A vertical borehole horizontal stress measurement device and method

Abstract

This invention discloses a device and method for measuring horizontal geostress in vertical boreholes. The device comprises, from bottom to top, a borehole wall topography scanning assembly, an acoustic-pressure coordinated lateral loading assembly, and a gyro-orientation assembly, all arranged sequentially on a cylindrical protective shell. The acoustic-pressure coordinated lateral loading assembly includes four sets of lateral loading cylinders evenly distributed outwards along the radial sidewall of the protective shell. An acoustic emission probe is integrated into the loading head of each lateral loading cylinder. The borehole wall topography scanning assembly, lateral loading cylinders, gyro-orientation assembly, and acoustic emission probe are connected to a ground monitoring and control system via a signal bus. This invention combines acoustic emission and the Kaiser effect of rock to perform a single, multi-directional coordinated loading measurement within the borehole, achieving the measurement of the horizontal geostress value and direction within a vertical geological borehole without the need for secondary sampling. This equipment requires no large-scale equipment and is easy to carry and use for on-site measurements.

Description

Technical Field

[0001] This invention relates to the field of geostress measurement technology, and more particularly to a device and method for measuring horizontal geostress in a vertical borehole. Background Technology

[0002] With the increasing demand for mineral resources and energy, shallow surface resources can no longer meet societal needs, leading to a shift in mining towards deeper layers. One of the key challenges in deep mining is the high ground stress, a dominant factor inducing rockbursts, large deformations and instability of surrounding rock, and damage to underground rock engineering structures. Therefore, accurately assessing the original ground stress state in deep mining areas is crucial for addressing the stability of surrounding rock and optimizing structural design. Currently, methods for measuring ground stress commonly include borehole hydraulic fracturing, borehole stress relief, and borehole acoustic emission.

[0003] Traditional borehole stress relief methods are typically applied to horizontal boreholes in tunnels or roadways, but are not suitable for deep vertical boreholes with abundant groundwater. This is because strain gauges used for measuring in-situ stress in horizontal boreholes require waterless bonding, which is difficult to achieve in deep, water-rich groundwater conditions. Therefore, methods for underwater bonding of strain gauges urgently need to be updated. The hydraulic fracturing method used for vertical borehole stress measurement requires high rock mass integrity. If the measurement area contains developed fissures, weak interlayers, or fracture zones, high-pressure water is prone to leakage, leading to distortion of key data such as fracturing pressure and shut-off pressure, making it difficult to accurately infer in-situ stress. Furthermore, traditional borehole core acoustic emission stress measurement methods require core redirection and secondary core sampling. The measurement process lacks prior information on the direction of in-situ principal stress and ignores the in-situ confining pressure effect, resulting in large measurement errors, blurred or premature manifestation of the Kaiser effect, and affecting the accuracy of in-situ stress measurement. Summary of the Invention

[0004] The purpose of this invention is to provide a device and method for measuring horizontal ground stress in vertical boreholes, so as to solve the problems of low efficiency and the need for secondary sampling in existing testing methods.

[0005] To address this, the present invention provides a vertical borehole horizontal stress measurement device, comprising a borehole wall topography scanning component, an acoustic-pressure coordinated lateral loading component, and a gyro orientation component arranged sequentially from bottom to top on a cylindrical protective shell; wherein, the acoustic-pressure coordinated lateral loading component includes four sets of lateral loading cylinders evenly distributed outward circumferentially along the radial sidewall of the protective shell, respectively corresponding to the directions of 0° / 180°, 45° / 225°, 90° / 270°, and 135° / 315°, and the loading head of each lateral loading cylinder integrates an acoustic emission probe, used to synchronously acquire acoustic emission signals generated inside the borehole wall rock mass during loading; the borehole wall topography scanning component, the lateral loading cylinders, the gyro orientation component, and the acoustic emission probe are connected to the ground monitoring and control system via a signal bus.

[0006] Specifically, the hole wall topography scanning assembly includes an image acquisition unit, a 360° laser scanner, and an image acquisition unit housing. The image acquisition unit and the 360° laser scanner are installed inside the image acquisition unit housing, and the 360° laser scanner is connected to the image acquisition unit via an imaging sub-line and a signal bus.

