Device for efficiently measuring crustal stress by using expanding agent and use method of device

Abstract

The invention discloses a device for efficiently measuring crustal stress by using an expanding agent and a use method thereof, the device comprises a shaft rod, the bottom of the shaft rod is fixedly connected with a lower pressure plate, the shaft rod is a hollow screw rod, two small holes are reserved in the side wall of the shaft rod, each small hole is fixedly communicated with a first support arm and a second support arm, and the first support arm and the second support arm are fixedly connected with the shaft rod. A first nut and a second nut are movably and spirally connected to the side wall of the shaft rod, a screw hole spirally connected with an upper pressure cover plate is movably formed in the side wall of the shaft rod, the upper pressure cover plate is installed between the first nut and the second nut, and one side of the bottom of the upper pressure cover plate is in contact with the top side walls of the first stress plate and the second stress plate in an attached mode. The ground stress is efficiently measured through the expanding agent, the device is easy to operate, the accuracy of measured data is improved, and the precision is higher. The device is easy to manufacture, low in requirement for equipment precision and suitable for complex mountainous areas and environments with insufficient electric power and inconvenient traffic, the equipment mainly depends on an expanding agent, the requirement for electric power is low, and measurement can be completed through a small mobile power source.

Description

Technical Field

[0001] The present invention belongs to the technical field of in-situ stress measurement, and particularly relates to a device for efficiently measuring in-situ stress by using an expansive agent and a method for using the same. Background Art

[0002] In the current fields of geoscience research and engineering applications, in-situ stress measurement always occupies a crucial position. In-situ stress, in essence, is a stress system widely existing within the earth's crust. The root causes of its generation are relatively complex and diverse. On the one hand, the weight of the rock itself will generate corresponding stress effects within the earth's crust, which is a relatively fundamental and continuously existing influencing factor. On the other hand, the frequent geological tectonic movements during the long geological history, such as the collision and extrusion of plates, the up-and-down undulation of the earth's crust, and the intense activities such as the folding and faulting of rock strata, are even more important driving forces for the formation and change of in-situ stress. The interaction of numerous complex factors has created the existence state and distribution characteristics of in-situ stress in the earth's crust. In-situ stress measurement is of irreplaceable importance for many engineering fields and geological research work. Taking underground engineering as an example, during the construction and operation of tunnel excavation projects and various other underground engineering facilities, the two key elements of the magnitude and direction of in-situ stress will fundamentally affect the overall stability of the project. If, during the project planning, design, and construction stages, there is a lack of sufficient in-depth, comprehensive, and accurate understanding of the relevant information of in-situ stress, then during the actual project progress, a series of serious engineering safety problems are very likely to occur. For example, the surrounding rock of underground engineering may gradually produce unexpected deformation under the continuous action of a complex in-situ stress environment. Once this deformation exceeds the limit that the surrounding rock itself can bear, it will further trigger the collapse of the surrounding rock, which will not only cause a great delay in the project construction progress but also may lead to heavy economic losses and casualties and other serious consequences, seriously endangering the smooth progress and long-term safe and stable operation of the project.

[0003] Currently, the common method for in-situ stress measurement is the hydraulic fracturing method. The hydraulic fracturing method has high requirements for equipment and requires professional equipment such as high-pressure pumps, packers, and impression packers. The accuracy of the hydraulic method is low. After the rock mass cracks in the hydraulic fracturing method, a large amount of water will be lost, resulting in an instant drop in pressure, and it can usually only be accurate to 0.1 MPa. And these devices need to have high reliability and accuracy. In some remote areas or harsh field environments, the transportation, installation, and debugging of the equipment may face many difficulties, affecting the smooth progress of the measurement work. The cost of the hydraulic fracturing method is between 150,000 and 200,000, with a relatively high economic cost, and it has great potential safety hazards. At the same time, it will waste a lot of manpower and financial resources.

[0004] The formula reference in the method for obtaining the principal stress of the present invention is as follows: "Rock Mass Mechanics", the first edition in September 1999, China University of Geosciences Press, written by Liu Yourong and Tang Huiming, Chapter 7 In-situ Stress, Section 3 Measurement of In-situ Stress in Rock Mass, page 130. Summary of the Invention

[0005] The present invention aims to solve the problems of large stress error and inaccurate precision when measuring the principal stress by the water pressure method.

