两种不同材质抗浮锚杆锚固性能的现场对比试验研究与机理分析

Field contrast test and mechanism analysis on anchorage performance of anti-floating anchors with two different materials

为深入研究中风化花岗岩中以全螺纹GFRP筋材为杆体的全长黏结抗浮锚杆锚固机理及破坏机制,进行了螺纹GFRP抗浮锚杆与螺纹钢抗浮锚杆现场拉拔试验。试验结果表明,GFRP抗浮锚杆的极限抗拔承载力高于钢筋抗浮锚杆;相同荷载水平,相同位置处GFRP锚杆的轴力大于钢筋锚杆,钢筋锚杆轴力沿深度衰减的速率比GFRP锚杆快;GFRP锚杆剪应力峰值点较钢筋锚杆更明显,钢筋锚杆的剪应力比GFRP锚杆发挥早,GFRP锚杆的峰值剪应力比钢筋锚杆大;就砂浆与围岩界面的平均黏结强度而言,GFRP抗浮锚杆高于钢筋抗浮锚杆;GFRP抗浮锚杆以杆体材料剪切破坏为主,而螺纹钢锚杆的破坏是锚固体与围岩界面产生剪切滑移破坏。

The pull-out contrast tests of threaded GFRP anti-floating anchor and threaded steel anchor rod were conducted to study the anchoring mechanism and the failure mechanism of full-length bonding anti-floating anchor in the moderately weathered granite. The following conclusion can be drawn： （1） The ultimate anti-lifting bearing capacity of GFRP anti-floating anchor is higher than that of steel anchor rod. （2） The axial force of GFRP anti-floating anchor is greater than that of steel anchor rod at the same loading level and the same position, and the axial force in steel anchor rod attenuates quickly along the depth compared to that of GFRP anchor rod. （3） The shear stress peak value point of GFRP anchor rod is more evident than that of steel anchor rod. However, the shear stress of steel anchor rod comes into play earlier than GFRP anchor, and the peak shear stress of GFRP anchor is larger than steel anchor rod. （4） The average bond strength of GFRP anti-floating anchor is higher than that of steel anti-floating anchor in terms of the mortar- rock interface. （5） GFRP anti-floating anchors mainly exhibit shear failure and the shear slip failure may occur at the anchorage section if the maximal shear stress exceeds shear strength of the mortar-rock interface.