A piling machine, a term encompassing equipment like piledrivers, piling rigs, pile boring machines, drill rigs, and rotary drills, is a cornerstone in construction for building strong foundations. While these terms are often used interchangeably, they refer to different machine configurations and applications. Understanding these distinctions is crucial for choosing the right equipment for specific construction tasks. The defining feature of a piling machine is its specialty attachment, which holds and drives the pile into the ground. This blog delves into the various types of these specialty attachments, their applications, and the distinct features of different piling machines.
The Different Types of a Piling Machine
Throughout history, the evolution of piling machines has seen various types emerge, each adapted to specific construction needs. Today, the most commonly used types include diesel hammers, vertical travel lead systems, hydraulic hammers, hydraulic press-ins, and vibratory pile drivers/extractors.
- Diesel Hammers
Modern diesel pile hammers operate as large two-stroke diesel engines. The key component, the piston, acts as the weight, and the cylinder attaches to the top of the pile. The process starts by lifting the weight, drawing air into the cylinder, where diesel fuel is injected. The falling weight compresses the mixture, causing ignition and transferring energy to the pile head. This cycle repeats, driving the pile deeper with each stroke.
- Vertical Travel Lead Systems
These systems come in two primary forms: spud and box leads. Box leads are prevalent in the Southern United States, while spud leads are more common in the Northern United States, Canada, and Europe. The choice between these two depends on regional preferences and specific construction requirements.
- Hydraulic Hammers
As a contemporary alternative to diesel and air hammers, hydraulic hammers are used for driving steel pipe, precast concrete, and timber piles. They are environmentally friendlier, producing less noise and pollution. Despite their quieter operation, the impact noise levels can be similar to diesel hammers, as the dominant sound often comes from the hammer striking the pile.
- Hydraulic Press-Ins
These machines use hydraulic rams to press piles into the ground, an ideal choice in situations where vibration is a concern. Press attachments can adapt to conventional rigs for simultaneous pressing of sheet piles, and other press equipment can be mounted on existing piles for greater force application. This method is particularly effective for precise pile installation.
- Vibratory Pile Drivers/Extractors
Equipped with a system of counter-rotating eccentric weights and powered by hydraulic motors, these machines focus on delivering vertical vibrations to the pile. Ideal for driving or extracting piles, they are often used in noise-sensitive areas or where vertical clearance is limited. Vibratory pile drivers can be attached to an excavator or crane and vary in vibration rates to accommodate different soil conditions and project requirements.
Why Use a Piling Machine?
A piling machine, particularly a piling rig, is indispensable in modern construction due to its crucial role in creating deep foundations. A piling rig, akin to a large track-mounted drill, is essential for foundation projects that involve drilling into varied ground types like sandy soil, clay, silty clay, and others. These rigs are functionally similar to oil drilling rigs and can be outfitted with diverse tools like a short screw for dry soil, a rotary bucket for wet soil, or a core drill for rock formations.
The necessity of piling machines stems from the need for deep foundations in certain construction scenarios. A deep foundation, as opposed to a shallow one, transfers the loads of a building deeper into the earth, reaching a subsurface layer or a range of depths. This is particularly vital for structures such as skyscrapers, where the loads are immense and the surface soil may not provide adequate support.
Geotechnical engineers often recommend deep foundations for several reasons, such as handling very large design loads, coping with poor soil conditions at shallow depths, or navigating site constraints like property lines. Deep foundations come in various forms, including piles (analogous to poles), piers (similar to columns), drilled shafts, and caissons. Each serves a specific purpose and is chosen based on the requirements of the building and the site conditions.
Piles, a key element in deep foundations, are typically driven into the ground in situ. They may be made from materials like timber, steel, reinforced concrete, or prestressed concrete. In projects requiring deep foundations, such as expressways, bridges, industrial and civil buildings, water conservancy projects, slope protection, and seismic retrofitting, piling machines play a critical role. The use of pile foundation systems, often involving groups of piles connected by a pile cap, helps distribute loads that exceed the bearing capacity of a single pile.
Pile caps and isolated piles are usually interlinked with grade beams, creating a cohesive foundation system. This arrangement allows for the distribution of structural loads, with lighter elements bearing on the grade beams and heavier elements directly on the pile cap.
A piling machine is integral to the construction of deep foundations, offering the necessary support and stability for a wide range of structures.