Steel pipe pile

Steel pipe piles are a type of cylindrical steel structure and a common deep foundation structure. They can transfer the load of the superstructure to the deep hard soil or rock layer by directly driving or drilling into the foundation through frictional resistance and end bearing force. The following is a detailed explanation of the definition, types, manufacturing processes, features and application scenarios of steel pipe piles for everyone.

What is a steel pipe pile?

Steel pipe piles are a type of structure that uses steel pipes as load-bearing materials. By driving or vibrating them into the foundation, the loads of buildings are transferred to the harder soil layer deep underground. It is commonly used in engineering fields such as buildings, Bridges, docks, offshore platforms and subways that require deep foundation support.

Types of Steel Pipe Piles

1. Open-End Steel Pipe Piles: Open at the bottom, allowing soil to potentially enter the pipe after driving. Suitable for many conventional driven pile foundations.

2. Closed-End Steel Pipe Piles: With steel plates, pile shoes, or other end structures at the pipe ends, improving end bearing capacity. Suitable for specific soil and rock conditions.

3. Concrete-Filled Steel Pipe Piles: The interior of the steel pipe is filled with concrete, forming a steel-concrete composite pile, improving axial bearing capacity and bending resistance.

4. Steel Pipe Sheet Piles: Connectors are installed on both sides of the steel pipe to form a continuous structure. Commonly used in wharves, cofferdams, revetments, and retaining structures.

Steel pipe piles are typically manufactured using three processes: ERW, LSAW, and SSAW.

ERW: Roll the original plate into a cylinder and weld the two ends through high-frequency current. This type of steel pipe is mainly used for fences, scaffolding, and some pipelines for gases and fluids. It is suitable for medium and small diameter piles and has a relatively low cost.

LSAW: Straight seam submerged arc welded pipe is made by rolling a discontinuous section of pipe into a cylinder and then welding it longitudinally and transversely. This method can produce the largest and thickest pipe sections, which can be used for load-bearing piles, composite wall piles or other purposes. It is suitable for large piles with large diameters and thick walls.

SSAW: It is formed by spiral forming and welded along the edge of the steel plate in a spiral manner. It is usually used as the main pile of the composite wall and also as the dredging pipe.

How to Choose the Right Steel Pipe Pile?

The selection of a steel pipe pile depends on several project-specific factors, including:

Required axial and lateral load capacity
Soil and geological conditions
Pile diameter and wall thickness
Required pile length
Installation method
Corrosion environment
Steel grade and applicable standard
Project budget and construction schedule

For example, LSAW steel pipe piles are often considered for large-diameter and heavy-load applications, while SSAW steel pipe piles can provide an economical solution for large-diameter piling projects. ERW piles may be suitable for smaller or medium-diameter applications where production efficiency and cost are important.

Installation method

Impact driving: Use an impact hammer to forcefully strike the top of the pile, driving the pile body to the predetermined depth.
Drilling/bored method: Drilling holes first and then driving piles in hard ground or rock areas can effectively reduce vibration and noise.
Static pressure/static hammer entry: Slowly press in with hydraulic pressure, suitable for urban environments that are sensitive to the impact on buildings.

Steel Pipe Pile Standards

ASTM A252 is one of the most commonly referenced standards for welded and seamless steel pipe piles. It specifies requirements for steel pipe piles used for load-bearing applications, including chemical composition, mechanical properties, dimensions, and testing.

Advantages and Limitations

Advantages: It has high axial load-bearing capacity and bending resistance. The construction is flexible and the pile length can be adjusted by welding. It has strong structural combination capacity and can fill the concrete territory to form composite piles, enhancing the bending resistance and anti-corrosion performance.
Limitation: Steel pipe piles are prone to corrosion when exposed to wet soil or seawater for a long time, and anti-corrosion measures need to be taken. The demand for professional equipment is relatively high, and the cost of manufacturing large pile foundations is also relatively high.

Main application fields

High-rise and heavy-load building foundations: Adapt to weak soil layers and provide stable support.
Bridges, ports and docks: They bear high pressure and hydrodynamic loads.
Subway tunnels and underground projects: They can effectively reduce soil disturbance and protect adjacent structures.
Composite retaining structure: Combined sheet piles form continuous walls for retaining soil, dredging, etc.
Offshore wind power piles and anchor piles: Large-diameter steel pipes are used for cross-sea structure foundations, such as single-pile foundations.

Frequently Asked Questions About Steel Pipe Piles

1. What is the difference between a steel pipe pile and a piling pipe?

Steel pipe pile refers specifically to a steel pipe used as a load-bearing foundation pile. Piling pipe is a broader term that can refer to steel pipes manufactured or supplied for piling applications, including foundation piles and other supporting structures.

2. What standard is commonly used for steel pipe piles?

ASTM A252 is one of the most commonly used standards for steel pipe piles. It covers welded and seamless steel pipe piles used for load-bearing applications.

3. What are the common types of steel pipe piles?

Common types include open-end steel pipe piles, closed-end steel pipe piles, concrete-filled steel pipe piles, and steel pipe sheet piles. They can also be classified according to their manufacturing process, such as ERW, LSAW, and SSAW.

4. What is the difference between LSAW and SSAW steel pipe piles?

LSAW steel pipe piles have a longitudinal weld seam and are commonly selected for large-diameter, thick-wall and high-load applications. SSAW steel pipe piles have a spiral weld seam and offer flexible diameter and length options with competitive production costs.

Summary

Steel pipe piles occupy an important position in the field of deep foundations due to their advantages such as high load-bearing capacity, flexible dimensions, fast construction and low environmental disturbance. It has been widely applied in urban architecture, Bridges and Marine engineering.

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