Micro-motion exploration method based on Koch fractal curve

Abstract

The invention relates to a Koch fractal curve-based micro-motion exploration method, which comprises the following steps of: determining a target area, setting an order N as zero, determining a zero-order Koch triangle, sequentially determining first to N-order Koch triangles until the order N is a final value, and substituting the order N into a Koch fractal curve to generate an N-order Koch triangle graph, the N-order Koch triangle graph comprises a plurality of sharp points and a central point, and all the sharp points and the central point are arrangement points of the seismograph; the method comprises the following steps: firstly, arranging a plurality of arrangement points, arranging a seismograph on the arrangement points, then monitoring by the seismograph to obtain a micro-motion signal, then obtaining a shear wave velocity three-dimensional structure, and obtaining a plurality of Koch triangles with different side lengths after arrangement, so that micro-motion signals with different station intervals are obtained, and the shear wave velocity three-dimensional structure with multiple depths can be obtained; and repeated arrangement is not needed, so that the exploration efficiency is relatively high. Therefore, the shear wave velocity three-dimensional structure of multiple depths can be obtained at the same time, and the exploration efficiency is high.

Description

Technical Field

[0001] The present invention relates to a microtremor exploration method, belonging to the field of microtremor exploration, and particularly relates to a microtremor exploration method based on Koch fractal curve. Background Art

[0002] Microtremor refers to the daily tiny tremors on the earth's surface. After exploring the microtremors in the target area to obtain microtremor signals, and then processing the microtremor signals by the spatial autocorrelation method, a three-dimensional structure of shear wave velocity below the target area can be obtained, thereby obtaining the underground structure of the target area.

[0003] Chinese Patent with application number 202210249722.5 and application date of March 14, 2022 discloses a layout and detection analysis method for a three-dimensional microtremor detection array. First, a three-dimensional microtremor detection array with a square matrix structure is laid out. In the three-dimensional microtremor detection array, a measuring point is set at the coordinate position of each node seismograph in each channel. Each measuring point uses an L-shaped array for microtremor detection. Then, each measuring point selects the corresponding measuring points according to the measuring point observation system combination formula to form an L-shaped array. The collected data of each measuring point's L-shaped array is then extracted for dispersion and inversion, and a three-dimensional phase velocity map is made and exported for display. Although this design can obtain the three-dimensional structure of shear wave velocity below the target area, it still has the following defects: In this design, the distance between each measuring point is the same. After being processed by the spatial autocorrelation method, only the three-dimensional structure of shear wave velocity at the same depth can be obtained. When it is necessary to obtain the three-dimensional structure of shear wave velocity at different depths, it is necessary to readjust the measuring point spacing and monitor again to obtain the three-dimensional structure of shear wave velocity at another depth. Therefore, the exploration efficiency is relatively low.

[0004] Disclosing the information of this background art section is only intended to increase the understanding of the overall background of the present application, and should not be regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects and problems in the prior art that the three-dimensional structure of shear wave velocity at multiple depths cannot be obtained simultaneously and the exploration efficiency is relatively low, and to provide a microtremor exploration method based on Koch fractal curve that can obtain the three-dimensional structure of shear wave velocity at multiple depths and has a relatively high exploration efficiency.

