Land spark source continuous pull-type seismic survey system and data imaging method

Abstract

The invention discloses a land spark source continuous towed seismic survey system and a data imaging method.The system comprises a continuous towed ground transducer, the continuous towed ground transducer comprises a barrel body, the bottom of the barrel body is provided with a barrel bottom, the top of the barrel body is provided with a barrel cover, and the barrel body is internally provided with a bell-jar-shaped discharge chamber; the bottom of the discharge chamber is outwards provided with a flange which abuts against the barrel bottom, a discharge electrode is fixedly arranged in the discharge chamber, the top of the discharge chamber and the top of the barrel cover are provided with a through hole for a cable of the discharge electrode to pass through and a cable passing hole respectively, the barrel cover is further provided with a pressure relief water injection hole, water is contained in the barrel body and the discharge chamber, and the height of the water is higher than the top end of the discharge chamber. The coupling skid is fixedly mounted at the outer bottom of the barrel bottom; the discharge electrode obtains a high-voltage electric pulse signal and excites a seismic wave. The invention aims to realize high-efficiency, low-cost and high-precision engineering seismic detection of the hard pavement.

Description

Technical Field

[0001] The present invention relates to the technical field of earthquake detection and engineering investigation, and in particular to a land electric spark source continuous dragging type earthquake investigation system and a data imaging method. Background Art

[0002] Existing active-source towed seismic exploration methods have low construction efficiency (0.5 km / h), which cannot meet the needs of rapid inspection and survey of targets such as long-distance urban roads and embankments. Continuous towed seismic exploration methods can significantly improve construction efficiency, but they have high requirements for continuity, speed, and a high signal-to-noise ratio during the construction process. They require loading an artificial seismic source while traveling to continuously release high-energy seismic waves into the ground to improve the data signal-to-noise ratio, which places higher demands on the artificial seismic source and receiving system.

[0003] Currently, commonly used artificial seismic sources include explosive sources, electromagnetic shock sources, and pneumatic shock sources. Explosive sources, because they require pre-drilling and burying and are highly destructive, are completely incapable of continuous drag seismic surveys. Electromagnetic shock sources and pneumatic shock sources require relative stationary conditions to stably excite seismic waves, resulting in low construction efficiency. Furthermore, the superposition time of controllable vibrators is too long and the excitation energy is weak, resulting in a low signal-to-noise ratio in drag seismic data. Compared to the aforementioned sources, spark sources are the only artificial seismic source capable of continuous drag seismic surveys.

[0004] When conducting continuous towed seismic detection and engineering surveys for hidden dangers on embankments, urban roads, frozen soil highway subgrades, and tunnel inverts, it is difficult to use a long string of detector arrays due to the long travel paths, fast moving speeds, and changing road conditions. In addition, considering the impact of offset distance on the quality and consistency of the detector acquisition signal, it is necessary to design a streamlined towed detector array to achieve rapid towing construction.

[0005] Continuous-drag seismic data has a low signal-to-noise ratio. Seismic signals generated by artificial sources are subject to interference from noise from the receiver base and environmental noise. Near-surface anomalies cannot be identified in raw continuous-drag seismic data. Therefore, research is needed on high-resolution stacking imaging methods to improve imaging resolution.

[0006] Existing towed seismic detection methods have a series of shortcomings in seismic detection and data imaging methods. Combining instrument technology and the principle of shallow space seismic wave propagation, the present invention proposes a land electric spark source continuous towed seismic survey system and data imaging method, aiming to achieve efficient, low-cost, and high-precision engineering seismic detection on hard roads such as embankments, frozen soil roads, tunnel inverts, airport runways, and urban roads. Summary of the Invention

[0007] In view of at least one defect of the prior art, the object of the present invention is to provide a land electric spark source continuous dragging seismic survey system, which is designed to achieve efficient, low-cost, high-precision engineering seismic detection on hard road surfaces such as embankments, frozen soil roads, tunnel arches, airport runways, and urban roads.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A land electric spark source continuous dragging type seismic survey system, the key of which is that it comprises a continuously dragged ground transducer (10), the continuously dragged ground transducer (10) comprising a barrel (1), the bottom of the barrel (1) being provided with a barrel bottom (11), the top of the barrel (1) being provided with a barrel cover (12), a bell-shaped discharge chamber (2) being provided in the barrel (1), the bottom of the discharge chamber (2) being provided with a flange (2a) facing outwards, the flange (2a) being in contact with the barrel bottom (11), and a discharge electrode ( 3), the tops of the discharge chamber (2) and the barrel cover (12) are respectively provided with a through hole (2b) for the cable (3a) of the discharge electrode (3) to pass through and a cable through hole (12a), the barrel cover (12) is also provided with a pressure relief water injection hole (12b), the barrel body (1) and the discharge chamber (2) are both filled with water, the height of the water being higher than the top of the discharge chamber (2), and also include a coupling skid (4), which is fixedly mounted on the outer bottom of the barrel bottom (11); the discharge electrode (3) obtains a high-voltage electric pulse signal to generate electric sparks and excite seismic waves.

[0010] A cable anti-sway through-hole tube (21) is passed through the through-hole (2b), and the cable (3a) passes through the cable anti-sway through-hole tube (21) to connect to the discharge electrode (3). The cable anti-sway through-hole tube (21) is installed on the top of the discharge chamber (2) through an adjustment mechanism (22). The cable anti-sway through-hole tube (21) is adjusted up and down in height through the adjustment mechanism (22) and locked on the discharge chamber (2), thereby adjusting the height of the discharge electrode (3). A cable locking mechanism (23) is provided at the top end of the cable anti-sway through-hole tube (21), and the cable locking mechanism (23) locks the cable (3a) of the discharge electrode (3).

[0011] Preferably, the adjustment mechanism (22) is a through-hole tube locking flange; and the cable locking mechanism (23) is a cable locking flange.

