Ground surface towed seismic detection device and detection method

Abstract

The invention relates to the technical field of urban shallow earth surface geophysical exploration, and provides an earth surface towed seismic detection device and a detection method. The detection device comprises a mobile seismic source platform, an earth surface observation array and a terminal, the mobile seismic source platform is used for exciting a frequency sweeping signal at a specified position; the earth surface observation array is used for acquiring a reflection signal generated by the excitation sweep frequency signal at the underground pipeline and sending the reflection signal to the terminal; the terminal is used for processing the reflection signal to obtain underground reflection information; performing wave velocity inversion on the underground reflection information to obtain underground medium velocity distribution; and based on the underground medium velocity distribution, an underground pipeline imaging result is obtained by adopting a reverse time migration imaging method.

Description

Technical Field

[0001] The present invention relates to the technical field of urban shallow surface geophysical exploration, and in particular to a surface towed earthquake detection device and a detection method. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Urban underground pipelines are an important part of urban infrastructure, responsible for the city's energy, domestic water, information transmission and other functions, and play an important role in maintaining the normal operation of the city. However, due to the lack of scientific management of some underground pipelines, the transformation, layout and repair of pipelines are prone to damage to existing pipelines. Therefore, the location of underground pipelines needs to be explored before construction.

[0004] At present, pipeline detectors and ground penetrating radars are mainly used to track and locate urban underground pipelines. Both methods are electromagnetic methods and are easily affected by electromagnetic signals such as urban electricity and communications. At the same time, these two methods have certain requirements for the buried depth and material of pipelines. Their detection depth is limited, making it difficult to detect deeply buried pipelines. In addition, since non-metals do not respond to electromagnetic signals, it is difficult to detect non-metallic pipelines. Summary of the invention

[0005] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a surface towed seismic detection device and detection method. The present invention drives the movement of the seismic source through a mobile platform, and can make the seismic source close to the surface through a telescopic device to stimulate a sweep frequency signal. The signal is collected through a surface observation array arranged on the surface, which can realize the fine detection of underground metal and non-metallic pipelines and improve the detection capability and efficiency.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A first aspect of the present invention provides a surface towed seismic detection device.

[0008] A surface towed seismic detection device, comprising a mobile source platform, a surface observation array and a terminal;

[0009] The mobile source platform is used to excite the sweep frequency signal at a specified position;

[0010] The surface observation array is used to obtain the reflection signal generated by the excitation sweep signal at the underground pipeline, and send the reflection signal to the terminal;

[0011] The terminal is used to process the reflection signal to obtain underground reflection information; perform wave velocity inversion on the underground reflection information to obtain underground medium velocity distribution; and obtain underground pipeline imaging results based on the underground medium velocity distribution by using a reverse time migration imaging method.

[0012] Furthermore, the mobile seismic source platform includes a cylinder rod, a mobile platform, a connecting piece and a detection structure, and the mobile platform is connected to the detection structure through the cylinder rod and the connecting piece; one end of the cylinder rod is fixed on the mobile platform, and the other end is connected to the middle part of the connecting piece; one end of the connecting piece is fixed on the mobile platform, and the other end is connected to the detection structure.

[0013] Furthermore, the detection structure includes a fixed structure, a controllable seismic source and a pad, the fixed structure is connected to the other end of the connecting member, the controllable seismic source is installed in the fixed structure, and the pad is connected to the fixed structure.

[0014] Furthermore, the surface observation array is arranged on the surface above the detection target.

[0015] Furthermore, the process of processing the reflection signal to obtain underground reflection information includes: using the empirical mode decomposition method to decompose the reflection signal into multiple IMF components, calculating the cross-correlation between the reflection signal and the IMF, and the autocorrelation of the reflection signal, thereby calculating the correlation coefficient; filtering the reflection signal according to the correlation coefficient, and obtaining the underground reflection information based on the correlation between the filtered information and the excitation sweep signal.

[0016] Furthermore, the correlation coefficient is calculated by the following formula:

[0017]

[0018] in, represents the correlation coefficient, represents the cross-correlation between the reflected signal and the IMF, represents the autocorrelation of the reflected signal, E(·) is the correlation operation, s(t) and x(t) represent the reflected signal and IMF component, respectively.