[0006] To solve the above problems, the present invention is realized through the following technical solutions: A device for efficiently measuring in-situ stress using an expansive agent, including a shaft rod, the bottom of the shaft rod is fixedly connected to a lower pressure plate. The shaft rod is a hollow spiral rod, and there are two small holes on the side wall of the shaft rod. Each small hole is fixedly connected to a first arm and a second arm respectively. A first nut and a second nut are movably spirally connected to the side wall of the shaft rod, and the inner wall of the screw hole of the upper pressure cover plate is spirally connected to the side wall of the shaft rod. The upper pressure cover plate is installed between the first nut and the second nut, and one side of the bottom of the upper pressure cover plate is in contact with the top side walls of the first stress plate and the second stress plate.

[0007] One side of the bottom of the upper pressure cover plate is in contact with the top side walls of the first stress plate and the second stress plate, and the first stress plate is a semi-hollow cylindrical height plate.

[0008] The top side walls of the first stress plate and the second stress plate are respectively in contact with the side walls on both sides of the limiting plate. The limiting plate separates the first stress plate and the second stress plate, and the first stress plate and the second stress plate are vertically placed at the edge of the circular side wall on the upper side of the pressure plate.

[0009] One side of the top of the lower pressure plate is in contact with the bottom side walls of the first stress plate and the second stress plate, and a first vibrator and a second vibrator are fixedly installed on the upper side of the pressure plate.

[0010] The upper pressure cover plate has a cover plate hole, the cover plate hole is a square hole, and two convex slide rails are fixedly installed on the parallel sides of the cover plate hole. The convex slide rails are semi-cylindrical convex slide rails.

[0011] Two limiting plates are fixedly installed on the inner side wall of the upper pressure cover plate. The two limiting plates are on the same horizontal line, the two limiting plates pass through the axis of the center of the upper pressure cover plate, and the length of the limiting plates extends to the edge of the side wall of the upper pressure cover plate.

[0012] On the outer side wall of the upper pressure cover plate, a telescopic device is fixedly installed. The push rod of the telescopic device is fixedly connected to the cover plate. There are two concave sliding grooves at the bottom of the cover plate, and each concave sliding groove is in sliding contact with a convex sliding rail; on the upper side of the upper pressure cover plate, two positioning plates are fixedly installed. The positions of each positioning plate and each limiting plate are vertically corresponding and arranged in the same direction; a lighting and photographing device is installed on one side of the positioning plate.

[0013] The first arm is a hollow rod, and the inside of the hollow rod is used to fill power lines and data lines. On one side wall of the first arm, a first stress gauge is horizontally fixedly installed, and on the other side wall of the first arm, a plurality of second stress gauges are vertically fixedly installed.

[0014] Wire holes are provided at the connection positions of the side wall of the first arm with the first stress gauge and the second stress gauges.

[0015] A method for using a device for efficiently measuring in-situ stress by using an expansive agent includes the following steps: S1. Remove the first stress plate and the second stress plate, place the device into the hole, open the cover plate, and use a suction machine to suck out all the rock fragments in the hole. S2. Use the suction machine and the suction pipeline to first pour the expansive material into the cover hole left on the upper pressure cover plate. After filling, retract the suction pipeline of the suction machine, and close the cover hole with the cover plate; the expansive material expands on the inner wall of the hole opening to generate cracks. S3. Use the first vibrator and the second vibrator to loosen the solidified expansive material, then use the suction machine to clean the expansive agent, and then take out the device from the hole. S4. Install the first stress plate and the second stress plate on the device, then place the device into the hole, and through the lighting and photographing device and rotate the shaft rod to make the positioning plate correspond to the position of the crack in step S2; the second pouring of the expansive material is the same as the operation in step S2. After the second pouring, measure and obtain and ; then calculate and obtain , , after the measurement is completed, repeat step S3. In step S1, the components and mass fractions of the rock fragments are 65% SiO2, 14% Al2O3, 4.5% K2O, 4.2% H2O, 3.2% Na2O, 2.1% Fe2O3, and the balance is ash impurities. In step S4, is the measured value of the tensile strength of the rock, is the stress in the hole, corresponding to on the stress curve. After that, the balance point of the stress in the hole and the minimum principal stress is ; is numerically equal to the minimum principal stress ; The minimum principal stress of the rock is , the maximum principal stress of the rock is ; = ; = ; , , , , and the unit of all of them is MPa.

[0016] Preferably, the expansive agent is powdered calcium oxide.

[0017] Preferably, the radius of the hole is 0.5 - 1.2 cm larger than the radius of the pressure cover plate.

[0018] Preferably, the thickness of the first stress plate and the second stress plate is 3 - 5 cm.

[0019] Preferably, the width of the limiting plate is below 0.5 cm.

[0020] Preferably, in step S2, the expansion time of the expansion material for the first perfusion is 4.2 - 5 hours.