[0006] To achieve the above purpose, the technical solution of the present invention is: A microtremor exploration method based on Koch fractal curve, the method comprising the following steps: Step 1: First, determine the target area, then determine the maximum and minimum underground depths to be detected in the target area. Then multiply the maximum underground depth by the conversion factor to obtain the maximum side length, and multiply the minimum underground depth by the conversion factor to obtain the minimum side length; Step 2: First, set the order N to zero, and then determine the side length of the Koch triangle of order zero as the side length of the Koch triangle of order zero, that is, obtain the Koch triangle of order zero; Then, based on the Koch triangle of order zero, start the determination process: first increase the order N by one, and then determine the proportionality coefficient between the side length of the Koch triangle of order N and the Koch triangle of order (N - 1). This proportionality coefficient is less than one, and then multiply the proportionality coefficient by the side length of the Koch triangle of order (N - 1) to obtain the side length of the Koch triangle of order N, that is, obtain the Koch triangle of order N; Step 3: First, based on the Koch triangle of order N, then repeat the determination process in Step 3 until the length of the side of the Koch triangle of order N is less than or equal to the minimum side length. At this time, the order N is the final value; Step 4: First, substitute the order N into the Koch fractal curve to generate a Koch triangle diagram of order N. There are multiple cusps distributed on the outer edge of the Koch triangle diagram of order N, and there is a center point in the middle of the Koch triangle diagram of order N. All the cusps and the center point are the layout points of the seismographs; Step 5: First, deploy seismographs on all the above-mentioned cusps in sequence, and then deploy a seismograph at the center point; Step 6: First, simultaneously monitor by all the seismographs, then obtain multiple microseismic signals, and then obtain the three-dimensional shear wave velocity structure under the target area based on the microseismic signals.

[0007] In the second step, the proportionality coefficient is one-third.

[0008] In the fourth step, the outer edge of the Koch triangle diagram of order N includes multiple straight line segments, and the points between adjacent two straight line segments are cusps.

[0009] In the fourth step, the included angle between adjacent two straight line segments is sixty degrees or one hundred and twenty degrees.

[0010] In the fourth step, the final value is two. At this time, the length of the side of the Koch triangle of order N is less than or equal to the minimum side length.

[0011] In the first step, the conversion factor is between one-fourth and one-tenth.

[0012] In the sixth step, the obtaining of the three-dimensional shear wave velocity structure under the target area based on the microseismic signals is to first analyze the microseismic signals to generate a dispersion curve, and then invert the dispersion curve to obtain the three-dimensional shear wave velocity structure under the target area.

[0013] In the sixth step, the analysis of the microtremor signal to generate the dispersion curve is as follows: First, the spatial autocorrelation method is used to calculate the microtremor signal to obtain the spatial autocorrelation coefficient. Then, the spatial autocorrelation coefficient is fitted with the Bessel function, and finally, the dispersion curve is generated.

[0014] In the sixth step, the inversion of the dispersion curve to obtain the three-dimensional shear wave velocity structure below the target area is as follows: The semi-wavelength empirical formula is used to invert the dispersion curve to obtain the relationship between the depth and the surface wave phase velocity. Then, the three-dimensional shear wave velocity structure below the target area is obtained from the relationship between the depth and the surface wave phase velocity.

[0015] In the sixth step, the analysis of the microtremor signal is as follows: First, the invalid signals in the microtremor signal are removed, then the effective microtremor signal is obtained, and finally, the effective microtremor signal is analyzed.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In the microtremor exploration method based on the Koch fractal curve of the present invention, the method includes the following steps: The first step: First, determine the target area, the maximum underground depth and the minimum underground depth to be detected, and then convert to obtain the maximum side length and the minimum side length; The second step: First, set the order N to zero, then determine the side length of the zero-order Koch triangle, and then sequentially determine the side lengths of the N-order Koch triangles; The third step: Repeat the second step until the side length of the N-order Koch triangle is less than or equal to the minimum side length. At this time, N is the final value; The fourth step: First, substitute the order N into the Koch fractal curve to generate the N-order Koch triangle diagram, and obtain the cusp points and the center points from the N-order Koch triangle diagram. The cusp points and the center points are the layout points of the seismographs; The fifth step: Layout the seismographs at the cusp points and the center points; The sixth step: First, all the seismographs are used for monitoring simultaneously, then the microtremor signals are obtained, and finally, the three-dimensional shear wave velocity structure is obtained based on the microtremor signals. In the second step, the proportionality coefficient is one-third. The advantages of the present invention also include: The first point: The side lengths of the zero-order Koch triangle, the first-order Koch triangle, the second-order Koch triangle... the N-order Koch triangle gradually become shorter. Therefore, the station spacings between the seismographs arranged at each vertex gradually become shorter. Thus, microtremor signals with different station spacings can be obtained. Then, the spatial autocorrelation method is used to process the microtremor signals with different station spacings, and the three-dimensional shear wave velocity structure at different depths can be obtained. The second point: After one layout, the seismograph monitoring can simultaneously obtain microtremor signals with different station spacings without the need for multiple layouts of seismographs with different station spacings, saving the layout time and labor costs. Therefore, the exploration efficiency is relatively high. The third point: A large number of equilateral triangles with different side lengths are perfectly nested in the Koch curve, which matches the triangular array required by the spatial autocorrelation method. Therefore, the Koch curve is very suitable for arranging the triangular array. Fourth: Take one-third of the length of the center of the side length of the (N-1)-order Koch triangle as the side length of the N-order Koch triangle. This can ensure the self-similarity of the fractal. Each iteration can generate an N-order Koch triangle with a shorter side length according to this method, and the N-order Koch triangles will not interfere with each other, so the iteration process is relatively stable; Therefore, the present invention can simultaneously obtain three-dimensional structures of shear wave velocities at multiple depths, and has a relatively high exploration efficiency.

