Non-contact vehicle-mounted towed seismic data acquisition system and method

Abstract

The application provides a non-contact vehicle-mounted towing type seismic data acquisition system and method, the system comprising a plurality of towing type movable mobile vehicles, a controller installed on a large towing type mobile vehicle and a movable vibration isolation table for carrying a laser Doppler vibration meter. The application realizes non-contact seismic trace collection through a laser Doppler vibration meter array networking; through the seismic trace collection, the same seismic signal synchronous measurement of different measuring points of the same measuring line is realized, and through signal processing, preliminary seismic data is obtained, and through further data processing, underground structure and stratum characteristics can be explained, which is an effective means for mineral resource exploration and urban underground space detection; the application adopts a non-contact seismic measurement method, can realize mobile measurement, is high in efficiency, easy to implement, wide in applicability, can be flexibly applied to complex geological conditions and is applied to various underground detection scenes such as mineral resource exploration of various surfaces and urban underground space detection.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of geophysical seismic exploration, and particularly relates to a non-contact vehicle-mounted towed seismic data acquisition system and method under complex topographic conditions. BACKGROUND

[0002] At present, the seismic exploration process is generally carried out by using a cable or cableless seismograph. As an absolute shallow surface seismic vibration measuring instrument, the coupling between the seismograph and the ground needs to be considered, which brings inconvenience to the large-scale deployment of the instrument. At the same time, with the development of new technologies, new seismic measurement technologies such as electrochemical geophone and DAS system have appeared. However, these new technologies still have their own limitations, and they have not broken through the traditional seismic signal measurement method and have not deviated from the traditional direct contact type measurement of seismic signals.

[0003] In order to realize non-contact mobile measurement of seismic signals, a new vibration measurement technology based on a new technology needs to be introduced. At present, the laser Doppler vibration measurement technology has developed to a relatively mature stage. With the reduction of the implementation cost of the technology, its characteristics of large bandwidth and high precision make it possible to be applied in the field of non-contact mobile seismic exploration. Therefore, it is necessary to develop a non-contact vehicle-mounted towed seismic data acquisition system and method, which has wide application value. SUMMARY

[0004] The purpose of the present application is to provide a non-contact mobile seismic data acquisition system and method based on laser Doppler vibration measurement technology. The laser Doppler vibration meter array directly collects the vibration signals of the measuring points on the ground, and reliable seismic data is obtained through signal processing algorithms, so as to solve the problem that the existing seismic exploration instrument needs to consider the coupling with the ground when it is deployed, which brings a large amount of labor cost and limits the application scene.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] A non-contact vehicle-mounted towed seismic data acquisition system, comprising a plurality of towed mobile vehicles 1, a controller 2 installed on a large towed mobile vehicle 1, and a movable vibration isolation table 3 installed on a plurality of small towed mobile vehicles 1 for carrying a laser Doppler vibration meter 4;

[0007] Each small towed mobile vehicle 1 is provided with one movable vibration isolation table 3, and each movable vibration isolation table 3 is provided with one laser Doppler vibration meter 4, which forms an array type laser Doppler seismic node. Each laser Doppler vibration meter 4 emits laser light vertically to the ground and forms a linear array type laser Doppler seismic node network. The array type laser Doppler seismic node network is connected to a computer;

[0008] The controller 2 is connected with each laser Doppler vibrometer 4, controls the array laser Doppler seismic node group network to synchronously collect data, the laser Doppler vibrometer 4 collects the ground vibration signal and synchronously outputs to the controller 2, and the controller 2 processes the collected signal in real time, effectively extracts the data collected to the effective earthquake signal, and the upper computer connected with it displays and stores the data of single node or linear array laser Doppler seismic node group network in real time.

[0009] Further, the rigid connection structure 6 is rigidly connected between each towed mobile vehicle 1.

[0010] Further, the controller 2 includes a non-contact node group network connection control and triggering unit, an earthquake data extraction unit, a vibration signal display unit and a gather imaging unit.

[0011] The non-contact node group network connection control and triggering unit controls the networking and synchronous triggering of multiple non-contact nodes, and can set the sampling rate according to engineering requirements.