[0007] Specifically, the gyroscope orientation component is equipped with a gyroscope and an angle scale. The angle scale is marked with angle markings in eight directions: 0°, 45°, 90°, 135°, 180°, 225°, 270° and 315°, corresponding to the eight lateral loading cylinders. The gyroscope orientation component transmits the azimuth angle signal to the signal bus through the orientation sub-line.

[0008] Specifically, the acoustic emission probe transmits the acoustic emission signal to the signal bus via an acoustic sub-line, and the lateral loading cylinder transmits the loading pressure signal to the signal bus via a pressure control sub-line.

[0009] Specifically, the loading head has an internal cavity, in which an acoustic emission probe is placed, and the gap between the acoustic emission probe and the cavity is filled with an acoustic emission noise reduction pad.

[0010] A method for measuring horizontal ground stress in a vertical borehole includes the following steps:

[0011] Step 1: Drill a vertical borehole in the geostress measurement area and send the horizontal geostress measurement device into the measurement section via a winch;

[0012] Step 2: Start the borehole wall topography scanning component to scan the borehole wall, calculate and obtain the convergence displacement of the borehole wall based on the scanning data, and record the horizontal orientation corresponding to each convergence displacement point in conjunction with the gyroscope orientation component.

[0013] Step 3: Analyze the borehole wall convergence displacement to obtain the directions of the minimum and maximum horizontal principal stresses; then, based on the radial convergence displacement calculation formula under far-field horizontal geostress, calculate the estimated value σ of the maximum horizontal principal stress. h max估算 And the estimated value of the minimum horizontal principal stress σ h min估算 and their proportions;

[0014] Step 4: Adjust the orientation of the horizontal ground stress measuring device placed in the vertical borehole. According to the angle marks on the gyroscope orientation component, align the loading head of the lateral loading cylinder corresponding to 0° and 180° with the direction of maximum ground stress on the borehole wall, and align the loading head of the lateral loading cylinder corresponding to 90° and 270° with the direction of minimum ground stress on the borehole wall.

[0015] Step 5: Calculate σ based on the value obtained in Step 2. h max估算σ h min估算， Set the target values ​​for loading in each direction:

[0016] ;

[0017] The target value for the maximum horizontal principal stress is defined in the 0° / 180° direction.

[0018] The target value for minimum horizontal principal stress loading corresponds to the 90° / 270° direction.

[0019] The target stress loading values ​​are set in the 45° / 225° directions.

[0020] The target stress loading values ​​are set in the 135° / 315° directions.

[0021] λ is the loading factor;

[0022] Step 6: Activate the acoustic-pressure coordinated lateral loading component for preloading, so that each loading head presses against the borehole wall outward, and the entire measuring device will not be misaligned or move relative to each other.

[0023] Step 7: Apply pressure to the borehole wall according to the loading values ​​set in Step 5 in each direction. At the same time, use acoustic emission probes to monitor the acoustic emission signals generated during the loading process. When the acoustic emission images of all eight loading heads show significant signal changes, stop applying pressure to the rock wall and record the points where the signals of each loading head show significant changes. These points are called "Kaiser points".

[0024] Step 8: The lateral loading cylinder is retracted to drive the loading head away from the borehole wall. The winch is used to move the horizontal stress measuring device up and down to change the measuring plane.

[0025] Step 9: Repeat steps (2) to (8) to measure at least three planes to avoid stress differences caused by stratigraphic differences;

[0026] Step 10: Process the collected acoustic emission signal values, and then, based on the direction confirmed in Step 4 and the geostress point corresponding to the "Kaiser point", calculate the measured value σ of the maximum horizontal principal stress. hmax Measured value of minimum horizontal principal stress σ hmin Measured value of intermediate horizontal principal stress σ 45° ;

[0027] Step 11: Based on the plane stress interpretation formula, calculate the horizontal stress azimuth angles β1 and β2 using the following formula, and then calculate the accurate maximum horizontal stress σ. H Minimum horizontal stress σ h ;

[0028] ;

[0029] ;

[0030] ;

[0031] .

[0032] 7. The method for measuring horizontal ground stress in vertical boreholes according to claim 6, characterized in that: the formula for calculating radial convergence displacement is:

[0033] ;

[0034] In the formula, u r (a,θ) represents the radial displacement at the borehole wall, a is the original borehole radius, and G is the shear modulus; σ H The maximum horizontal ground stress; σ h θ is the minimum horizontal ground stress; θ is the angle between the position direction and the direction of the maximum horizontal principal stress; E is the elastic modulus; v is Poisson's ratio.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. This invention combines acoustic emission devices and the Kaiser effect of rocks to perform one-time loading measurements within boreholes, achieving the measurement of horizontal stress values ​​and directions within vertical geological boreholes without the need for secondary core sampling at the surface. Furthermore, this equipment requires no large-scale equipment, making it easy to carry and perform on-site measurements.