[0012] The discharge electrode (3) comprises an inner conductor (31), an intermediate insulating layer (32) and an outer conductor (33) which are coaxially arranged. The inner conductor (31) is fixedly sheathed with the intermediate insulating layer (32), and the intermediate insulating layer (32) is fixedly sheathed with the outer conductor (33). The discharge electrode (3) is provided with at least two symmetrical pressure relief channels, and the pressure relief channels comprise an axial pressure relief hole (32a) and a radial pressure relief hole (33a) which are interconnected. The axial pressure relief hole (32a) is axially arranged on the outer wall of the intermediate insulating layer (32), and the radial pressure relief hole (33a) is radially arranged on the outer conductor (33). The lower end of the axial pressure relief hole (32a) extends downward to penetrate the lower end of the discharge electrode (3), and the upper end of the axial pressure relief hole (32a) extends axially upward to connect with the inner end of the corresponding radial pressure relief hole (33a). The outer end of the radial pressure relief hole (33a) extends radially outward to penetrate the outer wall of the outer conductor (33).

[0013] The inner conductor (31) is connected to the power supply end of the high-voltage electric pulse signal, and the outer conductor (33) is connected to the ground end of the high-voltage electric pulse signal.

[0014] The invention also includes an electric spark source host, the electric spark source host and the continuously dragged ground transducer (10) form an electric spark source, the electric spark source host includes an electric spark source control system, the electric spark source control system is connected to a high-voltage DC charging power supply, a high-voltage energy storage capacitor and a solid-state switch component, the electric spark source control system controls the high-voltage DC charging power supply to charge the high-voltage energy storage capacitor, the high-voltage energy storage capacitor supplies power to the solid-state switch component, the solid-state switch component is connected to the discharge electrode (3) of the continuously dragged ground transducer (10), the electric spark source control system controls the switch of the solid-state switch component, and the electric spark source control system controls the solid-state switch component to provide a high-voltage electric pulse signal to the continuously dragged ground transducer (10).

[0015] The high-voltage DC charging power supply is a 220VAC to 10kVDC charging power supply with a power density of not less than 0.25W / cm3; the high-voltage energy storage capacitor has a withstand voltage of 12kV, a capacitance value of 200uF, and an energy storage density of not less than 0.83MJ / m3.

[0016] The solid-state switch assembly comprises a pulse-type high-power semiconductor discharge switch, wherein the positive electrode of the pulse-type high-power semiconductor discharge switch is connected to one end of a high-voltage energy storage capacitor, the negative electrode of the pulse-type high-power semiconductor discharge switch is connected to the power supply end of a discharge electrode (3) of a continuously dragged ground transducer (10), the ground end of the discharge electrode (3) of the continuously dragged ground transducer (10) is connected to the other end of the high-voltage energy storage capacitor, the other end of the high-voltage energy storage capacitor is grounded, and the electric spark source control system is connected to the control end of the pulse-type high-power semiconductor discharge switch to control its switching;

[0017] The device also includes a protection diode A, a protection diode B, a protection diode C, and a protection resistor. The cathode of the protection diode A is connected to the anode of a pulse-type high-power semiconductor discharge switch. The anode of the protection diode A is connected to the cathode of the pulse-type high-power semiconductor discharge switch. The cathode of the protection diode B is connected to the cathode of the pulse-type high-power semiconductor discharge switch. The anode of the protection diode B is connected to the ground end of the discharge electrode (3) of the continuous drag ground transducer (10). The cathode of the protection diode C is connected to one end of a high-voltage energy storage capacitor via the protection resistor. The anode of the protection diode C is connected to the other end of the high-voltage energy storage capacitor.

[0018] The power supply end of the discharge electrode (3) is the inner conductor (31); the ground end of the discharge electrode (3) is the outer conductor (33).

[0019] The electric spark source control system includes a programmable microcontroller, which is connected to a master controller input module, an energy setting gear module, a high-voltage charging power peripheral control unit, a charge and discharge process management peripheral control unit, a solid-state discharge switch component peripheral control circuit and a synchronous trigger signal generating unit, wherein the charge and discharge process management peripheral control unit is also connected to the high-voltage charging power peripheral control unit, the solid-state discharge switch component peripheral control circuit, a first GPS module, a high-voltage monitoring module and an event storage module; the master controller input module is used to input control instructions to the programmable microcontroller, the energy setting gear module is used to input energy gear parameters to the programmable microcontroller, the programmable microcontroller is connected to the high-voltage charging power peripheral control unit to control it to charge the high-voltage energy storage capacitor, the programmable microcontroller also controls the operation of the high-voltage charging power peripheral control unit through the charge and discharge process management peripheral control unit, the charge and discharge process management peripheral control unit supplies power to the solid-state switch component through the solid-state discharge switch component peripheral control circuit, the programmable microcontroller also controls the switching of the solid-state switch component through the solid-state discharge switch component peripheral control circuit, the first GPS module provides GPS data to the programmable microcontroller, the high-voltage monitoring module is used to detect whether the high-voltage energy storage capacitor is charged to the specified energy gear and whether there is a fault; the event storage module is used to store the operation log of the high-voltage circuit. The programmable microcontroller sends a seismic synchronous trigger signal to a synchronous trigger module of a continuous towed geophone array acquisition system through a synchronous trigger signal generating unit.

[0020] The invention also includes a towing vehicle (5), wherein a semi-trailer (6) is connected to the front and / or rear of the towing vehicle (5), and the semi-trailer (6) includes a frame (61), one end of the frame (61) is connected to the body of the towing vehicle (5), and the other end of the frame (61) is provided with a wheel (62). The semi-trailer (6) is driven by the towing vehicle (5) to move continuously, and a continuously towed ground transducer (10) is fixedly arranged on the frame (61). A detector array (7) of a continuously towed detector array acquisition system is also provided on the frame (61). The detector array (7) is arranged in an arc shape around the continuously towed ground transducer (10) and is fixed on the frame (61). The distance between each detector of the detector array (7) and the continuously towed ground transducer (10) is equal.

