Seismic geoelectric field observation device design method and system

Abstract

The invention discloses a design method and system of an earthquake geoelectric field observation device, and relates to the technical field of earthquake monitoring, firstly, through a scientific pole arrangement mode and calculation of natural potential difference, electric field changes before and after an earthquake can be effectively monitored and described, and accurate and reliable data support is provided. And secondly, the layout in eight directions shaped like the Chinese character'mi 'and a multi-electrode connection form are adopted, so that the flexibility and adaptability of the observation system are enhanced, and the requirements of different terrains and environments are met. And meanwhile, a measuring line orientation selection and electrode stability judgment mechanism is added in the design, so that the reliability and the precision of data are further improved. Besides, the system is convenient to maintain and upgrade, a good monitoring effect can be provided in practical application, and an effective technical guarantee is provided for seismic research and monitoring forecast.

Description

Technical Field

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

[0002] At present, the geoelectric field network is established for the purpose of earthquake precursor monitoring and earthquake prediction. Geoelectric field observation has been widely used in the monitoring of earthquakes, volcanoes and other disaster events and geological exploration at home and abroad. There are anomalies in the geoelectric field 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, earthquake electromagnetic precursor phenomena are often superimposed on the normal earth's electromagnetic environment background and are difficult to distinguish. Therefore, understanding the reasonable pole arrangement of observation devices is the prerequisite for distinguishing earthquake geoelectric field interference signals and precursor anomalies.

[0003] At present, most of the geoelectric field observation devices in operation online are arranged in the following ways: two orthogonal directions NS and EW and one oblique direction are arranged horizontally on the ground, and two measuring tracks with long and short pole distances are arranged in each direction ("triangle" pole arrangement); a small number of pole arrangements are arranged horizontally in two orthogonal directions NS and EW, and three measuring tracks with long, medium and short pole distances are arranged in each direction ("L-shaped" pole arrangement). The advantages of these two pole arrangement methods are that the long and short pole distance arrangements can verify the observation data in the same geoelectric field observation device. However, the current pole arrangement method only measures the horizontal components of the geoelectric field in the north-south and east-west directions in one quadrant, and cannot fully describe the vector geoelectric field change information in the four quadrants.

[0004] The principle of geoelectric field observation is to bury two electrodes A and B in a specified direction according to a certain electrode spacing to form an observation device, measure the potential difference V between the two electrodes A and B under the device, and divide it by the spacing to obtain the geoelectric field. Generally, in a quadrant, long and short pole spacings are arranged in three directions in a triangular manner. Although this method can compare the observation results of long and short pole spacing, in fact, the geoelectric field observation includes natural electric field components and earth electric field components. The natural electric field is not uniform, and the earth electric field is wide-area, uniform in the short term, and has electric field vector characteristics. According to the electromagnetic field theory, it can be concluded that the potential at a certain point is measured relative to a reference point. Under the current observation principle, each direction is independent, and there is no unified reference point between the various measurement channels. 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 burial 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 of determining the burying method of the electrodes of the geoelectric field observation device specifically includes:

[0018] 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.

[0019] Optionally, the measuring line may be a three-core armored cable.

[0020] Optionally, there are three parallel measuring lines in each of the eight directions, and the accuracy of the observed data and the stability of the electrode can be determined by judging whether the measuring line results in the three directions are consistent.

[0021] Optionally, also include 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.

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

[0023] 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;

[0024] 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;

[0025] 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;

[0026] 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;

[0027] 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.

[0028] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a design method and system for an earthquake geoelectric field observation device. First, through the scientific pole arrangement method and the calculation of the natural potential difference, it can effectively monitor and describe the changes in the electric field before and after the earthquake, and provide accurate and reliable data support. Secondly, the layout of the eight directions of the cross shape and the multi-electrode connection form are adopted to enhance the flexibility and adaptability of the observation system, so as to adapt to the needs of different terrains and environments. At the same time, the measurement line selection and electrode stability judgment mechanism added to the design further improve the reliability and accuracy of the data. In addition, the present invention facilitates the maintenance and upgrading of the system, 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 embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0030] Figure 1 A flow chart of the method provided by the present invention;

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

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

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

[0034] Figure 5 A schematic diagram of the design and construction of the buried cable trough provided by the present invention;

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

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

[0037] Figure 8 A dynamic schematic diagram of the changes in the omnidirectional natural electric field provided by the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The embodiment of the present invention discloses a method for designing a seismic geoelectric field observation device. Figure 1 As shown, including:

[0040] 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;

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

[0042] 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;

[0043] 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;

[0044] 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.

