A device for efficiently measuring ground stress using an expanding agent and a method for using the same

Abstract

The application discloses a device for efficiently measuring ground stress by using expanding agent and a use method thereof. The device comprises a shaft rod, a lower pressure plate fixedly connected to the bottom of the shaft rod, the shaft rod being a hollow screw rod, two small holes being left in the side wall of the shaft rod, a first supporting arm and a second supporting arm being fixedly connected to each small hole respectively, a first nut and a second nut being movably and screwedly connected to the side wall of the shaft rod, a screw hole movably and screwedly connected to the side wall of the shaft rod and used for connecting an upper pressure cover plate, the upper pressure cover plate being arranged between the first nut and the second nut, and the bottom of the upper pressure cover plate being attached to the top side wall of a first stress plate and a second stress plate on one side. The device is simple in operation, high in accuracy of measured data and high in precision. The device is simple in manufacture, low in requirement for equipment precision, suitable for complex mountainous areas, power shortage and inconvenient traffic environment, mainly relies on expanding agent, low in requirement for power and capable of completing measurement by using a small mobile power supply.

Description

Technical Field

[0001] This invention belongs to the field of geostress measurement technology, and in particular relates to a device and method for efficiently measuring geostress using an expansive agent. Background Technology

[0002] In current geoscientific research and engineering applications, geostress measurement has always held a crucial position. Geostress, in essence, is a stress system that is widely present within the Earth's crust. Its origins are complex and multifaceted. On one hand, the weight of the rocks themselves generates stress within the crust, a fundamental and persistent influencing factor. On the other hand, frequent tectonic movements throughout geological history, such as plate collisions, crustal uplift and subsidence, and the folding and fracturing of rock strata, are significant driving forces behind the formation and changes in geostress. The interplay of numerous complex factors shapes the state and distribution characteristics of geostress within the Earth's crust. Geostress measurement is irreplaceable for many engineering fields and geological research. Taking underground engineering as an example, in the construction and operation of tunnel excavation and various other underground engineering facilities, the magnitude and direction of geostress—two key elements—fundamentally determine the overall stability of the project. If the relevant information on geostress is not sufficiently in-depth, comprehensive, and accurate during the planning, design, and construction phases of an engineering project, a series of serious engineering safety problems are highly likely to occur during the actual project implementation. For example, under the continuous action of a complex geostress environment, the surrounding rock of an underground project may gradually undergo unexpected deformation. Once this deformation exceeds the limits that the surrounding rock itself can withstand, it will further trigger a collapse accident, which will not only cause a great delay in the project construction progress, but may also lead to a large amount of economic losses and casualties, seriously endangering the smooth progress and long-term safe and stable operation of the project.

[0003] Currently, the most common method for measuring in-situ stress is hydraulic fracturing. Hydraulic fracturing requires sophisticated equipment, including specialized high-pressure pumps, packers, and impression devices. Its accuracy is low; after the rock mass fractures, a large amount of water is lost, causing a sudden drop in pressure, typically only accurate to 0.1 MPa. Furthermore, this equipment needs to be highly reliable and accurate. In remote areas or harsh field environments, the transportation, installation, and commissioning of the equipment can face numerous difficulties, affecting the smooth progress of the measurement work. The cost of hydraulic fracturing is between 150,000 and 200,000 yuan, which is relatively high, and it also carries significant safety risks, wasting considerable human and financial resources.

[0004] The formula references for the principal stress determination method of this invention are as follows: Rock Mechanics, First Edition, September 1999, China University of Geosciences Press, Liu Yourong and Tang Huiming, Chapter 7 Natural Geostress, Section 3 Natural Stress Measurement of Rock Mass, 130 pages. Summary of the Invention

[0005] The present invention aims to solve the problems of large stress error and inaccurate accuracy when measuring principal stress using the hydrostatic method.

[0006] To solve the above problems, the present invention is achieved through the following technical solution:

[0007] A device for efficiently measuring ground stress using an expansive agent includes a shaft, the bottom of which is fixedly connected to a lower pressure plate.

[0008] The shaft is a hollow helical rod with two small holes on its side wall. Each hole is fixedly connected to the first arm and the second arm, respectively.

[0009] The first nut and the second nut are movably connected to the side wall of the shaft via a screw thread, and the inner wall of the screw hole of the pressure cover plate is also connected to the side wall of the shaft via a screw thread.

[0010] The upper pressure cover is installed between the first nut and the second nut, and the bottom side of the upper pressure cover is in contact with the top sidewall of the first stress plate and the second stress plate.

[0011] The bottom side of the upper pressure cover plate is in contact with the top sidewall of the first stress plate and the second stress plate. The first stress plate is a semi-hollow cylindrical height plate.