[0021] Each detector of the detector array (7) is provided with a detector body (71), which is installed in a detector housing (72) and is in close contact with the detector housing (72); a lead-out socket (73) is provided on the upper part of the detector housing (72), and the lead-out socket (73) is connected to a host of a continuous dragging detector array acquisition system through a bus cable; the lower part of the detector housing (72) is connected to a counterweight support block (74), and the counterweight support block (74) is closely coupled with the ground during the dragging movement; a dot matrix coupling protrusion (74a) is distributed on the bottom of the counterweight support block (74), and a support block steel hook (75) is provided at the front end of the counterweight support block (74), and the support block steel hook (75) is connected to the vehicle frame (61) through a flexible connecting cable; the detector body (71) adopts a 60Hz dynamic coil detector.

[0022] Preferably, the frame (61) is made of rigid connecting rods and the wheels (62) are pulleys.

[0023] The mainframe of the continuous dragged geophone array acquisition system includes at least two geophone interfaces. The geophones are connected to corresponding signal conditioning and amplification circuits via the corresponding geophone interfaces. Each geophone undergoes signal conditioning through an independent signal conditioning and amplification circuit before inputting into an A / D converter. The converted output digital quantity is uniformly imaged and processed by an FPGA. The FPGA is connected to a computer via a USB controller, and the computer implements rapid imaging and storage of the real-time collected seismic wave signals.

[0024] FPGA is connected to the second GPS module and the synchronous trigger module. FPGA will record the real-time information of the second GPS module while receiving and processing seismic data. The synchronous trigger module is used to receive the synchronous trigger signal sent by the spark source host. The continuous drag detector array acquisition system is designed with three acquisition modes: single trigger mode, continuous acquisition mode and cyclic trigger mode. Two trigger modes are designed: internal trigger and external trigger. Among them, the external trigger is used in the single trigger mode. The continuous drag detector array acquisition system realizes single trigger mode after receiving the synchronous trigger signal sent by the spark source. The system can be triggered once to realize single-shot trigger acquisition and storage in seismic-detection connection, which is used for single-point acquisition in towed earthquakes. The continuous acquisition mode does not require a trigger source, which realizes real-time continuous acquisition and storage when the seismic-detection is not connected, which is used for continuous acquisition of active / passive sources in towed earthquakes. The cyclic trigger mode uses an external trigger. The continuous towed geophone array acquisition system triggers acquisition at the moment it receives the synchronous trigger signal from the electric spark source, and remains powered on waiting for the next synchronous trigger signal from the electric spark source, realizing cyclic trigger acquisition and storage in seismic-detection connection, which is used for continuous acquisition of active sources in towed earthquakes.

[0025] Seismic-detection refers to the electric spark source and continuous towed detector array acquisition system.

[0026] A data imaging method comprising the land spark source continuous towed seismic survey system, the key of which is that: the data imaging method is a continuous towed seismic data coherent stacking method, the land spark source continuous towed seismic survey system is provided with M geophones, M is greater than or equal to 2, the M geophones are moved and collected simultaneously, and the final profile can form M channels of seismic data; the time recording length at a lateral resolution of 0.5m during the movement is set to T, and the seismic data at position x is Y(x, T); the recording length after stacking is set to w, and the number of iterations in the single-point stacking calculation is N=T / w, and the derived calculation formula is:

[0027]

[0028] Where, l = 1, 2, ..., N, s = w × l, (w + 1) × l, ... (2w - 1) × l, 2 × w × l, The square of the observation record Y(x,s) at point x is summed up after N iterations and normalization.

[0029] Preferably, M is 6.

[0030] Significant effect: The present invention provides a land electric spark source continuous dragging seismic survey system and data imaging method, aiming to achieve efficient, low-cost, high-precision engineering earthquake detection on hard roads such as embankments, frozen soil roads, tunnel inverts, airport runways, and urban roads. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 .Module structure diagram of land-based electric spark source;

[0032] Figure 2 Solid-state switch assembly composite structure;

[0033] Figure 3 .Electric spark source discharge test waveform;

[0034] Figure 4 .Stereoscopic view of the continuously towed ground transducer;

[0035] Figure 5 . The structure of the discharge electrode; wherein (a) is a cross-sectional view of the discharge electrode, and (b) is an AA cross-sectional view of (a);

[0036] Figure 6 .Structure diagram of multifunctional isolated electric spark source control system;

[0037] Figure 7 .Multifunctional isolated spark source control system flow chart;

[0038] Figure 8 .Streamlined continuous towed detector array acquisition structure;

[0039] Figure 9 .Continuous towed geophone structure;

[0040] Figure 10 .Control structure diagram of the continuous drag seismic rapid acquisition system;

[0041] Figure 11 .Trigger mode interface of the host computer software interface;

[0042] Figure 12 .Continuous drag seismic stacking profile;

[0043] Figure 13 A cross-sectional view of a continuously towed ground transducer. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] The present invention relates to a land electric spark source continuous dragging seismic survey system and a data imaging method, aiming to achieve efficient, low-cost, high-precision engineering earthquake detection on hard roads such as embankments, frozen soil roads, tunnel inverts, airport runways, and urban roads.

[0046] like Figures 1-13As shown, the present invention adopts the following technical solutions: a land electric spark source continuous towed seismic exploration system and data imaging method, specifically using a fast and lightweight high-energy land electric spark source and a continuously towed ground transducer 10 to efficiently and strongly excite continuously towed seismic waves; using a streamlined continuously towed detector array acquisition system to losslessly collect continuously towed seismic data with a high signal-to-noise ratio; using a continuously towed seismic data coherent stacking method to obtain a continuously towed high-resolution stacking profile to identify the characteristics of underground cavities, caves and other diseased bodies.

[0047] The steps include:

[0048] Step 1: A fast and lightweight high-energy land electric spark source and a continuously dragged ground transducer 10 are used to achieve high-efficiency and high-energy excitation of continuously dragged seismic waves;

[0049] Step 2: A streamlined continuous-drag geophone array acquisition system is used to achieve lossless, high-SNR acquisition of continuous-drag seismic data.

[0050] Step 3: Continuous dragging seismic data coherent stacking method to achieve continuous dragging high-resolution stacking processing.

[0051] In step 1, the module structure of the land electric spark source is as follows Figure 1 As shown, it can be powered by a variety of 220VAC power supplies and does not require grounding, making it suitable for various survey engineering scenarios.