[0021] Preferably, the expansion material is calcium oxide and water that are uniformly mixed, and in terms of mass ratio, calcium oxide: water = 3:1.

[0022] Preferably, the reaction of the expansion material for the first perfusion causes cracks to have been generated in the hole, and the positions of the cracks correspond to the direction of the maximum principal stress.

[0023] Compared with the prior art, the beneficial effects of the present invention: a. The present invention provides a device and method for efficiently measuring in - situ stress using an expansive agent. This device takes the expansive agent as the stress source, and the huge expansion force generated by its expansion upon contact with water generates cracks in the rock and gradually breaks it. This device uses the expansive agent to efficiently measure in - situ stress, which is different from the hydraulic fracturing measurement method, and the device operation is simple.

[0024] b. The device of the present invention is simple to manufacture, suitable for complex mountainous areas, environments with insufficient power and inconvenient transportation. The equipment mainly relies on the expansive agent, has low power requirements, and can also complete the measurement with a small mobile power source.

[0025] c. The present invention uses the limiting plate 11 to restrict the moving directions of the first stress plate 1 and the second stress plate 101. After determining the direction of the principal stress, the direction of the limiting plate 11 is adjusted through the shaft rod 2, so that the first stress plate 1 and the second stress plate 101 correspond to the direction of the principal stress.

[0026] d. The present invention uses the first arm 12 and the second arm 13 to place stress gauges. The hollow design inside the two arms facilitates the connection of the power supply wires of the stress gauges, and stress gauges can be placed at different positions and in different directions on the arms, increasing the average randomness of the data. The first stress gauge 8 and the second stress gauge 801 of the present invention select piezoresistive sensors to collect stress data, and their operating temperature can be -40°C to 70°C, overcoming the difficulty that water is prone to freezing at sub-zero temperatures in the hydraulic fracturing method. The acquisition time is <1 ms, the measurement range is wider, and the accuracy of the collected data is greatly improved. Moreover, the first stress gauge 8 and the second stress gauge 801 are dispersed horizontally and vertically on the arms, and the stress data error is smaller. The stress accuracy of the device of the present invention is 0.0001 MPa.

[0027] e. The present invention uses a suction machine to clean the device and recover the expansive agent. Regarding the characteristics of the powder after the reaction of the expansive agent, the suction method is simple and fast.

[0028] f. Compared with the high measurement cost of the hydraulic fracturing method, the comprehensive cost of one measurement by the hydraulic fracturing method is 150,000 - 250,000. In contrast, this device uses inexpensive raw material costs of the expansive agent and has a simple device structure, requiring less manpower and material resources, reducing the measurement cost to 3,000 - 5,000, greatly reducing the economic cost.

[0029] g. The first stress plate 1 and the second stress plate 101 of the present invention are two arc-shaped thickness plates. There is a gap separated by a limiting plate 11 between the butt joints of the first stress plate 1 and the second stress plate 101. During measurement, through the positioning plate 16 and the lighting and photographing device 17, multiple comparisons are made with the cracks generated for the first time to achieve the accurate alignment of the limiting plate 11 with the cracks. After determining the principal stress direction through the cracks, the directions of the first stress plate 1 and the second stress plate 101 are adjusted to be consistent with the principal stress direction, and the magnitude of the principal stress can be accurately measured.

[0030] h. Compared with the traditional hydraulic fracturing method, the present invention selects calcium oxide as the expansive agent. After the expansive agent is mixed with water, due to the self-sealing of the device itself and the characteristic that the expansive agent gradually solidifies after the reaction, less loss of the expansive material occurs in the cracks, and the influence of stress changes is more gentle. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall device of the present invention.

[0032] Figure 2 It is the enlarged structural schematic diagram at position A of the device of the present invention Figure 1 at the dashed line.

[0033] Figure 3 It is the schematic diagram of the internal structure of the device of the present invention.

[0034] Figure 4Schematic diagrams of the first arm structure and the second arm structure of the device of the present invention.

[0035] Figure 5 Cross-sectional view of the underground operation of the device of the present invention.

[0036] Figure 6 Schematic diagram of the stress force on the stress plate of the device of the present invention.

[0037] Figure 7 Time history curve of the expansion stress in the fracture test hole of the device of the present invention.

[0038] Reference numerals: first stress plate 1, second stress plate 101, shaft rod 2, upper pressure cover plate 3, telescopic device 4, cover plate 5, convex slide rail 501, first nut 6, second nut 7, first stress gauge 8, second stress gauge 801, lower pressure plate 9, suction machine 10, limit plate 11, first arm 12, second arm 13, first vibrator 14, second vibrator 15, positioning plate 16, lighting and photographing device 17. Detailed implementation manners

[0039] It should be understood that the orientation or positional relationship indicated by terms such as "bottom, side wall, one side, top, inner side, upper side, outer side, the other side" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to the present invention.