[0012] The top sidewalls of the first stress plate and the second stress plate are respectively attached to and in contact with the sidewalls on both sides of the limiting plate. The limiting plate separates the first stress plate and the second stress plate. The first stress plate and the second stress plate are placed vertically on the upper circular sidewall edge of the pressure plate.

[0013] The top side of the lower pressure plate is in contact with the bottom sidewall of the first stress plate and the second stress plate, and the first vibrator and the second vibrator are fixedly mounted on the upper side of the pressure plate.

[0014] The upper pressure cover plate has a cover plate hole, which is a square hole. Two convex slide rails are fixedly installed on the parallel side of the cover plate hole. The convex slide rails are semi-cylindrical convex slide rails.

[0015] Two limiting plates are fixedly installed on the inner side wall of the upper pressure cover. The two limiting plates are on the same horizontal line and pass through the axis of the center of the upper pressure cover. The length of the limiting plates extends to the edge of the side wall of the upper pressure cover.

[0016] The outer sidewall of the upper pressure cover is fixedly equipped with a telescopic device. The push rod of the telescopic device is fixedly connected to the cover. There are two concave grooves at the bottom of the cover. Each concave groove fits and slides against the convex slide rail. Two positioning plates are fixedly installed on the upper side of the upper pressure cover. The position of each positioning plate corresponds to the position of each limiting plate and is set in the same direction. An illumination and shooting device is installed on one side of the positioning plate.

[0017] The first arm is a hollow rod, and the interior of the hollow rod is used to fill power cords and data cords. A first stress plate is horizontally fixed on one side wall of the first arm, and multiple second stress plates are vertically fixed on the other side wall of the first arm.

[0018] A wire hole is provided at the connection point between the first support arm sidewall and the first stress plate and the second stress plate.

[0019] A method for using a device that efficiently measures ground stress using an expansive agent includes the following steps:

[0020] S1. Remove the first stress plate and the second stress plate, put the device into the cave, open the cover plate, and use a suction machine to remove the rock debris from the cave.

[0021] S2. Use a suction machine and suction pipe to press upwards on the cover plate, leaving a hole in the cover plate. Inject the expansion material into the hole for the first time. After filling, retract the suction pipe of the suction machine and close the cover plate hole with the cover plate. The expansion material expands on the inner wall of the hole, creating cracks.

[0022] S3. Use the first vibrator and the second vibrator to loosen the solidified expansion material, then use a suction machine to clean the expansion agent, and then take the device out of the hole.

[0023] S4. Install the first stress plate and the second stress plate onto the device, then place the device into the hole. Use the illumination and imaging device and rotate the shaft to align the positioning plate with the crack position in step S2. The second injection of expansion material is performed in the same way as step S2. After the second injection, measurements are taken. and ; then calculate to get , After the measurement is completed, repeat step S3.

[0024] In step S1, the rock mass gravel components and their mass fractions are SiO2 65%, Al2O3 14%, K2O 4.5%, H2O 4.2%, Na2O 3.2%, Fe2O3 2.1%, with the remainder being ash impurities;

[0025] In step S4 It is the measured value of the tensile strength of the rock. It is the stress inside the hole, corresponding to the stress curve. The point where the internal stress and minimum principal stress of the hole balance out later is called the point where the internal stress and minimum principal stress balance out later. ; With minimum principal stress They are numerically equal;

[0026] The minimum principal stress of the rock is The maximum principal stress of the rock is ;

[0027] = ; = ; , , , The units are all MPa.

[0028] Preferably, the expanding agent is powdered calcium oxide.

[0029] Preferably, the radius of the opening is 0.5 to 1.2 cm larger than the radius of the upper pressure cover.

[0030] Preferably, the thickness of the first stress plate and the second stress plate is 3~5cm.

[0031] Preferably, the width of the limiting plate is less than 0.5cm.

[0032] Preferably, in step S2, the expansion time of the first injected expansion material is 4.2 to 5 hours.

[0033] Preferably, the expanding material is a uniformly mixed mixture of calcium oxide and water, with a mass ratio of calcium oxide to water of 3:1.

[0034] Preferably, the reaction of the expansion material injected during the first injection causes cracks to form inside the hole, and the location of the cracks corresponds to the direction of the maximum principal stress.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] a. This invention provides an apparatus and method for efficiently measuring in-situ stress using an expansive agent. This apparatus uses the expansive agent as a stress source; the enormous expansion force generated when the agent encounters water causes cracks in the rock, leading to gradual fracturing. This apparatus utilizes the expansive agent for efficient in-situ stress measurement, differing from the hydraulic fracturing method. The apparatus is also simple to operate.

[0037] b. The device of the present invention is simple to manufacture and is suitable for complex mountainous areas and environments with insufficient power and inconvenient transportation. The device mainly relies on an expanding agent and has low power requirements. A small mobile power supply can also be used to complete the measurement.