[0037] 2. The measurement process of this invention first estimates the geostress orientation based on borehole deformation convergence measurement, and then accurately measures the geostress magnitude through synergistic multi-directional stress loading and acoustic emission monitoring under lateral orientation matching. This overcomes the problems of inaccurate loading direction and neglect of confining pressure effect in traditional acoustic emission measurement process, which leads to the absence or premature manifestation of the Kaiser effect, thus improving the accuracy of acoustic emission geostress identification. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the overall structure of the geostress measuring device.

[0040] Figure 2Cross-sectional view of the internal structure of the geostress measuring device

[0041] Figure 3 Schematic diagram of the hole wall morphology scanning component;

[0042] Figure 4 This is a schematic diagram of a sound-pressure coordinated lateral loading component;

[0043] Figure 5 This is a schematic diagram of a servo hydraulic control system.

[0044] The components include: 1. Cylindrical protective housing; 2. Hole wall morphology scanning assembly; 201. Image acquisition unit; 202. 360° laser scanner; 203. Image acquisition unit housing; 3. Acoustic-pressure coordinated lateral loading assembly; 301. Lateral loading cylinder; 302. Loading head; 303. Acoustic emission probe; 304. Acoustic emission amplifier; 305. Servo hydraulic control system; 4. Acoustic emission noise reduction pad; 5. Gyroscope orientation assembly; 6. Signal bus; 7. Imaging sub-line; 8. Orientation sub-line; 9. Pressure control sub-line; 10. Acoustic sub-line. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0048] See Figure 1and Figure 2 A vertical borehole horizontal stress measurement device includes a borehole wall topography scanning component 2, an acoustic-pressure coordinated lateral loading component 3, and a gyro orientation component 5, arranged sequentially from bottom to top on a cylindrical protective housing 1. The borehole wall topography scanning component 2 is located at the bottom of the cylindrical protective housing 1 and is used to perform fine scanning of the borehole wall to obtain the borehole wall convergence displacement. The gyro orientation component 5 is located inside the protective housing and is used to determine the horizontal orientation corresponding to each convergence displacement point. The acoustic-pressure coordinated lateral loading component 3 includes four sets of lateral loading cylinders 301 evenly distributed outwards along the radial sidewall of the protective housing, with adjacent lateral loading cylinders 301 spaced at 45° intervals. The positions, corresponding to 0° / 180°, 45° / 225°, 90° / 270° and 135° / 315° respectively, are arranged on the loading head 302 of the lateral loading cylinder 301. An acoustic emission probe 303 is integrated on the loading head 302 to synchronously collect acoustic emission signals generated inside the borehole wall rock mass during the loading process. The borehole wall morphology scanning component 2, the lateral loading cylinder 301, the gyro orientation component 5 and the acoustic emission probe 303 are connected to the ground monitoring and control system (not shown in the figure) through the signal bus 6. The image signals, acoustic emission signals, pressure signals and orientation signals during the geostress measurement process are collected to the ground monitoring and control system through the signal bus 6.

[0049] See Figure 3 The borehole wall topography scanning assembly 2 includes an image acquisition unit 201, a 360° laser scanner 202, and an image acquisition unit housing 203. The image acquisition unit 201 and the 360° laser scanner 202 are installed inside the image acquisition unit housing 203. The 360° laser scanner 202 has a semi-circular glass dome on top. The 360° laser scanner 202 and the image acquisition unit 201 are connected to the signal bus 6 through the imaging sub-line 7. The collected images are transmitted upward to the signal bus 6 through the imaging sub-line 7.

