Generally, acrow steel props are inclined connected members which can enhance the stability of the structure. And the most common types are cross shape and herringbone shape. The cross-section of acrow steel prop can be a steel pipe, h-beam, Angle steel, etc.

The brace generally refers to the round steel bar that pulls the purline, namely rough steel bar. The brace is mounted for the purpose of enhancing the stability of purline to make it not easy to lose stability and damage under certain external forces. The section forms of purlines usually are divided into H-shaped, C-shaped, and Z-shaped, which reduce the span of the roof sheathing and fix the roof sheathing.

Simply speaking, the steel pipe, steel arch and steel grille with the thickness of 16mm wall used for subway construction are all used for support, which blocks the soil wall of culvert tunnel and prevents the foundation pit from collapsing. They are widely used in subway construction.

Key points of acrow steel props’ construction

1. Acrow steel props(grilling) shall be prefabricated before leaving the factory and shall be set up according to 1:1. The joint plate alignment of axis, dimension, and joint of splice plate shall be strictly controlled to be accurate, and shall meet the requirements of the standard on the welding seam.

2. The positioning of acrow steel prop (grilling) and positioning of anchor rod with locking foot shall be carried out after the section of the excavation is qualified. Installation shall be conducted strictly according to the design position. The drilling position, direction, depth and angle of anchor rod should meet the design requirements.

3. The acrow steel prop (grille) shall be erected, its axis shall be perpendicular to the central line of the tunnel. Sufficient solid foundation shall be reserved at the base of the steel frame, and grooves shall be dug when the steel frame has not been erected. The line and elevation shall be accurate, the support shall be stable, and its inclination shall be less than two degrees. Any part of the steel frame that deviates from the lead vertical should not be greater than 125px. The over-dug part shall be supported by the hard cement mortar pad.