[0012] The earthquake data extraction unit extracts effective earthquake signals and improves the data signal-to-noise ratio.

[0013] The vibration signal display unit displays real-time single-point or multi-point ground vibration data, and can set a digital filter according to user requirements.

[0014] After measurement, the gather imaging unit integrates the data collected by each non-contact node to generate a seismic gather image.

[0015] Further, the outgoing light of each laser Doppler vibrometer 4 is arranged vertically to the measured ground surface, which measures the vibration speed of the ground measuring point 5 by using the laser Doppler effect. When laser is incident on the vibrating ground, a Doppler shift is generated, which can be obtained by the following formula:

[0016]

[0017] Where Δf is the laser Doppler shift, v is the velocity information, and λ is the wavelength of the laser.

[0018] In order to convert the high-frequency optical signal into an obtainable signal, by means of optical beat technology, the optical signal is converted into an electrical signal by using a balanced photodetector 8, and the optical current is demodulated by the following formula, and then the measured vibration signal can be further obtained.

[0019]

[0020] Where K is the photoelectric conversion parameter of the photodetector 8, I s is the direct current component generated by the measuring light, I r is the direct current component generated by the reference light, and fb a frequency difference introduced for heterodyne interference, a phase difference generated for two light beams.

[0021] Further, the to-be-measured ground surface includes, but is not limited to, soil, sand, vegetation, concrete and asphalt and the like natural or artificial ground surfaces that can be applied in mineral resource exploration and urban underground space detection.

[0022] Further, when the to-be-measured ground surface is a soil ground surface, at the measuring point, the ground surface is compacted by artificial external force to perform compacting and flattening treatment on the loose ground surface, so as to enhance the conduction of vibration and enhance the reflection and receiving effect of the laser signal; the 3M reflective film is attached to the hard ground surface, so as to enhance the conduction of vibration and enhance the reflection and receiving effect of the laser signal.

[0023] Further, the arrayed laser Doppler seismometer nodes are connected with the computer in a wired mode, and are used for connection control of the nodes and transmission and storage of data.

[0024] A non-contact vehicle-mounted towing type seismic data acquisition method based on the above system comprises the following steps:

[0025] A. According to the detection requirement, the spacing and the number of the arrayed laser Doppler seismometer nodes are reasonably arranged, and the towing type mobile vehicle 1 is connected through a rigid medium, and is connected together through the movable vibration isolation table 3; wherein the outgoing light beam of the arrayed laser Doppler seismometer node is perpendicular to the measured ground surface;

[0026] B. The arrayed laser Doppler seismometer node group is configured, the upper computer triggers the control of the laser Doppler vibration meter 4 of each arrayed laser Doppler seismometer node to collect the ground vibration signal and synchronously outputs to the controller 2, and then is transmitted to the upper computer to synchronously record and store the high-speed image and the vibration velocity signal;

[0027] C. The upper computer performs effective signal extraction on the collected ground vibration signal to perform time-frequency domain analysis, obtains high-precision seismic data according to the arrayed arrangement of the non-contact node, and synthesizes the seismic record.

[0028] Further, the signal sampling rate of the laser Doppler vibration meter 4 is 1k-10kHz adjustable.

[0029] Compared with the prior art, the beneficial effects of the present application are:

[0030] The application realizes non-contact seismic trace gathering through laser Doppler vibrometer array networking; through the seismic trace gathering, the same seismic signal synchronous measurement of different measuring points of the same measuring line is realized, and through signal processing, preliminary seismic data can be obtained, and through further data processing of the seismic data, underground structure and stratum characteristics can be explained, which is an effective means for mineral resource exploration and urban underground space detection; compared with the traditional seismic exploration equipment, the non-contact movable seismic measurement method can realize mobile measurement, has high efficiency, is easy to implement, has wide applicability, can be flexibly applied to complex geological conditions, and is applied to various underground detection scenes such as mineral resource exploration of various surfaces and urban underground space detection. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed to be used in the embodiments will be briefly introduced as follows, and it should be understood that the following drawings only show some of the embodiments of the application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0032] Figure 1 It is a structural schematic diagram of the non-contact vehicle-mounted towed seismic data acquisition system of the application.

