Abstract: In this study, a model for a pre-stressed bolt with two anchorage segments was established, by considering both the superiority of point-anchoring bolts and the laws of destruction partitioning and gradually destructive depth development. The model is basically used to solve the following problems. When lengthening-anchoring or fully-anchoring bolts were applied in the deep roadway, the anchorage segments of the anchor was not as uniform as the whole, and the shear capacity was low. While point-anchoring bolts could not adapt to the large deformation. Afterwards the stress characteristics and bearing capacity of two anchorage segments were studied using theoretical calculations and numerical simulations. Moreover, a comparative analysis was also provided in this study. The results show that the bolt with two anchorage segments obviously changes the shear stress curve of the lengthening-anchoring or fully-anchoring bolts, which turns the trend of the original negative exponent into the gentle. Its shear bearing capacity is also improved by the partition supporting pattern with two anchorage segments. Under the conditions of the same pre-stressed force, the load and shear stress of the anchoring section are obviously lower than that of point-anchoring bolts. Under different pre-stressed conditions, these two anchorage sections are separately used as the supporting function of point-anchoring bolts according to various periods of surrounding rock deformation, which continues to show the superiority of point-anchoring bolts.

Key words: non-uniform stress, prestressed bolt with two anchorage segments, reinforcement of surrounding rock, shear stress curve