[0040] In addition, the description in the present invention only refers to the preferred embodiments of the present invention and is not used to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions recorded in each embodiment or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0041] Preferably, calcium oxide is in powder form, which is convenient for flowing after being mixed with water, and the powdered calcium oxide can be directly purchased from the market.

[0042] Preferably, the telescopic device 4 is purchased from Boyang Technology Co., Ltd., model YH8-522 and its related supporting power supply and circuit.

[0043] Preferably, the stress gauge 8 is purchased from Aidong Thin Film Electronic Technology Co., Ltd., model IMS-CO4A and its related supporting power supply and circuit.

[0044] Preferably, the suction machine 10 is purchased from Jieba Company, model BF501, along with its related power supply and circuit; and the suction pipe for the supporting suction machine 10.

[0045] Preferably, the first vibrator 14 is purchased from Zhenke Co., Ltd., model zk-0.1, along with its related power supply and circuit.

[0046] Preferably, a wire hole is also provided at the bottom of the side wall of the shaft rod 2, and the data lines and power lines of the first vibrator 14 and the second vibrator 15 are connected to an external power supply and a computer through the wire hole.

[0047] Preferably, the lighting and shooting device 17 is purchased from Rerwei Vision Co., Ltd., model RER-USB4KCAM03H, along with its related power supply and circuit.

[0048] Preferably, the lighting and shooting device 17 is powered by a storage battery.

[0049] The telescopic device 4, the stress gauge 8, the first vibrator 14, the suction machine 10, and the lighting and shooting device 17 are powered by an external power supply connected to a computer.

[0050] The name of the measurement software installed in the computer: strain DAQ; version: Version1.0, sold by Shanghai Chengke Electronic Technology Co., Ltd.

[0051] The telescopic device 4, the stress gauge 8, the suction machine 10, the first vibrator 14, and the second vibrator 15 are all connected to the computer through data lines, and the lighting and shooting device 17 is wirelessly connected to the computer.

[0052] The first stress plate 1, the second stress plate 101, the first arm 12, the second arm 13, the upper pressure cover plate 3, and the lower pressure plate 9 are preferably made of 7075 aluminum alloy. The model of the aluminum alloy is 7075 aluminum alloy, and the 7075 aluminum alloy is purchased from Yimai Aluminum Industry Jiangsu Group Co., Ltd.

[0053] This application does not improve the power circuit. All the device components used can be purchased in the market. The selected models in this patent are only for convenience of description, rather than limiting that only this type of instrument model must be used. The use of data lines or wireless connections for each component in this application is also only for convenience of description, rather than limiting that only this connection method must be used.

[0054] Example 1 Refer to Figures 1 to 6 , a device for efficiently measuring in-situ stress using an expansive agent, comprising a shaft rod 2, and the bottom of the shaft rod 2 is fixedly connected to a lower pressure plate 9. The shaft rod 2 is a hollow spiral rod, and there are two small holes left on the side wall of the shaft rod 2. Each small hole is fixedly connected and communicated with a first arm 12 and a second arm 13 respectively. The first nut 6 and the second nut 7 are movably and helically connected to the side wall of the shaft rod 2, and the side wall of the shaft rod 2 is movably mounted and helically connected to the inner wall of the screw hole of the upper pressure cover plate 3. The upper pressure cover plate 3 is installed between the first nut 6 and the second nut 7, and one side of the bottom of the upper pressure cover plate 3 is in close contact with the top side walls of the first stress plate 1 and the second stress plate 101.

[0055] One side of the bottom of the upper pressure cover plate 3 is in close contact with the top side walls of the first stress plate 1 and the second stress plate 101, and the first stress plate 1 is a semi-hollow cylindrical height plate.

[0056] The side walls of the first stress plate 1 and the second stress plate 101 are in close contact but not connected. The top side walls of the first stress plate 1 and the second stress plate 101 are respectively in close contact with the side walls on both sides of the limiting plate 11. The limiting plate 11 separates the first stress plate 1 and the second stress plate 101, and the first stress plate 1 and the second stress plate 101 are vertically placed at the edge of the circular side wall on the upper side of the pressure plate 9.

[0057] One side of the top of the lower pressure plate 9 is in close contact with the bottom side walls of the first stress plate 1 and the second stress plate 101, and the first vibrator 14 and the second vibrator 15 are fixedly installed on the upper side of the pressure plate 9.