[0017] 2. In the microtremor exploration method based on the Koch fractal curve of the present invention, in the fourth step, the N-order Koch triangle diagram includes multiple straight line segments, with a cusp between adjacent two straight line segments, and the included angle between adjacent two straight line segments is sixty degrees or one hundred and twenty degrees. When applied, the included angle between adjacent two straight line segments is sixty degrees or one hundred and twenty degrees, which ensures that the N-order Koch triangle is an equilateral triangle and meets the requirements of the triangular array commonly used in the spatial autocorrelation method. Therefore, the present invention cooperates well with the spatial autocorrelation method.

[0018] 3. In the microtremor exploration method based on the Koch fractal curve of the present invention, in the fourth step, the final value is two. In the first step, the conversion coefficient is between one-fourth and one-tenth. When applied, when the final value of N is two, substituting two into the Koch fractal curve can generate a second-order Koch triangle diagram, and then obtain the cusp and the center point of the second-order Koch triangle diagram. Under normal circumstances, the cusp and the center point of the second-order Koch triangle diagram can meet the exploration requirements, and the distribution of the cusp and the center point is relatively uniform, and the array spacing is appropriate, so the exploration effect on the three-dimensional structure of the shear wave velocity underground is better; the conversion coefficient is between one-fourth and one-tenth, which is determined by the characteristics of the spatial autocorrelation method, so the maximum side length and the minimum side length can be determined. Therefore, the exploration effect of the present invention is better.

[0019] 4. In the microtremor exploration method based on the Koch fractal curve of the present invention, in the fifth step, first process the microtremor signal by the spatial autocorrelation method to obtain the spatial autocorrelation coefficient, then fit the spatial autocorrelation coefficient with the Bessel function, then obtain the dispersion curve, and then invert the dispersion curve through the half-wavelength empirical formula to obtain the three-dimensional structure of the shear wave velocity below the target area, and then judge the underground structure of the target area through the three-dimensional structure of the shear wave velocity. When applied, the spatial autocorrelation method can take into account the spatial dependence and autocorrelation between microtremor signals, so an accurate three-dimensional structure of the shear wave velocity can be obtained, and the spatial autocorrelation method can efficiently process a large number of microtremor signals, so the data processing efficiency is relatively high. Therefore, the accuracy of the present invention is relatively high. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of the present invention.

[0021] Figure 2 is Figure 1 a schematic structural diagram of the zero - order Koch triangle in

[0022] Figure 3 is Figure 1 a schematic structural diagram of the (N - 1) - order Koch triangle in

[0023] Figure 4 is Figure 1 a schematic structural diagram of the N - order Koch triangle in

[0024] Figure 5 is Figure 4 a schematic structural diagram of the cusp in

[0025] Figure 6 is a schematic diagram of the three - dimensional structure of the shear wave velocity in the present invention.

[0026] Figure 7 is a schematic diagram of the judgment result in Example 4.

[0027] Figure 8 is a schematic structural diagram of Example 5.

