A Design Method and System for an Earthquake Geoelectric Field Observation Device

Abstract

The present invention discloses a design method and system for an earthquake geomagnetic field observation device, which relates to the technical field of earthquake monitoring. Firstly, through a scientific electrode arrangement method and the calculation of natural potential difference, it can effectively monitor and describe the electric field changes before and after an earthquake, providing accurate and reliable data support. Secondly, the use of an eight-direction layout in the shape of a "rice character" and a multi-electrode connection form enhances the flexibility and adaptability of the observation system, thus meeting the requirements of different terrains and environments. At the same time, the measurement line azimuth selection and electrode stability judgment mechanisms added in the design further improve the reliability and accuracy of the data. In addition, the present invention facilitates the maintenance and upgrade of the system, can provide good monitoring effects in practical applications, and provides effective technical support for earthquake research and monitoring and prediction.

Description

Technical Field

[0001] The present invention relates to the technical field of seismic monitoring, and more specifically, to a design method and system for a seismic geoelectric field observation device. Background Art

[0002] At present, the geoelectric field network is established for the purpose of seismic precursor monitoring and earthquake prediction. Geoelectric field observation has been widely used at home and abroad in the monitoring of disaster events such as earthquakes and volcanoes and geological exploration. There are anomalies in a certain area before disaster events such as earthquakes and volcanoes, which has important practical significance for the monitoring and prediction of such disaster events. However, seismic electromagnetic precursor phenomena are often superimposed on the normal background of the earth's electromagnetic environment and are difficult to distinguish. Therefore, understanding a reasonable electrode layout method for the observation device is the premise for distinguishing seismic geoelectric field interference signals and precursor anomalies.

[0003] At present, the electrode layout methods of most geoelectric field observation devices in operation are as follows: on the ground, two orthogonal directions NS and EW and one oblique direction are horizontally arranged, and two measuring channels with long and short pole distances are arranged in each direction ("triangle" electrode layout method); a small number are horizontally arranged in two orthogonal directions NS and EW, and three measuring channels with long, medium, and short pole distances are arranged in each direction ("L-shaped" electrode layout method). The advantage of these two electrode layout methods is that the long and short pole distance layout can be used to mutually verify the observation data in the same geoelectric field observation device. However, the current electrode layout method only measures the horizontal components of the geoelectric field in the north-south and east-west directions by arranging electrodes in one quadrant, and cannot comprehensively describe the vector geoelectric field change information in the four quadrants.

[0004] The observation principle of the geoelectric field is to bury 2 electrodes A and B in a specified direction according to a certain electrode pole distance to form an observation device, measure the potential difference V between the two electrodes A and B under this device, and divide by the pole distance to obtain the geoelectric field. Generally, in a certain quadrant, the long and short pole distances are arranged in three directions in a triangular manner. Although this method can compare the observation results of the long and short pole distances, in fact, the geoelectric field observation includes a natural electric field component and a telluric electric field component. Among them, the natural electric field is uneven, and the telluric electric field has a wide area and is uniform in the short term and has the characteristics of an electric field vector. According to the electromagnetic field theory, the potential at a certain point is measured relative to a certain reference point. Under the current observation principle, each direction is independent, and there is no unified reference point between each measuring channel. Therefore, it is not accurate to use it to characterize the vector information of the geoelectric field.

[0005] On the other hand, most of the current geoelectric field observation network uses Pb-Pbcl2 solid non-polarized electrodes buried about 3 meters underground. Solid non-polarized electrodes have a small polarization potential and are the best choice for geoelectric field observation electrodes, but their long-term stability has certain limitations. In addition, the long electrode leads are connected to the external observation lines, which will increase the possibility of instability of the observation device system during thunderstorms. Although in the current device layout, each measurement channel shares an electrode, and the direction of the problematic electrode or line can be determined, it is impossible to accurately determine which electrode is faulty or which line has a problem, nor can it accurately determine the specific location of the interference source.