[0033] Figure 2 It is a non-contact node measurement optical path schematic diagram.

[0034] Figure 3 It is an embodiment effect schematic diagram.

[0035] In the figure: 1. Mobile vehicle 2. Controller 3. Movable vibration isolation table 4. Laser Doppler vibrometer 5. Surface measuring point 6. Rigid connection structure 7. Laser 8. Photodetector 9. Internal optical path 10. Lens 11. Single node acquisition data 12. Synthetic seismic record. DETAILED DESCRIPTION

[0036] The application will be further described below in combination with the embodiments:

[0037] The application will be further described in detail below in combination with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the application, and not to limit the application. In addition, it should be noted that in order to facilitate the description, only the parts related to the application are shown in the drawings, not all structures.

[0038] It should be noted that similar reference numerals and letters refer to like items in the accompanying drawings, and once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings. Meanwhile, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0039] The present application is based on laser Doppler vibrometer technology, and uses laser Doppler vibrometer sensor networking synchronous measurement to realize single-channel set seismic signal measurement, thereby providing primary seismic data for mineral resource exploration and urban underground space detection. The system is convenient to operate, high in measurement accuracy, and can be flexibly applied to detection requirements under different surface conditions.

[0040] As shown in Figure 1 The non-contact vehicle-mounted towing type seismic data acquisition system of the present application comprises a plurality of towing type movable vehicles 1, a controller 2 installed on the large towing type movable vehicle 1, and movable vibration isolation tables 3 installed on the plurality of small towing type movable vehicles 1 and used for carrying laser Doppler vibrometers 4.

[0041] Each movable vibration isolation table 3 is provided with one laser Doppler vibrometer 4. Each laser Doppler vibrometer 4 emits laser light vertically to the ground and forms a linear array type laser Doppler seismic node networking, which is connected to a computer.

[0042] The plurality of movable vibration isolation tables 3 are used for carrying the laser Doppler vibrometers 4. The towing type movable vehicles 1 are rigidly connected through a rigid connection structure 6 such as a chain, thereby ensuring the stability of the system during the seismic data acquisition process. The movable vibration isolation table 3 has the characteristics of stability, low resonance frequency and low frequency vibration isolation, has high static-low dynamic stiffness characteristics, has extremely low natural frequency, and has good effects on isolation of other vibrations, especially low frequency vibrations conducted by the ground.

[0043] The controller 2 is connected to each laser Doppler vibrometer 4, synchronously controls the array type laser Doppler seismic node networking to synchronously collect data, the laser Doppler vibrometer 4 collects the ground vibration signal and synchronously outputs to the controller 2, the controller 2 processes the collected signal in real time, effectively extracts the seismic signal from the collected data, and displays and stores the data of the single node or linear array type laser Doppler seismic node networking in real time by the upper computer connected thereto. After the measurement is completed, primary seismic data is obtained.

[0044] Specifically, the controller 2 comprises a non-contact node networking connection control and triggering unit, a seismic data extraction unit, a vibration signal display unit, and a channel set imaging unit.

[0045] The non-contact node networking connection control and triggering unit controls networking and synchronization triggering start of the multiple non-contact nodes, and the sampling rate can be set according to engineering requirements.

[0046] The seismic data extraction unit extracts effective seismic signals, and improves the data signal-to-noise ratio.

[0047] The vibration signal display unit displays real-time single-point or multi-point ground surface vibration data, and can set a digital filter according to user requirements.

[0048] After the measurement is completed, the trace imaging unit integrates the data collected by each non-contact node to generate a seismic trace set image.

[0049] In the application, the outgoing light rays of each laser Doppler vibrometer 4 are arranged perpendicularly to the measured ground surface, and the vibration speed of the ground measurement point 5 is measured by utilizing the laser Doppler effect. When laser light is incident on the vibrating ground surface, a Doppler frequency shift is generated, which can be obtained by the following formula:

[0050]

[0051] Wherein, Delta f is the laser Doppler frequency shift, v is the speed information, and lambda is the wavelength of the laser.