[0028] Figure 9 is Figure 8 a schematic structural diagram of the lower half - plate in

[0029] Figure 10 is Figure 8 a schematic structural diagram of the upper half - plate in

[0030] Figure 11 is Figure 8 a schematic structural diagram of the fourth triangle in

[0031] In the figure: target area 1, zero - order Koch triangle 2, N - order Koch triangle 3, N - order Koch triangle figure 31, cusp 32, center point 33, straight - line segment 34, (N - 1) - order Koch triangle 4, device 5, upper half - plate 51, first triangle 511, second triangle 512, third triangle 513, upper half - center point 514, lower half - plate 52, fourth triangle 521, fifth triangle 522, sixth triangle 523, lower half - center point 524, three - dimensional structure of shear wave velocity 6, first layout point 71, second layout point 72, third layout point 73, fourth layout point 74, fifth layout point 75, sixth layout point 76, seventh layout point 77, eighth layout point 78, ninth layout point 79, tenth layout point 80, eleventh layout point 81, twelfth layout point 82. Detailed implementation manners

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0033] Please refer to Figure 1 — Figure 11 , a microtremor exploration method based on Koch fractal curves, the method comprising the following steps: First step: First, determine the target area 1, then determine the maximum and minimum underground depths to be detected in the target area 1, then multiply the maximum underground depth by a conversion factor to obtain the maximum side length, and then multiply the minimum underground depth by the conversion factor to obtain the minimum side length; Second step: First, set the order N to zero, then determine the side length of the zero-order Koch triangle 2 as the side length of the zero-order Koch triangle, that is, obtain the zero-order Koch triangle 2; then, based on the zero-order Koch triangle 2, start the determination process: first increase the order N by one, and then determine the proportionality coefficient between the side length of the N-order Koch triangle 3 and the (N - 1)-order Koch triangle 4, the proportionality coefficient is less than one, and then multiply the proportionality coefficient by the side length of the (N - 1)-order Koch triangle 4 to obtain the side length of the N-order Koch triangle 3, that is, obtain the N-order Koch triangle 3; Third step: First, based on the N-order Koch triangle 3, then repeat the determination process in the third step until the length of the side of the N-order Koch triangle 3 is less than or equal to the minimum side length. At this time, the order N is the final value; Fourth step: First, substitute the order N into the Koch fractal curve to generate the N-order Koch triangle diagram 31. A plurality of sharp points 32 are distributed on the outer edge of the N-order Koch triangle diagram 31, and a center point 33 exists in the middle of the N-order Koch triangle diagram 31. All the sharp points 32 and the center point 33 are the layout points of the seismographs; Fifth step: First, deploy seismographs on all the above-mentioned sharp points 32 in sequence, and then deploy a seismograph on the center point 33; Sixth step: First, all the seismographs monitor simultaneously, then obtain a plurality of microtremor signals, and then obtain the three-dimensional shear wave velocity structure 6 below the target area 1 based on the microtremor signals.

[0034] In the second step, the proportionality coefficient is one-third.

[0035] In the fourth step, the outer edge of the N-order Koch triangle diagram 31 includes a plurality of straight line segments 34, and the points between two adjacent straight line segments 34 are sharp points 32.

[0036] In the fourth step, the included angle between two adjacent straight line segments 34 is sixty degrees or one hundred and twenty degrees.

[0037] In the fourth step, the final value is two. At this time, the length of the side of the N-order Koch triangle 3 is less than or equal to the minimum side length.

[0038] In the first step, the conversion factor is between one-fourth and one-tenth.

[0039] In the sixth step, the three-dimensional shear wave velocity structure 6 below the target area 1 obtained based on the microtremor signal is to first analyze the microtremor signal to generate a dispersion curve, and then invert the dispersion curve to obtain the three-dimensional shear wave velocity structure 6 below the target area 1.

[0040] In the sixth step, the analysis of the microtremor signal to generate a dispersion curve is to first calculate the microtremor signal using the spatial autocorrelation method to obtain the spatial autocorrelation coefficient, then fit the spatial autocorrelation coefficient with the Bessel function, and then generate the dispersion curve.