[0006] Therefore, how to design an observation device that can obtain all-round description of geoelectric field observation information is an urgent problem that technicians in this field need to solve. Summary of the invention

[0007] In view of this, the present invention provides a multi-directional, multi-pole-pole arrangement method in the shape of a cross, in which multiple electrodes are arranged in the entire space, and potential reference points are selected to conduct multi-directional observations to obtain more reliable and comprehensive observation information, effectively solve the problem of geoelectric field vector characterization and the problem of long-term stability of the observation device and interference source judgment, and provide a judgment basis for the extraction of abnormal geoelectric field signals and the investigation of interference before disaster events such as earthquakes.

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

[0009] A design method for an earthquake geoelectric field observation device, comprising:

[0010] Set the pole arrangement of the geoelectric field observation device, select the center point, and determine the end point position based on the pole distance between the two electrodes;

[0011] Determine the buried method of the electrodes of the geoelectric field observation device according to the positions and pole distances of all endpoints;

[0012] Observe the natural potential difference between the two electrodes of each measuring line and describe the changes of the natural electric field based on the natural potential difference;

[0013] The change value of the natural potential difference between two points is obtained based on the natural potential difference and the potential value at zero o'clock every day;

[0014] The expression of the earth's electric field is obtained by dividing the change in the natural potential difference by the pole distance between the electrodes at the end points of the coaxial line.

[0015] Optionally, the arrangement of the geoelectric field observation device is specifically as follows:

[0016] It is laid out in 8 directions in a cross shape, with O as the center point and designed with equal pole spacing in the 8 directions.

[0017] Optionally, the method for burying the electrodes of the deterministic geoelectric field observation device specifically includes:

[0018] A total of 9 endpoints including the center point and the observation points are respectively buried with 3 electrodes. The electrode pits are set as squares with a side length of 1 meter or circles with a diameter of 1 meter. The 3 electrodes are respectively arranged at 3 corners within a range of 1 meter. The 8 observation points are respectively connected to the 3 electrodes of the center point.

[0019] Optionally, it further includes that the measurement line adopts a three-core armored cable.

[0020] Optionally, it further includes that there are three parallel measuring lines in each of the 8 directions. By judging whether the results of the measuring lines in the three directions are consistent, the accuracy of the observed data and the stability of the electrodes are judged.

[0021] Optionally, it further includes V in the east-west direction A11 、V A21 . Subtract the value V at 0:00 every day from the spontaneous potential difference of the 8 endpoints O to obtain ΔV A11O 、ΔV A21O . Finally, for each, the obtained ΔV A12 =ΔV A11O -ΔV A21O . The result is the changing part of the spontaneous potential difference, and then dividing it by the east-west pole distance is the expression of the earth electric field ΔE.

[0022] A seismic geoelectric field observation device design system includes:

[0023] A pole arrangement method determination module, which sets the pole arrangement method of the geoelectric field observation device, selects the center point, and determines the endpoint positions according to the pole distance between two electrodes;

[0024] A burying method determination module, which determines the burying method of the electrodes of the geoelectric field observation device according to the positions and pole distances of all endpoints;

[0025] A natural electric field description module, which observes the spontaneous potential difference between two electrodes of each measuring line and describes the change of the natural electric field based on the spontaneous potential difference;

[0026] A spontaneous potential difference change value calculation module, which obtains the spontaneous potential difference change value between two points based on the spontaneous potential difference and the potential value at 0:00 every day;

[0027] An earth electric field expression module, which obtains the expression of the earth electric field by dividing the spontaneous potential difference change value by the pole distance between the coaxial line endpoint electrodes.

