仰拱（Invert）.doc

仰拱（Invert） The inverted arch is the reverse arch structure set at the bottom of the tunnel for the improvement of the upper part of the supporting structure stress conditions, is one of the main part of the tunnel structure, it must be the formation pressure at the upper part of the tunnel side wall of tunnel structure or loads on pavement effectively to the ground, and the anti stress resistance of tunnel the lower formation is also effective to. The inverted arch and the two lining form the whole of the tunnel and increase the stability of the structure. Popularly interpreted as an upturned arch, that is, where the bar is placed on the right. The invert is generally made of reinforced concrete structure. The function of invert: the two lining forms the whole tunnel. Waterproof, increase structural stability. Edit this section of the tunnel invert construction operation guidance Inverted arch is one of the main parts of tunnel structure, and it is the foundation of tunnel structure. On the one hand, the formation pressure on the upper part of the tunnel passes through the side wall structure of the tunnel, or the load on the road is effectively transmitted to the ground, and it also resists the counterforce from the lower stratum of the tunnel effectively. In fact, it is a foundation beam (plate) that can endure the permanent load of the formation and the load (dynamic load) when the road is facing. Therefore, the stress state of the inverted arch is complex. From the case of traffic tunnel disease at home and abroad to see, because the structure of the design and construction of tunnel invert, and tunnel structure instability, pavement settlement and cracking, examples of mud disease of a few. Therefore, the structure of the invert structure must be fine, and the structure must comply with the specifications and design requirements. First, inverted arch excavation: 1. The size of the foundation pit to be inverted shall comply with the requirements of the design do