[0038] c. In this invention, a limiting plate 11 is used to restrict the movement direction of the first stress plate 1 and the second stress plate 101. After determining the principal stress direction, the direction of the limiting plate 11 is adjusted by the shaft 2 so that the first stress plate 1 and the second stress plate 101 correspond to the principal stress direction.

[0039] d. This invention employs a first arm 12 and a second arm 13 to house stress plates. The hollow design inside the two arms facilitates the connection of the stress plate power lines, and stress plates can be placed in different directions and positions on the arms, increasing the average randomness of the data. The first stress plate 8 and the second stress plate 801 of this invention use piezoresistive sensors to collect stress data. Their operating temperature range is -40℃ to 70℃, overcoming the difficulty of water freezing at sub-zero temperatures in the hydraulic fracturing method. The acquisition time is <1ms, the measurement range is wider, and the accuracy of the acquired data is significantly improved. Furthermore, the first stress plate 8 and the second stress plate 801 are evenly distributed in the horizontal and vertical directions on the arms, resulting in smaller stress data errors. The stress accuracy of the device of this invention is 0.0001MPa.

[0040] e. The present invention uses a suction machine to clean the device and recover the expanding agent. The suction method is simple and quick, taking into account the characteristics of the powder after the expanding agent reaction.

[0041] f. Compared to the high measurement cost of hydraulic fracturing, which has a comprehensive cost of 150,000 to 250,000 yuan per measurement, this device uses inexpensive raw materials such as expansion agents, has a simple device structure, and requires less manpower and resources, thus reducing the measurement cost to 3,000 to 5,000 yuan, greatly reducing economic costs.

[0042] g. The first stress plate 1 and the second stress plate 101 of the present invention are two arc-shaped thick plates. The first stress plate 1 and the second stress plate 101 are separated by a limiting plate 11 with a gap in the middle. During measurement, the positioning plate 16 and the lighting and imaging device 17 are compared with the crack generated in the first time to achieve accurate alignment between the limiting plate 11 and the crack. After determining the direction of the principal stress through the crack, the direction of the first stress plate 1 and the second stress plate 101 is adjusted to be consistent with the direction of the principal stress, so that the magnitude of the principal stress can be accurately measured.

[0043] h. Compared with the traditional hydraulic fracturing method, this invention selects calcium oxide as an expanding agent. After the expanding agent is mixed with water, the device itself is sealed and the expanding agent gradually solidifies after the reaction. As a result, the loss of expanding material into the crack is less and the influence of stress changes is more gradual. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the overall device of the present invention.

[0045] Figure 2 For the device of the present invention, point A is... Figure 1Enlarged structural diagram of the area indicated by the dotted line.

[0046] Figure 3 This is a schematic diagram of the internal structure of the device of the present invention.

[0047] Figure 4 This is a schematic diagram of the first and second arm structures of the device of the present invention.

[0048] Figure 5 This is a cross-sectional schematic diagram of the underground operation of the device of the present invention.

[0049] Figure 6 This is a schematic diagram of the stress plate of the device of the present invention.

[0050] Figure 7 This is a time history curve of the expansion stress inside the crack-induced test hole of the device of the present invention.

[0051] Reference numerals in the attached drawings: First stress plate 1, Second stress plate 101, Shaft 2, Upper pressure cover plate 3, Telescopic device 4, Cover plate 5, Convex slide rail 501, First nut 6, Second nut 7, First stress plate 8, Second stress plate 801, Lower pressure plate 9, Suction machine 10, Limiting plate 11, First support arm 12, Second support arm 13, First vibrator 14, Second vibrator 15, Positioning plate 16, Illumination and imaging device 17. Detailed Implementation

[0052] It should be understood that the terms "bottom," "sidewall," "one side," "top," "inner side," "upper side," "outer side," "other side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not 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 limiting the present invention.

[0053] Furthermore, the descriptions in this invention are merely preferred embodiments and are not intended to limit the invention. Although the invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

[0054] Preferably, the calcium oxide is in powder form, which makes it easy to flow after mixing with water. Powdered calcium oxide can be purchased directly from the market.

[0055] Preferably, the telescopic device 4 is purchased from Boyang Technology Co., Ltd., specifically model YH8-522, along with its associated power supply and circuitry.

[0056] Preferably, the stress sheet 8 is purchased from Aidong Thin Film Electronics Technology Co., Ltd., model IMS-CO4A, along with its related power supply and circuit.

[0057] Preferably, the suction machine 10 is purchased from Jieba Company BF501 model and its related power supply and circuit; as well as the suction tube of the suction machine 10.

[0058] Preferably, the first vibrator 14 is purchased from Zhenke Co., Ltd., model ZK-0.1, along with its related power supply and circuit.

