Design principles of prestressed anchors for tunnels considering bearing arch effect

Prestressed anchor has been gradually applied to the construction of large-span tunnel surrounding rock. This paper aims at the design principle of prestressed anchor considering the bearing arch theory of surrounding rock. The supporting mechanism of prestressed anchor in tunnel engineering was investigated. The anchorage section, free segment, prestress and bearing arch axial force and thickness of prestressed anchor were analyzed respec-tively. Combined with the engineering background, the design parameters of prestressed anchor were calculated theoretically. Based on the obtained theoretical results, the numerical simulation method was used to further determine the influence of several main factors such as anchor length, row spacing and prestress on the stability of surrounding rock, and to verify the effectiveness of the theoretical design method for controlling the stability of surrounding rock. Furthermore, a case study of the Badaling tunnel was introduced to illustrate effectiveness of the proposed method. The final monitoring results show that the maximum displacement of vault settlement is 20.35 mm, which is far below the control standard value. This study can provide a theoretical reference for the application of prestressed anchor to control large deformation of surrounding rock.

Automated summary

This paper investigates the supporting mechanism and design principle of prestressed anchor in tunnel engineering, based on the bearing arch theory. The design parameters of the anchor, including anchorage section, free segment, prestress, and bearing arch axial force and thickness, were analyzed. The numerical simulation method was then used to study the influence of factors such as anchor length, row spacing, and prestress on the stability of surrounding rock, and to verify the effectiveness of the theoretical design method. A case study of the Badaling tunnel demonstrated the effectiveness of the proposed method.