A full-array seismic reflection observation system for the positioning of large drainage culverts

Abstract

The present invention discloses a full-array seismic reflection observation system for the positioning of large drainage culverts, comprising: a seismic reflection detection line arranged on the ground surface above the drainage culvert; a seismic source arranged at the excitation point; a plurality of geophones arranged at the geophone points; wherein, all the geophones are at least evenly divided into two groups along the direction of the detection line and alternately switch positions in the extending direction of the detection line during the detection process, and a geophone rectangular array is formed on the seismic reflection plane; a plurality of excitation points are preset on the ground surface above the drainage culvert at intervals along the direction of the detection line, and the seismic source is successively located at the preset excitation points and gradually approaches the geophone distribution area. Based on the conventional detection line arrangement structure, the observation system is improved, the amount of collected data is increased, appropriate parameters can be selected without on-site testing, and the work efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of geotechnical engineering inspection and testing. Specifically, it is a full-array seismic reflection observation system for the positioning of large drainage pipe culverts. Background Art

[0002] Large drainage pipe culverts are important infrastructure of the urban drainage system, playing an important role in ensuring the orderly collection, transportation and treatment of urban sewage and maintaining the daily operation of the city. With the rapid development of urban construction, the traffic is becoming increasingly busy, the road load is increasing, the road widening and renovation and other surrounding engineering activities have more and more influence, resulting in certain safety hazards in large drainage pipe culverts that are generally in disrepair for a long time at the present stage. The protection work for them is becoming more and more urgent. However, due to the long age of large drainage pipe culverts and the lack or deviation of completion data, they have become obstacles in the process of underground space development and there are certain safety hazards. The positioning of underground drainage pipe culverts is one of the important basic problems in urban underground engineering construction.

[0003] At present, there are a small number of technologies for detecting large drainage pipe culverts in China. Among them, the non-destructive positioning means are mainly seismic reflection method, ground penetrating radar method and high-density resistivity method. When detecting pipe culverts by the ground penetrating radar method, it is based on the obvious difference in the dielectric constant between the pipe culvert and the surrounding soil. However, the difference in the dielectric constant between the pipe culvert and the surrounding soil is small, so the positioning effect of the ground penetrating radar is often not good, and it is even difficult to locate the boundary and burial depth of the pipe culvert. Especially in areas with high groundwater levels, the effective detection depth is relatively shallow, which is difficult to meet the actual engineering requirements; the high-density resistivity method can detect the position of the pipe culvert, but the detection error of this method is large and it cannot meet the actual engineering requirements. Moreover, in the implementation process, it is necessary to arrange a long measuring line and drill small holes to insert electrodes, and the detection time is long. For pipe culverts located around urban roads, the high-density resistivity method is difficult to have the space for arranging the measuring line and the conditions for long-time detection, and its application range is relatively narrow; the seismic reflection method can determine the boundary position of the pipe culvert, has strong site applicability and meets the actual engineering requirements. However, the detection of the position of the pipe culvert is greatly affected by parameters such as the frequency of the geophone and the offset distance, and it is necessary to try many times on site to determine the best pipe culvert positioning parameters, with low efficiency. Therefore, there is currently a lack of an efficient seismic reflection observation system for multi-parameter synchronous acquisition. Summary of the Invention

[0004] The purpose of the present invention is to provide a full-array seismic reflection observation system for the positioning of large drainage pipe culverts to solve the problems in the prior art.

[0005] The purpose of the present invention is achieved as follows: A full-array seismic reflection observation system for the positioning of large drainage pipe culverts, comprising:

[0006] A seismic reflection detection measuring line arranged on the ground surface above the drainage pipe culvert;

[0007] A seismic source arranged at the shock point;

[0008] A number of geophones arranged at the geophone points;

[0009] Among them, all the geophones are at least evenly divided into two groups along the direction of the survey line and alternately switch positions in the extending direction of the survey line during the detection process, and a rectangular array of geophones is formed on the seismic image plane;

[0010] A plurality of shock points arranged at intervals along the survey line are preset on the ground surface above the drainage pipe culvert, and the seismic source is successively located at the preset shock points and gradually approaches the geophone distribution area.

[0011] The beneficial effect of the present invention lies in:

[0012] Compared with the traditional seismic imaging method, the present invention realizes that arranging a full permutation seismic imaging survey line can form several seismic imaging profiles, can continuously shock multiple times, and can select appropriate parameters without on-site testing, greatly improving the detection efficiency, and can quickly and accurately realize the positioning of the drainage pipe culvert. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the working arrangement of the full permutation 24-channel seismic imaging of the present invention.

[0014] Figure 2 It is a schematic diagram of the working arrangement of the traditional single-channel seismic imaging.

[0015] Figure 3 It is a schematic diagram of the working arrangement of the traditional 3-channel seismic imaging.

[0016] Figure 4 It is a cross-sectional view of the detection result of the full permutation seismic imaging method (24 channels).

