关键词: 特征荷载, 预应力锚索, 拉拔试验, 数值模型, 荷载-增量位移曲线

Abstract: Composed of working load and ultimate load, the characteristic load of prestressed anchor cable is a critical basis for judging the anchoring effect of anchor cables. The load transfer mechanism of prestressed anchor cable is examined according to the load-incremental displacement curve obtained from six groups of in-situ pull out destructive tests. The method of determining the characteristic load of prestressed anchor cables is also proposed. The whole process of cable in pull load are divided into four stages: the fastening of external anchor segment, the drawing of outer anchor segment, the drawing of free segment, and the sliding of anchorage segment. The working load of anchor cable is determined as the average value between the upper and lower limits of the inflection point of the stage of free segment drawing, while the ultimate load is determined according to the steep increment point of pull-out curve, corresponding to that at incremental displacement 3 mm. In addition, numerical model of the pull-out test is also established using FLAC^3D to analyze the shear stress distribution of cable-grouting body and coupling body-rock interface in anchored segment, verifying the accuracy of the ultimate load displacement criterion.

Key words: characteristic load, prestressed anchor cable, pull-out test, numerical model, load-incremental displacement curve