[0041] In the sixth step, the inversion of the dispersion curve to obtain the three-dimensional shear wave velocity structure 6 below the target area 1 is to invert the dispersion curve through the half-wavelength empirical formula to obtain the relationship between depth and surface wave phase velocity, and then obtain the three-dimensional shear wave velocity structure 6 below the target area 1 from the relationship between depth and surface wave phase velocity.

[0042] In the sixth step, the analysis of the microtremor signal is to first remove the invalid signals in the microtremor signal, then obtain the effective microtremor signal, and then analyze the effective microtremor signal.

[0043] The supplementary description of the present invention is as follows: The Koch fractal curve described in the present invention refers to: The Koch fractal curve is generated by recursive definition. The specific construction process is to divide a line segment into three equal parts, then make an equilateral triangle with the middle segment as the side and remove the original line segment to form a first-order Koch triangle; then repeat the above steps for each line segment of the first-order Koch triangle to obtain a second-order Koch triangle; and so on, higher-order Koch triangles can be obtained; in the process of constructing the Koch triangle, different-sized triangles are added in each iteration, so this point can be combined with the spatial autocorrelation method to obtain a seismograph array with different station spacings, and thus a three-dimensional structure 6 of the underground shear wave velocity at different depths can be obtained.

[0044] Example 1: Please refer to Figure 1 — Figure 11 , a microtremor exploration method based on the Koch fractal curve, the method comprising the following steps: The first step: First determine the target area 1, then determine the maximum underground depth and the minimum underground depth to be detected in the target area 1, then multiply the maximum underground depth by a conversion coefficient to obtain the maximum side length, and then multiply the minimum underground depth by the conversion coefficient to obtain the minimum side length; Step 2: First, set the order N to zero, and then determine the maximum side length as the side length of the Koch triangle 2 of order zero, that is, obtain the Koch triangle 2 of order zero; then, based on the Koch triangle 2 of order zero, start the determination process: first increase the order N by one, and then determine the proportionality coefficient between the side length of the Koch triangle 3 of order N and the Koch triangle 4 of order (N - 1). This proportionality coefficient is less than one, and then multiply the proportionality coefficient by the side length of the Koch triangle 4 of order (N - 1) to obtain the side length of the Koch triangle 3 of order N, that is, obtain the Koch triangle 3 of order N; Step 3: First, based on the Koch triangle 3 of order N, then repeat the determination process in Step 3 until the length of the side of the Koch triangle 3 of order N is less than or equal to the minimum side length. At this time, the order N is the final value; Step 4: First, substitute the order N into the Koch fractal curve to generate the Koch triangle diagram 31 of order N. There are multiple cusps 32 distributed on the outer edge of the Koch triangle diagram 31 of order N, and there is a center point 33 in the middle of the Koch triangle diagram 31 of order N. All the cusps 32 and the center point 33 are the layout points of the seismographs; Step 5: First, deploy seismographs on all the above-mentioned cusps 32 in sequence, and then deploy a seismograph on the center point 33; Step 6: First, simultaneously monitor by all the seismographs, then obtain multiple microseismic signals, and then obtain the three-dimensional shear wave velocity structure 6 below the target area 1 based on the microseismic signals.

[0045] In the second step, the proportionality coefficient is one-third.

[0046] Embodiment 2: The basic content is the same as that of Embodiment 1, except that: Please refer to Figure 1 — Figure 5 , in the fourth step, the outer edge of the Koch triangle diagram 31 of order N includes multiple straight line segments 34, and the point between two adjacent straight line segments 34 is the cusp 32. In the fourth step, the included angle between two adjacent straight line segments 34 is sixty degrees or one hundred and twenty degrees.

[0047] During application, the point between two adjacent straight line segments 34 is the cusp 32, and the cusp 32 is the vertex of the Koch triangle 3 of order N, which is the layout point of the seismograph; the included angle between two adjacent straight line segments 34 is sixty degrees or one hundred and twenty degrees, ensuring that the Koch triangle 3 of order N is an equilateral triangle. Therefore, the Koch triangle 3 of order N can perfectly fit with the spatial autocorrelation method.