[0019] Furthermore, the process of obtaining underground reflection information based on the correlation between the filtered information and the excitation sweep signal adopts the following formula:

[0020] d cor (t) = E[s(t)d e (t+τ)]

[0021] d e (t+τ) represents the effective signal at time (t+τ), s(t) represents the reflected signal, and d cor(t) represents the reflection information obtained by cross-correlation.

[0022] Furthermore, the process of performing wave velocity inversion on the underground reflection information to obtain the velocity distribution of the underground medium adopts the following formula:

[0023]

[0024] Among them, J is the loss function and G(m) is the Green function, which is used to calculate the travel time of model m.

[0025] Furthermore, the process of using the reverse time migration imaging method adopts the following formula:

[0026]

[0027] Among them, F(x,z,t) is the forward wave field, and R(x,z,t) is the reverse wave field.

[0028] A second aspect of the present invention provides a surface towed seismic detection method.

[0029] A surface towed seismic detection method, using the surface towed seismic detection device described in the first aspect, comprising:

[0030] The mobile platform moves the controllable vibrator to the specified position, retracts the hydraulic rod, brings the controllable vibrator close to the ground surface, and performs sweep signal excitation;

[0031] The surface observation array collects the reflected signal reflected by the underground pipeline and sends the reflected signal to the terminal;

[0032] The terminal processes the reflection signal to obtain underground reflection information; performs wave velocity inversion on the underground reflection information to obtain underground medium velocity distribution; and obtains underground pipeline imaging results based on the underground medium velocity distribution by using a reverse time migration imaging method.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention overcomes the problem that the traditional pipeline instrument and geological radar method have poor detection effects on non-metallic pipelines; by moving the source platform, the source can be easily moved and the signal is automatically excited, thereby improving the detection efficiency.

[0035] The present invention adopts a controllable seismic source to excite the swept frequency signal, has the characteristics of wide frequency band and strong energy, can realize the detection of deep buried pipelines, and has the advantage of high resolution, and can obtain fine imaging results of underground pipelines.

[0036] Aiming at the serious problem of urban noise interference, the present invention adopts an empirical mode decomposition method and can effectively reflect signals through correlation evaluation to achieve effective noise removal. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0038] Figure 1 It is a structural schematic diagram of a surface towed seismic detection device shown in the present invention;

[0039] Figure 2 It is a schematic diagram of the structure of a mobile source platform shown in the present invention;

[0040] Figure 3 is a flow chart of a surface dragging seismic detection method shown in the present invention;

[0041] Among them: 1. Mobile source platform, 2. Terminal, 3. Surface observation array, 4. Underground pipeline, 5. Cylinder rod, 6. Mobile platform, 7. Connectors, 8. Fixed structure, 9. Controllable source, 10. Pad. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0043] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0044] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0045] It should be noted that the flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the methods and systems according to various embodiments of the present disclosure. It should be noted that each box in the flowchart or block diagram can represent a module, a program segment, or a part of a code, and the module, program segment, or a part of a code may include one or more executable instructions for implementing the logical functions specified in each embodiment. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, or they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the flowchart and / or block diagram, and the combination of boxes in the flowchart and / or block diagram can be implemented using a dedicated hardware-based system that performs a specified function or operation, or can be implemented using a combination of dedicated hardware and computer instructions.

[0046] The present invention combines a controllable seismic source device with a mobile platform, and uses a hydraulic rod to bring the controllable seismic source close to the surface to achieve effective excitation of the swept frequency signal. At the same time, a surface observation array is arranged on the surface above the target pipeline to collect and save the signals reflected from the underground pipeline. The collected data is transmitted to the terminal for processing through wireless transmission, which makes full use of the wide bandwidth and high energy characteristics of the swept frequency signal to achieve fine imaging of the distribution of underground pipelines.

[0047] The present invention is described in detail below through several embodiments:

[0048] Embodiment 1

[0049] This embodiment provides a surface towed seismic detection device, including a mobile source platform, a surface observation array and a terminal;

[0050] The mobile source platform is used to excite the sweep frequency signal at a specified position;

[0051] The surface observation array is used to obtain the reflection signal generated by the excitation sweep signal at the underground pipeline, and send the reflection signal to the terminal;

[0052] The terminal is used to process the reflection signal to obtain underground reflection information; perform wave velocity inversion on the underground reflection information to obtain underground medium velocity distribution; and obtain underground pipeline imaging results based on the underground medium velocity distribution by using a reverse time migration imaging method.