[0028] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a design method and system for a seismic geoelectric field observation device. First, through a scientific electrode layout method and the calculation of natural potential difference, it can effectively monitor and describe the electric field changes before and after an earthquake, providing accurate and reliable data support. Second, the adoption of an eight-direction layout in a cross shape and a multi-electrode connection form enhances the flexibility and adaptability of the observation system, thus meeting the requirements of different terrains and environments. At the same time, the measurement line selection and electrode stability judgment mechanisms added in the design further improve the reliability and accuracy of the data. In addition, the present invention is convenient for system maintenance and upgrade, can provide good monitoring effects in practical applications, and provides effective technical guarantees for earthquake research and early warning. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0030] Figure 1 It is the flowchart of the method provided by the present invention;

[0031] Figure 2 It is the design schematic diagram of the geoelectric field observation device provided by the present invention;

[0032] Figure 3 It is the electrode layout schematic diagram of the GT new geoelectric field observation device provided by the present invention;

[0033] Figure 4 It is the system wiring schematic diagram of the Gaotai Dazhuang new geoelectric field observation device provided by the present invention;

[0034] Figure 5 It is the design and construction schematic diagram of the buried wire groove provided by the present invention;

[0035] Figure 6 It is the electrode burial construction schematic diagram provided by the present invention;

[0036] Figure 7 It is the electrode pit construction schematic diagram provided by the present invention;

[0037] Figure 8 It is the dynamic schematic diagram of the change of the omnidirectional natural electric field provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] An embodiment of the present invention discloses a design method for a seismic geoelectric field observation device, as Figure 1 shown, including:

[0040] Set the electrode layout method of the geoelectric field observation device, select the center point, and determine the end point positions according to the pole distance between two electrodes;

[0041] Determine the burial method of the electrodes of the geoelectric field observation device according to the positions and pole distances of all end points;

[0042] Observe the natural potential difference between the two electrodes of each survey line, and describe the change of the natural electric field based on the natural potential difference;

[0043] Obtain the change value of the natural potential difference between two points based on the natural potential difference and the potential value at the zero point of each day;

[0044] According to the change value of the natural potential difference divided by the pole distance between the end electrodes of the coaxial line, obtain the expression of the earth electric field.

[0045] In a specific embodiment, setting the electrode layout method of the geoelectric field observation device is specifically:

[0046] Adopt a cross-shaped layout with 8 directions for layout (as Figure 2 ), with O as the center point, and design with equal pole distances in 8 directions. Take the center point O as the potential reference point V O , and observe the 8 end points relative to the center point to obtain V OA11 , V OA21 . It can be known from the electromagnetic field theory that the electric field itself has directionality. When the distance between two points is infinitesimal, it is obtained from the gradient of the potential. The potential differences obtained in 8 directions can completely measure the potential distribution of the entire survey area, and are used to describe the natural electric field changes in all directions within the four quadrants. This is more meaningful than the method of obtaining the average electric field intensity in a certain direction by a triangle.

[0047] In a specific embodiment, determining the burial method of the electrodes of the geoelectric field observation device specifically includes:

[0048] As Figure 2As shown in the figure, 3 electrodes are respectively buried at 9 endpoints including the center point and the end points. The electrode pits are squares with a side length of 1 meter or circles with a diameter of 1 meter. The 3 electrodes are respectively arranged at 3 corners within a range of 1 meter. The measurement line uses a three-core armored cable, and 8 endpoints are respectively connected to the 3 electrodes at the center point. There are three parallel measurement channels in each of the 8 directions. From the perspective of the measurement principle, the measurement results in the three directions should be consistent, which can conveniently judge the accuracy of the observed data and the stability of the electrodes, and can also more quickly and accurately judge the azimuth of external interference sources in the site.

