中文摘要：

针对预应力锚索锚固体的破坏形式，采用Hoek-Brown强度准则及其相关联的流动法则，分别考虑锚固体界面产生滑脱破坏与锚固体周围岩体发生整体破坏两种工况，根据塑性力学中的上限分析定理，推导出了锚索极限抗拔力的计算公式与锚固体的破裂机制，并分别讨论了锚固段灌浆压力、锚固段长度与岩体强度参数等对极限抗拔力与破裂面形状的影响。计算表明：一定范围内增大锚固段长度和采用压力灌浆是提高锚索极限抗拔力的有效措施；当锚固段周围岩体发生整体破坏时，随着岩体经验参数A、岩体抗拉强度、抗压强度与重度的增加，锚索极限抗拔力不断增大，而随着经验参数B的增加，锚索极限抗拔力则不断减小；锚固段周围岩体破裂面形状呈现出对称的“喇叭形”，这与现有文献中的研究成果相一致，而且岩体经验参数B是影响岩体破裂面形状的重要因素，它决定了岩体破裂面的曲率大小，当B=1时，岩体破裂曲面退化为圆锥面。

英文摘要：

Focused on the failure modes of prestressed anchor cables, according to Hoek-Brown failure criterion and associated flow rule, the ultimate pullout force and failure mechanism of anchor cable were deduced through upper bound limit analysis, where bond failure of anchorage body and anchored rock mass failure were considered respectively. The influences of grouting pressures, lengths of anchorage section and rock parameters on ultimate pullout forces and failure mechanisms were analyzed. The results reveal that, increasing anchorage length in a certain extent and using pressure grouting are effective measures to improve ultimate pullout forces of anchor cables. When anchored rock mass failure occurs, ultimate pullout forces will increase with the improving of empirical parameter A, tensile strength, compressive strength and unit weight of rock mass, while it will decrease with the improving of empirical parameter B. The shape of failure surface of anchored rock mass looks like horn, which is consistent with the conclusions of existing literatures;and parameter B is a key factor affecting the shape of failure surface of rock mass;it determines the curvature of failure curved surface;and curved surface will degenerate into circular conical surface when B is equal to 1.