[0053] like Figure 1As shown, as a typical implementation, a surface towed seismic detection device mainly includes a mobile source platform 1 and its hydraulic rod 5, a surface observation array 3 and a terminal 2. The surface observation array 3 is used to collect and save the reflected signal generated by the signal excited by the mobile source platform at the underground pipeline 4.

[0054] like Figure 2 As shown, one end of the connecting member 7 is connected to the mobile platform 6, and the other end is connected to the fixed structure 8, the cylinder rod 5 is connected to the middle part of the connecting member 7, and the other end is connected to the mobile platform, the controllable seismic source 9 is installed in the fixed structure 8, and the pad 10 is connected to the fixed structure 8, so as to ensure that the controllable seismic source is fully in contact with the ground surface and realize good excitation of the sweep frequency signal.

[0055] like Figure 1 As shown, the surface observation array 3 is arranged on the surface above the detection target. In this embodiment, 9 stations constitute the surface observation array 3 for collecting reflection signals from underground pipelines.

[0056] Of course, in other embodiments, the number of ground observation array stations can be changed, and the spacing and arrangement of the stations can be adjusted according to actual conditions.

[0057] It should be understood that the station referred to in the present invention is a data acquisition station in the detection field, and the data acquisition station is equipped with corresponding receiving equipment, such as a detector, a three-component detector, a vibration sensor or a sound sensor, etc., which are conventional technical terms in this field and will not be repeated here.

[0058] Terminal 2 receives data collected by the surface observation array and stores and processes it automatically.

[0059] Before detection, the hydraulic rod 5 is in an extended state, lifting the controllable vibrator 9 for easy movement. During detection, the mobile platform 6 moves the controllable vibrator 9 to a specified position, retracts the hydraulic rod 5, and makes the controllable vibrator 9 close to the surface to excite the sweep signal. When the sweep signal encounters the wave impedance interface between the underground pipeline and the rock and soil during underground propagation, a reflected wave is generated and propagated to the surface, and is continuously collected by the surface observation array 3. The above-mentioned collected data will be transmitted to the terminal by wireless for automatic processing, and the underground pipeline imaging results will be output.

[0060] Embodiment 2

[0061] This embodiment provides a surface towed seismic detection method, using the surface towed seismic detection device described in Embodiment 1, including:

[0062] The mobile platform moves the controllable vibrator to the specified position, retracts the hydraulic rod, brings the controllable vibrator close to the ground surface, and performs sweep signal excitation;

[0063] The surface observation array collects the reflected signal reflected by the underground pipeline and sends the reflected signal to the terminal;

[0064] The terminal processes the reflection signal to obtain underground reflection information; performs wave velocity inversion on the underground reflection information to obtain underground medium velocity distribution; and obtains underground pipeline imaging results based on the underground medium velocity distribution by using a reverse time migration imaging method.

[0065] like Figure 3 As shown, the specific solution of this embodiment includes the following steps:

[0066] Step (1) Data preprocessing

[0067] Firstly, the effective signal energy is enhanced by means of gather stacking, and then the background noise such as urban traffic noise is removed by means of bandpass filtering.

[0068] Step (2) Data collection noise removal

[0069] The collected data is decomposed into multiple IMF components using the empirical mode decomposition method, and the cross-correlation between the collected data and IMF is calculated using the following formula:

[0070]

[0071] Among them, E(·) is the correlation operation, d(t) and x(t) are the collected data and IMF components respectively. The autocorrelation of the collected data is further calculated:

[0072]

[0073] Then calculate the correlation coefficient

[0074]

[0075] Select the IMF with the largest correlation coefficient to superimpose and separate the effective signal d e (t).

[0076] Step (3) Signal Interference

[0077] Using the excitation signal s(t) and the effective signal d obtained in step (2) e (t) performing cross-correlation to obtain underground reflection information;

[0078] d cor (t) = E[s(t)d e (t+τ)]

[0079] Step (4) Tomography wave velocity inversion

[0080] After recovery, the data d cor(t) The velocity distribution of underground medium is obtained by performing velocity inversion using the following formula;

[0081]

[0082] Among them, J is the loss function and G(m) is the Green function, which is used to calculate the travel time of model m.

