A method for detecting the position and direction of a non-metallic gas pipeline in a yard

Abstract

This invention provides a method for detecting the location and direction of non-metallic gas pipelines in a courtyard, comprising the following steps: Step 1, Ground Penetrating Radar (GPR): Calculate the center frequency f of the antenna; Step 2, Weak Magnetic Induction Method: Calculate the burial depth h = S × 0.1 meters for each section of the non-metallic pipeline; Step 3, Acoustic Wave Method: Connect an acoustic oscillator to the connection port of the non-metallic pipeline, receive the acoustic signal using a microphone and handheld analysis software, and analyze the direction of the maximum signal point. The direction of the maximum signal point is the direction of the non-metallic pipeline. The GPR method determines the horizontal positioning information of the pipeline; the weak magnetic induction method then probes the area where the pipeline with the obtained horizontal positioning information is located to obtain the burial depth information; finally, the acoustic wave method detects the pipeline position and direction. This method can more accurately and reliably determine the pipeline position based on the different material types and surrounding conditions of the non-metallic pipeline in the courtyard.

Description

Technical Field

[0001] This invention relates to the field of gas pipeline inspection technology, and in particular to a method for detecting the location and direction of a non-metallic gas pipeline in a courtyard. Background Technology

[0002] Underground pipelines carry out the transportation of various material flows, energy flows, and information flows. They are the infrastructure and "lifeline" upon which cities depend for survival and development. With the development of the social economy, the scale of underground pipelines in my country has developed rapidly and has been widely used in infrastructure construction. Currently, the location of many underground pipelines is unknown. Once they are damaged by external forces, resulting in pipeline damage and leakage, serious safety hazards will be generated, leading to serious economic losses and adverse social impacts.

[0003] In recent years, with the development of technology, methods for detecting underground metal pipelines have become relatively mature, such as metal detectors, tracer lines, ground-penetrating radar, and high-density resistivity methods. These methods are mostly derived from the principles of electricity, magnetism, and electromagnetic induction. They generally require the pipeline material to be metallic or to have an additional metal tracer line installed. However, non-metallic pipelines have the characteristics of being non-conductive and non-magnetic, leading to inaccurate detection results and susceptibility to soil moisture effects when using electrical and magnetic methods for detecting non-metallic pipelines. In particular, urban... For non-metallic gas pipelines in town courtyards, the main inspection items include leak detection, location and direction inspection, and direct excavation inspection. Since non-metallic pipelines in courtyards are non-conductive, location detection technologies such as AC current attenuation method, AC potential gradient method, and DC potential gradient method are not applicable. Currently, ground-penetrating radar is used to detect the location and direction of non-metallic pipelines in courtyards. However, due to the dense pipeline network in courtyards, ground-penetrating radar is not particularly accurate in detecting the location and direction of non-metallic pipelines (PE pipes). Therefore, a reliable method for location and direction detection tailored to the characteristics of non-metallic gas pipelines in courtyards is needed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for detecting the location and direction of non-metallic gas pipelines in courtyards. The method selects a detection method based on the interference source of the non-metallic pipeline, the overlapping of pipeline locations, and the external joints. It can obtain both the direction information and the depth information of the underground pipeline.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A method for detecting the location and orientation of non-metallic gas pipelines in a courtyard includes the following steps:

[0007] Step 1: Ground Penetrating Radar Method

[0008] S1. Turn on the ground-penetrating radar device and set the antenna center frequency, sampling rate, and coordinate reference. The center frequency f of the antenna is calculated using the following formula:

[0009]

[0010] In Equation 1, E is the dielectric constant and D is the expected detection depth;

[0011] S2. Place the transmitting and receiving antennas on the ground penetrating radar device at a fixed separation distance, and move the ground penetrating radar device along the detection direction. The moving distance is 1 / 4 of the electromagnetic wavelength.

