Abstract: Basalt fiber-reinforced polymer (BFRP) anchor, which has much higher tensile strength, better corrosion resistance and lighter weight than steel bar, is a new kind high performance fiber-reinforced anchor. However, its application in slope engineering is still at preliminary stage. In this study, a series of pull out tests for BFRP anchors were performed at a loess slope site, based on which the performances of BFRP anchor systems with different bolt diameter and anchorage length were studied. The failure modes of BFRP anchor system were investigated by examining the excavated anchors at the slope site. The test results show that the failure modes of anchor system depend on the relative strength of interfaces. The anchors with 12 mm and 16 mm diameters tend to fail in shear at the interface between bar and grout (the 1st interface), and 25 mm fail in shear at the interface between grout and surrounding soil (the 2nd interface). Under certain anchorage conditions, the increase in the bolt diameter can significantly improve the ultimate pullout load of the anchor system. With the increase of the anchorage length, the ultimate pullout force does not always increase linearly but with the increasing trend decreases gradually, showing the existence of a critical value in the anchorage length. The average bond strength of the interface between 1st and 2nd decreases with the increase of the anchor length. The recommended values for average bond strength of interfaces are also presented for practical engineering design. The axial force of the anchors gradually attenuates along the depth with its distribution pattern related to the magnitude of the tensile load, the diameter of the bolt and the length of the anchorage. The shear stress distribution, which increases first and then decreases with the anchorage depth, obeys the single peak shape with the peak value located within the range of 0.5 m at the front of the anchorage, also influencing by the length and diameter of the anchorage. It is suggested that the performance of shear resistance, the design of surface morphology design and fabrication process of BFRP anchor should be further improved in the future.

Key words: BFRP anchor, loess slope, field experiment, failure mechanism, interface bonding strength