[0048] Embodiment 3: The basic content is the same as that of Embodiment 1, except that: Please refer to Figure 1 — Figure 5, in the fourth step, the final value is two. At this time, the length of the side of the N - order Koch triangle 3 is less than or equal to the minimum side length. In the first step, the conversion coefficient is between one - quarter and one - tenth.

[0049] In application, when the final value is two, first substitute two into the Koch fractal curve, and then generate a second - order Koch triangle diagram as shown in Figure 4 . Then obtain the cusp 32 and the center point 33 according to the second - order Koch triangle diagram, and then deploy seismographs at the cusp 32 and the center point 33. The second - order Koch triangle can meet the basic exploration requirements, and the station spacing of the seismographs at the cusp 32 and the center point 33 is appropriate, and it can explore the three - dimensional structure 6 of the shear wave velocity at the required depth; the number of repetitions of the determination process in the second step can also be set as needed. When the number of repetitions is large, the distribution of seismographs near the center point 33 will be less. When there is an exploration requirement for a shallower depth at the center point 33, it is necessary to increase the seismograph array at the center point 33 according to the actual situation; the conversion coefficient is determined by the characteristics of the spatial autocorrelation method, and the maximum side length and the minimum side length can be determined by combining the detection requirements with the conversion coefficient.

[0050] Example 4: The basic content is the same as that of Example 1, with the difference that: Please refer to Figure 1 — Figure 7 , in the sixth step, obtaining the three - dimensional structure 6 of the shear wave velocity below the target area 1 based on the micro - motion signal is to first analyze the micro - motion signal to generate a dispersion curve, and then invert the dispersion curve to obtain the three - dimensional structure 6 of the shear wave velocity below the target area 1. In the sixth step, analyzing the micro - motion signal to generate a dispersion curve is to first use the spatial autocorrelation method to calculate the micro - motion signal to obtain the spatial autocorrelation coefficient, then fit the spatial autocorrelation coefficient with the Bessel function, and then generate a dispersion curve. In the sixth step, inverting the dispersion curve to obtain the three - dimensional structure 6 of the shear wave velocity below the target area 1 is to invert the dispersion curve through the half - wavelength empirical formula to obtain the relationship between depth and surface wave phase velocity, and then obtain the three - dimensional structure 6 of the shear wave velocity below the target area 1 from the relationship between depth and surface wave phase velocity. In the sixth step, analyzing the micro - motion signal is to first remove the invalid signals in the micro - motion signal, then obtain the effective micro - motion signal, and then analyze the effective micro - motion signal.

[0051] During application, in the fifth step, first preprocess the obtained microtremor signal to remove the invalid signals in the microtremor signal, then obtain the effective microtremor signal, then calculate the effective microtremor signal by the spatial autocorrelation method, then obtain the spatial autocorrelation coefficient, then fit the spatial autocorrelation coefficient with the Bessel function, then obtain the dispersion curve, then obtain the surface wave phase velocity and frequency through the dispersion curve, then substitute the surface wave phase velocity and frequency into the semi-wavelength empirical formula to calculate the relationship between the depth and the surface wave phase velocity, then convert the surface wave phase velocity into the shear wave velocity, and then obtain the relationship between the depth and the shear wave velocity, that is, obtain the processing result of the microtremor signal of a Koch triangle; repeat the processing process until the processing results of the microtremor signals of the remaining Koch triangles are obtained, and then process all the processing results by the interpolation method, and then obtain Figure 6 the three-dimensional shear wave velocity structure 6 underground in the target area 1 as shown in Figure 7 .