[0045] In a specific embodiment, the arrangement of the geoelectric field observation device is specifically as follows:

[0046] Use the M-shaped layout in 8 directions (such as Figure 2 ), with O as the center point, the design is performed with equal pole spacing in 8 directions. The center point O is used as the potential reference point V O , the 8 endpoints are observed relative to the center point to obtain V OA11 、V OA21 From the electromagnetic field theory, we know that the electric field itself has directionality. When the distance between two points is infinitely small, it is obtained by the gradient of the potential. The potential difference obtained in 8 directions can fully measure the potential distribution of the entire measurement area and be used to describe the omnidirectional natural electric field changes in the four quadrants. This is more meaningful than the method of obtaining the average electric field strength in a certain direction from a triangle.

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

[0048] like Figure 2As shown in the figure, 3 electrodes are buried at the center point and the end points, and 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 3 electrodes are arranged at 3 corners within a range of 1 meter. The measurement line uses a three-core armored cable, and the 8 end points are connected to the 3 electrodes at the center point. There are three parallel measurement channels in each of the 8 directions. From the measurement principle, the measurement results of the three directions should be consistent, which can easily judge the accuracy of the observation data and the stability of the electrode, and can also more quickly and accurately judge the location of the external interference source of the site.

[0049] Vector Expression of Earthquake Geoelectric Field Observation

[0050] by Figure 2 Taking the east-west direction as an example, the expressions for describing the natural electric field and the earth's electric field are:

[0051] In a certain time domain, the distribution of the natural potential difference measured by the eight endpoints other than the center point relative to the center point O can describe the change of the natural electric field. The time axis can also be used as the Z axis to describe the dynamic change of the omnidirectional natural electric field in the whole space. A11 、V A21 For example, the natural potential difference of the eight endpoints is subtracted from 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 then divided by the east-west pole distance to express the earth's electric field ΔE. This expression overcomes the situation where the natural electric field and the earth's electric field cannot be separated, and provides another way to extract the earth's electric field anomaly.

[0052] An embodiment is introduced below for specific description.

[0053] The 360-degree all-round electrode arrangement overcomes the defect of only arranging electrodes in one quadrant. Setting the reference electrode at the center point can not only describe the vector information of the geoelectric field in all directions, but also can conveniently quasi-separate the natural electric field and the earth's electric field components. Electrodes are arranged in four quadrants at the same time, but when interference occurs in the observation site, the direction and position of the interference source can be accurately determined. Three electrodes are arranged at each endpoint, which can also easily determine whether the electrode is faulty, eliminate interference in time, and obtain accurate observation data.

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

[0055] 1. Site selection

[0056] The GT observation site is a wasteland forest with flat terrain, which meets the requirements of the observation site. Therefore, a flat area with convenient construction within a range of 50m*50m was selected in the south of the Gaotai Dazhuang geoelectric observation station to realize the construction of the new geoelectric field observation device system.

[0057] Combined with the topography and construction requirements of the survey area, the pole arrangement method of "M" shape is adopted. The long pole spacing of the geoelectric field observation is designed to be 100m, and the short pole spacing is 50m. The external line adopts the "full underground" method.

[0058] The latitude and longitude of the polar pit points selected by satellite maps are statistically shown in Table 1 after verification by handheld GPS on site. Figure 3 shown.

[0059] Table 1 Coordinates of electrode pit points

[0060] Extreme 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] Taking into account the error range of handheld GPS and the short distance of pole layout, in actual construction, after pole pit O is selected, the positions of other pole pits will be determined mainly by compass direction measurement and GPS-assisted positioning.

[0062] 2. External line construction

[0063] (I) Cable laying

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

[0065] Wiring and cable trench excavation methods are as follows: Figure 4 During the construction, the cable length used was 1043m, the buried cable trench length was 384m, three buried cable trenches were dug and gathered near the NE pole pit, and a main buried cable trench was dug from the NE pole pit to the observation room. All lines were gathered near the NE pole pit and then led into the observation room from the main buried cable trench. See the wiring diagram Figure 4 , the cable length is shown in Table 2.

[0066] During the construction process, the cable trench is excavated according to the theoretical design, and the cables are laid out manually. During the laying process, the lengths of the cable heads and tails are recorded to calculate the actual wiring length.