[0050] See Figure 4 and Figure 5Understandably, in the actual design, each lateral loading cylinder 301 includes a loading head 302, a cylinder liner, and a piston. The piston is coaxially and slidably installed inside the cylinder liner, which is vertically fixed to the side wall of the protective housing. The piston rod is threadedly connected to the loading head 302. The protective housing contains three sets of servo hydraulic control systems 305. One set of servo hydraulic control systems 305 is connected to the 0° lateral loading cylinder and the 180° lateral loading cylinder, used to control the synchronous movement of the 0° lateral loading cylinder and the 180° lateral loading cylinder to achieve synchronous loading or unloading. Another set of servo hydraulic control systems 301... Unit 5 is connected to the 90° lateral loading cylinder and the 270° lateral loading cylinder, used to control the 90° lateral loading cylinder and the 270° lateral loading cylinder to achieve synchronous loading or unloading. The last set of servo hydraulic control system 305 is connected to the 45° lateral loading cylinder, the 135° lateral loading cylinder, the 225° lateral loading cylinder, and the 315° lateral loading cylinder, used to control the 45° lateral loading cylinder, the 135° lateral loading cylinder, the 225° lateral loading cylinder, and the 315° lateral loading cylinder to achieve synchronous loading or unloading. The servo hydraulic control system 305 is connected to the signal bus 6 through the pressure control sub-line 10. As for the specific structure of the servo hydraulic control system 305, it is all existing technology and will not be described in detail here.

[0051] Specifically, a cavity is provided inside the loading head 302, and an acoustic emission probe 303 is placed in the cavity. The gap between the acoustic emission probe 303 and the cavity is filled with an acoustic emission noise reduction pad 4. The acoustic emission probe 303 transmits the acoustic emission signal through an acoustic emission amplifier 304 to the signal bus 6 via an acoustic sub-line. The loading head 302 near the borehole wall has an arc surface adapted to the borehole wall. The acoustic sub-line 10, pressure control sub-line 9, imaging sub-line 7, and orientation sub-line 8 form four branches that converge into the signal bus 6. The signal bus 6 then aggregates the image signal, acoustic emission signal, pressure signal, and orientation signal during the ground stress measurement process to the ground monitoring and control system.

[0052] See Figure 1 and Figure 2 The gyroscope orientation component 5 is equipped with a gyroscope and an angle scale. The angle scale is marked with angle marks in eight directions, namely 0°, 45°, 90°, 135°, 180°, 225°, 270° and 315°, corresponding to the eight lateral loading cylinders. The gyroscope orientation component 5 transmits the azimuth angle signal to the signal bus 6 through the orientation sub-line 8.

[0053] The method for measuring horizontal ground stress in vertical boreholes based on the above-mentioned measuring device specifically includes the following steps:

[0054] (1) Drill a vertical borehole in the geostress measurement area and send the horizontal geostress measurement device of the vertical borehole to the measurement section via a winch;

[0055] (2) Start the borehole wall topography scanning component to scan the borehole wall, obtain the borehole wall circumferential panorama by recognizing and stitching the borehole wall image, and obtain the three-dimensional point cloud data of the circumferential panorama by using 360° laser ranging. Based on the coordinate parameters of the point cloud data, perform cross-section fitting calculation to obtain the borehole wall convergence displacement, and then use the gyroscope orientation component to record the horizontal orientation corresponding to each convergence displacement point.

[0056] (3) Based on the preliminary analysis of borehole wall convergence displacement, the maximum convergence displacement point is the direction of the minimum horizontal principal stress, and the minimum convergence displacement point is the direction of the maximum horizontal principal stress; then, based on the radial convergence displacement calculation formula under far-field horizontal geostress:

[0057] ;

[0058] The estimated value σ of the maximum horizontal principal stress can be calculated. h max估算 And the estimated value of the minimum horizontal principal stress σ h min估算 And their proportions.

[0059] In the formula, u r (a, θ) represents the radial displacement at the borehole wall (negative towards the inside of the borehole, representing convergent deformation; positive towards the outside of the borehole, representing dilatational deformation); a is the original borehole radius; G is the shear modulus; σ H The maximum horizontal ground stress; σ h θ is the minimum horizontal ground stress; θ is the angle between the position direction and the direction of the maximum horizontal principal stress; E is the elastic modulus; v is Poisson's ratio.

[0060] (4) Adjust the orientation of the horizontal stress measuring device placed in the vertical borehole. According to the angle markings on the angle scale on the gyroscope orientation component, align the acoustic-pressure co-loading head corresponding to 0° and 180° with the direction of maximum stress on the borehole wall, and align the acoustic-pressure co-loading head corresponding to 90° and 270° with the direction of minimum stress on the borehole wall.