[0052] Example 5: The basic content is the same as that of Example 1, the difference is: Please refer to Figure 1 — Figure 11 , a layout device for a microtremor exploration method based on a Koch fractal curve, the device 5 includes an upper half plate 51 and a lower half plate 52, the upper half plate 51 includes a first triangle 511, the first triangle 511 is an equilateral triangle, a second triangle 512 is arranged on one side of the first triangle 511 close to the bottom, the second triangle 512 is an equilateral triangle, a third triangle 513 is arranged on the other side of the first triangle 511 close to the bottom, the third triangle 513 is an equilateral triangle, and an upper half midpoint 514 is arranged in the middle of the bottom of the first triangle 511; the lower half plate 52 includes a fourth triangle 521, the fourth triangle 521 is an equilateral triangle, a fifth triangle 522 is arranged on one side of the fourth triangle 521 close to the bottom, the fifth triangle 522 is an equilateral triangle, a sixth triangle 523 is arranged on the other side of the fourth triangle 521 close to the bottom, the sixth triangle 523 is an equilateral triangle, and a lower half midpoint 524 is arranged in the middle of the bottom of the fourth triangle 521. Preferably, the vertices on the mold 5 are successively the first layout point 71, the second layout point 72, the third layout point 73, the fourth layout point 74, the fifth layout point 75, the sixth layout point 76, the seventh layout point 77, the eighth layout point 78, the ninth layout point 79, the tenth layout point 80, the eleventh layout point 81, and the twelfth layout point 82.

[0053] During application, first determine the target area 1, then place the upper half plate 51 and the lower half plate 52 within the target area 1. Then align the upper half midpoint 514 with the lower half midpoint 524. Next, sequentially deploy seismographs between the first deployment point 71, the second deployment point 72, the third deployment point 73, the fourth deployment point 74, the fifth deployment point 75, the sixth deployment point 76, the seventh deployment point 77, the eighth deployment point 78, the ninth deployment point 79, the tenth deployment point 80, the eleventh deployment point 81, the twelfth deployment point 82, the thirteenth deployment point 83, the fourteenth deployment point 84, and between the upper half midpoint 514 and the lower half midpoint 524. Then make the seismographs conduct monitoring. The first deployment point 71, the twelfth deployment point 82, and the tenth deployment point 80 form a zero-order Koch triangle 2. The station spacing of the seismographs at the first deployment point 71, the twelfth deployment point 82, and the tenth deployment point 80 is relatively large, so it is used to explore the three-dimensional structure 6 of the shear wave velocity at a relatively deep depth; the station spacing of the seismographs at the fifth deployment point 75, the sixth deployment point 76, and the seventh deployment point 77 is relatively small, so it can explore the three-dimensional structure 6 of the shear wave velocity at a relatively shallow depth; the station spacing of the seismographs at the second deployment point 72, the third deployment point 73, and the fourth deployment point 74 is relatively small, so it can explore the three-dimensional structure 6 of the shear wave velocity at a relatively shallow depth; the station spacing of the seismographs at the ninth deployment point 79, the tenth deployment point 80, and the fourth deployment point 74 is relatively small, so it can explore the three-dimensional structure 6 of the shear wave velocity at a relatively shallow depth; the station spacing of the seismographs at the eleventh deployment point 81, the twelfth deployment point 82, and the fifth deployment point 75 is relatively small, so it can explore the three-dimensional structure 6 of the shear wave velocity at a relatively shallow depth; when using the mold 5, there is no need to measure and determine the station spacing between seismographs. Just sequentially deploy the seismographs between the first deployment point 71, the second deployment point 72, the third deployment point 73, the fourth deployment point 74, the fifth deployment point 75, the sixth deployment point 76, the seventh deployment point 77, the eighth deployment point 78, the ninth deployment point 79, the tenth deployment point 80, the eleventh deployment point 81, the twelfth deployment point 82, the thirteenth deployment point 83, the fourteenth deployment point 84, and between the upper half midpoint 514 and the lower half midpoint 524. Therefore, the deployment time is saved and the deployment efficiency is improved.

[0054] The above description is only the preferred embodiment of the present invention. The protection scope of the present invention is not limited to the above embodiment. Any equivalent modification or change made by those of ordinary skill in the art according to the disclosure of the present invention shall be included in the protection scope recorded in the claims.