[0052] The fast, lightweight, high-energy spark source mainframe of this invention features an integrated structural design, internally comprising: a high-power-density, high-voltage DC charging power supply, a high-energy-ratio, high-voltage energy storage capacitor, a high-performance solid-state switch assembly, and a multifunctional isolated spark source control system. The high-power-density, high-voltage DC charging power supply is a 220VAC to 10kVDC charging power supply with a power density of no less than 0.25W / cm³. The high-energy-ratio, high-voltage energy storage capacitor has a withstand voltage of 12kV, a capacitance of 200uF, and an energy storage density of no less than 0.83MJ / m³.

[0053] In step 1, the high-performance solid-state switch component adopts a composite structure of a pulse-type high-power semiconductor discharge switch and a fast recovery protection diode. Its topology is as follows: Figure 2 shown.

[0054] like Figure 2As shown, the switch component of the composite structure can ensure the effective opening of high-voltage pulses and large currents of tens of kiloamperes at the 10kV voltage level, and can also ensure the safety, reliability and stability of the main discharge circuit. Among them, the role of the protection diode 1 (protection diode A) is to withstand the reverse impact current generated by the time-varying characteristics of the load; the role of the protection diode 2 (protection diode B) is to provide a freewheeling circuit to improve energy utilization; the role of the protection diode 3 (protection diode C) and the protection resistor is to prevent the reverse energy storage of the capacitor in extreme cases from damaging the component. The load equivalent time-varying capacitance, load equivalent time-varying resistance and load equivalent time-varying inductance are the equivalent capacitance, equivalent resistance and equivalent inductance of the continuously dragged ground transducer 10.

[0055] The discharge waveform of the spark source is as follows: Figure 3 As shown, channel 1 is the voltage across the high-voltage energy storage capacitor, channel 2 is the voltage across the pulsed high-power semiconductor discharge switch, and channel 3 is the discharge current. The composite structure discharge switch assembly of this patent invention can support the safe, stable, and reliable opening of tens of thousands of amperes of pulse current at the 10 kilovolt level.

[0056] In step 1, the ground transducer 10 is continuously dragged, and its structure is as follows Figure 4 As shown, its main structure includes: a barrel body (1), a barrel cover (12), a barrel bottom (11), a discharge chamber (2), and a coupling skid (4). Among them, the barrel body (1), the barrel cover (12), and the barrel bottom (11) are all made of thick stainless steel materials, the purpose of which is to provide self-weight and prevent the transducer from jumping when the electric spark source releases energy, causing low coupling energy transmission efficiency. Among them, there are cable through holes (12a) and pressure relief water injection holes (12b) on the barrel cover (12). The cable through hole (12a) is used to pass the cable (3a) and the discharge electrode (3). The pressure relief water injection hole (12b) is used to discharge the positive pressure generated inside due to the release of electric spark energy, and can be used as a hole for injecting water medium. Before using the continuous drag ground transducer 10, a sufficient amount of water medium should be injected into the interior, and the lowest water level line is as shown in FIG. Figure 4As shown by the middle water level line. Among them, the coupling skid (4) is firmly installed at the bottom of the barrel bottom (11). According to the size of the barrel bottom (11), there can be multiple skids. The front and rear ends are both sled-shaped. Its function is to ensure the passability of the entire transducer during continuous dragging. Its function is to couple well with the ground so that the elastic wave excited by the electric spark source can be effectively transmitted to the underground. The discharge chamber (2) is designed as a metal cover with a semi-elliptical structure. A through hole (2b) is provided at the upper end. The through hole (2b) passes through a cable anti-sway through-hole tube (21). The cable anti-sway through-hole tube (21) can be adjusted in height up and down and locked by the through-hole tube locking flange. The cable locking flange at its top is used to lock the cable (3a). The discharge electrode (3) can be controlled by the two flanges to hover at any height position in the discharge chamber (2) without swinging, ensuring the focusing of the seismic wave energy at the bottom. The bottom of the discharge chamber (2) is hollow. When the electric spark source releases energy, the energy is directly transferred to the barrel bottom (11). The outer side of the bottom edge of the discharge chamber (2) is an outer flange structure, provided with a flange (2a), which is used to provide downward pressure for the discharge chamber (2) through the internal and external pressure difference generated by energy release, thereby achieving better bottom energy focusing. The discharge chamber (2) is made of a thick material to provide its own counterweight and to withstand huge impact energy.

[0057] Preferably, the barrel bottom (11) is provided with a spherical crown-shaped lower groove, which takes the lower end of the discharge electrode (3) as the center of the circle and is used to converge energy and make the energy as vertical as possible to the ground. The figure of the lower groove is omitted.

[0058] like Figure 13 As shown, the barrel cover (12) is detachably connected to the barrel body (1), and the barrel body (1) is sealed to the barrel bottom (11); an annular wave-proof plate (24) is provided on the water surface in the barrel body (1), and the wave-proof plate (24) floats on the water surface in the barrel body (1); a through hole for the cable anti-sway through-hole tube (21) is provided at the center of the wave-proof plate (24); a plurality of anti-collision blocks (25) are evenly fixedly provided on the periphery of the wave-proof plate (24); the wave-proof plate (24) and the anti-collision blocks (25) are made of elastic material, and the anti-collision blocks (25) abut against the inner wall of the barrel body (1). The wave-proof plate (24) and the anti-collision blocks (25) reduce the oscillation of the water in the barrel body (1) when the ground transducer 10 is dragged. Gaps are provided between the anti-collision blocks (25) to play a pressure relief role. At least three protrusions (26) are evenly and symmetrically arranged at the center of the wave-proof plate (24), and the protrusions (26) abut against the outer wall of the cable anti-sway through-hole tube (21) to prevent the cable anti-sway through-hole tube (21) from sliding left and right when the transducer is dragged, and the gaps between the protrusions (26) can play a role in pressure relief.