[0012] S3. Acquire radar image profile, where the horizontal axis represents the antenna's position in the horizontal direction, and the vertical axis records the travel time of the reflected wave.

[0013] S4. Identify the pipeline and read its minimum dimension. Calculate the pipeline burial depth h using the following formula:

[0014] h = 2L 2 / λ(II)

[0015] In Equation 2, L represents the minimum size of the pipeline, and λ represents the radar wave wavelength.

[0016] Step 2: Weak magnetic induction method

[0017] K1. Turn on the two detectors. The detectors include a handle and a detection antenna. The detection antenna is a rotatable and telescopic antenna. Extend the detection antenna to its longest length and keep the detection antenna at a 90° right angle to the handle.

[0018] K2. The operator holds one detector in each hand, stands naturally, and places the two detector antennas horizontally, parallel to each other, pointing forward, shoulder-width apart.

[0019] K3, the operator walks at a step frequency of 0.1m / step. When approaching the underground target non-metallic pipe, the two detection antennas attract each other and rotate to cross.

[0020] K4. When the detection antenna is directly above the non-metallic pipe, manually rotate the two detection antennas until they are parallel to each other. The operator moves in the parallel direction with a step frequency of 0.1m / step.

[0021] K5. When the detection antennas approach the bend of the non-metallic pipe, the two detection antennas attract each other and rotate until they cross.

[0022] K6. When the detection antenna is directly above the bend, manually rotate the two detection antennas until they are parallel to each other. The operator moves in the parallel direction with a step frequency of 0.1m / step.

[0023] K7. Repeat steps K5 to K6;

[0024] In steps K8 and K4 to K7, calculate the number of steps S required for the detection antenna to change from a parallel to a crossed state.

[0025] K9. Calculate the burial depth of each section of non-metallic pipe, h = S × 0.1 meters;

[0026] Step 3: Acoustic Wave Method

[0027] J1. Connect the acoustic oscillator to the connection port of the non-metallic pipe;

[0028] J2. Set up a signal transmitter and connect the resonant cavity of the acoustic oscillator to the resonant cavity of the signal transmitter through a connector;

[0029] J3. Receive sound wave signals and analyze the direction of the maximum signal point using a microphone and handheld analysis software;

[0030] J4. The direction of the point with the maximum signal is the direction of the non-metallic pipe.

[0031] In step one, the ground radar device includes a radar instrument, which is connected to a transmitting antenna and a receiving antenna. The transmitting antenna and the receiving antenna are placed on the ground surface at a fixed distance. When the transmitting antenna transmits radar waves to the pipeline, an upper layer reflected wave and a lower layer reflected wave are formed. The upper layer reflected wave and the lower layer reflected wave are reflected back to the receiving antenna. The distance between the upper layer reflected wave and the lower layer reflected wave is L.

[0032] In step one, the pipeline is a non-metallic pipe.

[0033] In step one, before implementing the ground-penetrating radar method, the initial information of the pipeline is obtained (collecting characteristic information of the courtyard pipeline). The initial information includes the pipeline material (including pipeline type), the surrounding conditions of the pipeline (environment), the tracer line and the connection port. If it is not non-metallic (N), the pipe detector positioning method, the multi-frequency pipe current method, and then the weak point induction method are used. If it is non-metallic (Y), the next step is to use the tracer line.

[0034] In step three, the detection range of the acoustic method is within 300 meters.

[0035] The weak magnetic induction method was verified through excavation. The maximum vertical deviation rate of the weak magnetic induction method was 18.6%, and the maximum horizontal deviation was 1.62m.

[0036] The acoustic method employs GT pipe detection technology, which includes:

[0037] First, a connection port needs to be found on the gas pipeline to transmit the acoustic signal to the pipeline medium;

[0038] 2. Starting from the access point, the detection distance of the pipeline on one side shall not exceed 300 meters;

[0039] 3. The burial depth of PE pipes shall not exceed 3 meters;

[0040] IV. Underground PE pipes must not be fitted with sleeves, and there must be no non-PE protective covers, pre-drilled perforated bricks, or gaps between the PE pipe and the ground surface.

