Abstract

In the existing upper bound limit analyses (UBLA) of rotational slopes reinforced with prestressed anchor cables, the mobilized axial forces of all cables are assumed to be equal to the ultimate pullout force. However, such an assumption overestimates the mechanical contribution of prestressed anchor cables, resulting in excessively high safety factors. In this technical note, we aim to tackle this issue by proposing a pseudo-plastic design concept, in which soil masses and prestressed cables are treated as plastic and elastic-plastic, respectively, when slopes collapse. A pseudo-plastic failure model of prestressed anchor cables is proposed, where the variation of tension forces and movement of anchor heads are accounted for. Several interesting conclusions are drawn as follows: (1) Contrary to the conventional plastic failure mode of cables, upper bound solutions obtained by the proposed model are much closer to the exact solutions. (2) Variation of factors of safety (FSs) against the accumulated rotational displacement can be explained by the force-displacement curve obtained in the pullout test of prestressed anchor cables. (3) The sliding slope reinforced with cables may turn out to be stable after a slight rotational movement, which can be utilized in the economical design.

摘要

在现有的预应力锚索加固旋转边坡上限分析（UBLA）中，假设所有锚索的移动轴向力等于极限拉拔力。然而，这种假设高估了预应力锚索的力学贡献，导致安全系数过高。在本技术说明中，我们旨在通过提出一种伪塑性设计概念来解决这个问题，其中土体和预应力索在边坡坍塌时分别被视为塑性和弹塑性。提出了一种预应力锚索的拟塑性破坏模型，其中考虑了拉力的变化和锚头的移动。得出几个有趣的结论如下：（1）与传统的电缆塑性失效模式相反，所提出模型获得的上界解更接近于精确解。(2) 安全系数(FSs)随累积旋转位移的变化可以用预应力锚索拉拔试验中得到的力-位移曲线来解释。(3) 钢索加固的滑坡在轻微的转动后可能会变得稳定，可用于经济设计。