[0058] 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 sides of the cover plate hole. The convex slide rails are semi-cylindrical convex slide rails 501.

[0059] 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. The two limiting plates 11 pass through the axis where the center of the upper pressure cover plate 3 is located, and the length of the limiting plates 11 extends to the edge of the side wall of the upper pressure cover plate 3.

[0060] The telescopic device 4 is fixedly installed on the outer side wall of the upper pressure cover plate 3. The push rod of the telescopic device 4 is fixedly connected to the cover plate 5. There are two concave chutes at the bottom of the cover plate 5, and each concave chute is in sliding contact with the convex slide rail.

[0061] 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 and the position of each limiting plate 11 are vertically corresponding and parallel in the same direction. A lighting and photographing device 17 is installed on one side of the positioning plate 16.

[0062] The first arm 12 is a hollow rod, and the inside of the hollow rod is used to load power lines and data lines. One side wall of the first arm 12 is horizontally fixedly installed with a first stress sheet 8, and the other side wall of the first arm 12 is vertically fixedly installed with a plurality of second stress sheets 801.

[0063] Wire holes are provided at the connection positions of the side wall of the first arm 12 with the first stress sheet 8 and the second stress sheets 801.

[0064] Preferably, the first nut 6 and the second nut 7 are used to fix the upper pressure cover plate 3.

[0065] Preferably, the cover plate holes on the upper pressure cover plate 3 are used for the suction machine 10 to suck the rock debris and impurities inside the device.

[0066] Preferably, the side wall of the shaft rod 2 has threads.

[0067] Preferably, two second stress gauges 801 are vertically fixed on the other side wall of the first arm 12.

[0068] Preferably, the first stress plate 1 and the second stress plate 101 are exactly the same.

[0069] Preferably, the first stress gauge 8 and the second stress gauge 801 are exactly the same.

[0070] Preferably, the first vibrator 14 and the second vibrator 15 are exactly the same.

[0071] The upper pressure cover plate 3 and the lower pressure plate 9 are fixed by the shaft rod 2 penetrating up and down and form an open space of a cylinder with the first stress plate 1 and the second stress plate 101.

[0072] The upper pressure cover plate 3 is fixed by the first nut 6 and the second nut 7 on the shaft rod 2. At the same time, the relative height of the upper pressure cover plate 3 is also adjusted by the first nut 6 and the second nut 7.

[0073] The shaft rod 2 is made of 7075 aluminum alloy. The side wall of the shaft rod 2 has threads. The bottom of the shaft rod 2 is welded to the lower pressure plate 9 to form an integral body. The lower pressure plate 9 does not need to reserve an opening and can be directly welded, which simplifies the installation process and can also improve the connection stability.

[0074] The upper part of the upper pressure cover plate 3 is provided with cover plate holes for cleaning the dust in the hole wall, placing the expansive agent, and recovering the subsequent expansive agent.

[0075] A movable cover plate 5 is placed at the edge of the upper pressure cover plate 3. A groove slide rail is left on the side of the cover plate 5 for pulling back and forth. One side of the cover plate 5 is fixedly connected with a telescopic device 4, which is convenient for the subsequent filling and recovery of the expansive agent.

[0076] There are two vertical first arms 12 and second arms 13 on the side wall of the shaft rod 2. A first stress gauge 8 is horizontally fixed on one side wall of the first arm 12, and multiple second stress gauges 801 are vertically fixed on the other side wall of the first arm 12. The second arm 13 is exactly the same as the first arm 12. Second stress gauges 801 are vertically and vertically installed on the first arm 12 and the second arm 13 respectively, and the first stress gauges 8 are horizontally. A plurality of first stress gauges 7 and second stress gauges 8 are arranged in parallel in the device to prevent all stress gauges from failing due to high temperature and extrusion damage pressure.

[0077] 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.

[0078] Place the device of the present invention in the hole. First, open the cover plate 5, and the suction machine 10 sucks the rock debris and impurities inside the device. After the stress detection is completed, the suction machine 10 is also used to clean the inside of the device.

[0079] The cylindrical first vibrator 14 and the second vibrator 15 are fixed on the lower pressure plate 9. When recovering the expansive agent, since the expansive agent is compacted, it cannot be directly sucked. First, turn on the first vibrator 14 and the second vibrator 15 to vibrate, so that the expansive agent loosens into relatively loose fine particles for suction cleaning.

[0080] 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 and shift when they are lowered into the hole.

[0081] The upper pressure cover plate 3 and the lower pressure plate 9 have the same radius.

[0082] The radius of the hole is 0.5 - 1.2 cm larger than the radius of the upper pressure cover plate 3.

