预应力喷砂玻璃纤维聚合物锚杆的黏结损伤

BOND DAMAGE OF PRESTRESSED SAND-COATED GLASS FIBRE REINFORCED POLYMER ANCHOR

纤维增强聚合物(FRP)可替代钢筋用于边坡加固来解决锚杆耐久性问题。FRP筋模量较小,为限制加固体的前期变形,需对其施加预应力。采用预应力施加装置完成循环加荷,光栅传感技术监测杆体应变,研究预应力施加及循环荷载下喷砂GFRP锚杆的黏结性能。研究表明,施加预应力使锚杆结构承受的过载会导致锚杆体界面黏结力损伤,同级荷载多次循环产生的损伤效应相对于过载的影响可以忽略不计;喷砂GFRP锚杆的黏结力损伤仅受过载的影响,与当前运行荷载无关;喷砂GFRP锚杆体上不同位置的界面剪力,在剪力较小时由黏结力承担,剪力较大时黏结力完全丧失转由摩阻力承担;喷砂GFRP锚杆加固结构承受峰值荷载过大后会导致黏结损伤造成锚固结构松动;预应力喷砂GFRP锚杆结构的超张荷载需超过运行荷载一定量值,以保障运行期锚固力稳定。

The durability problem of anchor rods used to reinforce slopes can be solved by substituting fiber reinforced polymer（FRP） bars for steel bars. The FRP bars have small elastic moduli,and therefore should be prestressed in order to limit the deformation of the reinforced slope during its service stage. This paper described the grating sensing technology to be applied to monitor the bond behavior of sand-coated GFRP anchor rod under cyclic prestressing. The results showed that prestressing of the sand-coated GFRP anchor rod led to the damage of rod-mortar interface bonding of the anchor. The effect of repeated load on the bonding was negligible and the effect of the surcharge load was significant. The damage to the bonding of rod-mortar interface of the anchor is dependent only on the surcharge load,and not on the service load. The shear force of the anchor rod is provided by the bonding force and friction;with the bonding force generated at the initial stage,and then changed into friction at the later stage. The excessive peak loading leads to the damage to the bonding and the loosening of the anchor structure. The over tension load of the prestressed anchor rod structure must exceed the service load to an extent in＆amp;nbsp;order to ensure a stable anchorage force in the service stage.