[0083] Step (5) Reverse time migration imaging

[0084] Using the wave velocity distribution obtained in step (4), reverse time migration under the cross-correlation imaging condition is adopted to obtain the underground pipeline distribution imaging result.

[0085]

[0086] Among them, F(x,z,t) is the forward wave field, and R(x,z,t) is the reverse wave field.

[0087] Based on the obtained velocity model and imaging results, the underground pipeline can be located, providing a reference for the construction of urban underground pipelines.

[0088] The above description is only 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 may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A surface towed seismic detection device, characterized in that: Includes mobile source platform, surface observation array and terminal; The mobile source platform is used to excite the sweep frequency signal at a specified position; The surface observation array is used to obtain the reflection signal generated by the excitation sweep signal at the underground pipeline, and send the reflection signal to the terminal; The terminal is used to process the reflected signal to obtain underground reflection information; Perform wave velocity inversion on underground reflection information to obtain underground medium velocity distribution; Based on the velocity distribution of underground media, the reverse time migration imaging method is used to obtain the imaging results of underground pipelines.

2. The surface towed seismic detection device according to claim 1, characterized in that: The mobile seismic source platform includes a cylinder rod, a mobile platform, a connecting piece and a detection structure, wherein the mobile platform is connected to the detection structure via the cylinder rod and the connecting piece; one end of the cylinder rod is fixed on the mobile platform, and the other end is connected to the middle part of the connecting piece; one end of the connecting piece is fixed on the mobile platform, and the other end is connected to the detection structure.

3. The surface towed seismic detection device according to claim 2, characterized in that: The detection structure comprises a fixed structure, a controllable seismic source and a pad, the fixed structure is connected to the other end of the connecting member, the controllable seismic source is installed in the fixed structure, and the pad is connected to the fixed structure.

4. The surface towed seismic detection device according to claim 1, characterized in that: The surface observation array is arranged on the surface above the detection target.

5. The surface towed seismic detection device according to claim 1, characterized in that: The process of processing the reflection signal to obtain underground reflection information includes: using the empirical mode decomposition method to decompose the reflection signal into multiple IMF components, calculating the cross-correlation between the reflection signal and the IMF, and the autocorrelation of the reflection signal, thereby calculating the correlation coefficient; filtering the reflection signal according to the correlation coefficient, and obtaining the underground reflection information based on the correlation between the filtered information and the excitation sweep signal.

6. The surface towed seismic detection device according to claim 5, characterized in that: The correlation coefficient is calculated by the following formula: in, represents the correlation coefficient, represents the cross-correlation between the reflected signal and the IMF, represents the autocorrelation of the reflected signal, E(·) is the correlation operation, s(t) and x(t) represent the reflected signal and IMF component, respectively.

7. The surface towed seismic detection device according to claim 5, characterized in that: The process of obtaining underground reflection information based on the correlation between the filtered information and the excitation sweep signal adopts the following formula: d cor (t)=E[s(t)d e (t+τ)] d e (t+τ) represents the effective signal at time (t+τ), s(t) represents the reflected signal, and d cor (t) represents the reflection information obtained by cross-correlation.

8. The surface towed seismic detection device according to claim 1, characterized in that: The process of performing wave velocity inversion on underground reflection information to obtain underground medium velocity distribution adopts the following formula: Among them, J is the loss function and G(m) is the Green function, which is used to calculate the travel time of model m.

9. The surface towed seismic detection device according to claim 1, characterized in that: The process of using the reverse time migration imaging method adopts the following formula: Among them, F(x,z,t) is the forward wave field, and R(x,z,t) is the reverse wave field.

10. A surface dragging seismic detection method, characterized in that: The surface towed seismic detection device according to any one of claims 1 to 9 comprises: The mobile platform moves the controllable vibrator to the specified position, retracts the hydraulic rod, brings the controllable vibrator close to the ground surface, and performs sweep signal excitation; The surface observation array collects the reflected signal reflected by the underground pipeline and sends the reflected signal to the terminal; The terminal processes the reflection signal to obtain underground reflection information; performs wave velocity inversion on the underground reflection information to obtain underground medium velocity distribution; and obtains underground pipeline imaging results based on the underground medium velocity distribution by using a reverse time migration imaging method.

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