[0059] The inner hole of the through-hole tube locking flange is provided with a vertical first flange (22a), i.e., a cylindrical flange. The through-hole tube locking flange is provided with a first sliding hole through which the cable anti-sway through-hole tube (21) passes. The cable anti-sway through-hole tube (21) can be manually controlled to slide up and down in the first sliding hole. The first flange (22a) is penetrated by a first fixing screw, which is used to lock the cable anti-sway through-hole tube (21). The lower end of the first flange (22a) is welded to the top of the discharge chamber (2).

[0060] Preferably, an annular sealing ring is provided in the first sliding hole to seal the gap between the cable anti-swaying through-hole tube (21) and the first sliding hole, so that when the discharge chamber (2) moves upward during discharge, negative pressure is formed therein (not shown).

[0061] The inner hole of the cable locking flange is provided with a vertical second flange (23a), i.e., a cylindrical flange. The cable locking flange is provided with a second sliding hole through which the cable (3a) passes. The cable (3a) can be manually controlled to slide up and down in the second sliding hole. The second flange (23a) is penetrated by a second set screw, which is used to lock the cable (3a). The second set screw is a rubber screw. The lower end of the second flange (23a) is welded to the top of the cable anti-sway through-hole tube (21).

[0062] Preferably, an annular sealing ring is also provided in the second sliding hole for sealing the gap between the second sliding hole and the cable (not shown).

[0063] The lower end of the cable anti-sway through-hole tube (21) is provided with a stepped hole (21a), the inner circle of the stepped hole (21a) is slightly smaller than the outer diameter of the discharge electrode (3), and the outer circle of the stepped hole (21a) is slightly larger than the outer diameter of the discharge electrode (3). The discharge electrode (3) abuts against the stepped hole (21a) to prevent the discharge electrode (3) from moving upward and left and right when releasing electric sparks. The cable anti-sway through-hole tube (21) is provided with a cable hole through which the cable (3a) passes, that is, the inner circle of the stepped hole (21a).

[0064] The flange (2a) of the discharge chamber (2) is not connected to the barrel bottom (11), so that it can move upward, thereby forming a pressure difference at the flange (2a) to push it back downward; when the discharge chamber (2) discharges, it moves upward and the water inside and outside it is connected.

[0065] In step 1, the structure of the discharge electrode (3) is as follows Figure 5 As shown, the discharge electrode (3) adopts a coaxial planar electrode, the outer conductor (33) is stainless steel, the inner conductor (31) is a high heat-resistant copper alloy, the intermediate insulating layer (32) is made of a high-temperature-resistant, strong and tough composite insulating plastic, and an axial pressure relief hole (32a) and a radial pressure relief hole (33a) are designed to discharge local instantaneous impact pressure waves to prevent damage to the internal structure of the electrode head, thereby improving the service life of the electrode head.

[0066] The outer conductor (33) is connected to the negative electrode of the high-voltage energy storage capacitor, and the inner conductor (31) is connected to the cathode of the pulse-type high-power semiconductor discharge switch.

[0067] Step 1 involves a multifunctional isolated spark source control system, which has good high and low voltage isolation performance and electromagnetic interference isolation performance, and realizes the integration of main control. Figure 6 The specific circuit and structure diagram are omitted. The control flow chart of the electric spark source control system is as follows: Figure 7 As shown, among them, charging to the set gear / charging time limit / pressing the stop button means that when charging the high-voltage energy storage capacitor, charging to the set voltage or charging time limit is reached or the stop button is manually pressed, then charging of the high-voltage energy storage capacitor is stopped.

[0068] Its multi-functions are reflected in: manual / automatic mode; pause memory function; output of various types of synchronous trigger signals (including 3.3V / 5V / 12V level / edge trigger, and open / short circuit trigger); GPS positioning data storage function at the energy release moment; ability to set energy release gear; ability to set cyclic energy release frequency, etc.

[0069] Its isolation performance is reflected in: the low-voltage and high-voltage control circuits adopt reasonable creepage distance design and optocoupler isolation devices, and a streamlined wiring method is adopted in wiring, which can ensure that the programmable microcontroller and its peripheral control circuits are not affected by insulation breakdown and spatial electromagnetic interference in the high-voltage charging and discharging circuit environment. The specific structure diagram is omitted.

[0070] The high-voltage monitoring module detects the voltage status of each node in the main circuit to determine whether the high-voltage energy storage capacitor is charged to the specified energy level and whether there is a fault. The event storage module stores the operation log of the high-voltage circuit.

[0071] The streamlined wiring method refers to the layout design between internal modules and the wiring layout being as reasonable and streamlined as possible, so that high-voltage and high-current circuits avoid weak-current control circuits as much as possible to avoid interfering with them. Streamlined wiring will also reduce parasitic parameters on the line and reduce their impact on pulse discharge characteristics.

[0072] The simplified continuous drag detector array acquisition system in step 2 has the following structure: Figure 8 shown.

[0073] Continuous towed seismic surveys on land are difficult to perform using long strings of geophone arrays due to the long travel paths, high speeds, and changing road conditions. Furthermore, considering the impact of offset on the quality and consistency of geophone signals, this paper designs a streamlined towed geophone array to enable rapid, continuous towed seismic data acquisition. The number of geophone modules in the array structure can be adjusted to meet actual survey requirements, and can be expanded to 6 or 12.

[0074] Step 2 involves a continuous drag detector structure, such as Figure 9 shown.

[0075] The detector module structure and hoisting diagram are as follows: Figure 9 As shown, the detector body (71) is installed in a cylindrical detector housing (72) and is in close contact with the peripheral contact surface. The upper part of the detector housing (72) is provided with a detector lead-out socket (73), which is connected to the seismic wave acquisition system host through a bus cable. The lower part of the detector housing (72) is connected to a counterweight support block (74). The weight of the counterweight support block (74) ensures the close coupling between the detector module and the ground during the towing movement. The bottom of the counterweight support block (74) is distributed with a dot matrix coupling protrusion (74a), which is used to enhance the coupling effect between the detector module and the uneven road surface. The front end of the counterweight support block (74) is provided with a rod-shaped support block steel hook (75), which is connected to the rigid connecting rod through a flexible connecting cable (76). The function of the flexible connecting cable (76) is to adjust the detector module's posture adaptively according to the vehicle's moving state and the road surface state, thereby ensuring a good coupling relationship between the detector base and the ground. Whether the towing vehicle (5) is moving forward, backward or turning, on a paved road or an unpaved road, the detector module can always follow and maintain good coupling with the ground.

