Introduction to the construction process of steel pipe piles

The purpose of steel pipe pile construction is to transfer the load of the superstructure to the deep soil layer with a strong bearing capacity or to compact the weak soil layer to improve the bearing capacity and compactness of the foundation soil. Therefore, it is necessary to ensure that the steel pipe pile The quality of the construction, otherwise the building will be unstable. The construction steps of steel pipe piles are: 8

1. Measurement and setting out: The measurement engineer sets out according to the design pile position diagram, and marks the piling points with wooden piles or white ash.

2. The pile driver is in place: the pile driver is in place, aligned with the pile position, and the construction is carried out vertically and stably, ensuring that it does not tilt or move during construction. The pile driver is in place on the pile position, the steel pipe pile is hoisted into the pile driver, and then the pile end is positioned at the center of the pile position, the mast is lifted, and the level and pile center are corrected.

3. Welding pile tip: Taking the commonly used cross pile tip as an example, the cross pile tip is placed at the pile position after checking, and the bottom end plate of the single-section steel pipe pile is welded together with its alignment. The welding adopts CO2-shielded welding. After finishing, the pile tips are painted with anti-corrosion asphalt.

4. Verticality detection: adjust the extension length of the oil plug rod of the outrigger cylinder of the pile driver to ensure the level of the pile driver platform. After the pile is 500mm into the soil, use two theodolites to measure the verticality of the pile in a mutually perpendicular direction. The error should not be greater than 0.5%.

5. Pile pressing: The concrete strength of the steel pipe pile reaches 100% of the design strength, and the pile can be pressed only when the pile remains vertical without abnormality under the check of two theodolites. If there are serious cracks, inclinations, Sudden deviations, drastic changes in penetration, and other phenomena should stop the construction, and start construction after treatment. Pay attention to the speed of the pile when pressing the pile. When the pile enters the sand layer, the speed of the pile should be accelerated appropriately to ensure that the pile tip has a certain penetration ability. When the pile reaches the bearing layer or the oil pressure suddenly increases, it should Slow down the pressing speed to prevent the pile from breaking.

6. Pile connection: Generally, the length of a single-section steel pipe pile does not exceed 15m. If the design pile is longer than the length of a single-section steel pipe pile, a pile connection is required. Generally, electric welding is used to weld the pile. For symmetrical welding, the weld seam should be continuous and full without construction defects. After the pile connection is completed, the piling construction can only be continued after passing the acceptance inspection.

7. Pile delivery: When the pile is pressed to 500mm from the filling ground, use the pile delivery device to press the pile to the design elevation, and increase the static pressure appropriately. Before sending the pile, the depth of the pile delivery should be calculated according to the design requirements, and the pile delivery Make eye-catching marks on the device. When the piles are delivered to about 1m from the design elevation, the surveyors instruct the operator of the pile machine to reduce the pile pressing speed, and track and observe the pile delivery situation, until the piles are sent to the design elevation, a signal is sent to stop the pile delivery.

8. Final pile: Double control of pressure value and pile length is required during the construction of engineering piles. When entering the bearing layer, the pile length control is the main method, and the pressure value control is supplemented. If there is any abnormality, the design unit must be notified.