[0083] The length of the shaft rod 2 is greater than the depth of the hole, and the length of the shaft rod 2 can be set according to the depth of the hole.

[0084] 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.

[0085] The thickness of the first stress plate 1 and the second stress plate 101 is 3 - 5 cm. If the first stress plate 1 and the second stress plate 101 are too thick, when filling the same volume of expansive 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 measured. The expansive agent will not be able to fully push open the first stress plate 1 and the second stress plate 101, and the cracking effect cannot be achieved. If the first stress plate 1 and the second stress plate 101 are too thin, they will fall into the gap reserved between the hole and the device during the process of moving or adjusting the device.

[0086] Embodiment 2 A method for using a device for efficiently measuring in-situ stress by using an expander, comprising the following steps: S1. Remove the first stress plate 1 and the second stress plate 101, place the device into the hole, open the cover plate 5, and use the suction machine 10 to suck out all the rock fragments in the hole; S2. Use the suction machine 10 and the suction pipeline to first pour the expansion material into the cover plate hole left in the upward pressure cover plate 3. After filling, retract the suction pipeline of the suction machine 10, and use the cover plate 5 to close the cover plate hole; the expansion material expands on the inner wall of the hole entrance to generate cracks; 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 expander, and then take out the device from the hole; S4. Install the first stress plate 1 and the second stress plate 101 on the device, then place the device into the hole, and through the lighting and photographing device 17 and rotate the shaft rod 2 to make the positioning plate 16 correspond to the position of the crack in step S2; the second pouring of the expansion material is the same as the operation in step S2. After the second pouring, measure to obtain and ; then calculate to obtain , , after the measurement is completed, repeat step S3.

[0087] In the above step S1, place the device into the hole, control the telescopic device 4 to open the cover plate 5, and use the suction machine 10 to suck the hole clean. In this case, the first stress plate 1 and the second stress plate 101 are not placed; In the above step S2, after the hole is sucked clean, prepare the expansion material, configure it according to the ratio of expander: water = 3:1, fully mix and stir, use the suction machine 10 and the suction pipeline to pour the expansion material, retract the suction pipeline after pouring, and close the cover plate 5 of the reserved hole; wait for the expander to react and expand; In the above step S3, after the expander reacts and no longer generates expansion force, at this time, first use the first vibrator 14 and the second vibrator 15 to loosen the solidified expander, then use the suction machine 10 to clean the expander, and then take the device out of the hole; In the above step S4, due to the first reaction, cracks have been generated in the hole, and the position of the cracks corresponds to the direction of the maximum principal stress; when the device is placed for the second time, put it into the hole together with the first stress plate 1 and the second stress plate 101. In this measurement, the position of the device needs to be adjusted. Observe the position of the crack through the lighting and photographing device 17, and manually rotate the shaft rod 2 of the device to make both ends of the positioning plate 16 correspond to the position of the crack; after adjusting the position of the positioning plate 16, the second pouring of the expansion agent material is the same as that in step S2, and then start the stress detection. Each stress gauge transmits the data back to the computer, and measure to obtain and ; thus calculate to obtain , , after the measurement, repeat step S3 once.

[0088] As Figure 6 shown, the direction of the minimum principal stress is perpendicular to the direction of the maximum principal stress . Therefore, when the limiting plate 11 is placed parallel to the crack, the measured and ; then calculate to obtain , .

[0089] A structural positioning plate 16 parallel to the limiting plate 11 is fixedly connected and installed on the upper surface of the upper pressure cover plate 3, which is convenient for keeping the position of the limiting plate 11 parallel to the crack when the shaft rod 2 rotates during the second placement into the hole, with the assistance of the lighting and photographing device 17.

[0090] Preferably, calcium oxide is used as the expansive agent, and the mass ratio of the expansive agent to water is 3:1. Stir evenly and put it into the suction machine 10. The reaction between the expansive agent and water generates a huge expansive force, causing the rock to be cracked to produce cracks.

[0091] When cleaning the expansive agent, first turn on the first vibrator 14 and the second vibrator 15; loosen the expansive agent for 3 - 5 minutes, then open the upper cover plate 5. After the reaction between the expansive agent and water is completed, it becomes powdery, and the suction machine 10 can be used to suck and clean the expansive agent.

[0092] Example 3 After drilling the rock, the residual rock fragments at the bottom of the hole, the components and mass fractions of the rock fragments are SiO2 65%, Al2O3 14%, K2O 4.5%, H2O 4.2%, Na2O 3.2%, Fe2O3 2.1%, and the balance is ash impurities; the depth of the hole of the rock is 15 meters, the radius of the hole of the rock is 8 cm, the radius of the upper pressure cover plate 3 of the device is 7 cm, the inner wall spacing between the upper pressure cover plate 3 and the lower pressure plate 9 is 40 cm, and the mass ratio of calcium oxide expansive agent to water is 3:1. The expansive material calcium oxide and water are stirred at 1400 r / min for 10 minutes.

