Pre-placed inspection pipe

(1) Piles with a diameter of 0.6-0.8 meters should be installed with double pipes; those with a diameter of 0.8-2.0 meters should have three pipes; and for diameters above 2.0 meters, four pipes should be installed. According to the specific conditions of Chifeng Bridge, the pile foundation can be installed with three pipes.

(2) The ultrasonic detection tubes should be made of steel pipe, plastic pipe, or steel corrugated pipe, with an inner diameter of 50 to 60mm. The connection points of the detection tubes should have a smooth transition, and the tube openings should be at least 100mm above the top of the pile. The heights of the tube openings of all detection tubes should be consistent, the lower end of the tubes should be sealed, the upper end should be capped, and there should be no foreign objects inside the tubes, nor any damage to the tube body.

(3) The inspection tubes can be welded or tied to the inside of the reinforcing bars, and the tubes should be parallel to each other.

Comparison of Pre-buried Inspection and On-site Inspection of Grouting Pipes

Before on-site testing, measure the delay time t of the sound wave monitor's transmission to the receiving system. Calculate the sound time correction value.

(2) During measurement, the transmitting and receiving probes should be at the same elevation or maintain a fixed height difference while synchronously rising and falling.

(3) Measurement points are initially set at 40 cm, and are densified to 20 cm upon detection of anomalies.

(4) Select an appropriate发射 voltage and amplifier gain, and maintain them unchanged throughout the testing process.

(5) Real-time display and recording of the time course curve of received signals.

(6) Combine multiple grouting pipes into two-section detection profiles and perform full inspections on each profile.

(7) After each test tube group is tested, 10% of the test points should be randomly retested. The relative standard deviation of the sound time should not exceed 5%; the relative standard deviation of the amplitude should not exceed 10%.