[0059] Preferably, the bottom of the side wall of the shaft 2 is also provided with a wire hole, through which the data cable and power cable of the first vibrator 14 and the second vibrator 15 are connected to an external power source and a computer.

[0060] Preferably, the lighting and shooting device 17 is a RER-USB4KCAM03H model from Ruier Vision Co., Ltd., along with related power supplies and circuits.

[0061] Preferably, the lighting and shooting device 17 is powered by a storage battery.

[0062] The telescopic device 4, stress plate 8, first vibrator 14, suction machine 10, lighting and shooting device 17, and computer are powered by an external power source.

[0063] The measurement software installed on the computer is named Strain DAQ; version 1.0; and it is sold by Shanghai Chengke Electronic Technology Co., Ltd.

[0064] The telescopic device 4, stress plate 8, suction machine 10, first vibrator 14 and second vibrator 15 are all connected to the computer via data cable, and the lighting and shooting device 17 is wirelessly connected to the computer.

[0065] The first stress plate 1, the second stress plate 101, the first support arm 12 and the second support arm 13, the upper pressure cover plate 3, and the lower pressure plate 9 are preferably made of 7075 aluminum alloy. The aluminum alloy is 7075 aluminum alloy and is purchased from Yimai Aluminum Jiangsu Group Co., Ltd.

[0066] This application does not improve the power supply circuit, and all the components used are commercially available. The model numbers selected in this patent are merely for illustrative purposes and not to restrict the use of specific instrument models. The use of data cables or wireless connections for the various components in this application is also for illustrative purposes and not to restrict the use of these connection methods.

[0067] Example 1

[0068] See Figures 1-6 A device for efficiently measuring ground stress using an expansive agent includes a shaft 2, with a lower pressure plate 9 fixedly connected to the bottom of the shaft 2.

[0069] Shaft 2 is a hollow helical rod. Two small holes are provided on the side wall of shaft 2, and each small hole is fixedly connected to the first arm 12 and the second arm 13 respectively.

[0070] The first nut 6 and the second nut 7 are movably and helically connected to the side wall of the shaft 2. The inner wall of the screw hole on the side wall of the shaft 2 is movably fitted and helically connected to the pressure cover plate 3.

[0071] The upper pressure cover plate 3 is installed between the first nut 6 and the second nut 7, and the bottom side of the upper pressure cover plate 3 is in contact with the top sidewall of the first stress plate 1 and the second stress plate 101.

[0072] The bottom side of the upper pressure cover plate 3 is in contact with the top sidewall of the first stress plate 1 and the second stress plate 101. The first stress plate 1 is a semi-hollow cylindrical height plate.

[0073] The sidewalls of the first stress plate 1 and the second stress plate 101 are attached but not connected. The top sidewalls of the first stress plate 1 and the second stress plate 101 are respectively attached to and in contact with the sidewalls on both sides of the limiting plate 11. The limiting plate 11 separates the first stress plate 1 and the second stress plate 101. The first stress plate 1 and the second stress plate 101 are placed vertically on the edge of the upper circular sidewall of the pressure plate 9.

[0074] The lower pressure plate 9 is in contact with the bottom sidewall of the first stress plate 1 and the second stress plate 101 on one side of its top. The first vibrator 14 and the second vibrator 15 are fixedly mounted on the upper side of the pressure plate 9.

[0075] The upper pressure cover plate 3 has a cover plate hole, which is a square hole. Two convex slide rails are fixedly installed on the parallel side of the cover plate hole. The convex slide rails are semi-cylindrical convex slide rails 501.

[0076] Two limiting plates 11 are fixedly installed on the inner side wall of the upper pressure cover plate 3. The two limiting plates 11 are on the same horizontal line and pass through the axis where the center of the upper pressure cover plate 3 is located. The length of the limiting plates 11 extends to the edge of the side wall of the upper pressure cover plate 3.

[0077] The outer sidewall of the upper pressure cover plate 3 is fixedly equipped with a telescopic device 4. The push rod of the telescopic device 4 is fixedly connected to the cover plate 5. There are two concave grooves at the bottom of the cover plate 5, and each concave groove fits and slides in contact with the convex slide rail.

[0078] Two positioning plates 16 are fixedly installed on the upper side of the upper pressure cover plate 3. The position of each positioning plate 16 corresponds vertically to the position of each limiting plate 11, and they are arranged parallel to each other in the same direction. An illumination and imaging device 17 is installed on one side of the positioning plate 16.

[0079] The first arm 12 is a hollow rod, and the inside of the hollow rod is used to fill power cords and data cords. A first stress plate 8 is horizontally fixed on one side wall of the first arm 12, and multiple second stress plates 801 are vertically fixed on the other side wall of the first arm 12.