[0017] In the figure, 1 is the main machine, 2 is the first cable, 3 is the second cable, 4 is the shock point, 5 is the shock trigger cable, 6 is the interface, and 7 is the geophone. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0019] As Figure 1 shown, a full permutation seismic imaging observation system for the positioning of large drainage pipe culverts includes:

[0020] The main machine 1, and the main machine 1 has an interface for displaying the seismic imaging profile image;

[0021] A seismic imaging detection survey line arranged on the ground surface above the drainage pipe culvert, the survey line is arranged perpendicular to the extending direction of the pipe culvert, and the length of the survey line is greater than 0.5 times the width or outer diameter of the pipe culvert;

[0022] The seismic source can be a controllable seismic source device, which is electrically connected to the host 1 through a shock excitation trigger cable 5, or it can be a hammer with a trigger device;

[0023] Multiple shock excitation points 4 preset on the ground surface above the drainage pipe culvert and arranged at intervals along the survey line direction, and the shock excitation points 4 are arranged on the ground surface above the drainage pipe culvert;

[0024] Several geophones 7 arranged at the geophone points, and the host 1 is electrically connected to the geophones 7 in a wireless or wired manner to collect seismic reflection data. All the geophones 7 form a geophone rectangular array on the seismic reflection plane. In this embodiment, 24 geophone points are set (the number of geophone points can be a multiple of 3), and each geophone point has a geophone 7.

[0025] Among them, the geophone points are numbered 1 - 24 and evenly divided into two groups along the survey line direction, namely the 1 - 12 geophone point group and the 13 - 24 geophone point group. During the detection process, the 1 - 12 geophone point group and the 13 - 24 geophone point group alternately switch positions in the extending direction of the survey line. The geophones 7 of the 1 - 12 geophone points are connected to the host 1 through cable one 2, and the geophones 7 of the 13 - 24 geophone points are connected to the host 1 through cable two 3; it can be considered that the host 1 is electrically connected to the geophones 7 in a wireless manner, which is more convenient.

[0026] The basic principle of this embodiment is: The seismic source is used to output seismic wave signals. The seismic wave signals propagate in the soil layer. When the seismic wave signals encounter the interface 6 between the drainage pipe culvert and the soil layer, reflection signals will be generated. The geophones 7 receive the reflection signals and store them; after being processed by the host 1, the reflection signals can obtain seismic reflection profile data; the drainage pipe culvert will show reflection phenomena different from the surrounding medium such as strong reflection, multiple reflection, and diffraction on the seismic reflection profile. According to the positions where the above - mentioned reflection phenomena appear, the planar position of the drainage pipe culvert can be determined.

[0027] Define that several rows of the above - mentioned geophone rectangular array are perpendicular to the survey line and arranged at equal intervals. Each row has three geophones 7 with different frequencies, namely geophones 7 of 4Hz, 28Hz, and 100Hz (the frequency value can be any one of 1 - 100Hz). The distance between any two adjacent shock excitation points 4 is equal to the distance between any two adjacent rows in the geophone rectangular array, both being 0.3m, which can be any value in the range of 0.1 - 1m. Define that several rows of the above - mentioned geophone rectangular array are parallel to the survey line and arranged at equal intervals, with a row spacing of 1m. Each row is composed of geophones 7 with the same frequency, and the shock excitation points 4 are centered and directly opposite to the geophone rectangular array along the survey line direction.

[0028] Such as Figure 1As shown, during the operation of this embodiment, eight groups of detection points, namely, detection points 1 - 3, 4 - 6, 7 - 9, 10 - 12, 13 - 15, 16 - 18, 19 - 21, and 22 - 24, are successively placed at the positions of 1.0 m, 1.3 m, 1.6 m, 1.9 m, 2.2 m, 2.5 m, 2.8 m, and 3.1 m on the survey line, with a spacing of 0.3 m between each group and an offset of 1 m. The shot point 4 is aligned with the arrangement line of detection points 2 / 5 / 8 / 11 / 14 / 17 / 20 / 23 along the survey line direction; 4 Hz geophones 7 are used for detection points 1 / 4 / 7 / 10 / 13 / 16 / 19 / 22, 28 Hz geophones 7 are used for detection points 2 / 5 / 8 / 11 / 14 / 17 / 20 / 23, and 100 Hz geophones 7 are used for detection points 3 / 6 / 9 / 12 / 15 / 18 / 21 / 24. Acquisition process: During acquisition, a shot is fired at the first shot point 4 at 0 m, and detection points 1 - 12 receive the signal. Then, the shot point 4 is moved 0.3 m, and a shot is fired at the second shot point 4 at 0.3 m, and detection points 2 - 13 receive the signal. After that, the shot point 4 is moved 0.3 m, and a shot is fired at the third shot point 4 at 0.9 m, and detection points 3 - 14 receive the signal, and so on... until detection points 13 - 24 receive the signal; during the data acquisition process, continuous shots can be fired at 0 m, 0.3 m, 0.6 m, and 0.9 m. Then, the cable 2 (the cable connecting the geophones 7 of detection points 1 - 12) together with the geophones 7 is moved behind detection points 13 - 24 (i.e., cable 3). After continuous shooting 4 times, the geophones 7 of detection points 13 - 24 and their cable 3 are moved in the extending direction of the survey line, and the above acquisition is continued until the survey line task is completed.