[0052] In order to convert the high-frequency optical signal into an obtainable signal, by means of optical beat technology, the optical signal is converted into an electrical signal by the balanced photodetector 8, and the optical current is demodulated by the following formula, and then the measured vibration signal can be further obtained.

[0053]

[0054] Wherein, K is the photoelectric conversion parameter of the photodetector 8, I s is the direct current component generated by the measurement light, I r is the direct current component generated by the reference light, f b is the frequency difference introduced by heterodyne interference, is the phase difference generated by the two light beams.

[0055] The single-point laser Doppler vibrometer 4 is based on the principle of Doppler frequency shift, and measures the single-point array seismic signal of the ground surface by networking, and has the characteristics of high synchronization, high precision, high sensitivity, adjustable sampling frequency, etc.

[0056] In the present application, the surface to be measured includes, but is not limited to, soil, sand, vegetation, concrete, asphalt and other natural or artificial surfaces that can be applied in mineral resource exploration and urban underground space detection. In necessary cases, loose surfaces are compacted and leveled to enhance the conduction of vibration and the reflection and reception of laser signals; 3M reflective film is attached to hard surfaces to enhance the conduction of vibration and the reflection and reception of laser signals. Specifically, the surface to be measured is a soil surface, and at the measurement point, the surface is compacted by artificial external force to ensure the relative flatness of the surface and reduce speckle noise. The outgoing laser of the non-contact node is focused on the plane of the measured surface to enhance the reflection and reception of the laser. The non-contact nodes are connected to the computer in a wired manner for connection control of the nodes and transmission and storage of data.

[0057] A non-contact vehicle-mounted towed seismic data acquisition method based on the above system, comprising the following steps:

[0058] A. According to the detection requirements, the spacing and number of array laser Doppler seismometer nodes, i.e. non-contact seismometer nodes, are reasonably arranged, and the nodes are connected to the towed mobile vehicle 1 through a rigid medium, and are connected together through a movable vibration isolation table 3;

[0059] Among them, the outgoing beam of the non-contact seismometer node is perpendicular to the measured surface, reducing false vibration and collecting seismic data with the best quality as much as possible;

[0060] The measured surface area is as flat as possible to minimize speckle noise caused by the roughness of the measured surface at the experimental arrangement level.

[0061] B. Configure the non-contact node networking, and the upper computer triggers each laser Doppler seismometer 4 of the array laser Doppler seismometer node to collect the surface vibration signal and synchronously output to the controller 2, and then transmit to the upper computer for storage;

[0062] The signal sampling rate of the laser Doppler seismometer 4 is adjustable from 1k to 10kHz.

[0063] The upper computer has the ability of real-time display, processing and storage of single node or multiple node data.

[0064] C. The upper computer performs effective signal extraction analysis on the collected surface vibration signal to obtain high-precision seismic data according to the array arrangement of the non-contact node.

[0065] In the present application, the laser Doppler seismometer array starts recording and storing data after receiving the trigger signal of the synchronous trigger. The upper computer displays the collected seismic data of the single-point or array laser Doppler seismometer in real time, synchronously records and stores high-speed images and vibration velocity signals, and performs time-frequency domain analysis, and finally synthesizes the seismic record.

[0066] As Figure 2 shown, the laser 7 emits infrared single-frequency narrow linewidth laser, through the internal optical path 9, the laser is divided into two beams, one as reference light, the other as measurement light, the measurement light is emitted vertically to the ground measuring point 5 through the lens 10, wherein the focal length of the lens 10 is adjusted to the position of the beam waist of the measurement light beam on the ground measuring point 5, then the lens 10 receives the interference of the light beam carrying Doppler information modulated by the ground vibration and the reference light beam, which are received by the photodetector 8 together. The demodulation and correlation processing of the signal are completed by the controller 2.

[0067] As Figure 3 shown, for the measurement results of single node and the generated gather imaging diagram, when a shock signal is applied by using a seismic source near the system, each node records the waveform of the measuring point, which is shown as the time delay and amplitude attenuation of the vibration shock on each node on the gather diagram.