[0080] A wire hole is provided on the side wall of the first support arm 12 at the connection point with the first stress plate 8 and the second stress plate 801.

[0081] Preferably, the first nut 6 and the second nut 7 are used to fix the upper pressure cover plate 3.

[0082] Preferably, the cover hole on the upper pressure cover plate 3 is used by the suction machine 10 to suction rock debris and impurities inside the device.

[0083] Preferably, the side wall of shaft 2 is threaded.

[0084] Preferably, two second stress plates 801 are vertically fixed to the other side wall of the first arm 12.

[0085] Preferably, the first stress plate 1 and the second stress plate 101 are completely identical.

[0086] Preferably, the first stress sheet 8 and the second stress sheet 801 are exactly the same.

[0087] Preferably, the first vibrator 14 and the second vibrator 15 are exactly the same.

[0088] The upper pressure cover plate 3 and the lower pressure plate 9 are fixed by a shaft 2 that runs through them from top to bottom, and together with the first stress plate 1 and the second stress plate 101, they form an open cylindrical space.

[0089] The upper pressure cover plate 3 is fixed by the first nut 6 and the second nut 7 on the shaft 2, and the relative height of the upper pressure cover plate 3 is also adjusted by the first nut 6 and the second nut 7.

[0090] Shaft 2 is made of 7075 aluminum alloy. The side wall of shaft 2 is threaded, and the bottom of shaft 2 is welded to the lower pressure plate 9 to form a whole. The lower pressure plate 9 does not require a pre-drilled opening and can be directly welded, which simplifies the installation process and improves the connection stability.

[0091] The upper part of the pressure cover plate 3 is provided with a cover plate hole, which is used to clean the dust in the hole wall, place the expansion agent, and recover the expansion agent in the future.

[0092] A movable cover plate 5 is placed at the edge of the upper pressure cover plate 3. The side of the cover plate 5 has a grooved slide rail that can be pulled back and forth. The cover plate 5 is fixedly connected to a telescopic device 4 on one side to facilitate the filling and recycling of the expansion agent.

[0093] The shaft 2 has two vertical first arms 12 and second arms 13 on its side wall.

[0094] A first stress plate 8 is horizontally fixed to one side wall of the first support arm 12, and multiple second stress plates 801 are vertically fixed to the other side wall of the first support arm 12.

[0095] The second arm 13 is exactly the same as the first arm 12. The second stress plate 801 is installed vertically on the first arm 12 and the second arm 13 respectively, and the first stress plate 8 is installed horizontally. Multiple first stress plates 7 and second stress plates 8 are arranged in parallel in the device to prevent the stress plates from failing due to high temperature and crushing pressure.

[0096] A total of 6 stress gauges are placed on the two arms, including four second stress gauges 801 in the vertical direction and two first stress gauges 8 in the horizontal direction. Multiple stress gauges can be placed on the two arms to reduce the error of stress data.

[0097] Place the device of the present invention in the hole, first open the cover plate 5, and use the suction machine 10 to suck up the rock debris and impurities inside the device. After the stress test is completed, use the suction machine 10 to clean the inside of the device.

[0098] The first and second cylindrical vibrators 14 and 15 are fixed on the lower pressure plate 9. When recovering the expanding agent, since the expanding agent is compacted and cannot be directly sucked up, the first vibrator 14 and the second vibrator 15 are turned on first to vibrate, so that the expanding agent is loosened into more loose and fine particles, which can be sucked up and cleaned up.

[0099] The function of the limiting plate 11 is to ensure that the first stress plate 1 and the second stress plate 101 do not rotate or shift when they are lowered into the opening.

[0100] The upper pressure cover plate 3 and the lower pressure plate 9 have the same radius.

[0101] The radius of the opening is 0.5 to 1.2 cm larger than the radius of the upper pressure cover plate 3.

[0102] The length of shaft 2 is greater than the depth of the opening, and the length of shaft 2 can be set according to the depth of the opening.

[0103] The width of the limiting plate 11 is less than 0.5 cm, and the width of the limiting plate 11 is the same as the gap width between the first stress plate 1 and the second stress plate 101. The width of the positioning plate 16 can be set according to the width of the limiting plate 11.

[0104] The thickness of the first stress plate 1 and the second stress plate 101 is 3~5cm. If the first stress plate 1 and the second stress plate 101 are too thick, when filling with an equal volume of expanding agent, the side wall height of the first stress plate 1 and the second stress plate 101 will be higher, and there will be a larger contact area with the rock to be tested. The expanding agent will not be able to fully push the first stress plate 1 and the second stress plate 101, and the cracking effect will not be achieved. If the first stress plate 1 and the second stress plate 101 are too thin, they will fall into the reserved gap between the hole and the device during the movement or adjustment of the device.

