Principles for the Material Selection of Prestressed Plastic Corrugated Pipes

Plastic corrugated pipes are easy to handle due to their lightweight nature. However, attention must be paid to maintaining the straightness of the axis during installation. The sound impedance of plastic corrugated pipes is relatively low, making them suitable for use in small灌注桩. Caution should be exercised when using them in large灌注桩, as larger diameter piles require significant amounts of concrete. The hydration heat of cement is not easily dissipated, and considering the significant difference in thermal expansion coefficients between the plastic corrugated pipes and concrete, the plastic pipe may undergo radial and longitudinal shrinkage as the temperature drops after concrete curing. This may cause the plastic corrugated pipe to partially脱离 from the concrete, creating gaps filled with air or water. The plastic corrugated pipe also increases the number of strong reflective interfaces in the sound path, which can easily lead to misjudgment.

Plastic corrugated pipes typically have a larger diameter than radial transducers, and in principle, there are no restrictions on wall thickness. However, from a steel-saving perspective, the wall must be able to withstand lateral pressure from newly poured concrete, and thinner walls are generally more cost-effective. Sound pulses are emitted from the transmitter transducer by coupling water to the interface between the water and the plastic corrugated pipe wall. Then, the pulses pass through the wall to the interface between the plastic corrugated pipe wall and concrete, and after passing through the concrete, they must traverse another plastic corrugated pipe's two different interfaces to reach the receiver transducer. Plastic corrugated pipes are a superior device, featuring thin walls, reduced steel usage, impermeability, high pressure resistance, and good flexibility. They are commonly used in post-tensioned structures for reserved holes, directly tied to the steel reinforcement frame with a larger corrugated pipe sleeve at the joint.