[0049] Vector expression method of seismic geoelectric field observation

[0050] Taking Figure 2 the east-west direction as an example, the expression methods of natural electric field and telluric electric field are described as follows:

[0051] Within a certain time domain, the distribution of the natural potential difference measured by the above 8 endpoints except the center point relative to the center point O can describe the change of the natural electric field. It can also use the time axis as the Z axis to describe the dynamic change of the omnidirectional natural electric field in the whole space. Taking the east-west direction V A11 and V A21 as examples, subtract the value V O at 0:00 every day from the natural potential differences of the 8 endpoints to obtain ΔV A11O and ΔV A21O . Finally, for each, the obtained ΔV A12 =ΔV A11O -ΔV A21O is the changing part of the natural potential difference, and dividing it by the east-west pole distance is the expression method of the telluric electric field ΔE. This expression method overcomes the situation where the natural electric field and the telluric electric field cannot be separated, providing another idea for extracting geoelectric field anomalies.

[0052] The following introduces an embodiment for specific illustration.

[0053] The pole arrangement is set up in a 360-degree omnidirectional manner, which overcomes the defect of only arranging poles in one quadrant. A reference electrode is set at the center point, which can not only describe the vector information of the geoelectric field omni-directionally, but also more conveniently and accurately separate the components of the natural electric field and the telluric electric field; electrodes are arranged in 4 quadrants at the same time, and when there are interference situations in the observation site, the azimuth and position of the interference source can be accurately judged; 3 electrodes are arranged at each endpoint, which can also conveniently judge whether the electrodes are faulty, eliminate interference in time, and obtain accurate observed data.

[0054] Implementation plan: Taking the GT observation site in Gansu as an example, the design method of this observation device is implemented.

[0055] 1. Site selection

[0056] The GT observation site is a wasteland forestland with a flat terrain, meeting the requirements of the observation site. Therefore, an area with a flat terrain and convenient construction within a range of 50m * 50m south of the Gaotai Dazhuang geoelectricity observation station is selected to realize the construction of this new geoelectric field observation device system.

[0057] Combined with the terrain of the survey area and construction requirements, the "meter" - shaped electrode layout method is adopted. The designed long pole distance for geoelectric field observation is 100m, and the short pole distance is 50m. The external line adopts the "fully buried" method.

[0058] The longitude and latitude of the pole pits selected through satellite maps are statistically shown in Table 1 after on - site GPS verification with a handheld device. The actual electrode layout diagram is as Figure 3 shown.

[0059] Table 1 Coordinates of electrode pit positions

[0060] Pit Latitude (North) Longitude (East) O 99.84147012° 39.32213309° N 99.84146476° 39.32258750° S 99.84147012° 39.32168697° E 99.84204143° 39.32213309° W 99.84088272° 39.32212894° NE 99.84188050° 39.32245263° NW 99.84104902° 39.32244848° SE 99.84188586° 39.32181354° SW 99.84106779° 39.32180109°

[0061] Considering the error range of the handheld GPS and the short electrode layout distance, after the pole pit O is selected in actual construction, the positions of other pole pits will be mainly determined by using a compass to measure the direction and distance, with GPS for auxiliary positioning.

[0062] 2. Construction of external lines

[0063] (1) Cable laying

[0064] The external line cable selects a three - core insulated cable suitable for underground burial.

[0065] The wiring and the excavation method of the cable trench are carried out according to Figure 4 the construction. The length of the cable used is 1043m, and the length of the cable trench is 384m. Three cable trenches are excavated and converge near the NE pole pit. A total cable trench is excavated at the NE pole pit position to the observation room. All lines converge near the NE pole pit and then are introduced into the observation room through the total cable trench. The wiring diagram is shown in Figure 4 , and the used length of the cable is shown in Table 2.

[0066] During the construction process, according to the theoretical design, the cable trench is excavated, and manual cable laying is adopted. During the cable laying process, the head and tail lengths of the cable are recorded to calculate the actual wiring length.

[0067] Table 2 Table of used lengths of external lines of the new geoelectric field

[0068]

[0069]

[0070] (2) Cable marking and burial

[0071] To prevent the wire ends from getting chaotic after the external lines are buried, marks need to be made in advance at the cable connection terminals. Use 3 marks, paste them on the connection terminals and wrap them with transparent tape. The specific marking method is shown in Table 3. For the specific connection of each 3-core cable to electrodes with different burial depths, it is uniformly determined according to the color of the wire core outer skin after the actual cables arrive. For example: for the red, blue, and green wire cores, the electrode with the red wire core is buried at a depth of 3 meters, the electrode with the blue wire core is buried at a depth of 2 meters, and the electrode with the green wire core is buried at a depth of 1 meter. Such a method defines the specific electrode numbers.