[0068] Compared with the prior art, the present application realizes non-contact movable measurement of seismic data, and brings more possible implementation means for seismic exploration. Meanwhile, the laser Doppler vibration measurement node carrier is improved, and remote seismic exploration can be realized.

[0069] Note that the above is only the preferred embodiment of the present application and the applied technical principles. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A non-contact, vehicle-towed, seismic data acquisition system, characterized by: The application relates to a movable mobile vehicle (1) comprising a plurality of small movable mobile vehicles (1) and a movable vibration isolation platform (3) installed on the small movable mobile vehicles (1) and used for carrying a laser Doppler vibration tester (4). Each small movable mobile vehicle (1) is provided with one movable vibration isolation platform (3), each movable vibration isolation platform (3) is provided with one laser Doppler vibration tester (4), and the laser Doppler vibration testers (4) are arranged to form an array laser Doppler vibration node, the laser Doppler vibration testers (4) are arranged to vertically emit laser light to the ground, and the array laser Doppler vibration node is connected with a computer. The controller (2) is connected with the laser Doppler vibration testers (4) and controls the array laser Doppler vibration node to synchronously collect data, the laser Doppler vibration testers (4) collect ground vibration signals and synchronously output the signals to the controller (2), the controller (2) processes the collected signals in real time, effectively extracts effective seismic signals, and displays and stores the data of single nodes or the array laser Doppler vibration node in real time by the upper computer connected with the controller (2). The movable mobile vehicles (1) are rigidly connected through a rigid connection structure (6). The controller (2) comprises a non-contact node networking connection control and triggering unit, a seismic data extraction unit, a vibration signal display unit and a gather imaging unit. The non-contact node networking connection control and triggering unit controls the networking and synchronous triggering of multiple non-contact nodes and can set a sampling rate according to engineering requirements. The seismic data extraction unit extracts effective seismic signals and improves the signal-to-noise ratio of data. The vibration signal display unit displays real-time single-point or multi-point ground vibration data and can set a digital filter according to user requirements. After measurement, the gather imaging unit synthesizes the data collected by the non-contact nodes and generates a seismic gather image. The laser light emitted by the laser Doppler vibration testers (4) is arranged perpendicularly to the measured ground, the laser Doppler effect is used to measure the vibration speed of the ground measuring point (5), when laser light is incident on the vibrating ground, a Doppler frequency shift is generated, and the following formula can be used to obtain the Doppler frequency shift: Wherein, Delta f is the laser Doppler frequency shift, v is the speed information, and lambda is the wavelength of laser light. In order to convert the high-frequency optical signal into an obtainable signal, the optical signal is converted into an electrical signal by means of the optical beat technology and a balanced photodetector (8), the optical current is demodulated through the following formula, and then the measured vibration signal can be further obtained. Wherein, K is the photoelectric conversion parameter of the photoelectric detector (8), It is the direct current component generated by the measurement light, Is is the direct current component generated by the reference light, fb is the frequency difference introduced by the heterodyne interference, Is the phase difference generated by the two beams; The measured ground includes soil, gravel, vegetation, concrete and asphalt and can be applied to natural or artificial ground in mineral resource exploration and urban underground space detection. When the measured ground is soil ground, the ground is compacted by artificial external force at the measuring point, the loose ground is compacted and leveled, the conduction of vibration is enhanced, and the reflection and receiving effect of laser signals is enhanced; 3M reflective film is attached to the hard ground to enhance the conduction of vibration and enhance the reflection and receiving effect of laser signals. The array laser Doppler seism node is connected with a computer in a wired mode, and is used for connection control of the node and transmission and storage of data.

2. A non-contact vehicle-towed seismic data acquisition method based on the non-contact vehicle-towed seismic data acquisition system of claim 1, characterized in that, The method comprises the following steps: A. The array laser Doppler seism node is connected with a computer in a wired mode, and is used for connection control of the node and transmission and storage of data. B. The array laser Doppler seism node is connected with a computer in a wired mode, and is used for connection control of the node and transmission and storage of data. C. The array laser Doppler seism node is connected with a computer in a wired mode, and is used for connection control of the node and transmission and storage of data. The signal sampling rate of the laser Doppler seism node is 1k-10kHz adjustable.

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