[0105] Example 2

[0106] A method for using a device that efficiently measures ground stress using an expansive agent includes the following steps:

[0107] S1. Remove the first stress plate 1 and the second stress plate 101, put the device into the cave, open the cover plate 5, and use the suction machine 10 to remove the rock debris from the cave.

[0108] S2. Use the suction machine 10 and suction pipe to press upwards on the cover plate 3, leaving a cover plate hole, and inject the expansion material into it for the first time. After filling, retract the suction pipe of the suction machine 10 and close the cover plate hole with the cover plate 5. The expansion material expands on the inner wall of the hole, causing cracks.

[0109] S3. Use the first vibrator 14 and the second vibrator 15 to loosen the solidified expansion material, then use the suction machine 10 to clean the expansion agent, and then take the device out of the hole.

[0110] S4. Install the first stress plate 1 and the second stress plate 101 onto the device, then place the device into the hole. Use the illumination and imaging device 17 and rotate the shaft 2 to make the positioning plate 16 correspond to the position of the crack in step S2. The second injection of expansion material is performed in the same way as in step S2. After the second injection, the measurement is obtained. and ; then calculate to get , After the measurement is completed, repeat step S3.

[0111] In step S1 above, the device is placed into the hole, the telescopic device 4 is controlled to open the cover plate 5, and the hole is cleaned by the suction machine 10. The first stress plate 1 and the second stress plate 101 are not placed this time.

[0112] In step S2 above, after the hole is emptied, prepare the expansion material, mix it with water at a ratio of 3:1, stir it thoroughly, and inject the expansion material using the suction machine 10 and suction pipe. After injection, retract the suction pipe and close the pre-reserved hole cover plate 5; wait for the expansion agent to react and expand.

[0113] In step S3 above, after the expansion agent has reacted completely, it no longer generates expansion force. At this time, the first vibrator 14 and the second vibrator 15 are used to loosen the solidified expansion agent, and then the suction machine 10 is used to clean the expansion agent. After that, the device is taken out of the hole.

[0114] In step S4 above, the first reaction caused cracks to form inside the hole, and the location of the cracks corresponds to the direction of the maximum principal stress. When the device is placed in the hole for the second time, the first stress plate 1 and the second stress plate 101 are placed together. This measurement requires adjusting the position of the device. The location of the cracks is observed using the illumination and imaging device 17. The shaft 2 of the device is manually rotated so that the two ends of the positioning plate 16 correspond to the location of the cracks. After adjusting the position of the positioning plate 16, the expansion agent material is injected for the second time in the same way as in step S2. Then, stress detection is activated, and each stress plate transmits data back to the computer, and the measured values ​​are obtained. and Therefore, the calculation is obtained. , After the measurement is completed, repeat step S3 once.

[0115] like Figure 6 As shown, minimum principal stress The direction is perpendicular to the maximum principal stress The direction, therefore, when the limiting plate 11 is placed parallel to the crack, the measurement is obtained. and ; then calculate to get , .

[0116] The upper surface of the upper pressure cover plate 3 is fixedly connected to a structural positioning plate 16 parallel to the limiting plate 11, so that when the shaft 2 is rotated during the second insertion into the opening, the lighting and shooting device 17 assists in adjusting the position of the limiting plate 11 to keep it parallel to the crack.

[0117] Preferably, calcium oxide is used as the expanding agent, with a mass ratio of expanding agent to water of 3:1. The mixture is thoroughly and evenly stirred and then placed into the suction machine 10. The expanding agent reacts with water to generate a huge expanding force, causing the rock to be pulled apart and cracks to form.

[0118] When cleaning the expanding agent, first turn on the first vibrator 14 and the second vibrator 15; loosen the expanding agent for 3-5 minutes, then open the upper cover 5. After the expanding agent reacts with water, it will be in powder form. Use the suction machine 10 to suction and clean the expanding agent.

[0119] Example 3

[0120] After drilling, the rock fragments remaining at the bottom of the borehole had the following composition and mass fractions: SiO2 65%, Al2O3 14%, K2O 4.5%, H2O 4.2%, Na2O 3.2%, Fe2O3 2.1%, with the remainder being ash impurities. The borehole depth was 15 meters, the borehole radius was 8 cm, the upper pressure cover plate 3 of the device had a radius of 7 cm, the distance between the inner walls of the upper pressure cover plate 3 and the lower pressure plate 9 was 40 cm, and the mass ratio of calcium oxide expanding agent to water was 3:1.

[0121] The expansion material, calcium oxide, and water were stirred at 1400 r / min for 10 min.

[0122] The outer diameter of shaft 2 is 1 cm.

[0123] The thickness of the first stress plate 1 and the second stress plate 101 is 5 cm.