[0029] During the above acquisition process, one layout can be continuously shot 4 times. Compared with the traditional seismic reflection method (as Figure 2 , 3 shown, where Figure 2 in one layout is shot once, Figure 3 is a schematic diagram of the traditional three - channel seismic reflection work layout), the efficiency is greatly improved.

[0030] After the above data acquisition is completed, by extracting seismic trace gathers with the same offset and the same frequency, seismic reflection profiles with 4 kinds of offsets, namely 1.0 m, 1.3 m, 1.6 m, 1.9 m, and 3 kinds of frequencies, namely 4 Hz, 28 Hz, 100 Hz, can be formed. Finally, 12 different - parameter seismic reflection profiles can be obtained. As Figure 4 shown, by integrating the measurement results of each survey line, processing the seismic reflection data to obtain seismic reflection profile data, and determining the planar position and orientation information of the drain culvert according to the seismic reflection profile image; appropriate parameters can be selected without on - site testing, and the detection efficiency is greatly improved, and the positioning of the drain culvert can be quickly and accurately achieved.

[0031] The above are the preferred embodiments of the present invention. Those of ordinary skill in the art can also make various transformations or improvements based on this. Without departing from the general concept of the present invention, these transformations or improvements should all fall within the scope of protection required by the present invention.

Claims

1. A full array seismic imaging observation system for positioning large drainage culverts, comprising: A seismic imaging detection line set on the ground above the drainage culvert; A seismic source arranged at the exciting point; Several detectors arranged at detection points; Features: All geophones are divided into two groups along the detection direction and their positions are alternately switched in the detection direction during the detection process, forming a rectangular array of geophones on the seismic imaging plane; A plurality of exciting points arranged at intervals along the detection direction are preset on the surface above the drainage culvert, and the seismic sources are sequentially located at the preset exciting points and gradually approach the detector distribution area; The survey line is arranged perpendicular to the extension direction of the culvert; The detection points are defined to be numbered from 1 to 24, where 1-3 detection points, 4-6 detection points, 7-9 detection points, 10-12 detection points, 13-15 detection points, 16-18 detection points, 19-21 detection points, and 22-24 detection points are located at 1.0m, 1.3m, 1.6m, 1.9m, 2.2m, 2.5m, 2.8m, and 3.1m of the survey line, respectively. The spacing between each group is 0.3m, and the offset distance is 1m. The excitation point is directly opposite to the arrangement line of 2 / 5 / 8 / 11 / 14 / 17 / 20 / 23 detection points; the frequencies of the detectors used in 1 / 4 / 7 / 10 / 13 / 16 / 19 / 22 detection points, 2 / 5 / 8 / 11 / 14 / 17 / 20 / 23 detection points, and 3 / 6 / 9 / 12 / 15 / 18 / 21 / 24 detection points are not The same; acquisition process: during acquisition, fire at the first exciting point at 0m, and the signals are received at detection points 1 to 12. Then move the exciting point by 0.3m, fire at the second exciting point at 0.3m, and receive signals at detection points 2 to 13. Then move the exciting point by 0.3m, fire at the third exciting point at 0.9m, and receive signals at detection points 3 to 14, and so on, until all signals are received at detection points 13 to 24. During data acquisition, continuously excite at 0m, 0.3m, 0.6m and 0.9m, and then move the cables connecting the detectors at detection points 1 to 12 together with the detectors to the back of detection points 13 to 24. After continuous excitation for multiple times, move the detectors and their cables at detection points 13 to 24 along the detection direction, and continue to repeat the above acquisition until the survey line task is completed.

2. The full permutation seismic reflection observation system for large drainage culvert positioning according to claim 1, characterized in that: The distance between any two adjacent excitation points is equal to the distance between any two adjacent rows in the rectangular array of detectors.

3. The full permutation seismic reflection observation system for positioning large drainage culverts according to claim 1, wherein: The excitation point is centered along the survey line and faces the rectangular array of detectors.

4. The all - permutation seismic reflection observation system for large - diameter drainage culvert positioning according to claim 1, wherein: Also includes the host; The host is connected to the detector by electrical signals in a wireless or wired manner to collect seismic imaging data, and the host has an interface for displaying seismic imaging profile images.

5. The full permutation seismic reflection observation system for large drainage culvert positioning according to claim 4, characterized in that: The seismic source is configured as a controllable seismic source device, and the controllable seismic source device is electrically connected to the host through a shock trigger cable.

6. The all - permutation seismic reflection observation system for large - diameter drainage culvert positioning according to claim 1, wherein: The seismic source is configured as a hammer with a trigger device.

7. A full permutation seismic reflection observation system for large drainage culvert positioning according to claim 1, characterized in that: The length of the measuring line is greater than 0.5 times the width or outer diameter of the culvert.

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