[0093] The outer diameter of the shaft rod 2 is 1 cm.

[0094] The thickness of the first stress plate 1 and the second stress plate 101 is 5 cm.

[0095] The width of the two limiting plates 11 is 0.2 cm, the height is 0.5 cm, and the length is 4 cm.

[0096] The width of the gap between the first stress plate 1 and the second stress plate 101 is also 0.2 cm.

[0097] The thickness of the first stress plate 1 and the second stress plate 101 is 3 - 5 cm.

[0098] For the following operation of pouring the expansive agent, just finish pouring the expansive agent within 40 - 50 s.

[0099] For the first filling of the expansive 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 the expansive agent. After filling, close it and let it stand for 4.2 - 5 hours.

[0100] For the second filling of the expansive material, set 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 the expansive agent. After filling, close it and start measuring; the second measurement time is 20 h.

[0101] As Figure 7 shown, the stress change process is divided into four stages. Figure 7 The stress data

[0102] The functions of the first stress plate 1 and the second stress plate 101 are to concentrate the stress.

[0103] In the first stage, the expansive agent reacts with water in the device to accumulate stress, and the expansive force generated by the expansion continuously rises, and the stress data continuously increases.

[0104] In the second stage, the stress reaches the maximum value at the vertex A. Since cracks have appeared in the first measurement, at this time, the measured expansion pressure in the device is slightly less than the tensile strength of the rock. In this application, the expansion pressure in the device can be approximated as the tensile strength of the rock. When the cracks in the surrounding rock around the borehole are pulled open again, the stress at this time is recorded as , and the physical meaning of point A is: represents the tensile strength of the rock, that is, the first stress peak of the stress curve, and the direction of the generated crack is the direction of the maximum principal stress. After cracks appear, the first stress plate 1 and the second stress plate 101 expand outwards, the gap between the first stress plate 1 and the second stress plate 101 becomes larger, and a small amount of the expansive agent flows into the cracks, resulting in a rapid drop in the expansion pressure in the device.

[0105] ​In the third stage, the expansion pressure in the device decreases gradually. Point B is used as the dividing point between the second stage and the third stage. The selection mark of point B is: the stress change rate k=-4.5 in the selected point c on the left side of point B and the stress change rate in the selected point d on the right side changes from k=-1 to k=0.2. It can be judged that the stress change rate around point B increases from k=-4.5 to k=-1, and the change range is the most obvious. This characteristic point is used as the selection standard of point B. The physical meaning of the inflection point B is: the equilibrium point between the stress in the hole and the minimum principal stress. is the hole stress at B, Minimum principal stress Numerically equal, .

[0106] In stage IV, the stress slowly decreases. After cracks have formed in the surrounding rock around the closed fracture space, the pressure dissipates to the stage III platform for a short stay, and then the stress drops further, showing a fluctuating drop, and the drop speed is significantly slower than that in stage II, gradually slowing down until the stress drops to 0.

[0107] Refer to the method of obtaining the principal stress values in Rock Mechanics: , .

[0108] Measured Take the stress value at point A, Take the stress value at point B, see the attached Figure 7 The stress values of all the first stress sheets 8 and the second stress sheets 801 in the device are averaged. , , , The unit is MPa.

[0109] The present invention sets the above parameters in the embodiments for the convenience of explaining the method of using the device. Those skilled in the art can adjust and modify the above parameters as needed through the experimental parameters disclosed in the embodiments of this application without making any creative efforts. For example, the inner wall spacing between the upper pressure cover plate 3 and the lower pressure plate 9 can be modified 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 sheets, replace the materials of various components of the device, etc. Such modifications also fall within the scope of protection of the present application.

[0110] Since the vertex A and inflection point B of the rock are independent of the ratio of the expansive agent and the mass of the expansive agent, the addition amount of the expansive agent can be adjusted as needed. Without special instructions in this application, it is considered filled as long as it is filled until the expansive agent contacts the bottom wall of the upper pressure cover plate 3. Those skilled in the art can adjust the amount of the added expansive agent and the ratio of the expansive agent as needed, and these improvements also fall within the protection scope of the present invention.

