为解决公路隧道中采用预应力锚索支护时如何选择合适锚具及其最佳限位距离的问题，选用A、B、C 3类常见矿用锚具，通过理论分析、室内试验以及现场试验的方法，探究3类锚具锚固效果及与之对应的最佳限位距离。结果表明： 1）预应力损失与限位距离存在慢速下降、快速下降和稳定损失3个阶段，拐点x2为锚具的理论最佳限位距离； 2）根据锚具结构、相同限位距离下预应力损失情况和锚具张拉前后的回缩长度综合得出，在相同的条件下，B型锚具的锚固效果优于A型和C型； 3）锚具的实际最佳限位距离应低于理论最佳限位距离和锚索张拉前夹片平均外露长度，则对于最佳限位距离A型锚具为12.0 mm，B型锚具为10.0 mm，C型锚具为13.0 mm。

 To rationally select the appropriate anchors and optimal limit distances when using prestressed anchor cable support in highway tunnels, three common mine anchoring tools, A, B, and C, are selected to explore the anchoring effect and the corresponding optimal limit distance of the anchoring tools through theoretical analysis and laboratory and field tests. The results reveal the following: (1) There are three stages of slow decline, rapid decline, and stable loss of prestress loss and limit distance. The inflection point 〖WTBX〗x2 〖WT５《TNR》〗is the theoretical optimal limit distance of anchors. (2) According to the anchorage structure, the prestress loss under the same limit distance, and the anchor retraction length before and after the tension, it is concluded that under the same conditions, the anchoring effect of type B anchorage outperforms that of types A and C. (3) The actual optimal limit distance of the anchor should be smaller than the theoretical optimal limit distance and the average exposed length of the clamp before the anchor cable tension. Thus, the optimal limit distances of types A, B, and C anchors are 12.0, 10.0, and 13.0 mm, respectively.