[0061] (5) σ calculated according to step (3) h max估算 σ h min估算， Set the target values ​​for loading in each direction:

[0062] ;

[0063] The target value for the maximum horizontal principal stress is defined in the 0° / 180° direction.

[0064] The target value for minimum horizontal principal stress loading corresponds to the 90° / 270° direction.

[0065] The target stress loading values ​​are set in the 45° / 225° directions.

[0066] The target stress loading values ​​are: 135° / 315° directions;

[0067] λ is the loading factor;

[0068] (6) The servo hydraulic control system supplies oil to each loading cylinder for preloading, so that each loading head presses against the hole wall outward, and the device will not be misaligned or move relative to each other.

[0069] (7) Start the servo hydraulic control system and pressurize the borehole wall according to the loading values ​​set in step (5). At the same time, use the acoustic emission probe on the loading head to monitor the acoustic emission signal. After the acoustic emission images of all eight loading heads show a significant change in signal, i.e. "Kaiser effect", turn off all the servo hydraulic control systems, stop the loading head from pressurizing the rock wall, and record the point where the signal of each loading head shows a significant change, which is called "Kaiser point".

[0070] (8) Start the servo hydraulic control system to unload each loading cylinder, so that each loading head is relaxed. Use the winch to move the horizontal stress measuring device of the vertical borehole up and down and change the measuring plane.

[0071] (9) Repeat steps (2) to (8) to measure at least three planes to avoid stress differences caused by stratigraphic differences;

[0072] (10) The collected acoustic emission signal values ​​are processed, and then the measured value of the maximum horizontal principal stress σ is obtained according to the direction confirmed in step (4) and the geostress point corresponding to the "Kaiser point". hmax Measured value of minimum horizontal principal stress σ hmin Measured value of intermediate horizontal principal stress σ 45° ;

[0073] (11) Based on the plane stress interpretation formula, calculate the horizontal stress azimuth angles β1 and β2 according to the following formula, and then calculate the accurate maximum horizontal stress σ. H Minimum horizontal stress σ h ;

[0074] ;

[0075] ;

[0076] ;

[0077] .

[0078] This invention employs a borehole wall morphology scanning component to perform refined scanning and measurement of the convergence displacement of the borehole wall, and uses a gyro orientation component to determine the horizontal orientation corresponding to each convergence displacement point, thus making a preliminary estimate of the magnitude and direction of the principal ground stress. An acoustic-pressure synergistic lateral loading component is used to collect acoustic emission signals inside the borehole wall while loading. Based on the "Kaiser effect," the acoustic-pressure synergistic lateral loading component is used to measure ground stress, achieving the measurement of the horizontal ground stress value and direction within a vertical geological borehole without the need for secondary sampling.

[0079] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A device for measuring horizontal ground stress in a vertical borehole, characterized in that, The system includes a borehole wall morphology scanning component (2), an acoustic-pressure coordinated lateral loading component (3), and a gyroscope orientation component (5), which are arranged sequentially from bottom to top on a cylindrical protective shell (1). The acoustic-pressure coordinated lateral loading component (3) includes four sets of lateral loading cylinders (301) evenly distributed outward along the radial sidewall of the protective shell, respectively corresponding to the directions of 0° / 180°, 45° / 225°, 90° / 270° and 135° / 315°. The loading head (302) of the lateral loading cylinder (301) is equipped with an acoustic emission probe (303) for synchronously collecting acoustic emission signals generated inside the borehole wall rock mass during the loading process. The borehole wall morphology scanning component (2), the lateral loading cylinder (301), the gyroscope orientation component (5) and the acoustic emission probe (303) are connected to the ground monitoring and control system via a signal bus (6).

2. The vertical borehole horizontal stress measuring device according to claim 1, characterized in that: The hole wall topography scanning assembly (2) includes an image acquisition unit (201), a 360° laser scanner (202), and an image acquisition unit housing (203). The image acquisition unit (201) and the 360° laser scanner (202) are installed inside the image acquisition unit housing (203). The 360° laser scanner (202) and the image acquisition unit (201) are connected to the signal bus (6) via an imaging sub-line (7).

3. The vertical borehole horizontal stress measuring device according to claim 2, characterized in that: The gyroscope orientation component (5) is equipped with a gyroscope and an angle scale. The angle scale is marked with angle markings in eight directions, namely 0°, 45°, 90°, 135°, 180°, 225°, 270° and 315°, corresponding to the eight lateral loading cylinders (301). The gyroscope orientation component (5) transmits the azimuth angle signal to the signal bus (6) through the orientation sub-line (8).

