Pullout mechanism of GFRP soil nails

Recently, great attention has been drawn to the new soil nail materials represented by glass fiber reinforced polymer (GFRP) as the traditional materials show certain disadvantages, including low corrosion resistance and poor durability. According to the loading characteristics of GFRP soil nails, a model using a hyperbolic shear stress-shear strain relationship is proposed to describe the pullout performance of GFRP soil nails during pullout. Numerical analysis is made to solve the pullout governing equation, based on which the distribution of axial force, shear stress and displacement along the nail length is calculated. Besides, laboratory pullout tests on a model soil nail are conducted, and the accuracy of the predicted results by the proposed model is verified by the test results. Furthermore, a parametric study of the pullout model is conducted to analyze the influence of nail diameter, shear resistance of soil-nail interface, and modulus ratio between soil and nail. Finally, the allowable pullout resistance of GFRP soil nails is suggested to be determined using the displacement control approach.