[0067] Table 2: Length of new geoelectric field lines

[0068]

[0069]

[0070] (II) Cable marking and burial

[0071] To prevent confusion of wire ends after external lines are buried, it is necessary to mark the cable terminals in advance. Use 3 marks, stick them on the terminals and wrap them with transparent tape. See Table 3 for specific marking methods. The specific connection of each 3-core cable to electrodes with different buried depths is uniformly formulated according to the color of the wire core sheath after the actual cable arrives. For example: red, blue and green three-color wire cores, the red wire core electrode is buried at a depth of 3 meters, the blue wire core electrode is buried at a depth of 2 meters, and the green wire core electrode is buried at a depth of 1 meter. This method defines the specific electrode number.

[0072] Table 3 External line marking situation 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 North East NE NW 133 NW northwest NWNorthwest SE 127 SE South East SESoutheast SW 155 SW south west SW South West O 106 O center O Center

[0074] Since the external line is buried, combined with the local frozen soil depth of 40cm-50cm in the survey area, the buried cable trench is designed to be 80cm deep and 40cm wide. After the cable is placed at the bottom of the buried cable trench, the original soil is backfilled and compacted, and then the line is backfilled mechanically to reduce damage to the cable during mechanical backfilling. The buried cable trench design and construction diagram is as follows Figure 5 As shown, the cable trench is then excavated.

[0075] (III) Wiring and burying of non-polarized electrodes

[0076] The connection method of the non-polarized electrode lead and extension wire follows the wiring method provided by the LGB-3 solid non-polarized 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 extend layer by layer from the inside to the outside, tightly wrap them for processing, and add PVC sleeves to fill with structural adhesive to protect the joints from damage during backfilling.

[0077] Each electrode pit is designed to bury three electrodes. Considering the presence of gravel in the soil of the measurement area, in order to ensure good contact between the non-polarized electrode and the soil, 40 cm thick fine original soil should be backfilled during construction to completely cover the contact surface between the non-polarized electrode and the soil, and then the backfill soil should be compacted. The designed electrode pit depth is 250 cm. When burying the electrode, the electrode welded to the red core of the cable is placed in the middle of the north side of the electrode pit, the electrode welded to the green core of the cable is placed in the southeast position of the electrode pit, and the electrode welded to the blue core of the cable is placed in the southwest position of the electrode pit. All non-polarized electrodes do not lean against the electrode pit wall. During the burial process, the sieved fine original soil is first manually backfilled to completely bury the non-polarized electrode, and then mechanical backfilling is used. The schematic diagram of the electrode burial construction is shown as follows: Figure 6 As shown, manual backfilling was then carried out.

[0078] (IV) Excavation of the extreme pit

[0079] The electrode pits are excavated at the designed locations with a square pit length of 200cm*200cm*2500cm to bury the electrodes. All the electrode pits are excavated in the north-south direction, which is convenient for reference when laying out the electrodes. Figure 7 As shown, the electrode pit is excavated.

[0080] 6. Construction of external line introduction into observation room

[0081] During the construction process, cable trenches are dug to the wall of the observation room. All buried cables are installed with casings and then led into the observation room. After being properly fixed, they are introduced into the observation room.

[0082] 7. Indoor lines

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

[0084] 8. Instrument connection

[0085] After the line enters the observation room, it is connected to the instrument in the order of the line markings, so that continuous observation, data acquisition and analysis can be carried out.

[0086] Based on data obtained from continuous observations, such as Figure 8 As shown, the changing dynamics of the omnidirectional natural electric field are described in the whole space.

[0087] A seismic geoelectric field observation device design system, comprising:

[0088] 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;

[0089] 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;

[0090] 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;

[0091] 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;

[0092] 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.

[0093] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred 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 the relevant parts can be referred to the method part.

[0094] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one 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. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to 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 in the natural potential difference by the pole distance between the electrodes at the end points of the coaxial line.

2. A method for designing an earthquake geoelectric field observation device according to claim 1, characterized in that: The specific arrangement of the geoelectric field observation device is as follows: 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.

3. A method for designing an earthquake geoelectric field observation device according to claim 1, characterized in that: The method of burying 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.

4. A method for designing an earthquake geoelectric field observation device according to claim 3, characterized in that: It also includes a three-core armored cable for the measurement line.

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

6. 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.

7. 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 6, 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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