Claims

1. A micro-seismic exploration method based on Koch fractal curve, characterized in that: The method comprises the following steps: Step 1: first determine the target area (1), then determine the maximum underground depth and minimum underground depth that need to be detected in the target area (1), then multiply the maximum underground depth by a conversion factor to obtain a maximum side length, and then multiply the minimum underground depth by the conversion factor to obtain a minimum side length; Step 2: first set the order N to zero, and then determine the maximum side length as the side length of the zero-order Koch triangle (2), that is, the zero-order Koch triangle (2); then, based on the zero-order Koch triangle (2), start the determination process again: first increase the order N by one, and then determine the proportionality coefficient between the side length of the N-order Koch triangle (3) and the (N-1)-order Koch triangle (4), the proportionality coefficient is less than one, and then multiply the proportionality coefficient by the side length of the (N-1)-order Koch triangle (4) to obtain the side length of the N-order Koch triangle (3), that is, the N-order Koch triangle (3); Step 3: First, take the N-order Koch triangle (3) as the basis, and then repeat the determination process in the third step until the length of the side of the N-order Koch triangle (3) is less than or equal to the minimum side length. At this time, the order N is the final value; Step 4: first, the order N is introduced into the Koch fractal curve to generate an N-order Koch triangle diagram (31), wherein the outer edge of the N-order Koch triangle diagram (31) is distributed with a plurality of cusps (32), and there is a central point (33) in the middle of the N-order Koch triangle diagram (31), and all the cusps (32) and the central point (33) are the layout points of the seismograph; Step 5: First, arrange seismographs on all the aforementioned sharp points (32) in sequence, and then arrange a seismograph on the central point (33); Step 6: All seismographs are used to monitor simultaneously, and then multiple micromotion signals are obtained. Then, the three-dimensional structure (6) of the shear wave velocity below the target area (1) is obtained based on the micromotion signals.

2. The micro-seismic exploration method based on Koch fractal curve according to claim 1, characterized in that: In the second step, the proportionality factor is one third.

3. A micro-seismic exploration method based on Koch fractal curve according to claim 1 or 2, characterized in that: In the fourth step, the outer edge of the N-order Koch triangle diagram (31) includes a plurality of straight line segments (34), and the point between two adjacent straight line segments (34) is a cusp (32).

4. The micro-seismic exploration method based on Koch fractal curve according to claim 3 is characterized in that: In the fourth step, the angle between two adjacent straight line segments (34) is sixty degrees or one hundred and twenty degrees.

5. The micro-seismic exploration method based on Koch fractal curve according to claim 1 or 2, characterized in that: In the fourth step, the final value is 2, and at this time, the length of the side of the N-order Koch triangle (3) is less than or equal to the minimum side length.

6. The micro-seismic exploration method based on Koch fractal curve according to claim 5, characterized in that: In the first step, the conversion factor is between one quarter and one tenth.

7. The micro-seismic exploration method based on Koch fractal curve according to claim 1, characterized in that: In the sixth step, the three-dimensional structure (6) of the shear wave velocity below the target area (1) is obtained based on the micro-motion signal by first analyzing the micro-motion signal to generate a dispersion curve, and then inverting the dispersion curve to obtain the three-dimensional structure (6) of the shear wave velocity below the target area (1).

8. The micro-seismic exploration method based on Koch fractal curve according to claim 7, characterized in that: In the sixth step, the micro-motion signal is analyzed to generate a dispersion curve by first calculating the micro-motion signal using a spatial autocorrelation method to obtain a spatial autocorrelation coefficient, then fitting the spatial autocorrelation coefficient with a Bessel function, and then generating a dispersion curve.

9. The micro-seismic exploration method based on Koch fractal curve according to claim 8, characterized in that: In the sixth step, the dispersion curve is inverted to obtain the three-dimensional structure (6) of the shear wave velocity below the target area (1). The dispersion curve is inverted by a half-wavelength empirical formula to obtain the relationship between the depth and the surface wave phase velocity, and then the three-dimensional structure (6) of the shear wave velocity below the target area (1) is obtained from the relationship between the depth and the surface wave phase velocity.

10. The micro-seismic exploration method based on Koch fractal curve according to claim 9, characterized in that: In the sixth step, the micro-motion signal is analyzed by first removing invalid signals from the micro-motion signal, then obtaining a valid micro-motion signal, and then analyzing the valid micro-motion signal.

Images