Abstract:  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.