When the surrounding rock of the steel arch support is weak and broken and its self-stability is poor, the steel arch frame has such good mechanical properties that the initial support is required to have greater stiffness after excavation to prevent the surrounding rock from transitional deformation and to bear part of the relaxation load. Therefore, the steel arch support should be applied in time after excavation. The steel arch is based on the crushing degree of surrounding rock. The arch frame can be well combined with anchor rod, steel mesh and shotcrete to form joint support and enhance the effectiveness of support, and the stress condition is better.
1. Before processing, the steel arch support should release the large sample on the flat steel plate according to the design size, control the radian and length, and ensure the arch frame curve smooth and beautiful.
2. According to the released sample, the steel arch is processed in sections on the section bending machine according to the lofting size.
3. During processing, the influence of factors such as increased size of trolley formwork and reserved deformation amount of hole excavation should be taken into account, and the radius of arch frame should be appropriately increased during segmental processing to ensure the clearance size of tunnel. As the radius of each assembly section increases, the arch length also lengthens.
4. Steel arch frames processed in sections shall be classified and placed before welding and assembly, and shall be marked to avoid confusion during assembly.