[0041] The GT pipeline detection technology was verified through excavation, and the maximum horizontal position deviation of the pipeline was 0.18m.

[0042] When the ground-penetrating radar method and the weak magnetic induction method detect PE gas pipelines without tracer lines, the deviation of the ground-penetrating radar method in terms of horizontal positioning of the pipeline is 0.06 to 1.60 m, and the deviation of the weak magnetic induction method is 0.14 to 1.62 m.

[0043] When the ground-penetrating radar (GPR) method and the weak magnetic induction method detect PE gas pipelines without tracers, the deviation rate of the GPR method in burial depth detection is 14.1% to 56.0%, and the deviation rate of the weak magnetic induction method is 3.4% to 18.6%.

[0044] The beneficial effects of this invention are:

[0045] 1. The method employs ground-penetrating radar (GPR), weak magnetic induction, and acoustic wave detection (GT pipeline detection technology). First, GPR is used to determine the horizontal positioning information of the pipeline. Then, weak magnetic induction is used to detect the area where the pipeline with the obtained horizontal positioning information is located to obtain the pipeline's burial depth information. Finally, acoustic wave detection is used to detect the pipeline location, including: identifying a connection point on the gas pipeline network to transmit acoustic signals to the pipeline medium; using the connection point as the starting point, detecting the pipeline on one side; detecting the pipeline within a 300-meter distance; and detecting the pipeline's direction. Based on the pipeline's horizontal positioning information and burial depth information, the pipeline location information is determined. This method can more accurately and reliably determine the pipeline location for different material types and surrounding conditions of non-metallic pipelines in courtyards. Attached Figure Description

[0046] Figure 1 This is a schematic diagram illustrating the principle of ground-penetrating radar detection.

[0047] Figure 2 Antenna intersection diagram above the target pipe;

[0048] Figure 3 Parallel view of the antenna above the target pipe;

[0049] Figure 4 This is a flowchart illustrating the selection process for the detection method of the present invention.

[0050] In the diagram: 1-Radar instrument; 2-Transmitting antenna; 3-Receiving antenna; 4-Ground surface; 5-Upper layer reflected wave; 6-Lower layer reflected wave; 7-Handle; 8-Detection antenna; 9-Non-metallic pipe. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0052] like Figure 1 As shown, a method for detecting the location and orientation of a non-metallic gas pipeline in a courtyard includes the following steps:

[0053] Step 1: Ground Penetrating Radar Method

[0054] S1. Turn on the ground-penetrating radar device, and set the antenna center frequency, sampling rate, and coordinate reference. The center frequency f of the antenna is calculated using the following formula:

[0055]

[0056] In Equation 1, E is the dielectric constant and D is the expected detection depth;

[0057] S2. Place the transmitting antenna 2 and receiving antenna 3 on the ground penetrating radar device at a fixed separation distance, and move the ground penetrating radar device along the detection direction. The moving distance is 1 / 4 of the electromagnetic wavelength.

[0058] S3. Acquire radar image profile, where the horizontal axis represents the antenna's position in the horizontal direction, and the vertical axis records the travel time of the reflected wave.

[0059] S4. Identify the pipeline and read its minimum dimension. Calculate the pipeline burial depth h using the following formula:

[0060] h = 2L 2 / λ(II)

[0061] In Equation 2, L represents the minimum size of the pipeline, and λ represents the radar wave wavelength.

[0062] Step 2: Weak magnetic induction method

[0063] like Figures 2 to 3 As shown, K1 activates two detectors. The detectors include a handle 7 and a detection antenna 8. The detection antenna 8 is a rotatable and telescopic antenna. When the detection antenna 8 is extended to its longest length, the detection antenna 8 and the handle 7 are at a 90° right angle.

