Adjustable Steel Pipe Columns for Subways

Adjustable steel pipe columns for subways are steel structural components used in deep foundation pit support or top-down construction methods in subway stations. Their adjustable design (e.g., height, position, or angle) allows them to adapt to complex construction environments and precise installation requirements.
 

Steel Pipe Column Fabrication and Installation:

• Structural Composition:
  • Steel Pipe Column Main Body: Typically a circular or square hollow steel pipe (diameter 1000-1500mm, wall thickness 20-30mm), made of Q355B or Q235 steel, and filled with C30-C50 self-compacting concrete to enhance compressive strength.
  • Adjustable Components:
    • Height Adjustment: Such as external threaded pipes with internal threaded components, achieving automated height adjustment through rotating bearings and motors. The adjustment range is proportional to the screw length.
    • Planar and Verticality Adjustment: Adjust the spatial position and verticality of the steel pipe column through positioning brackets, limit plates, jacks, or hydraulic insertion machines.
    • Support Rods: Some designs include hinged support rods (at least 3, evenly distributed) on the outer wall of the pile hole section to ensure the steel pipe column is centered and stable.
  • Tool Column: Often used to extend the steel pipe column above ground for easy ground adjustment. The tool column is connected to the steel pipe column with high-strength bolts, and the outer diameter difference is controlled within ±5mm.
• Prefabrication: Steel pipe columns are processed in the factory, ensuring an ovality ≤ 3D/1000 (D is the diameter), smooth welds, and reserved shrinkage allowance.
• Lifting and Insertion:
  • Use crawler cranes or truck cranes (50-240T) for lifting, using two-point lifting to ensure verticality.
  • Use HPE hydraulic vertical insertion machines or adjustable positioning brackets to insert into retarded concrete, with a centerline deviation ≤ 5mm.
• Adjustment and Correction:
  • Horizontal Adjustment: Place the insertion machine in the middle position for automatic horizontal adjustment and verify the levelness.
  • Verticality Control: Monitor with total stations and theodolites, set limit plates (radius 5mm larger than the steel pipe column) and jacks on the tool column, and adjust the verticality to ≤ 1/500.
  • Height Adjustment: Use threaded pipes and motors, or hydraulic systems, to precisely adjust the elevation, with a deviation ≤ 10mm.
• Concrete Pouring: Pour in multiple stages (usually 3 times), controlling the pouring speed to reduce disturbance to the steel pipe column and prevent displacement.