[0076] Considering the influence of friction noise between the detector module and the ground during towing construction, the selection of the type and parameters of the detector body (71) is also very important. The present invention adopts a 60Hz moving coil type detector, which can ensure high efficiency towing construction while meeting the requirements of high signal-to-noise ratio data acquisition when ensuring continuous towing seismic detection, greatly reducing costs. The type and parameters of the detector can also be changed according to the requirements of seismic exploration.

[0077] Step 2 involves a continuous drag seismic rapid acquisition system, the system consists of Figure 10 shown.

[0078] It contains 24 detector interfaces. Each detector is conditioned by an independent signal conditioning and amplification circuit and then input into the A / D converter. The converted digital output is uniformly imaged and processed by FPGA. It is connected to the computer through a USB controller to realize the rapid imaging and storage of real-time collected seismic wave signals, fully meeting the needs of fast and continuous seismic towing surveys.

[0079] While receiving and processing seismic data, the FPGA also records real-time information from the second GPS module. The synchronous trigger module receives the synchronous trigger signal from the spark source host. The system features three acquisition modes: single-shot, continuous, and cyclic. Two triggering methods are also designed: internal and external.

[0080] External triggering means waiting for an external signal to trigger the acquisition. Internal triggering means the acquisition is automatically triggered according to certain rules within the acquisition instrument. Internal triggering does not require an external trigger signal and directly acquires data; external triggering requires an external trigger signal.

[0081] Among them, in single trigger mode, external trigger is used, and the seismic acquisition instrument can realize single triggering when receiving the synchronous trigger signal sent by the electric spark source, realizing single trigger acquisition and storage of seismic-detection connection, which can be used for single-point acquisition in towed earthquakes; continuous acquisition mode does not require a trigger source, and can realize real-time continuous acquisition and storage when seismic-detection is not online, which can be used for continuous acquisition of active / passive sources in towed earthquakes; in cyclic trigger mode, external trigger is used, and the seismic acquisition instrument can trigger acquisition at the moment of receiving the synchronous trigger signal sent by the electric spark source, and wait for the next synchronous trigger signal sent by the source, which can realize cyclic trigger acquisition and storage of seismic-detection connection, which can be used for continuous acquisition of active sources in towed earthquakes. The trigger mode selection icon of the upper computer software interface is as follows Figure 11 shown.

[0082] The present invention employs a design that arranges six geophones in an arc centered around a spark source. These six geophones are equidistant from the spark source, receiving the same seismic wave energy. Continuous-drag seismic data has a low signal-to-noise ratio. Seismic signals generated by artificial sources are subject to interference from noise from the geophone base and ambient noise. Continuous-drag seismic raw data cannot yet identify near-surface anomalies. Therefore, research is needed on high-resolution stacking imaging methods to improve imaging resolution.

[0083] Step three involves the coherent stacking method of continuous towed seismic data, which aims to extract high-resolution seismic signals from continuous towed active and passive source data. Six gravity detectors move and collect data simultaneously, and the final profile can be composed of 6 seismic data. Assume that the time record length at a lateral resolution of 0.5m during the movement is T, and the seismic data at position x is Y(x,T). Assuming that the record length after stacking is w, the number of iterations in the single-point stacking calculation is N=T / w, and the derived calculation formula is:

[0084]

[0085] Among them, l=1,2,...,N,s=w*l,(w+1)*l,...(2w-1)*l,2*w*l. The square of the observation record Y(x,s) at point x is summed up after N iterations and normalization.

[0086] The specific advantages of the present invention are:

[0087] (1) Design the circuit topology of the high-performance solid-state switch component and the ground transducer structure of the electric spark source to achieve efficient and high-energy excitation of continuous drag seismic waves;

[0088] (2) Design a streamlined towed geophone array layout, including the structure and connection of geophone modules, to achieve continuous towed seismic wave non-destructive high-resolution acquisition;

[0089] (3) A coherent stacking method for continuous dragging seismic data is proposed to achieve high-resolution stacking of continuous dragging seismic data, obtain continuous dragging high-resolution stacking profiles, and clearly identify underground space karst caves, pipelines and other diseased bodies.

[0090] The present invention creatively proposes a circuit topology structure of a high-performance solid-state switch component of an electric spark source and a structure of a ground transducer; proposes a streamlined towed detector array arrangement structure, including the structure and connection method of the detector module; and proposes a method for coherent superposition of continuous towed seismic data to improve seismic wave excitation, acquisition efficiency and data processing accuracy.

[0091] The circuit topology of the high-performance solid-state switch assembly of the electric spark source and the structure of the ground transducer, the streamlined towed detector array arrangement structure, including the structure and connection method of the detector module, the continuous rapid seismic wave acquisition system, and the coherent superposition method of continuous towed seismic data fall within the scope of patent protection. The number of continuous towed detectors is not limited to 6 and 12 in the application patent specification, but is expanded to 24 and 48, and the design of the detectors as a linear arrangement structure also falls within the scope of patent protection.

[0092] Engineering Experiment

[0093] In June 2024, a continuous towed seismic survey experiment was conducted on a road in Chongqing. A drainage pipe existed in the test area, buried approximately 2.0 m deep. The asphalt layer was approximately 0.3 m thick, and beneath it lay a gravel layer approximately 2.0 m thick, below which lay the bedrock. Continuous towed seismic data were collected using a vehicle-mounted seismic and geophone system with six detectors. The sampling interval was 10.4 μs. Continuous towed seismic data were acquired using a spark source with continuous blasting.

[0094] like Figure 12The figure shows the stacked section after 6 data processing. The data resolution is high and the continuity of reflection phase axis is good. There are obvious diffraction features in the red frame, especially in Figure 12 The most obvious diffraction waves are in (c) and 12(d), which are determined to be caused by the drainage pipe. Combining the survey data in the area and the location of the drainage pipe outlet, the location of the drainage pipe determined based on the six superimposed sections is highly consistent with the actual pipe location.