[0064] K2. The operator holds one detector in each hand, stands naturally, and places the two detector antennas 8 horizontally, parallel to each other and pointing forward, shoulder-width apart.

[0065] K3, the operator walks at a step frequency of 0.1m / step. When approaching the underground target non-metallic pipe 9, the two detection antennas 8 attract each other and rotate to cross.

[0066] K4. When the detection antenna 8 is directly above the non-metallic pipe 9, manually rotate the two detection antennas 8 until they are parallel to each other. The operator moves in the parallel direction with a step frequency of 0.1m / step.

[0067] K5. When the detection antenna 8 approaches the bend of the non-metallic pipe 9, the two detection antennas 8 attract each other and rotate until they cross.

[0068] When K6 and the detection antenna 8 are directly above the bend, manually rotate the two detection antennas 8 until they are parallel to each other. The operator moves in the parallel direction with a step frequency of 0.1m / step.

[0069] K7. Repeat steps K5 to K6;

[0070] In steps K8 and K4 to K7, calculate the number of steps S required for the detection antenna 8 to change from a parallel to a crossed state.

[0071] K9. Calculate the burial depth h = S × 0.1 meters for each section of non-metallic pipe 9;

[0072] Step 3: Acoustic Wave Method

[0073] J1. Connect the acoustic oscillator to the connection port of the non-metallic pipe 9.

[0074] J2. Set up a signal transmitter and connect the resonant cavity of the acoustic oscillator to the resonant cavity of the signal transmitter through a connector;

[0075] J3. Receive sound wave signals and analyze the direction of the maximum signal point using a microphone and handheld analysis software;

[0076] J4, the direction of the maximum signal point is the direction of the non-metallic pipe 9.

[0077] In step one, the ground radar device includes a radar instrument 1, which is connected to a transmitting antenna 2 and a receiving antenna 3. The transmitting antenna 2 and the receiving antenna 3 are placed on the ground surface 4 at a fixed distance. When the transmitting antenna 2 transmits radar waves to the pipeline, it forms an upper reflected wave 5 and a lower reflected wave 6. The upper reflected wave 5 and the lower reflected wave 6 are reflected back to the receiving antenna 3. The distance between the upper reflected wave 5 and the lower reflected wave 6 is L.

[0078] In step one, the pipeline is a non-metallic pipe 9.

[0079] In step one, such as Figure 4As shown, before implementing the ground penetrating radar method, the initial information of the pipeline is obtained (collecting characteristic information of the courtyard pipeline). The initial information includes the pipeline material (including pipeline type), the surrounding conditions of the pipeline (environment), the tracer line and the connection port. If it is not non-metallic (N), the pipe detector positioning method, the multi-frequency pipe current method, and then the weak point induction method are used. If it is non-metallic (Y), the next step is to use the tracer line.

[0080] In step three, the detection range of the acoustic method is within 300 meters.

[0081] The method employs ground-penetrating radar (GPR), weak magnetic induction, and acoustic wave detection (GT pipeline detection technology). First, GPR determines the horizontal positioning information of the pipeline. Then, weak magnetic induction is used to detect the area where the pipeline with the obtained horizontal positioning information is located, obtaining the pipeline's burial depth information. Finally, acoustic wave detection is used to detect the pipeline location, including: identifying a connection point on the gas pipeline network to transmit acoustic signals to the pipeline medium; using the connection point as a starting point, detecting the pipeline on one side; detecting the pipeline within a 300-meter range; and detecting the pipeline's direction. Based on the pipeline's horizontal positioning information and burial depth information, the pipeline location information is determined. This method can more accurately and reliably determine the pipeline location for different material types and surrounding conditions of non-metallic pipelines in courtyards.

