A casing oscillator, also known as a casing rotator or oscillator, is a specialized piece of equipment used in foundation construction to install large-diameter casings into the ground. It is commonly employed when constructing bored piles or drilled shafts in challenging ground conditions, such as hard rock or unstable soil.
The casing oscillator works by rotating and vibrating the casing while applying downward force to advance it into the ground. This rotational and vibratory motion helps to reduce friction between the casing and the surrounding soil or rock, making it easier to insert the casing.
Here are the key components and features of a casing oscillator:
Power Pack: The casing oscillator is typically powered by a hydraulic power unit that provides the necessary force and controls for the rotational and vibratory movements.
Oscillator Head: The oscillator head is attached to the top of the casing and transmits the rotational and vibratory forces to the casing. It usually incorporates a clamp or gripping mechanism to securely hold the casing during the installation process.
Exciter: The exciter is a component within the casing oscillator that generates the vibratory motion. It consists of an eccentric weight or weights that rotate at high speeds, creating vibrations that aid in the insertion of the casing.
Rotary Drive: The rotary drive mechanism is responsible for rotating the casing during installation. It may include hydraulic motors or other mechanisms that provide the necessary torque to turn the casing.
Hydraulic Cylinders: Hydraulic cylinders are employed to apply downward force to advance the casing into the ground. These cylinders can exert significant thrust to overcome resistance from the soil or rock.
Control System: A control system, typically operated by the equipment operator, allows for precise control of the rotational speed, vibratory intensity, and downward force applied during casing installation.
The use of a casing oscillator offers several advantages in foundation construction:
Efficient installation: Casing oscillators allow for faster and more efficient installation of large-diameter casings compared to traditional methods like casing driving or drilling with a drilling rig.
Reduced soil disturbance: The rotational and vibratory motion of the casing oscillator reduces soil displacement and disturbance during casing insertion, minimizing the potential for ground heave or settlement.
Improved stability: By minimizing soil disturbance, casing oscillators help maintain the stability of the surrounding ground, particularly in loose or unstable soil conditions.
Casing oscillators are commonly used in various foundation construction projects, including bridge construction, high-rise buildings, and infrastructure development.