[0124] The two limiting plates 11 are 0.2cm wide, 0.5cm high, and 4cm long.

[0125] The gap width between the first stress plate 1 and the second stress plate 101 is also 0.2cm.

[0126] The thickness of the first stress plate 1 and the second stress plate 101 is 3~5cm.

[0127] The following procedure for injecting the expansion agent should be completed within 40-50 seconds.

[0128] For the first filling of the expansion material, without setting the first stress plate 1 and the second stress plate 101, fill the cover hole of the pressure cover plate 3 on the device with expansion agent, close it after filling, and let it stand for 4.2 to 5 hours.

[0129] The second filling of expansion material involves setting up the first stress plate 1 and the second stress plate 101, filling the cover hole of the pressure cover plate 3 on the device with expansion agent, closing it after filling, and starting the measurement; the second measurement time is 20 hours.

[0130] like Figure 7 As shown, the stress change process is divided into four stages. Figure 7 The stress data comes from the stress plate measurement data of the device after the first stress plate 1 and the second stress plate 101 were added for the second time.

[0131] The function of the first stress plate 1 and the second stress plate 101 is to concentrate the stress.

[0132] In the first stage, the expanding agent reacts with water in the device to accumulate stress, and the expansion force generated by the expansion continues to rise, resulting in a continuous increase in stress data.

[0133] In stage II, the stress reaches its maximum at vertex A. Since cracks were already present in the first measurement, the expansion pressure measured inside the device at this point is slightly less than the tensile strength of the rock. In this application, the expansion pressure inside the device can be approximated as the tensile strength of the rock. When the cracks in the surrounding rock around the borehole reopen, the stress at this point is denoted as... , The physical meaning of point A is: The direction of the crack, representing the tensile strength of the rock (i.e., the first stress peak of the stress curve), is the direction of the maximum principal stress. After the crack appears, the first stress plate 1 and the second stress plate 101 expand outward, the gap between the first stress plate 1 and the second stress plate 101 widens, and a small amount of expanding agent flows into the crack, causing the expansion pressure inside the device to drop rapidly.

[0134] In stage III, the decrease in expansion pressure within the device tends to level off. Point B serves as the distinguishing point between stages II and III. The selection criteria for point B are: the stress change rate k = -4.5 at point c to the left of point B and the stress change rate k = -1 to 0.2 at point d to the right of point B. This indicates that the stress change rate around point B increases most significantly from k = -4.5 to k = -1; this characteristic point is used as the selection criterion for point B. The physical significance of the inflection point B is: the point where the internal stress and the minimum principal stress reach equilibrium. It is the internal stress of the hole at point B. With minimum principal stress They are numerically equal. .

[0135] In stage IV, the stress slowly decreases. After the surrounding rock around the closed fracturing space has developed cracks, the pressure dissipates to the plateau period of stage III, where it pauses briefly before the stress drops further, exhibiting a fluctuating drop. The rate of drop is significantly slower than in stage II, gradually slowing down until the stress drops to 0.

[0136] Refer to the principal stress determination method described in "Rock Mechanics": , .

[0137] Measured Take the stress value at point A. Take the stress value at point B; the value is shown in the appendix. Figure 7 The stress values ​​of all the first stress plates 8 and the second stress plates 801 within the device are taken as the average value. Among them, , , , The unit is MPa.

[0138] The present invention sets the above parameters in the embodiments for the purpose of facilitating the explanation of the use of the device. Those skilled in the art can adjust and modify the above parameters as needed based on the experimental parameters disclosed in the embodiments of this application without creative effort. For example, they can modify the distance between the inner walls of the upper pressure cover plate 3 and the lower pressure plate 9 to adjust the amount of expansion agent and water added, the ratio of expansion agent and water, the size of the stress plate of the device, increase the number of support walls on the shaft 2, increase the number of stress plates, change the material of each component of the device, etc. Such modifications also fall within the protection scope of this application.

[0139] Since the rock's apex A and inflection point B are independent of the expansion agent's ratio and mass, the amount of expansion agent added can be adjusted as needed. Unless otherwise specified in this application, filling until the expansion agent contacts the bottom wall of the upper pressure cover plate 3 is considered full. Those skilled in the art can adjust the amount and ratio of expansion agent added as needed, and these improvements also fall within the scope of protection of this invention.

