Abutment type

Cone-shaped fill soil is set on both sides of abutment and its slope surface (such as masonry) is protected, which has the same function as splayed wing wall. Because of the fixed position of train track, railway bridges need narrow abutment width and often need high abutment, so cone filling is widely used instead of wing wall, which has good technical and economic effects. There are many abutment structures without wing wall, such as U-shape, T-shape, embedded type and ear wall type. ① U-shaped abutment. The abutment consists of a front wall supporting the superstructure and two side walls (perpendicular to the front wall) extending to the embankment in a U shape, and conical fillers are arranged on the outside of the side walls. Because of its simple structure, strong integrity and simple construction, it is widely used in cities and highway bridges. Railways are only used for low abutments with small bridge spans; Because the abutment is narrow, when the abutment is high, the inner slopes of the two sides meet at the lower part and become solid, and the number of masonry will increase sharply, which is uneconomical. ②T-shaped abutment. Usually used in railway bridges, highway bridges and urban bridges, but not used because of the narrow abutment. The platform body is T-shaped and has a front wall and a back wall perpendicular to it. The front wall supports the superstructure; The back wall is parallel to the line, and the top of the wall is provided with ballast grooves to support the upper structure of the line between the bridge span and the embankment; The two have different uses and form a whole, which has the advantages of reasonable structure, strong adaptability and less masonry. ③ Embedded abutment. Named after the abutment is buried in the conical fill, it is suitable for high embankment and long-span bridges at the bridgehead, and has the characteristics of short abutment and low masonry. There are two forms of abutment with ear wall and without ear wall. The ear wall must be made of reinforced concrete. In order to reduce and effectively resist the earth pressure behind the abutment, the abutment body is generally made in the form of backward inclination, which is also called backward embedded abutment. There are still piled embedded abutments in highway bridges, and the ear wall is made on the abutment cover, which is also a light abutment. Most of the cone fill of the embedded abutment extends out of the front of the abutment, which has the disadvantage of occupying the water area under the bridge and being easily washed away by the current. Therefore, embedded abutments are mostly used for dry bridges and bridges with slow water flow under them. In the collocation of bridge span and abutment height, it is advisable to choose a longer span to avoid the unilateral slope earth pressure caused by the leading edge of conical fill on adjacent piers. ④ Ear wall abutment. It consists of two ear walls and a front wall, and only a few abutment bodies are buried under the inclined plane of the vertebral body, which also has the characteristics of reducing masonry. However, the reinforced concrete ear wall is more complicated and more difficult to construct, and it is not as widely used as the first three in China.