How to correct the testing accuracy of the bending sound velocity of a sonic tube?

The specific steps include:

S1. Oblique measurement data collection: Slowly lower two probes to the bottom of two acoustic measurement tubes, and control the two probes to be in the center position of the two acoustic measurement tubes with sliding beads. The inclinometer equipment on the two probes obtains the inclinometer data at the center of the two acoustic measurement tubes, and transmits the inclinometer data to the computer through connecting cables to obtain the spatial distribution curve of the centers of the two acoustic measurement tubes;

S2. Establish a three-dimensional model of the measured profile: measure the net distance between the outer walls of two acoustic measuring tubes at the top of the pile, input it into the acoustic detector, and the computer in the acoustic detector combines the input data of the inner and outer diameters of the two acoustic measuring tubes, as well as the spatial distribution curves of the center of the two acoustic measuring tubes obtained from step S1, to establish a three-dimensional model of the measured profile;

S3. Sound time measurement: During the process of simultaneously and uniformly lifting two probes in two sound measuring tubes, the computer controls the high-voltage transmission and control module, and a controlled high-voltage pulse is generated by connecting a cable to excite the transmitter and receiver integrated transducer on the probe in a certain sound measuring tube. The electrical energy is converted into ultrasonic pulses, which are sequentially transmitted to the pile concrete through the coupling agent and sound measuring tube wall in the sound measuring tube. The transmitter and receiver integrated transducer on the probe in the other sound measuring tube receives ultrasonic signals that pass through the concrete, sound measuring tube wall, and coupling agent in the sound measuring tube in sequence, and then converts the signal into an electrical signal. The signal is transmitted to the programmable amplification and attenuation module in the sound measuring instrument through the connecting cable. After automatic adjustment of the electrical signal, it is transmitted to the A/D conversion and acquisition module, The A/D conversion and acquisition module transmits the converted digital signal to the computer and calculates the sound time test value. After deducting the test system delay and geometric factors sound time correction value (sound time delay occurring in the sound measurement tube wall and coupling agent), the propagation sound time of the measurement line in the concrete medium is obtained;

S4. Sound velocity calculation: During the process of simultaneously and uniformly raising two probes in two sound measuring tubes, the computer extracts the distance measurement of the measured profile at each measuring line based on the three-dimensional model established in step S2 and the depth of the two probes. Combined with the propagation sound at the measured line in the pile concrete, the actual sound velocity at each measuring line of the measured profile is calculated.

This method avoids the measurement error of sound velocity caused by the bending of the acoustic tube, thereby greatly improving the accuracy of the acoustic transmission method in detecting the quality of the concrete pouring pile body.