[0082] First, obtain preliminary information about the pipeline (topography, joint characteristics) to determine the material type of the pipeline;

[0083] Second, when the pipeline is a non-metallic pipeline, the first detection is performed;

[0084] The first detection includes: using ground-penetrating radar to determine the horizontal positioning information of the pipeline; using weak magnetic induction to detect the area where the pipeline with the obtained horizontal positioning information is located to obtain the pipeline burial depth information; and determining the pipeline location information based on the pipeline horizontal positioning information and the pipeline burial depth information.

[0085] When the pipeline has an external connection, a second detection is performed;

[0086] The second detection method includes: using GT pipeline detection (sonic method) to detect the pipeline location, including: determining a connection point on the gas pipeline network to transmit acoustic signals to the pipeline medium, and detecting the pipeline on one side from the connection point (connection point) as the starting point, with a detection distance of 300 meters.

[0087] Specifically:

[0088] Ground Penetrating Radar

[0089] (1) Technical characteristics: Ground penetrating radar can detect the location of PE pipelines without tracer lines, but it needs to be used on relatively flat terrain; in order to obtain more accurate burial depth data, it is usually necessary to make corrections based on the on-site geological conditions.

[0090] (2) Field application test

[0091] ①Inspection and analysis of buried PE pipelines

[0092] Because the underground conditions in cities are quite complex, when using ground-penetrating radar to detect buried pipelines, reflected waves generated by various underground pipelines or other objects will be encountered. Differences in the medium, pipeline specifications, terrain, etc. will lead to differences in the reflected waves.

[0093] ② Depth and horizontal deviation

[0094] a. Test pipe section 1: Material PE100, pipe diameter D160, no tracer wire, located on the west side of a certain community, the detection results are shown in Table 1;

[0095] Pit number Detection depth (m) Measured depth (m) Horizontal deviation (m) Vertical deviation rate Remark 1 1.52 1.77 0.36 14.1％ straight pipe section 2 1.0 0.87 0.06 14.9％ straight pipe section 3 1.95 1.25 1.60 56.0％ corner

[0096] Table 1 shows the results of the investigation of test section 1.

[0097] In Table 1, through excavation verification, the maximum vertical deviation rate of the ground penetrating radar method is 56%, and the maximum horizontal deviation is 1.60m.

[0098] b. Test section two: material PE100, pipe diameter D160, no tracer wire, located on the east side of a certain community, near a strong magnetic interference source (10KV substation) and power pipeline.

[0099] Verification was conducted at two excavation sites; at one site, only a water supply PE pipe was found, while at the other site, no pipe was found.

[0100] ③Results Analysis

[0101] a. Ground penetrating radar has a large error in detecting the burial depth of pipelines and has very low accuracy in quantitatively determining the location of pipeline bends.

[0102] b. Strong magnetic interference sources can significantly affect ground-penetrating radar signals, making accurate detection impossible.

[0103] c. When the pipes are in an overlapping position, the upper pipe has a shielding effect on the signal, so the presence of the PE water supply pipe hinders the detection signal.

[0104] The test results show that ground-penetrating radar can detect the location signal of buried PE gas pipelines without tracer lines, but there may be a large deviation in positioning; in addition, when multiple pipelines are close to each other, the target pipeline cannot be distinguished.

[0105] 2. Weak magnetic induction method

[0106] (1) Technical characteristics: The weak magnetic induction method uses natural gas as the detection target and can detect the position of PE pipelines without tracer lines.

[0107] (2) Field application test

[0108] ① Depth and horizontal deviation

[0109] a. Test pipe section 1: Material PE100, pipe diameter D160, no tracer wire, located in a town, the detection results are shown in Table 2;

[0110] Pit number Detection depth (m) Measured depth (m) Horizontal deviation (m) Vertical deviation rate Remark 1 2.10 1.68 0.68 18.6％ straight pipe section 2 0.9 0.87 0.14 3.4％ straight pipe section 3 1.15 1.24 1.62 8.0％ corner

[0111] Table 2 shows the results of the investigation of test section 1.

