玻璃纤维增强聚合物(GFRP)抗浮锚杆是一种由树脂和玻璃纤维复合而成的新型材料,与传统的钢筋锚杆相比,它具有比强度高、耐腐蚀性强和抗电磁干扰能力强的优点。基于6根GFRP抗浮锚杆和4根钢筋抗浮锚杆现场足尺拉拔破坏性试验,研究了中风化花岗岩中GFRP抗浮锚杆的承载特征和界面黏结特性。试验结果表明,抗浮锚杆的破坏形式有2种:锚杆和砂浆界面剪切破坏,砂浆和围岩界面剪切破坏。直径为28 mm的GFRP抗浮锚杆和钢筋抗浮锚杆的极限抗拔承载力均为225kN,直径为32 mm GFRP抗浮锚杆极限抗拔承载力为250 kN,能够满足工程实际需要;GFRP抗浮锚杆与砂浆(第一界面)的平均黏结强度为1.50~1.54 MPa;GFRP抗浮锚杆砂浆与围岩(第二界面)的平均黏结强度为0.32~0.37 MPa,略低于钢筋抗浮锚杆第二界面的平均黏结强度;直径为32 mm的GFRP抗浮锚杆第二界面平均黏结强度高于直径为28mm的GFRP抗浮锚杆。在此基础上,进一步分析论证了GFRP抗浮锚杆的破坏机制,为GFRP抗浮锚杆的工程应用提供了理论依据。
The glass fiber reinforced plastics(GFRP) anti-floating anchor is one kind of new materials which bonds by the resin and the glass fiber. Compared with the steel bar anchor rod, it has the high specific strength, nonelectric conductivity, nonmagnetic nature and corrosion resistance. Based on the full-scale drawing destructive field tests of six GFRP anti-floating anchor and four steel bolts, the load-bearing characteristics and interface bond properties of GFRP anti-floating anchor in moderately weathered granite are studied. By the test results, several conclusions are drawn:(1) There are two failure modes of anti-floating anchor as follows:shear failure between the anchorage rod and grout;and shear failure between the grout and surrounding rock mass. (2) Under the condition of M32.5 grout and the anchorage length with 2.0 m, ultimate anti-lifting bearing capacity of GFRP anti-floating anchor and steel bolt with diameter of 28 mm are 225 kN, ultimated anti-lifting bearing capacity of GFRP anti-floating anchors with diameter of 32 mm is 250 kN, which can be satisfied with engineering demands. (3) The average bond strength between GFRP anti-floating anchor and grout (the first interface) is 1.50-1.54 MPa;(4) The average bond strength between the grout and surrounding rock mass (the second interface) is 0.32-0.37 MPa, which is slightly lower than the average bond strength of the second interface of steel bolt;(5) The average bond strength of the second interface of GFRP anti-floating anchor with diameter of 32 mm is higher than GFRP anti-floating anchor with diameter of 28 mm. According to the test results, the probable failure form and mechanism of GFRP anti-floating anchor are further analyzed. The research results can provide theoretical basis for application of GFRP anti-floating anchor.