Experimental Study on the Mechanical Properties of Prestressed GFRP Composite Anchors for Slope Support

Addressing the issue of insufficient corrosion resistance of metal anchors in permanent slope support systems, this paper proposes the use of prestressed glass fiber reinforced polymer (GFRP) composite anchors for slope support. Field experiments were conducted to investigate the mechanical properties of prestressed GFRP composite anchors in different combinations. Based on a permanent slope project, three GFRP composite anchors were designed for comparative testing with conventional steel anchors. Vibrating wire strain gauges and resistance strain gauges were used to monitor the load-displacement curve at the anchor head, axial force distribution, and prestress loss during the anchor rod pull-out test. The results showed that under the maximum test load, both composite anchors with GFRP bars and steel strands in the free section were in the elastic deformation stage. Due to the friction at the casing interface, the measured deformation of the composite anchor rod with GFRP bars in the free section was lower than the theoretical elastic deformation. In sandy clay soil, the axial force of the anchored section of the GFRP composite anchor rod exhibited an exponential decay characteristic along the burial depth, with an effective transfer depth of anchoring stress of about 5 m. The prestress loss rate of the GFRP composite anchor rod was 9% to 12%, with the loss rate being higher for anchors with GFRP bars in the free section compared to those with steel strand combinations. This study preliminarily verifies the feasibility of replacing traditional steel anchors with GFRP composite anchors for permanent slope support, providing experimental data and theoretical support for the application of fiber-reinforced composite material anchors.