The prestressed glass fiber-reinforced polymer (GFRP) rock bolt, characterized by its lightweight, high-strength, fatigue-resistant, and corrosion-resistant, effectively addresses the durability challenges associated with rock bolts in soil applications. This study was based on the shear test of GFRP anchor rods under varying levels of prestressing. The present study designed and conducted shear tests on GFRP anchor bolt joint surfaces under varying prestress levels, utilizing the double shear test method. Based on the experimental results, this research analyzed the influence of prestress on failure modes, shear bearing capacity, and shear deformation of GFRP anchor bolt joint surfaces. Furthermore, by employing an equivalent strain assumption in conjunction with damage mechanics theory, a predictive model for shear displacement-shear stiffness and shear displacementshear stress was established for GFRP anchor bolts. The results indicated that the failure mode of the prestressed GFRP anchor rod joint surface shear specimen was the shear failure following the splitting of the GFRP anchor rod. The shear carrying capacity of the joint surface with 20 % and 40 % pre-stressed GFRP anchor rods increased by 8.2 % and 20.3 % compared to the non-prestressed anchor rod, respectively. However, the ultimate displacements decreased by 22.7 % and 49.7 %, respectively. The initial stiffness of the 20 % and 40 % prestressed GFRP anchor rods was higher than that of non-prestressed GFRP anchor rods. However, under shear loading, the fracture strain of prestressed GFRP anchor rods decreased by 33 % and 44 %, respectively, compared to non-prestressed counterparts. The shear displacement-shear stiffness and shear displacement-shear stress relationships of prestressed GFRP anchor rods under the action of shear load were found to conform to the exponential distribution and Weibull distribution, respectively. The mechanical models proposed in this paper for shear displacement-shear stiffness and shear displacement-shear stress could effectively predict the mechanical behavior of shear damage on the joint surface of prestressed GFRP anchor rods.

This paper aims to systematically describe the mesostructural and mechanical changes in the surrounding soil of glass fiber-reinforced polymer-trapezoidal core sandwich piles (GFRP-TCSPs) under lateral loads. A lateral loading device for hydraulic gradient testing is introduced, and a corresponding numerical model is established using a continuum-discrete coupling method. The dynamic interaction between the GFRP-TCSP and the soil during incremental loading is analyzed, including the effect of the soil particle contact parameters on the pile-soil interaction (PSI), changes in the pile bending moment, and the displacement field of the surrounding soil. The development of soil force chains and changes in porosity and coordination number in different zones of the soil around the pile are investigated. The results indicate that the attraction and friction between particles are crucial for the PSI behavior of the soil. In addition, the bending moment of the pile increases with increasing lateral load but decreases when the pile inclination angle diverges significantly. Different regions of the soil around the pile exhibit different variations in average contact force, porosity, and coordination number as the GFRP-TCSP overturns. These variations provide a theoretical basis for detecting pile instability.

Traditional suction bucket foundations incur high maintenance costs and are susceptible to corrosion, resulting in a diminished bearing capacity over prolonged service. The suction bucket foundation, constructed with a glass fibre -reinforced polymer (GFRP), introduces a novel approach to iteratively optimise conventional steel bucket foundations. In this study, three-dimensional finite element models of the GFRP bucket -soil interaction were established using the VUMAT subroutine, which incorporates the stress -strain damage relationship of GFRP materials. The mechanical response during installation was analyzed for different fibre -laying angles( A ) and wall thicknesses( t ) of the GFRP bucket, and the results were compared with those of a steel bucket. The results indicated increased circumferential stress, radial deformation, and out -of -roundness of the GFRP bucket as the fibre laying angle increased. Deformation and stress of the bucket skirt remained low at A of 0 - 45 degrees . When A >= 60 degrees , the matrix ' s damage area significantly increases, with the minimum damage occurring at 45 degrees . For A <= 30 degrees , it approaches the maximum radial deformation of an equivalent -sized steel suction bucket. As the wall thickness increased, the circumferential stress, radial deformation, and out -of -roundness of the GFRP bucket skirt gradually decreased. When the GFRP bucket t was four times that of the steel bucket, its radial deformation was approximately equal.

Steel rebars have been used in soil-cement mixtures to increase their flexural capacity in shoring projects. However, the interaction of the reinforcing rebars and soil-cement and their bond strength has been rarely considered. A practical formula for predicting the rebar-soil-cement bond strength considering the strength characteristics of both has not been developed. The current study performed 60 pullout tests of rebars embedded in soil-cement and analyzed the pullout mechanisms as well as the effective parameters on the pullout force. The test parameters were rebar type, size and embedded length. Smooth, ribbed steel and GFRP rebars in diameters of 8 and 12 mm were tested. A pullout frame was added to a universal testing machine and the load-displacement behavior of the rebars and induced cracking were analyzed. The results showed that the prevailing failure mechanism during pullout of the rebars from the soil-cement was slippage and not cone/splitting failure. During slippage, some the soil-cement adhered to the rebar between its ribs because of the low compressive strength of the soil-cement. With a 50 % increase in rebar diameter, the bond strength decreased about 18 % and 30 % for the ribbed and GFRP rebars, respectively. This indicates the importance of the rebar diameter on the bond strength. The steel rebars exhibited greater bond strength with soil-cement in comparison with the GFRP rebars. A new equation has been proposed to calculate the reinforcement-soil-cement bond strength by applying a reduction factor to the ACI equation.