[0112] In Table 2, through excavation verification, the maximum vertical deviation rate of the weak magnetic induction method is 18.6%, and the maximum horizontal deviation is 1.62m.

[0113] b. Test section two: Material PE100, pipe diameter D160, no tracer wire, located in a residential area of ​​a certain town. There are strong magnetic interference sources (10KV substation) and power pipelines near the pipeline.

[0114] Verification was conducted at two excavation sites; at one site, only a water supply PE pipe was found, while at the other site, no pipe was found.

[0115] ②Results Analysis

[0116] a. The weak magnetic induction method has certain errors in detecting the burial depth of pipelines, and its accuracy in horizontal positioning at pipeline bends is very low.

[0117] b. Strong magnetic interference sources can significantly affect weak magnetic signals, making accurate detection impossible.

[0118] c. When the pipes are in an overlapping position, the upper pipe has a shielding effect on the signal, so the presence of the PE water supply pipe hinders the accuracy of the detection.

[0119] The test results show that the weak magnetic induction method can detect the location signal of buried PE gas pipelines without tracer lines, but there may be a large deviation in positioning; in addition, when pipelines are arranged in an overlapping manner, the target pipeline below cannot be detected.

[0120] 3. GT Pipeline Detection Technology

[0121] (1) Technical characteristics of GT pipeline detection technology

[0122] ① A suitable connection port needs to be found on the gas pipeline to transmit the sound wave signal to the pipeline medium;

[0123] ②Starting from the access point, the detection distance of the pipeline on one side generally does not exceed 300 meters;

[0124] ③The PE pipe should be buried at a depth of no more than 3 meters;

[0125] ④ Underground PE pipes cannot be fitted with sleeves. Non-PE protective covers, pre-drilled bricks, and gaps between the PE pipe and the ground surface will greatly weaken the sound wave signal.

[0126] (2) Field application test

[0127] The location of buried PE pipes was detected in the Shuangliu Tanghu Lake Forest Town residential area. An acoustic signal was transmitted to the pipes under inspection through the interface at the inlet pressure regulating valve. (Pipe diameters were 110mm and 50mm).

[0128] ① Horizontal deviation, as shown in Table 3.

[0129] Pit number Measured depth (m) Horizontal deviation (m) Permissible deviation (m) 1 1.24 0.18 0.124 2 1.06 0.11 0.106

[0130] Table 3 shows the results of the investigation of the test pipe section.

[0131] In Table 3, the maximum deviation of the horizontal position of the pipeline detected by the GT method was 0.18m, as verified by excavation.

[0132] ②Results Analysis

[0133] a. In residential areas, the compacted soil of the driveway receives a stronger signal than that of the sidewalk, and the sidewalk receives a better signal than the soft soil of the green belt; the signal strength is even greater at turning points, which is helpful for identifying the direction of pipelines.

[0134] b. It can achieve good results in the inspection of courtyard pipe networks without tracer wires.

[0135] 4. Conclusion

[0136] (1) Neither the ground-penetrating radar method nor the weak magnetic induction method is applicable to places with strong magnetic interference sources or other pipelines above the PE gas pipeline.

[0137] (2) Both ground-penetrating radar and weak magnetic induction methods can detect PE gas pipelines without tracer lines; ground-penetrating radar is slightly better than weak magnetic induction method in pipeline horizontal positioning, while weak magnetic induction method is slightly better in burial depth detection.

[0138] (3) Under the premise of meeting the testing implementation conditions, GT pipeline detection technology has a good detection effect on the direction and location of underground PE pipelines and can be used for the location detection of courtyard gas pipeline networks with complex underground lines.

[0139] Pipeline location and orientation inspection

[0140] ①PE pipes with metal tracer lines can be detected using the principle of metal detection, so the detection method is the same as that for metal pipes.