[0095] The results of measured data collection and processing show that the invented land electric spark source continuous towing seismic survey system can achieve high-efficiency and high-precision engineering surveys in shallow layers.

[0096] The above invention content is currently mainly used in the field of shallow engineering earthquakes.

[0097] Finally, it should be noted that the above examples are only specific implementation examples of the present invention. Of course, those skilled in the art can make changes and modifications to the present invention. If these modifications and variations fall within the scope of the claims of the present invention and their equivalent technologies, they should be considered to be within the scope of protection of the present invention.

Claims

1. A land electric spark source continuous towing seismic survey system, characterized in that: The invention comprises a continuously dragged ground transducer (10), which comprises a barrel body (1), a barrel bottom (11) is provided at the bottom of the barrel body (1), a barrel cover (12) is provided at the top of the barrel body (1), a bell-shaped discharge chamber (2) is provided in the barrel body (1), a flange (2a) is provided outwardly at the bottom of the discharge chamber (2), the flange (2a) is in contact with the barrel bottom (11), a discharge electrode (3) is fixedly provided in the discharge chamber (2), and the discharge chamber (2) and the barrel cover (12) are connected to each other. The top of the barrel (12) is provided with a through hole (2b) for the cable (3a) of the discharge electrode (3) to pass through and a cable through hole (12a), and the barrel cover (12) is also provided with a pressure relief water injection hole (12b). The barrel body (1) and the discharge chamber (2) are both filled with water, the height of the water exceeding the top of the discharge chamber (2). The barrel also includes a coupling skid (4), which is fixedly mounted on the outer bottom of the barrel bottom (11); the discharge electrode (3) obtains a high-voltage electric pulse signal to generate electric sparks and excite seismic waves.

2. The land electric spark source continuous towing seismic survey system according to claim 1, characterized in that: A cable anti-sway through-hole tube (21) is passed through the through-hole (2b), and the cable (3a) passes through the cable anti-sway through-hole tube (21) to connect to the discharge electrode (3). The cable anti-sway through-hole tube (21) is installed on the top of the discharge chamber (2) through an adjustment mechanism (22). The cable anti-sway through-hole tube (21) is adjusted up and down in height through the adjustment mechanism (22) and locked on the discharge chamber (2), thereby adjusting the height of the discharge electrode (3). A cable locking mechanism (23) is provided at the top end of the cable anti-sway through-hole tube (21), and the cable locking mechanism (23) locks the cable (3a) of the discharge electrode (3).

3. The land electric spark source continuous towing seismic survey system according to claim 1, characterized in that: The discharge electrode (3) comprises an inner conductor (31), an intermediate insulating layer (32) and an outer conductor (33) which are coaxially arranged. The inner conductor (31) is fixedly sheathed with the intermediate insulating layer (32), and the intermediate insulating layer (32) is fixedly sheathed with the outer conductor (33). The discharge electrode (3) is provided with at least two symmetrical pressure relief channels, and the pressure relief channels comprise an axial pressure relief hole (32a) and a radial pressure relief hole (33a) which are interconnected. The axial pressure relief hole (32a) is axially arranged on the outer wall of the intermediate insulating layer (32), and the radial pressure relief hole (33a) is radially arranged on the outer conductor (33). The lower end of the axial pressure relief hole (32a) extends downward to penetrate the lower end of the discharge electrode (3), and the upper end of the axial pressure relief hole (32a) extends axially upward to connect with the inner end of the corresponding radial pressure relief hole (33a). The outer end of the radial pressure relief hole (33a) extends radially outward to penetrate the outer wall of the outer conductor (33). The inner conductor (31) is connected to the power supply end of the high-voltage electric pulse signal, and the outer conductor (33) is connected to the ground end of the high-voltage electric pulse signal.

4. The land electric spark source continuous towing seismic survey system according to claim 1, characterized in that: The invention also includes an electric spark source host, the electric spark source host and the continuously dragged ground transducer (10) form an electric spark source, the electric spark source host includes an electric spark source control system, the electric spark source control system is connected to a high-voltage DC charging power supply, a high-voltage energy storage capacitor and a solid-state switch component, the electric spark source control system controls the high-voltage DC charging power supply to charge the high-voltage energy storage capacitor, the high-voltage energy storage capacitor supplies power to the solid-state switch component, the solid-state switch component is connected to the discharge electrode (3) of the continuously dragged ground transducer (10), the electric spark source control system controls the switch of the solid-state switch component, and the electric spark source control system controls the solid-state switch component to provide a high-voltage electric pulse signal to the continuously dragged ground transducer (10).

5. The land electric spark source continuous towed seismic survey system according to claim 4, characterized in that: The high-voltage DC charging power supply is a 220VAC to 10kVDC charging power supply with a power density of not less than 0.25W / cm3; the high-voltage energy storage capacitor has a withstand voltage of 12kV, a capacitance value of 200uF, and an energy storage density of not less than 0.83MJ / m3.

6. The land electric spark source continuous towing seismic survey system according to claim 4, characterized in that: The solid-state switch assembly comprises a pulse-type high-power semiconductor discharge switch, wherein the positive electrode of the pulse-type high-power semiconductor discharge switch is connected to one end of a high-voltage energy storage capacitor, the negative electrode of the pulse-type high-power semiconductor discharge switch is connected to the power supply end of a discharge electrode (3) of a continuously dragged ground transducer (10), the ground end of the discharge electrode (3) of the continuously dragged ground transducer (10) is connected to the other end of the high-voltage energy storage capacitor, the other end of the high-voltage energy storage capacitor is grounded, and the electric spark source control system is connected to the control end of the pulse-type high-power semiconductor discharge switch to control its switching; The device also includes a protection diode A, a protection diode B, a protection diode C, and a protection resistor. The cathode of the protection diode A is connected to the anode of a pulse-type high-power semiconductor discharge switch. The anode of the protection diode A is connected to the cathode of the pulse-type high-power semiconductor discharge switch. The cathode of the protection diode B is connected to the cathode of the pulse-type high-power semiconductor discharge switch. The anode of the protection diode B is connected to the ground end of the discharge electrode (3) of the continuous drag ground transducer (10). The cathode of the protection diode C is connected to one end of a high-voltage energy storage capacitor via the protection resistor. The anode of the protection diode C is connected to the other end of the high-voltage energy storage capacitor.

