Understanding Sonic Logging Pipes for Cast-in-Place Piles

Before specifying requirements for Sonic Logging Pipes used in cast-in-place piles, it's important to understand what Sonic Logging Pipe is.

A Sonic Logging Pipe is a sonic detection tool, also known as a pre-buried sonic detection pipe.  It serves as a channel for the probe to access the pile body during ultrasonic testing.  These pipes are primarily used to assess the density, strength, and other properties of concrete in structures such as bridges and buildings.

Applications of Sonic Logging Pipes

-  Detecting Concrete Quality:

By emitting ultrasonic waves into concrete and receiving echo signals, the propagation speed and attenuation of sound waves are analyzed.  This data allows for the evaluation of concrete quality, including compressive strength, uniformity, and integrity.  Sonic Logging Pipes are a critical component in the ultrasonic detection system for cast-in-place piles, enabling non-destructive testing of concrete without damaging the structure.

-  Monitoring Structural Safety:

During the construction of structures like bridges and buildings, sonic logging pipes are utilized to monitor the structural health.  They help detect potential issues, such as cracks or voids.  Regular analysis of sonic data enables the evaluation of the structure's stability and safety, providing insights for necessary maintenance and reinforcement.

-  Other Applications:

Sonic logging pipes can be used for foundation soil surveys, contributing to building stability evaluations.  In pipeline engineering, they help assess the working status of pipelines, facilitating timely repairs.  Additionally, sonic logging pipes play a role in acoustic research and environmental monitoring by measuring sound frequency, intensity, and duration.

Specification Requirements for Sonic Logging Pipes

The specification for the sonic logging pipe used in cast-in-place piles includes several aspects from installation to operation.  These standards are designed to ensure proper function and reliable measurement data:

-  Installation and Burial:

-  Burial Depth:  The burial depth should be between 50mm to 150mm above the pile's bottom, with the lower end of the pipe sealed.  The pipe should be positioned at the pile’s base, with its depth generally not less than two-thirds of the pile length.

-  Upper End Height:  The upper end must extend 300mm to 500mm above the top of the pile, with consistent exposed heights across the same pile.

-  Quantity and Arrangement:

- For piles with diameters ≤ 800mm, a minimum of two pipes should be used.

- For piles with diameters between 800mm and 1600mm, at least three pipes are required.

- For piles with diameters greater than 1600mm or over 2.5 meters, a minimum of four pipes, symmetrically arranged (e.g., in a square pattern), should be used.

-  Fixing Method:  The pipe can be fixed directly to the steel cage, with fixing points spaced no more than 2 meters apart.  The bottom end and joints must be secured, typically by wire binding or welding, to prevent displacement or deformation during the concrete pouring process.

-  Connection Method:

There are various methods to connect the acoustic detection pipes, such as clamping, spiral, and sleeve types.  Connections must be firm and sealed, ensuring no leakage of water or slurry:

-  Clamping Type:  Connected using special hydraulic clamps for quick and reliable sealing.

-  Spiral Type:  Features a sealing rubber ring and requires no on-site welding, offering cost savings.

-  Sleeve Type:  Sealed with electric welding, providing high tensile strength and resistance to torque.  Welding should be thorough, without slag inclusions or pores, and the weld strength must match or exceed that of the parent material.

-  Material Requirements:

The acoustic detection pipe should be made of durable, corrosion-resistant, and high-strength materials, such as steel or plastic:

-  Steel Pipe:  Should meet national standards, with a wall thickness not less than 3mm.

-  Plastic Pipe:  Should have excellent corrosion resistance and anti-aging properties.

-  Size and Appearance Requirements:

-  Size:  The pipe’s outer diameter, wall thickness, and other dimensions must meet design specifications, with allowable deviations of ±2.0% for the outer diameter and ±5% for the wall thickness.  When the distance between two flat plates is 75% of the outer diameter, the pipe should not have cracks.

-  Appearance:  The pipe should be straight, with a curvature of no more than 5mm/m.  Defects such as cracks, scars, or folds are prohibited.  Scratches and misalignment of longitudinal welds should not exceed 0.1mm.  Both ends should be perpendicular to the axis, and there should be no external burrs (internal burrs should not exceed 0.5mm).  The ends should be sealed, with clear mar