[0141] ② In the absence of a tracer or if the tracer fails, ground-penetrating radar (GPR) or weak magnetic induction methods can be used. However, these two methods have significant positioning deviations at pipeline bends and cannot effectively identify the target pipeline when multiple pipelines are close together. Therefore, in practical applications, cross-verification can be used to determine the accurate location of the pipeline, and further analysis based on known data may be necessary.

[0142] ③ The GT method is relatively accurate in horizontal positioning of buried PE pipelines, but it requires that there be a signal inlet on the pipeline, and the length of a single detection is limited.

[0143] Ground penetrating radar and weak magnetic induction methods:

[0144] ① Neither the ground-penetrating radar method nor the weak magnetic induction method is suitable for locations with strong magnetic interference sources or where there are other pipelines above the PE gas pipeline;

[0145] ② Both ground-penetrating radar (GPR) and weak magnetic induction (WMI) methods can detect PE gas pipelines without tracer lines. In terms of pipeline horizontal positioning, the deviation of GPR is 0.06–1.60 m, while that of WMI is 0.14–1.62 m, so GPR is slightly better. In terms of burial depth detection, the deviation rate of GPR is 14.1%–56.0%, while that of WMI is 3.4%–18.6%, so WMI is slightly better.

[0146] GT Pipeline Detection Technology:

[0147] ①The target pipeline must be a PE pipeline;

[0148] ② A suitable connection port needs to be found on the gas pipeline network to transmit the sound wave signal into the pipeline medium;

[0149] ③The PE pipe should be buried at a depth of no more than 3 meters;

[0150] ④ This technology has a horizontal positioning deviation of 0.11 to 0.18m for underground PE pipelines, thus it has a good detection effect on the pipeline's direction and can be used for the location detection of complex underground gas pipeline networks in courtyards.

[0151] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for detecting the location and orientation of non-metallic gas pipelines in a courtyard, characterized in that: Includes the following steps: Step 1: Ground Penetrating Radar Method S1. Turn on the ground-penetrating radar device and set the antenna center frequency, sampling rate, and coordinate reference. The center frequency f of the antenna is calculated using the following formula: In Equation 1, E is the dielectric constant and D is the expected detection depth; S2. Place the transmitting antenna (2) and receiving antenna (3) on the ground penetrating radar device at a fixed separation distance, and move the ground penetrating radar device along the detection direction. The moving distance is 1 / 4 of the electromagnetic wavelength. S3. Acquire radar image profile, where the horizontal axis represents the antenna's position in the horizontal direction, and the vertical axis records the travel time of the reflected wave. S4. Identify the pipeline and read its minimum dimension. Calculate the pipeline burial depth h using the following formula: h = 2L 2 / λ(II) In Equation 2, L represents the minimum size of the pipeline, and λ represents the radar wave wavelength. Step 2: Weak magnetic induction method K1. Turn on the two detectors. The detectors include a handle (7) and a detection antenna (8). The detection antenna (8) is a rotatable and telescopic antenna. Stretch the detection antenna (8) to its longest length. The detection antenna (8) and the handle (7) are at a 90° right angle. K2. The operator holds one detector in each hand, stands naturally, and places the two detector antennas (8) horizontally and parallel to each other, pointing forward at shoulder width. K3, the operator walks at a step frequency of 0.1m / step. When approaching the underground target non-metallic pipe (9), the two detection antennas (8) attract each other and rotate to cross. K4. When the detection antenna (8) is directly above the non-metallic pipe (9), manually rotate the two detection antennas (8) to be parallel to each other, and the operator moves in the parallel direction with a step frequency of 0.1m / step. K5. When the detection antenna (8) approaches the bend of the non-metallic pipe (9), the two detection antennas (8) attract each other and rotate to cross. K6. When the detection antenna (8) is directly above the bend, manually rotate the two detection antennas (8) to be parallel to each other. The operator moves in the parallel direction with a step frequency of 0.1m / step. K7. Repeat steps K5 to K6; In steps K8 and K4 to K7, calculate the number of steps S required for the detection antenna (8) to change from a parallel state to a cross state; K9. Calculate the burial depth h = S × 0.1 meters for each section of non-metallic pipe (9); Step 3: Acoustic Wave Method J1. Connect the acoustic oscillator to the connection port of the non-metallic pipe (9); J2. Set up a signal transmitter and connect the resonant cavity of the acoustic oscillator to the resonant cavity of the signal transmitter through a connector; J3. Receive sound wave signals and analyze the direction of the maximum signal point using a microphone and handheld analysis software; J4. The direction of the maximum signal point is the direction of the non-metallic pipe (9).

