玄武岩纤维与钢筋锚杆锚固性能现场对比试验研究

Experimental comparison of anchorage performance between basalt fiber and steel bars

玄武岩纤维(BFRP)锚杆具有抗拉强度高、耐腐蚀性能好等优点,是岩土锚固结构中钢筋的良好替代品,近年颇受业界关注。通过在黄土地层中开展4组Ф25 mm BFRP锚杆和钢锚杆的现场拉拔试验,初步研究两种材质锚杆的破坏模式和锚固性能差异。研究结果表明:对于诸如Ф25 mm类较大直径土层锚杆,拉拔过程中锚固体系的灌浆体内外界面破坏迹象共存,但最终破坏模式受控于灌浆体与土层界面(第二界面),且BFRP锚杆与砂浆内界面(第一界面)破坏程度明显高于钢锚杆;两种材质锚杆的极限承载力相近,界面黏结强度均随锚固长度的增大而减小;受两种材质锚杆本身的加工工艺和材料力学性能影响,试验中钢锚杆与灌浆体的黏结性能优于BFRP锚杆;相同荷载水平,相同位置处,BFRP锚杆杆体轴力大于钢锚杆,轴力衰减速率略小于钢锚杆;峰值剪应力BFRP锚杆小于钢锚杆。

Basalt fiber(BFRP) anchor has many advantages, such as high tensile strength, good corrosion resistance, etc. It is a good substitute for reinforcement in geotechnical anchorage structure, and has attracted much attention in recent years. Four groups of field pull-out tests were carried out in the loess stratum to study the failure modes and anchorage performance difference between the 25 mm diameter BFRP bolts and steel bolts. The results show that the failure signs on inner and outer surface of grouting coexist in the process of drawing for large diameter soil anchor. However, the ultimate failure mode is controlled by the interface between grouting and soil(the 2 nd interface), and the damage degree of the interface between BFRP bolt and grouting(the 1 st interface) is evidently higher than that of steel bolt. The ultimate bearing capacity of two bolts is similar, and the interfacial bond strength decreases with increasing anchorage length. The bond performance between the steel bolt and grouting is better than that of the BFRP bolt, which is mainly caused by the different processing technology and material mechanical properties between the two bolts. At the same load level and position, the axial force of BFRP bolt is larger than that of steel bolt, and the attenuation rate of axial force is slightly smaller than that of steel bolt;the peak shear stress of BFRP bolt is also smaller than that of steel bolt.