4. The vertical borehole horizontal stress measuring device according to claim 3, characterized in that: The acoustic emission probe (303) transmits the acoustic emission signal to the signal bus (6) through the acoustic sub-line (10), and the lateral loading cylinder (301) transmits the loading pressure signal to the signal bus (6) through the pressure control sub-line (9).

5. The vertical borehole horizontal stress measuring device according to claim 4, characterized in that: The loading head (302) has a cavity inside, and an acoustic emission probe (303) is placed inside the cavity. The gap between the acoustic emission probe (303) and the cavity is filled with an acoustic emission noise reduction pad (4).

6. A method for measuring horizontal ground stress in a vertical borehole, comprising using the horizontal ground stress measuring device for a vertical borehole as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Drill a vertical borehole in the geostress measurement area and send the horizontal geostress measurement device into the measurement section via a winch; Step 2: Start the borehole wall topography scanning component to scan the borehole wall, calculate and obtain the convergence displacement of the borehole wall based on the scanning data, and record the horizontal orientation corresponding to each convergence displacement point in conjunction with the gyroscope orientation component. Step 3: Analyze the borehole wall convergence displacement to obtain the directions of the minimum and maximum horizontal principal stresses; then, based on the radial convergence displacement calculation formula under far-field horizontal geostress, calculate the estimated value σ of the maximum horizontal principal stress. h max估算 And the estimated value of the minimum horizontal principal stress σ h min估算 and their proportions; Step 4: Adjust the orientation of the horizontal ground stress measuring device placed in the vertical borehole. According to the angle marks on the gyroscope orientation component, align the loading head of the lateral loading cylinder corresponding to 0° and 180° with the direction of maximum ground stress on the borehole wall, and align the loading head of the lateral loading cylinder corresponding to 90° and 270° with the direction of minimum ground stress on the borehole wall. Step 5: Calculate σ based on the value obtained in Step 2. h max估算 σ h min估算， Set the target values ​​for loading in each direction: ； The target value for the maximum horizontal principal stress is defined in the 0° / 180° direction. The target value for minimum horizontal principal stress loading corresponds to the 90° / 270° direction. The target stress loading values ​​are set in the 45° / 225° directions. The target stress loading values ​​are set in the 135° / 315° directions. λ is the loading factor; Step 6: Activate the acoustic-pressure coordinated lateral loading component for preloading, so that each loading head presses against the borehole wall outward, and the entire measuring device will not be misaligned or move relative to each other. Step 7: Apply pressure to the borehole wall according to the loading values ​​set in Step 5 in each direction. At the same time, use acoustic emission probes to monitor the acoustic emission signals generated during the loading process. When the acoustic emission images of all eight loading heads show significant signal changes, stop applying pressure to the rock wall and record the points where the signals of each loading head show significant changes. These points are called "Kaiser points". Step 8: The lateral loading cylinder is retracted to drive the loading head away from the borehole wall. The winch is used to move the horizontal stress measuring device up and down to change the measuring plane. Step 9: Repeat steps (2) to (8) to measure at least three planes to avoid stress differences caused by stratigraphic differences; Step 10: Process the collected acoustic emission signal values, and then, based on the direction confirmed in Step 4 and the geostress point corresponding to the "Kaiser point", calculate the measured value σ of the maximum horizontal principal stress. hmax Measured value of minimum horizontal principal stress σ hmin Measured value of intermediate horizontal principal stress σ 45° ; Step 11: Based on the plane stress interpretation formula, calculate the horizontal stress azimuth angles β1 and β2 using the following formula, and then calculate the accurate maximum horizontal stress σ. H Minimum horizontal stress σ h ; ； ； ； 。 7. The method for measuring horizontal ground stress in vertical boreholes according to claim 6, characterized in that: The formula for calculating radial convergent displacement is: ； In the formula, u r (a,θ) represents the radial displacement at the borehole wall, a is the original borehole radius, and G is the shear modulus; σ H The maximum horizontal ground stress; σ h θ is the minimum horizontal ground stress; θ is the angle between the position direction and the direction of the maximum horizontal principal stress; E is the elastic modulus; v is Poisson's ratio.

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