2. The method for detecting the location and orientation of a non-metallic gas pipeline in a courtyard as described in claim 1, characterized in that: In step one, the ground radar device includes a radar instrument (1), which is connected to a transmitting antenna (2) and a receiving antenna (3). The transmitting antenna (2) and the receiving antenna (3) are placed on the ground surface (4) at a fixed distance. When the transmitting antenna (2) transmits radar waves to the pipeline, an upper reflected wave (5) and a lower reflected wave (6) are formed. The upper reflected wave (5) and the lower reflected wave (6) are reflected back to the receiving antenna (3). The distance between the upper reflected wave (5) and the lower reflected wave (6) is L.

3. The method for detecting the location and orientation of a non-metallic gas pipeline in a courtyard as described in claim 1, characterized in that: In step one, the pipeline is a non-metallic pipe (9).

4. The method for detecting the location and orientation of a non-metallic gas pipeline in a courtyard as described in claim 1, characterized in that: In step one, before implementing the ground-penetrating radar method, preliminary information about the pipeline is obtained. This preliminary information includes the pipeline material, the surrounding environment of the pipeline, the tracer wire, and the connection port.

5. The method for detecting the location and orientation of a non-metallic gas pipeline in a courtyard as described in claim 1, characterized in that: In step three, the detection range of the acoustic method is within 300 meters.

6. The method for detecting the location and orientation of a non-metallic gas pipeline in a courtyard as described in claim 1, characterized in that: The weak magnetic induction method was verified through excavation. The maximum vertical deviation rate of the weak magnetic induction method was 18.6%, and the maximum horizontal deviation was 1.62m.

7. The method for detecting the location and orientation of a non-metallic gas pipeline in a courtyard as described in claim 1, characterized in that: The acoustic method employs GT pipe detection technology, which includes: First, a connection port needs to be found on the gas pipeline to transmit the acoustic signal to the pipeline medium; 2. Starting from the access point, the detection distance of the pipeline on one side shall not exceed 300 meters; 3. The burial depth of PE pipes shall not exceed 3 meters; IV. Underground PE pipes must not be fitted with sleeves, and there must be no non-PE protective covers, pre-cast perforated bricks, or gaps between the PE pipe and the ground surface.

8. The method for detecting the location and orientation of a non-metallic gas pipeline in a courtyard as described in claim 7, characterized in that: The GT pipeline detection technology was verified through excavation, and the maximum horizontal position deviation of the pipeline was 0.18m.

9. The method for detecting the location and orientation of a non-metallic gas pipeline in a courtyard as described in claim 1, characterized in that: When the ground-penetrating radar method and the weak magnetic induction method detect PE gas pipelines without tracer lines, the deviation of the ground-penetrating radar method in terms of horizontal positioning of the pipeline is 0.06 to 1.60 m, and the deviation of the weak magnetic induction method is 0.14 to 1.62 m.

10. The method for detecting the location and orientation of a non-metallic gas pipeline in a courtyard as described in claim 1, characterized in that: When the ground-penetrating radar (GPR) method and the weak magnetic induction method detect PE gas pipelines without tracers, the deviation rate of the GPR method in burial depth detection is 14.1% to 56.0%, and the deviation rate of the weak magnetic induction method is 3.4% to 18.6%.

Images