Claims

1. A device for efficiently measuring ground stress using an expansive agent, comprising a shaft (2), characterized in that, The bottom of the shaft (2) is fixedly connected to the lower pressure plate (9). The shaft (2) is a hollow helical rod. Two small holes are left on the side wall of the shaft (2), and each small hole is fixedly connected to the first arm (12) and the second arm (13). The first nut (6) and the second nut (7) are movably screwed onto the side wall of the shaft (2), and the inner wall of the screw hole of the pressure cover plate (3) is screwed onto the side wall of the shaft (2). The upper pressure cover plate (3) is installed between the first nut (6) and the second nut (7), and the bottom side of the upper pressure cover plate (3) is in contact with the top sidewall of the first stress plate (1) and the second stress plate (101). The bottom side of the upper pressure cover plate (3) is in contact with the top sidewall of the first stress plate (1) and the second stress plate (101). The first stress plate (1) is a semi-hollow cylindrical height plate. The top sidewalls of the first stress plate (1) and the second stress plate (101) are respectively attached to and in contact with the sidewalls on both sides of the limiting plate (11). The limiting plate (11) separates the first stress plate (1) and the second stress plate (101). The first stress plate (1) and the second stress plate (101) are placed vertically on the edge of the upper circular sidewall of the lower pressure plate (9). The bottom side wall of the first stress plate (1) and the second stress plate (101) is in contact with the top side of the lower pressure plate (9). The first vibrator (14) and the second vibrator (15) are fixedly installed on the upper side of the lower pressure plate (9). Two limiting plates (11) are fixedly installed on the inner side wall of the upper pressure cover (3). The two limiting plates (11) are on the same horizontal line and pass through the axis of the center of the upper pressure cover (3). The length of the limiting plates (11) extends to the edge of the side wall of the upper pressure cover (3). The outer sidewall of the upper pressure cover (3) is fixedly equipped with a telescopic device (4), and the push rod of the telescopic device (4) is fixedly connected to the cover (5). There are two concave grooves at the bottom of the cover (5), and each concave groove fits and slides against the convex slide rail. Two positioning plates (16) are fixedly installed on the upper side of the upper pressure cover (3). The position of each positioning plate (16) and the position of each limiting plate (11) are vertically corresponding and set in the same direction. An illumination and shooting device (17) is installed on one side of the positioning plate (16). During measurement, the positioning plate (16) and the lighting and shooting device (17) are compared with the crack generated in the first time multiple times to achieve accurate alignment between the limiting plate (11) and the crack. After determining the direction of the principal stress through the crack, the direction of the first stress plate (1) and the second stress plate (101) is adjusted to be consistent with the direction of the principal stress.

2. The device for efficiently measuring ground stress using an expanding agent according to claim 1, characterized in that, The upper pressure cover plate (3) has a cover plate hole, which is a square hole. Two convex slide rails (501) are fixedly installed on the parallel side of the cover plate hole. The convex slide rails are semi-cylindrical convex slide rails (501).

3. The device for efficiently measuring ground stress using an expanding agent according to claim 1, characterized in that, The first arm (12) is a hollow rod, and the inside of the hollow rod is used to fill power lines and data lines. A first stress plate (8) is fixedly mounted horizontally on one side wall of the first arm (12), and a plurality of second stress plates (801) are fixedly mounted vertically on the other side wall of the first arm (12).

4. The device for efficiently measuring ground stress using an expanding agent according to claim 1, characterized in that, A wire hole is provided at the connection point between the first support arm (12) and the first stress plate (8) and the second stress plate (801).

5. A method of using the device for efficiently measuring ground stress using an expanding agent according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Remove the first stress plate (1) and the second stress plate (101), put the device into the cave, open the cover plate (5), and use the suction machine (10) to remove the rock debris in the cave. S2. Use the suction machine (10) and suction pipe to press the cover plate (3) upwards and inject the expansion material into the cover plate hole for the first time. After filling, retract the suction pipe of the suction machine (10) and close the cover plate hole with the cover plate (5); the expansion material expands and cracks are generated in the inner wall of the hole. S3. Use the first vibrator (14) and the second vibrator (15) to loosen the solidified expansion material, then use the suction machine (10) to clean the expansion agent, and then take the device out of the hole. S4. Install the first stress plate (1) and the second stress plate (101) onto the device, then place the device into the hole. Use the lighting and imaging device (17) and rotate the shaft (2) to make the positioning plate (16) correspond to the position of the crack in step S2. The second injection of expansion material is the same as the operation in step S2. After the second injection, the measurement is obtained. and ; then calculate to get , After the measurement is completed, repeat step S3. In step S1, the rock mass gravel components and their mass fractions are SiO2 65%, Al2O3 14%, K2O 4.5%, H2O 4.2%, Na2O 3.2%, Fe2O3 2.1%, with the remainder being ash impurities; In step S4 It is the measured value of the tensile strength of the rock. It is the stress inside the hole, corresponding to the stress curve. The point where the internal stress and minimum principal stress of the hole balance out later is called the point where the internal stress and minimum principal stress balance out later. ; With minimum principal stress They are numerically equal; The minimum principal stress of the rock is The maximum principal stress of the rock is ; = ; = ; , , , The units are all MPa.

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