1. The surface of the steel arch support processing site shall be paved with concrete. According to the design drawings, the machining site can accurately measure and release the large sample of the arch frame, and draw its contour line with paint. A positioning device should be installed every 2m, and the positioning device should be firm and reliable.
2. After the processing of the steel arch support is completed, the test shall be carried out, and the plane distortion, dimensional deviation and contour deviation shall meet the requirements of current specifications and design drawings.
3. Connection plates, bolts and nuts shall be used to connect the i-steel support units, and the connection materials shall meet the design and specification requirements and be firmly connected.
4. Longitudinal connecting bars are used between each steel arch support to strengthen the overall effect of support.
5. When installing the steel arch, it shall be vertically perpendicular to the tunnel, and the allowable deviation of its top, bottom and left and right shall be 5cm, and the inclination of the steel frame shall not be more than 2 degrees. If the elevation of the arch foot is insufficient, it shall not be backfilled with earth and stone, but steel plates shall be set for adjustment, and concrete shall be used to reinforce the base when necessary.
6. The gap between the steel arch support and the surrounding rock is densely filled with shotcrete. When the gap is too large, the concrete wedge can be jacked tightly, and its number shall not be less than 8 on one side. When spraying concrete, it should be sprayed symmetrically upward by the arch feet of both sides, and the steel frame should be covered to ensure that the protective layer of the steel frame is not less than 3cm.