[0072] Table 3 External Line Marking Table

[0073] Electrode Pit Cable Length (m) Content 1 Content 2 Content 3 N 66 N North N North S 166 S South S South E 60 E East E East W 171 W West W West NE 59 NE Northeast NE Northeast NW 133 NW Northwest NW Northwest SE 127 SE Southeast SE Southeast SW 155 SW Southwest SW Southwest O 106 O Center O Center

[0074] Since the external lines are buried underground, considering the local frozen soil depth in the survey area reaches 40 cm - 50 cm, the designed buried cable trench is 80 cm deep and 40 cm wide. After the cable is placed at the bottom of the buried cable trench, the original soil is backfilled and compacted along the line, and then mechanical backfilling of soil is carried out to reduce the damage to the cable during mechanical backfilling. The schematic diagram of the designed construction of the buried cable trench is as Figure 5 shown, and then the excavation of the buried cable trench is carried out.

[0075] (III) Connection and Burial of Non-Polarizable Electrodes

[0076] The connection method of the leads and extension wires of non-polarizable electrodes follows the wiring method provided by the LGB-3 type solid non-polarizable electrode. The specific construction steps are as follows: solder the joints, and use 2 layers of waterproof tape, 2 layers of insulating tape, and 2 layers of waterproof tape to lengthen layer by layer from the inside to the outside, and tightly wrap them for treatment. Additionally, fill the pvc sleeve with structural adhesive to protect the joints from being damaged during backfilling.

[0077] Each electrode pit is designed to bury 3 electrodes. Considering that there are gravels in the soil of the survey area, to ensure good contact between the non-polarizable electrodes and the soil, during construction, 40 cm thick fine original soil needs to be backfilled to completely cover the contact surface between the non-polarizable electrodes and the soil, and then the soil is backfilled and compacted. The designed depth of the electrode pit is 250 cm. When burying the electrodes, place the electrode welded to the red wire core of the cable at the middle position on the north side of the electrode pit, place the electrode welded to the green wire core of the cable at the southeast position of the electrode pit, and place the electrode welded to the blue wire core of the cable at the southwest position of the electrode pit. All non-polarizable electrodes do not lean against the electrode pit wall. During the burial process, first manually backfill the sieved fine original soil until the non-polarizable electrodes are completely buried, and then use mechanical backfilling. The schematic diagram of the electrode burial construction is as Figure 6 shown, and then manual backfilling is carried out.

[0078] (IV) Excavation of Electrode Pits

[0079] The electrode pits are all excavated into square pits with side lengths of 200 cm * 200 cm * 2500 cm at the designed points to bury the electrodes. All electrode pit excavations are in the due north-south direction for convenience in reference when arranging the electrodes. The schematic diagram of the electrode pit construction is asFigure 7 As shown, excavation of the electrode pits is carried out.

[0080] VI. Construction of the external line introduced into the observation room

[0081] During the construction process, the buried cable trench is excavated down to the wall of the observation room. After all the buried cables are installed with sleeves, they are led into the observation room and fixed properly before being introduced into the observation room.

[0082] VII. Indoor lines

[0083] After the external line is introduced into the observation room, the line is sorted out and linked to the connector, and then connected to the observation instrument according to the relevant technical requirements. The instrument is powered by a UPS, and the lightning protection grounding is connected to the common grounding network.

[0084] VIII. Instrument connection

[0085] After the line enters the observation room, it is connected to the instrument in the order of the line identification, and then continuous observation can be carried out to obtain data for analysis.

