关键词: 预应力锚索, 自由段先注浆, 界面脱黏, 抗拔特性, 荷载传递

Abstract: To overcome the drawback that the ultimate pullout resistance of prestressed anchor cable cannot be directly obtained by the pullout test, this study proposes a pullout resistance performance evaluation method of pre-stressed anchor cable based on the pullout tests on prestressed anchor cable with pre-grounting in the free segment. Based on the interfacial debonding shear model and the theories of load transfer and elastic deformation, the length ratio of the anchor segment to the free segment was considered in the evaluation method. The results indicate that pre-grouting in free segment can significantly improve the pullout resistance capability of anchor cable. When the interfacial deformation behavior transfers from an elastic manner to debonding stage, the improvement of the pullout resistance will be more pronounced, which will tend to be stable after debonding. The shear displacement and axial force at the interface of the free segment and grouting segment is the highest. With increasing the pullout force, both the shear displacement and axial force increase but the increment declines to the two ends of anchor cable. The shear stress curve is one peak type in the elastic stage and then becomes a saddle type in the debonding stage. The opening of the saddle type curve becomes larger with the improvement of the pullout resistance. Finally, the length ratio of anchoring and free segment has insignificant effects to the ultimate pullout resistance. The reduction coefficient ?Q of the ultimate pullout resistance of pre-grouting anchor cable is in the range from 0.81 to 0.83. The empirical method in paper is feasible due to the fact that merely 6.02% error is existed between the measured ultimate pullout resistance and calculation result when Lb /La is 2.5.

Key words: prestressed anchor cable, pre-grouting in free segment, interfacial debonding, pullout resistance feature, load transfer