Claims

1. An apparatus for efficiently measuring in-situ stress using an expander, comprising a shaft rod (2), characterized in that, The bottom of the shaft rod (2) is fixedly connected to the lower pressure plate (9). The shaft rod (2) is a hollow spiral rod. There are two small holes on the side wall of the shaft rod (2), and each small hole is fixedly connected to the first support arm (12) and the second support arm (13) respectively. The first nut (6) and the second nut (7) are movably spirally connected to the side wall of the shaft rod (2), and the inner wall of the threaded hole of the upper pressure cover plate (3) is spirally connected to the side wall of the shaft rod (2). The upper pressure cover plate (3) is installed between the first nut (6) and the second nut (7). One side of the bottom of the upper pressure cover plate (3) is in close contact with the top side walls of the first stress plate (1) and the second stress plate (101).

2. The device for efficiently measuring in-situ stress by using an expander according to claim 1, characterized in that, One side of the bottom of the upper pressure cover plate (3) is in close contact with the top side walls of the first stress plate (1) and the second stress plate (101). The first stress plate (1) is a semi-hollow cylindrical height plate.

3. The device for efficiently measuring in-situ stress by using an expander according to claim 1, characterized in that, The top side walls of the first stress plate (1) and the second stress plate (101) are respectively in close contact with the side walls 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 vertically placed at the edge of the circular side wall on the upper side of the pressure plate (9).

4. The device for efficiently measuring in-situ stress using an expansive agent according to claim 1, characterized in that, One side of the top of the lower pressure plate (9) is in close contact with the bottom side walls of the first stress plate (1) and the second stress plate (101). The first vibrator (14) and the second vibrator (15) are fixedly installed on the upper side of the pressure plate (9).

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

6. The device for efficiently measuring in-situ stress using an expander according to claim 1, wherein 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. The two limiting plates (11) pass through the axis where the center of the upper pressure cover plate (3) is located, and the length of the limiting plates (11) extends to the edge of the side wall of the upper pressure cover plate (3).

7. The device for efficiently measuring in-situ stress by using an expander according to claim 1, wherein, A telescopic device (4) is fixedly installed on the outer side wall of the upper pressure cover plate (3). The push rod of the telescopic device (4) is fixedly connected to the cover plate (5). There are two concave slide grooves at the bottom of the cover plate (5), and each concave slide groove is in close sliding contact with the convex slide rail; 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 to the position of each limiting plate (11) up and down and is set in the same direction; a lighting and photographing device (17) is installed on one side of the positioning plate (16).

8. The device for efficiently measuring in-situ stress by using an expander according to claim 1, wherein The first support arm (12) is a hollow rod, and the inside of the hollow rod is used for filling power lines and data lines. One side wall of the first support arm (12) is horizontally fixedly installed with a first stress sheet (8), and the other side wall of the first support arm (12) is vertically fixedly installed with a plurality of second stress sheets (801).

9. The device for efficiently measuring in-situ stress by using an expansive agent according to claim 1, wherein Wire holes are arranged at the connection positions of the side wall of the first support arm (12) with the first stress sheet (8) and the second stress sheets (801).

10. The usage method of a device for efficiently measuring in-situ stress by using an expansive agent according to any one of claims 1 to 9, characterized in that, It includes the following steps: S1. Remove the first stress plate (1) and the second stress plate (101), place the device into the hole, open the cover plate (5), and use the suction machine (10) to suck out all the rock fragments in the hole. S2. Use a suction machine (10) and a suction pipeline to first pour the expansion material into the cover hole left on the upward pressure cover plate (3). After filling, retract the suction pipeline of the suction machine (10), and use a cover plate (5) to close the cover hole; the expansion material expands on the inner wall of the hole to generate cracks. S3. Use a first vibrator (14) and a second vibrator (15) to loosen the solidified expansion material, then use a suction machine (10) to clean the expander, and then take out the device from the hole. S4. Install the device on the first stress plate (1) and the second stress plate (101), then place the device into the hole. Take pictures through the lighting device (17) and rotate the shaft rod (2) to align the positioning plate (16) with the position of the crack in step S2. The operation of the second injection of the expansion material is the same as that in step S2. After the second injection, measure to obtain and ; then calculate to obtain , . After the measurement, repeat step S3; In the step S1, the rock mass gravel components and mass fractions are respectively SiO2 65%, Al2O3 14%, K2O 4.5%, H2O 4.2%, Na2O 3.2%, Fe2O3 2.1%, and the balance is ash impurities. In the step S4, is the measured value of the tensile strength of the rock, is the in-hole stress, corresponding to on the stress curve. The balance point between the in-hole stress and the minimum principal stress is ; is numerically equal to the minimum principal stress . The minimum principal stress of the rock is , and the maximum principal stress of the rock is ; = ; = ; , , , The units of all are MPa.

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