Basic knowledge of engineering supervision: cast-in-place concrete pier and capping beam?

Pier and abutment are the general names of piers and abutments, and they are the buildings that support the superstructure of the bridge. Abutment is located at both ends of the bridge and connected with subgrade, which has the function of retaining soil; The pier is located between two abutments. Pier and bridge foundation are collectively called bridge substructure. The capping beam refers to the beam set at the top of the high-piled pier to support, distribute and transfer the load of the upper structure. Also known as the cap beam. Set reinforced concrete or less reinforced concrete beams on piers (platforms) or row piles. Its main function is to support the superstructure of the bridge and transfer all loads to the substructure. Some bridge piles are directly connected with the capping beam, and some bridge piles are connected with the capping beam after the columns are connected. 1. The construction of gravity concrete pier and abutment shall meet the following requirements: 1) Before concrete pouring of pier and abutment, the top surface of foundation concrete shall be roughened to remove anchor bar pollution. 2) The pier concrete shall be poured horizontally in layers, and the height of each pouring shall not be lower than 1.5 ~ 2m. 3) When the pier concrete is poured in blocks, the joints should be parallel to the smaller side of the pier section, and the joints of adjacent layers should be staggered and tongue-and-groove. The number of blocks, the horizontal cross-sectional area of piers and abutments shall not exceed 2 blocks within 200m2; No more than 3 pieces within 300㎡, each piece with an area of not less than 50㎡. 2. The construction of column piers and abutments shall meet the following requirements: 1) Besides the strength and rigidity, the influence of wind should also be considered in the stability calculation of formwork and support. 2) The contact surface between pier, abutment and pile cap foundation should be roughened to remove the corrosion of steel bars. When pouring pier concrete, a layer of cement mortar with the same mixture ratio should be laid. Concrete for piers and abutment columns shall be poured continuously at one time. 3) When the tie beam is connected within the height of the column, the tie beam should be poured synchronously with the column, and the V-shaped pier concrete should be poured symmetrically. 4) When precast concrete pipes are used as external formwork of columns, the installation of precast pipes shall meet the following requirements: ① Grooved joints shall be adopted for the foundation surface, and the groove depth shall not be less than 5㎝. (2) After the upper and lower pipe joints are installed in place, four vertical squares should be symmetrically arranged around the pipe string and tied firmly to prevent collision and dislocation. (3) The external formwork of concrete column shall be provided with diagonal braces to ensure the stability during pouring. (4) the pipeline interface shall be sealed with cement mortar. 3. The concrete filled steel tube pier adopts shrinkage compensating concrete, which is continuously poured at one time. Welding and anticorrosion of steel pipes shall comply with relevant regulations. 4. When the capping beam is a cantilever beam, concrete pouring should start from the cantilever end; Demolition time of bottom formwork of prestressed reinforced concrete capping beam should meet the design requirements; If there is no provision in the design, the formwork can only be removed after the grouting strength of prestressed channel reaches the design strength. 5. In the construction of capping beams in busy traffic sections, it is advisable to adopt integral assembling formwork and quick assembling combined support.

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