低周往复荷载作用下预应力锚索震害特征研究

SEISMIC DAMAGE OF PRESTRESSED ANCHOR CABLES UNDER LOW FREQUENCY CYCLING LOADS

以地震灾区的震害斜坡为原型搭建锚固工程模型,采用低周往复荷载试验方法,研究预应力锚索在往复荷载作用下的震害特征与变形规律。结果表明:在往复荷载作用下,预应力锚索最先发生破坏且破坏最为严重的是位于模型最上排的锚索,其破坏形式以锚索体自由段根部拉断和外锚头脱落为主,未出现内锚固段黏结力和握裹力失效现象;锚索体应变显著变化的部位集中在锚固段,一处靠近锚固段底部,另一处靠近滑面位置,且尤以靠近滑面处的应变较大;往复荷载比单一的水平推力对锚索的变形影响更大,更容易导致材料的破坏。该成果对地震灾区预应力锚索的健康诊断与震害评估具有一定的参考价值和指导意义。

An experimental model was constructed based on a real prestressed anchor cable project in the earthquake zone. The seismic loading was imposed through low frequency cycling loading. The results of the experiment demonstrated that the failure of the prestressed anchor cables occurred in sequence from top to down under cycling loading. The top row of cables was the most severely damaged and the failure types were dominated by the breakage at the tail of the cable and the detachment at the head of the cable. The failure of bonding force and bonding stress of the anchoring section was not observed. The deformation of the cable was concentrated on the anchoring section with the large strain occurred at the bottom of the section and the part adjacent to the sliding surface. Small strain was found in the free segment. The cycling loading imposed greater impact on the deformation of prestressed anchor cables than the constant mono-directional thrust or single mono-directional thrust.