Construction Methods of Piling Pipes
Piling pipes, also known as foundation piles, are critical components in deep foundation construction projects, ensuring the stability and safety of buildings, bridges, docks, and other infrastructure. They are used to transfer loads from the superstructure to deeper, more stable soil layers. Understanding the construction methods of piling pipes is essential for ensuring the effectiveness, efficiency, and environmental safety of these crucial structures.Piling pipes can be made of
SSAW steel pipes and
seamless steel pipes, as well as some large-diameter LSAW steel pipes and ERW pipes. In this article, we will explore the different construction methods of piling pipes, providing a detailed guide for both precast and cast-in-place piles.
Types of Piling Pipes
Before delving into the construction methods, it’s essential to understand the different types of piling pipes commonly used in construction projects:
1. Precast Piles
Precast piles are manufactured in factories or construction sites and include concrete precast piles, steel pipe piles, and H-shaped steel piles. These piles are driven, pressed, or vibrated into the soil to provide support for the structure above.
2. Cast-in-Place Piles
Cast-in-place piles are made by drilling a hole at the pile location, inserting a steel skeleton, and then pouring concrete into the hole. Depending on the method of forming the hole, cast-in-place piles can be divided into excavation piles, drilling piles, casing piles, and explosive expansion piles.
Construction Methods for Piling Pipes
Piling pipe construction involves various methods, each suited for different soil conditions, pile types, and project requirements. Here are the main construction methods:
1. Hammer Pile Driving (Precast Piles)
The construction method of hammer pile driving is to use the impact force of the pile hammer falling on the pile top to overcome the resistance of the soil to the pile, so that the pile sinks to a predetermined depth or reaches the bearing layer. Hammer pile driving is a commonly used pile driving method for precast concrete piles. It has a fast construction speed, a high degree of mechanization, and a wide range of applications. However, there is impact noise and vibration to the surface layer during construction, which has some limitations in urban areas and at night.
Equipment Used:
Pile Hammer: Includes drop hammers, steam hammers, diesel hammers, and hydraulic hammers.
Pile Frame: Supports the pile and pile hammer, guiding the pile during driving.
Power Device: Powers the pile hammer and winch.
2. Vibrating Piles
Vibrating piles are another common method for driving precast piles, especially in loose or sandy soils. In this method, a vibrating mechanism is used to reduce soil friction, making it easier to drive the piles into the ground.Working principle: Its main device is a vibrator, which uses the exciting force generated by the vibrator to make the pile body vibrate at high frequency. At this time, the pile sinks into the soil under its own weight or a small additional pressure, or is pulled out of the soil under a small lifting force.
Equipment Used:
Vibrator: A device that creates vibration to ease pile penetration into the ground.
Pile Frame: Guides the pile during the driving process.
3. Static Pressure Piles (Prestressed Concrete Pipe Piles)
Static pile driving is a method of driving piles in uniform soft soil. The deadweight and counterweight of the pile driving frame (made of steel) are used to counter-press the weight of the entire pile driver (800-1500kN) on the top of the pile by steel wire rope, pulley and pressure beam to overcome the friction between the pile body and the soil when it sinks, forcing the prefabricated pile to sink and press the pile into the soil section by section. This pile driving method is vibration-free, noise-free, and has little impact on the surrounding environment. It is suitable for construction in cities. Pile driving construction generally adopts the construction method of pressing in sections and extending them section by section.
There are currently three methods for connecting piles: welding, flange bolt connection, and sulfur slurry anchor method.
4. Drilling and Grouting Piles (Cast-in-Place Piles)
Drilling and grouting piles are used to create a deep, stable foundation by drilling holes and then injecting grout or concrete into the hole. This method is commonly used for cast-in-place piles, especially in challenging soil conditions.
Steps:
Drilling: A borehole is drilled at the designated pile location.
Grouting: Concrete or grout is injected into the hole, stabilizing the surrounding soil and creating a solid foundation.
5. Casing Method (Pipe Sinking Method)
The casing method involves using a steel pipe casing to drill and stabilize the pile location before pouring concrete. This method is used to create deep foundations, especially in areas with loose or soft soils.
Steps:
Casing Insertion: A steel pipe is sunk into the ground at the pile location.
Concrete Pouring: Concrete is poured into the casing to form the pile.
6. Explosive Expansion Method (Cast-in-Place Piles)
This method involves the use of explosive materials to expand the soil, allowing the pile to sink into place. It is a less commonly used technique but can be effective in certain conditions.
Factors to Consider in Pile Construction
The construction method chosen depends on several factors, including:
Soil Conditions: The type of soil (soft, hard, sandy, etc.) greatly influences the choice of pile and construction method.
Pile Type: Precast piles are generally easier and faster to install, while cast-in-place piles may be necessary for deeper foundations.
Project Location: Urban environments may require quieter methods like static pressure piles, while remote locations may allow the use of more disruptive methods like hammer pile driving.
Several issues that should be noted during construction
The plane position deviation of the centerline of the pile hole should not exceed 50㎜, and the verticality deviation of the pile should not exceed 0.5%
The pile diameter should not be less than the design diameter of the pile. In the excavation hole area, no residual soil and building materials should be piled up, and local concentrated loads and mechanical vibrations should be prevented.
The pile foundation must be located on the bearing layer required by the design, and the excavation depth of the pile hole should be determined by the designer based on the actual situation of the foundation soil layer on site.
Manual excavation holes should be constructed continuously, and concrete pouring should be carried out immediately after the hole is accepted. Carefully remove the floating slag and residual soil at the bottom of the hole and drain the accumulated water, and prevent groundwater from flowing in during the pouring process.
During the manual excavation hole process, the construction should be strictly carried out in accordance with the operating procedures. A safety guardrail should be set up on the well surface. When the net distance between the pile holes is less than 2 times the pile diameter and less than 2.5m, the holes should be dug at intervals.
Conclusion
The construction methods of piling pipes are diverse, each offering unique advantages and limitations depending on the project requirements. Whether using precast piles with hammer pile driving, or installing cast-in-place piles through drilling and grouting, selecting the right construction method is essential for the long-term stability and safety of any foundation. By considering factors such as soil conditions, pile types, and project scope, contractors can choose the most suitable method to ensure a successful foundation installation.
English
Español
بالعربية
Phone : 
Whatsapp : 
Email : 