7. The land electric spark source continuous towed seismic survey system according to claim 4, characterized in that: The electric spark source control system includes a programmable microcontroller, which is connected to a master controller input module, an energy setting gear module, a high-voltage charging power peripheral control unit, a charge and discharge process management peripheral control unit, a solid-state discharge switch component peripheral control circuit and a synchronous trigger signal generating unit, wherein the charge and discharge process management peripheral control unit is also connected to the high-voltage charging power peripheral control unit, the solid-state discharge switch component peripheral control circuit, a first GPS module, a high-voltage monitoring module and an event storage module; the master controller input module is used to input control instructions to the programmable microcontroller, the energy setting gear module is used to input energy gear parameters to the programmable microcontroller, and the programmable microcontroller is connected to the high-voltage charging power peripheral control unit to control it to be a high-voltage storage The energy storage capacitor is charged, and the programmable microcontroller also controls the operation of the high-voltage charging power peripheral control unit through the charge and discharge process management peripheral control unit. The charge and discharge process management peripheral control unit supplies power to the solid-state switch component through the solid-state discharge switch component peripheral control circuit. The programmable microcontroller also controls the switch of the solid-state switch component through the solid-state discharge switch component peripheral control circuit. The first GPS module provides GPS data to the programmable microcontroller. The high-voltage monitoring module is used to detect whether the high-voltage energy storage capacitor is charged to the specified energy level and whether there is a fault; the event storage module is used to store the operation log of the high-voltage circuit; the programmable microcontroller sends a seismic synchronization trigger signal to the synchronization trigger module of the continuous towed detector array acquisition system through the synchronization trigger signal generating unit.

8. The land electric spark source continuous towing seismic survey system according to any one of claims 1 to 7, characterized in that: The invention also includes a towing vehicle (5), wherein a semi-trailer (6) is connected to the front and / or rear of the towing vehicle (5), and the semi-trailer (6) includes a frame (61), one end of the frame (61) is connected to the body of the towing vehicle (5), and the other end of the frame (61) is provided with a wheel (62). The semi-trailer (6) is driven by the towing vehicle (5) to move continuously, and a continuously towed ground transducer (10) is fixedly arranged on the frame (61). A detector array (7) of a continuously towed detector array acquisition system is also provided on the frame (61). The detector array (7) is arranged in an arc shape around the continuously towed ground transducer (10) and is fixed on the frame (61). The distance between each detector of the detector array (7) and the continuously towed ground transducer (10) is equal. Each detector of the detector array (7) is provided with a detector body (71), which is installed in a detector housing (72) and is in close contact with the detector housing (72); a lead-out socket (73) is provided on the upper part of the detector housing (72), and the lead-out socket (73) is connected to a host of a continuous dragging detector array acquisition system through a bus cable; the lower part of the detector housing (72) is connected to a counterweight support block (74), and the counterweight support block (74) is closely coupled with the ground during the dragging movement; a dot matrix coupling protrusion (74a) is distributed on the bottom of the counterweight support block (74), and a support block steel hook (75) is provided at the front end of the counterweight support block (74), and the support block steel hook (75) is connected to the vehicle frame (61) through a flexible connecting cable (76); the detector body (71) adopts a 60Hz moving coil detector.

9. The land electric spark source continuous towing seismic survey system according to claim 8, characterized in that: The mainframe of the continuous dragged geophone array acquisition system includes at least two geophone interfaces. The geophones are connected to corresponding signal conditioning and amplification circuits via the corresponding geophone interfaces. Each geophone undergoes signal conditioning through an independent signal conditioning and amplification circuit before inputting into an A / D converter. The converted output digital quantity is uniformly imaged and processed by an FPGA. The FPGA is connected to a computer via a USB controller, and the computer implements rapid imaging and storage of the real-time collected seismic wave signals. FPGA is connected to the second GPS module and the synchronous trigger module. FPGA will record the real-time information of the second GPS module while receiving and processing seismic data. The synchronous trigger module is used to receive the synchronous trigger signal sent by the spark source host. The continuous drag detector array acquisition system is designed with three acquisition modes: single trigger mode, continuous acquisition mode and cyclic trigger mode. Two trigger modes are designed: internal trigger and external trigger. Among them, the external trigger is used in the single trigger mode. The continuous drag detector array acquisition system realizes single trigger mode after receiving the synchronous trigger signal sent by the spark source. The system can be triggered once to realize single-shot trigger acquisition and storage in seismic-detection connection, which is used for single-point acquisition in towed earthquakes. The continuous acquisition mode does not require a trigger source, which realizes real-time continuous acquisition and storage when the seismic-detection is not connected, which is used for continuous acquisition of active / passive sources in towed earthquakes. The cyclic trigger mode uses an external trigger. The continuous towed geophone array acquisition system triggers acquisition at the moment it receives the synchronous trigger signal from the electric spark source, and remains powered on waiting for the next synchronous trigger signal from the electric spark source, realizing cyclic trigger acquisition and storage in seismic-detection connection, which is used for continuous acquisition of active sources in towed earthquakes.

10. A data imaging method comprising the land electric spark source continuous towed seismic survey system according to any one of claims 1 to 9, characterized in that: The data imaging method is a coherent stacking method of continuous towed seismic data. The land electric spark source continuous towed seismic survey system is equipped with M detectors, M greater than or equal to 2. The M detectors move and collect data simultaneously, and the final profile can form M channels of seismic data. The time record length at a lateral resolution of 0.5m during the movement is set to T, and the seismic data at position x is Y(x, T). The record length after stacking is set to w, and the number of iterations in the single-point stacking calculation is N = T / w. The derived calculation formula is: Where, l = 1, 2, ..., N, s = w × l, (w + 1) × l, ... (2w - 1) × l, 2 × w × l, The square of the observation record Y(x,s) at point x is summed up after N iterations and normalization.

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