Common Pile Foundation Construction Techniques for Highway Bridges

In highway bridge construction, pile foundation construction is a critical step to ensure the stability and safety of the bridge. The primary function of the pile foundation is to transfer the load from the superstructure of the bridge to the deep soil or rock layers, providing reliable support and resistance against overturning. Depending on geological conditions and project requirements, the following pile foundation construction techniques are commonly employed:

1. Rotary Drilling Cast-in-Place Pile

Rotary drilling cast-in-place piles are one of the most widely used methods in bridge pile foundation construction, especially suitable for soft soil layers, sand layers, and complex geological conditions with some hard rocks.

• Construction Process:

1. Use a rotary drilling rig to drill to the design depth.

2. Insert the reinforcement cage into the borehole after drilling.

3. Use a conduit or pumping system to pour concrete underwater, forming a complete pile.

• Advantages:

• High construction efficiency, suitable for large-diameter and deep foundation piles.

• Minimal environmental disturbance, with low noise and vibration.

• Capable of high-quality pile construction in complex geological conditions.

• Precautions:

• Mud performance must be controlled to prevent borehole collapse.

• Concrete pouring should be continuous to avoid joints or voids.

2. Long Auger Cast-in-Place Pile

The long auger cast-in-place pile is an environmentally friendly method that requires no mud circulation, mainly suitable for soft soils and silty clay.

• Construction Process:

1. Use a long auger drilling machine to drill and simultaneously remove soil.

2. While withdrawing the drill rod, continuously pour concrete through the central pipe of the rod.

3. After pouring, insert the reinforcement cage to form the pile.

• Advantages:

• No need for mud circulation, reducing pollution and ensuring environmental protection.

• Simple procedure, suitable for large-scale pile foundation projects.

• Limitations:

• Not suitable for layers with poor borehole wall stability.

• The withdrawal speed of the drill rod and concrete pouring volume must be carefully coordinated to avoid voids or narrowing.

3. Steel Pipe Piles and Precast Piles

Steel pipe piles and precast piles are mainly used in bridge projects with good geological conditions and high precision requirements for pile driving.

• Construction Process:

1. Steel pipe piles are driven into the ground using vibration or hammering methods.

2. Precast piles are prepared in factories and driven into the ground using static pressing or hammering methods.

• Advantages:

• Fast construction speed, ideal for time-sensitive projects.

• No borehole formation is required, avoiding collapse risks.

• Disadvantages:

• Pile driving generates high noise and vibration, unsuitable for environmentally sensitive areas.

• Limited applicability depending on geological conditions.

4. Driven Cast-in-Place Pile

Driven cast-in-place piles are suitable for soft ground foundations, characterized by pipe sinking for borehole formation, followed by concrete pouring to form the pile.

• Construction Process:

1. Sink the pile pipe using vibration or hammering methods.

2. Pour concrete while withdrawing the pipe to form a complete pile.

• Advantages:

• Requires low site conditions, suitable for soft ground.

• No drilling equipment needed, resulting in lower costs.

• Drawbacks:

• Limited precision, easily affected by soil compression.

• Suitable for shallow foundations, less effective for deep foundations.

5. Combined Drilled and Jet Grouting Pile

In special geological conditions, a combined technique of drilled piles and jet grouting piles is often used to enhance load capacity and impermeability.

• Construction Process:

1. Use jet grouting piles to form a high-strength reinforced zone around the pile.

2. Perform drilled pile construction to enhance overall pile foundation strength.

• Advantages:

• Improves pile load capacity and impermeability.

• Especially suitable for soft ground and water-saturated soil layers.

• Applications:

• Large-scale bridge projects in special environments, such as river or lake crossings.

Conclusion

The selection of pile foundation construction techniques for highway bridges should comprehensively consider geological conditions, project scale, and construction environment. Rotary drilling cast-in-place piles and long auger cast-in-place piles are widely adopted due to their efficiency and environmental advantages. Steel pipe piles and driven cast-in-place piles offer simplicity and versatility for specific scenarios. By reasonably selecting and optimizing construction techniques, it is possible to improve project quality, reduce construction risks and costs, and ensure the long-term safety and stability of the bridge.

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