Test Study On Anchor Head Of GFRP Anchor And Application Of GFRP Anchor In Slope Support

Glass fiber reinforced polymer (GFRP) anchor is the new kind of anchors which glass fiber as a reinforcing material and synthetic resin as a matrix material. Compared with the ordinary steel bar, GFRP anchors have the advantages of high specific strength, corrosion resistance strong,nonelectric conductivity and so on. It is effective to solve the problem of structural durability by using the steel bar instead of the reinforced anchor. But this kind of anchors have some weaknesses in anchor head anchorage bearing capacity. Based on this, the tensile failure test of GFRP anchor metal anchors with diameter of 25,26,28mm series are conducted through changing the nut length to study the bearing characteristics of anchor head and the slippage rule of anchorages.Numerical simulation analysis are conducted by changing the height of the bolt thread and support temporary slope with GFRP anchors. The test results are as bellow:(1) The GFRP anchor head is in the elastic deformation stage before shearing and breaking. When the length of the nut reaches 10cm, the anchoring force of the GFRP anchor head reaches its ultimate resistance.As increasing the length of the nut, the displacement value tends to decrease, but the bearing capacity is no longer increased. When the GFRP anchor is applied to the rock and soil anchorage, the length of the nut can be extended according to the engineering needs in order to improve the bearing capacity of the anchor head, but not more than 10cm.(2) The failure of the GFRP anchor metal anchor is the result of the deburring of the rod, the average skin loss is between 2.4 and 2.7mm,and the overall debonding phenomenon at the interface is related to the height of the thread and the content of the skin matrix. The shear length(mm) of GFRP anchor rod is about 5 times of that of GFRP screw thread.According to this rule, the shear strength formula of GFRP bolt rod is deduced. It can be used as GFRP anchor design basis.(3) Nuts with a length of 8cm GFRP anchor head ultimate resistance to the load is equivalent to the metal nut length range of 6.5cm anchor head tensile load, the displacement is about 2 times the latter. The use of a material higher than the GFRP elastic modulus (such as carbon fiber reinforced polymer) makes a significant increase in the anchoring effect of the GFRP anchor head.(4) The maximum equivalent stress produces the first lap of the root of the thread in contact with the ribs, and the stress decreases rapidly with the number of threads increasing. The failure of the thread on the first lap of the contact surface is the source of the debarking. Increasing the height of the thread is beneficial to share the thread load and improve the bearing capacity of the GFRP anchor head.(5) Support slope with GFRP anchors can guarantee the stability of slope. GFRP anchors support slopes have good application values and should be strongly advocated.