Buried pipeline detection technology scheme (3) - acoustic detector detection method

Buried pipeline detection technology scheme (3) - acoustic detector detection method

(1) Principle and equipment

The working principle of the active sound source detection method is to send a specific frequency acoustic signal into the pipeline through the audio transmitter, and the signal is transmitted to the far end along the pipeline. The acoustic signal is transmitted in the pipeline pressure gas, and at the same time, it is transmitted to the ground through the soil on the pipe wall. At the same time, the receiver captures the acoustic signal on the ground, and accurately locates the vertical disturbance range of the tube by continuously receiving the signal and finding the volume area.

(2) Horizontal positioning method

The hidden point of the urban gas pipe network consists of the straight pipe section, elbow, tee and other parts of the pipeline. In the field detection, the known valve well is generally used as the starting point to probe far away, and the location of each part of the pipe network is gradually verified and the connection relationship of each part of the pipeline is clarified, and finally the various parts of the pipeline are connected.

(1) Linear pipe section detection method

After the sound source PE gas pipeline detector is connected from the known valve well, it is probed along the pipeline in an S-shaped route perpendicular to the general direction of the known pipeline. As shown in Figure 3-3, the measurement point distance is determined according to the signal value. Before the maximum value is detected, the point distance can be increased to quickly find the position of the strongest signal, and then precision measurement is carried out at the position where the signal intensity is concentrated. The distance between each detection point is about 15cm.

(2) Feature point detection method

The characteristic points of the pipeline include elbow, tee and other connection points. When the sound source signal passes through the elbow and tee, because the vibration signal meets the resistance of the pipe wall and the influence of echo, the signal will be extremely strong, and the signal accumulation effect will be generated around the characteristic point, so it is difficult to directly determine the location of the pipeline, and the geometric intersection method can be used for detection.

(3) Depth detection methods

The buried depth of gas pipeline is closely related to the buried way of pipeline laying. The depth of directly buried pipeline is generally affected by the backfill and transformation of the overlying layer above the pipeline, and the depth of the pipeline passing through is related to the crossing depth during construction, and the depth changes greatly. Therefore, in the process of PE gas pipeline detection, the depth of the pipeline passing through is greatly changed. It is very important to use the sound source detection method to distinguish the signals of directly buried and through pipelines. The signal characteristics are obviously different at the exit and entry points of directly buried and through pipelines, and the sound source detection method can quickly distinguish the buried ways of pipelines.