Abstract：Steel anchor rod is one of the widely used reinforcement materials in slope engineering，tunnel engineering or large caves；but it may be eroded by groundwater or chemical solutions，which will cause the reductions of mechanical strength and service life. Compared with steel，the glass fiber reinforced plastic(GFRP) rod has higher strength and corrosion-resistance behavior. The GFRP rods are then adopted in reinforcement of various cases；and therefore a series of field tests with different surrounding rock masses are performed. The field tests show the feasibility of GFRP rods. According to the test results，the GFRP rod failure mechanism，its stress-strain behaviors，and the theory under cyclic loading are considered. In the tests，cyclic loading is applied by jacking apparatus；and the strain is measured by strain gauge. The tests show that there are three failure modes of GFRP rods as follows：brittle fracture of unbonded section；shear failure between the anchorage rod and grout；and shear failure between the grout and surrounding rock mass. The tests also show that the reinforcement mechanism is different for surrounding rock masses with different weathered grades；and the influential depth of pullout force increases with the increase of weathered grades of surrounding rock masses. For the strong weathered rock mass，a relative shear displacement appears between the anchorage grout and rock mass with the increase of pullout force. The reason is that for surrounding rock，the cohesive strength of interface between anchorage grout and surrounding rock mass is relative low.
