TBM has been discussed; The key parameters of the thrust force and the pressure of the soil chambert are calculated when the TBM shield launching and breakthrough.According to subjects of Beijing Science and Technology Plan and Beijing Natural Science Foundation, the GFRP bars are installed in that portion of concrete shaft walls which the TBM has to penetrate, the so called soft-eye. The foundation pit engineering of Datunlu east station in line 15 Beijing subway construction, as well as the TBM breakthrough, and the technology of soft-eye in abroad are taken as research background. At the same time, the design guidelines, construction methods, the thrust force when the shield launching and breakthrough are been researched through the experimental beam tests, the deriving simplified calculation formula and numerical analysis.First, design guidelines for GFRP reinforced concrete structuresBased on the experimental beam tests mainly and some design approach for GFRP reinforced concrete structures, the difference of flexural strength and the shear strength of the beams reinforced GFRP were discussed, and main work could be described as follows:(1) According to the research results of the several codes and design guidelines addressing GFRP bars. There are three possible modes of flexural failure of a concrete section reinforced with GFRP bars: balanced failure, compression failure and tension failure. The compression failure mode is reasonable in the design of the engineering.(2) Based on this, the calculating formulas of uniform GFRP bars concrete member with circle section are derived. The formulas are simplified in order to apply in the engineering. Finally, the rationality of the simplified formulas is verified on the basis of the flexural bearing capacity test of uniform GFRP bars concrete beam.(3) The behavior and shear strength of concrete slender rectangle beams reinforced with GFRP bars and members with shear reinforcement were investigated. The proposed equations were presented for shear strength of GFRP-reinforced concrete rectangle beams without transverse reinforcement and shear strength of GFRP reinforced concrete rectangle members with stirrups.(4) Based on the experimental results, shear strength equations for a GFRP-reinforced concrete structure with a circular cross section were developed. These equations include algorithms for the determination of the concrete shear strength and the contribution to the shear reinforcement of a circular cross section for a GFRP-reinforced concrete structureSecond, the analysis of the safety of the drilled pile walls where the GFRP bars are installed in that portion of concrete shaft walls.With line 15 Beijing metro as the engineering background, the numerical simulation calculation and field monitoring data showed that(1) Due to the lower longitudinal stiffness of drilled pile of reinforced GFRP than the steel one, the lateral deflection of pile of reinforced GFRP was bigger than the steel one when the excavation constructed the scope of pile of reinforced GFRP.(2) The results of analysis of numerical simulation calculation and field monitoring data showed that: the maximum lateral deflection of pile of reinforced GFRP under the control range of the standard of 30 mm, it means that foundation pits is stability evaluation.Third, numerical simulation of thrust at TBM launching and break through area(1) The numerical simulation of the displacement of the piles and the displacement of ground in different value thrust at TBM break through was been done.(2) Based on the first analysis, the varied process of thrust and pressure of the soil chamber at TBM launching was analyzed in order to confirm the mechanical parameters.