Overview of the Construction Process of Industrial Steel Pipe Piles

The purpose of steel pipe pile construction is to transfer the load of the superstructure to deeper, stronger soil layers or to compact weak soil layers to improve the bearing capacity and density of the foundation soil. Therefore, it is crucial to ensure the quality of steel pipe pile construction; otherwise, the structure will be unstable. The construction steps for steel pipe piles are:

1. Surveying and Setting Out: The surveying engineer sets out the pile positions according to the design plan and marks the pile driving points with wooden stakes or lime.

2. Pile Driver Positioning: The pile driver is positioned, aligned with the pile position, and constructed vertically and stably, ensuring no tilting or movement during construction. The pile driver is positioned at the pile driving position, the steel pipe pile is hoisted into the pile driver, and then the end of the steel pipe pile is positioned at the center of the pile position. The gantry crane is erected, and the level and pile center are corrected.

3. Welding the Pile Tip: Taking the commonly used cross-shaped pile tip as an example, the cross-shaped pile tip is placed at the verified pile position, and the bottom end plate of the steel pipe pile is welded to it. CO2 shielded welding is used for welding, and the pile tip is coated with anti-corrosion asphalt after welding.

4. Verticality Inspection: Adjust the extension length of the hydraulic cylinder piston rod of the pile driver's outriggers to ensure the pile driver platform is level. After the steel pipe pile is driven 500mm into the ground, use two theodolites set up perpendicularly to measure the verticality of the steel pipe pile. The error should not exceed 0.5%.

5. Pile Driving: Pile driving can only begin when the concrete strength of the pile reaches 100% of the design strength, and the pile remains vertical without abnormalities under the verification of two theodolites. If serious cracks, tilting, sudden displacement, or drastic changes in penetration occur during pile driving, construction should be stopped, and the problem should be addressed before resuming construction.

6. Pile Driving: When driving piles into sandy soil layers, the driving speed should be increased appropriately to ensure sufficient penetration at the pile tip. Upon reaching the bearing layer or when the hydraulic pressure suddenly increases, the driving speed should be slowed down to prevent pile breakage.

7. Pile Splicing: Generally, the length of a single steel pipe pile section should not exceed 15m. If the designed pile length exceeds the length of a single section, pile splicing is required. Electric welding is typically used for splicing. Two people should weld simultaneously and symmetrically, ensuring the weld is continuous, full, and free of defects. After splicing, acceptance testing is required before continuing pile driving.

8. Pile Delivery: When the pile is driven to 500mm from the fill surface, a pile driver should be used to drive the pile to the design elevation, and the static pressure should be appropriately increased. Before driving the pile, the driving depth should be calculated according to the design requirements, and a clear mark should be made on the pile driver. When the pile is driven to approximately 1 meter from the design elevation, the surveyor instructs the pile driver operator to reduce the pile driving speed and monitors the pile driving process until the pile reaches the design elevation, at which point a signal is given to stop driving the pile.

9. Final Pile Construction: During the construction of engineering piles, both the pressure value and pile length must be controlled. When entering the bearing stratum, pile length control is primary, with pressure value control as a secondary measure. Any abnormalities must be reported to the design unit for handling.