[0086] Based on the data obtained from continuous observation, as Figure 8 shown, the variation dynamics of the omnidirectional natural electric field are described in the full space.

[0087] A design system for a seismic geo - electric field observation device includes:

[0088] A pole - layout determination module, which sets the pole - layout of the geo - electric field observation device, selects the center point, and determines the end - point positions according to the pole distance between two electrodes;

[0089] A burial - method determination module, which determines the burial method of the electrodes of the geo - electric field observation device according to the positions and pole distances of all the end - points;

[0090] A natural - electric - field description module, which observes the natural potential difference between two electrodes of each survey line and describes the variation of the natural electric field based on the natural potential difference;

[0091] A natural - potential - difference variation - value calculation module, which obtains the natural - potential - difference variation value between two points based on the natural potential difference and the potential value at the zero - point of each day;

[0092] A telluric - electric - field expression module, which obtains the expression of the telluric electric field by dividing the natural - potential - difference variation value by the pole distance between the end - point electrodes of the coaxial line.

[0093] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and reference can be made to the description in the method part for relevant parts.

[0094] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for designing an earthquake geoelectric field observation device, characterized in that: include: Set the pole arrangement of the geoelectric field observation device, select the center point, and determine the end point position based on the pole distance between the two electrodes; Determine the buried method of the electrodes of the geoelectric field observation device according to the positions and pole distances of all endpoints; Observe the natural potential difference between the two electrodes of each measuring line and describe the changes of the natural electric field based on the natural potential difference; The change value of the natural potential difference between two points is obtained based on the natural potential difference and the potential value at zero o'clock every day; The expression of the earth's electric field is obtained by dividing the change of the natural potential difference by the distance between the electrodes at the end points of the coaxial line. The specific arrangement of the geoelectric field observation device is as follows: The electrodes are laid out in 8 directions in a cross shape, with O as the center point, and are designed with equal pole spacing in 8 directions; the buried method of the electrodes of the geoelectric field observation device specifically includes: Three electrodes are buried at each of the nine endpoints, the center point and the observation point. The electrode pit is set as a square with a side length of 1 meter or a circle with a diameter of 1 meter. The three electrodes are arranged at three corners within a range of 1 meter. The eight observation points are connected to the three electrodes at the center point respectively.

2. A method for designing an earthquake geoelectric field observation device according to claim 1, characterized in that: It also includes the use of three-core armored cable for the measuring line.

3. A method for designing an earthquake geoelectric field observation device according to claim 1, characterized in that: It also includes eight directions with three parallel measuring lines in each direction. By judging whether the measuring line results in the three directions are consistent, the accuracy of the observation data and the stability of the electrode can be judged.

4. The method for designing an earthquake geoelectric field observation device according to claim 1, characterized in that: Also includes V in the east-west direction A11 、V A21 , use the natural potential difference of the 8 endpoints minus the value V at 0 o'clock every day O Get ΔV A11O , ΔV A21O , each finally obtains ΔV A12 =ΔV A11O -ΔV A21O The result is the change in the natural potential difference, which is divided by the east-west pole distance to express the earth's electric field ΔE.

5. A seismic geoelectric field observation device design system, characterized in that: A method for designing an earthquake geoelectric field observation device according to any one of claims 1 to 4, comprising: The module for determining the pole arrangement mode sets the pole arrangement mode of the geoelectric field observation device, selects the center point, and determines the end point position according to the pole distance between the two electrodes; The embedding mode determination module determines the embedding mode of the electrodes of the geoelectric field observation device according to the positions and pole distances of all endpoints; The natural electric field description module observes the natural potential difference between the two electrodes of each measuring line and describes the changes of the natural electric field based on the natural potential difference; A natural potential difference change value calculation module, which obtains the natural potential difference change value between two points based on the natural potential difference and the potential value at zero o'clock every day; The earth electric field expression module obtains the expression of the earth electric field by dividing the change value of the natural potential difference by the pole distance between the electrodes at the end points of the coaxial line.

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