In a bridge, the wing wall is adjacent to the abutment and acts as a retaining wall. They are usually made of the same material as abutments.
The soil and filler supporting the road and approach embankment are blocked by wing walls, which can be opened at right angles or at different angles to the abutment. Wing walls are usually built at the same time as abutment and made of the same material.
The plane layout of wing wall mainly considers the diversion requirements. For water-crossing buildings with water retaining tasks, the requirements of shore seepage prevention should also be considered in the plane layout of water retaining side walls. The projection length along the water flow direction is not less than the bedding length. No matter the entrance or exit, the Hebei wall should be smooth on the plane and spread to both sides of the entrance to avoid adverse flow patterns such as backflow and vortex in front of the wall.
The plane layout of wing wall includes straight line, broken line and curve, which can be selected according to the inlet and outlet velocity and terrain conditions. Generally, imported wing walls can use straight lines, broken lines or arcs; Ellipse or other curves with gradual curvature should be adopted at the outlet, and the curvature can be gradually increased from the outlet to the downstream.
The wing wall facing the water surface has vertical, inclined and twisted surfaces, and the water flow is in good condition. At the junction of the inclined wing wall and the outlet, the cross section of the water suddenly changes, which often causes vortex or even backflow.
Large wing walls are mostly vertical, while small and medium wing walls can be twisted. The elevation of wing wall top is determined according to the operation requirements of water-passing buildings. In principle, it should be higher than the water level when flowing. When the flow rate is low, it can also be lower than the water level. When there is a water retaining task, the top of the water retaining wing wall should be higher than the highest water retaining level.
Wing walls enable water to enter the bridge site smoothly and provide support and protection for the embankment. Wing walls can be used as buttresses to support walls. They can also be purely decorative.
Classification of wing wall
Wing walls can be classified according to their position relative to banks and abutments in plan view. The classification is as follows:
1. Straight wing wall: used for small bridges, low-bank drainage ditches and urban railway bridges (with drainage holes).
2. splayed wing wall: used for river-crossing bridges. They provide a smooth water inlet and outlet. The oblique angle is usually 45. Their top width is 0.5 m, and there are 12 sets on the front and 1 set on the back, and they are provided with drainage holes.
3. Return wing wall: used in places where the embankment is high, hard or solid. Their top width is 1.5 m, the front is vertical, and the back has an impact of 1 on 4. Scouring may be the problem of wing wall and abutment, because the stream will scour the supporting soil.