In-situ stress level measuring device and measuring method

Abstract

The present application relates to geotechnical mechanics measurement technical field, provide a kind of original rock stress level measuring device and measuring method, measuring device includes main frame, contact plate, expansion assembly, telescopic detection piece and, the inside of main frame is formed with accommodating chamber;Contact plate is connected with main frame by elastic connecting piece, and it is evenly spaced and arranged in the outer periphery of main frame;Expansion assembly is located in accommodating chamber, expansion assembly is used to drive each contact plate to move towards the direction of moving away from the main frame simultaneously;Telescopic detection piece is located between two opposite contact plates, to sense the relative displacement of opposite contact plate.The measurement of original rock stress level, usually need to drill hole sampling in the region to be measured, to measure.The present application is simple in structure, easy to operate, and has the characteristics of data and information, overcomes the problem of low measurement accuracy of original rock stress level in traditional method, high rock quality dependency, efficient process, easy to repeat test.

Description

Technical Field

[0001] This invention relates to the field of geotechnical mechanics measurement technology, specifically to a device and method for measuring the stress level of original rock. Background Technology

[0002] Measuring the stress level of the original rock is a fundamental prerequisite for preventing rockbursts, selecting cavern sites, conducting scientific construction, and designing support systems. If construction proceeds blindly without accurately understanding the stress level of the original rock in the project area, it will lead to delays in construction progress, potential quality problems, and even induce safety accidents such as rock instability, resulting in significant economic losses. Therefore, a quantitative assessment of the stress level of the original rock is essential during the construction and design process.

[0003] In related technologies, methods for obtaining rock mass stress levels mainly fall into two categories: one is to indirectly infer the original rock stress level by drilling rock cores in the field and sending them to the laboratory for stress recovery or stress relief tests. This method is complex and costly, and as it involves non-in-situ testing, the rock cores are easily disturbed during sampling, transportation, and preparation, leading to significant deviations between experimental results and actual in-situ stress. The other type of method relies on localized in-situ testing techniques, such as borehole collapse and hydraulic fracturing. While these methods offer advantages such as short testing cycles and simple sample processing, their overall accuracy is limited, and they are highly dependent on the integrity of the rock mass. They are also insufficient to comprehensively reflect the distribution characteristics of the original rock stress level at the engineering scale. Summary of the Invention

[0004] This invention provides a device and method for measuring the stress level of original rock, which solves the defects of existing technologies such as high measurement difficulty and limited measurement accuracy.

[0005] This invention provides a device for measuring the stress level of original rock, comprising: a main frame, contact plates, an expansion assembly, and a telescopic detection element; a receiving chamber is formed inside the main frame; the contact plates are connected to the main frame via elastic connectors and are evenly spaced on the outer periphery of the main frame; the expansion assembly is disposed in the receiving chamber and is used to drive each contact plate to move simultaneously in a direction away from the main frame; the telescopic detection element is disposed between two opposing contact plates to sense the relative displacement of the opposing contact plates.

[0006] According to the original rock stress level measuring device provided by the present invention, the main frame includes a plurality of support columns and fixed plates disposed at both ends of the support columns. The fixed plates are fixedly connected to the support columns and form the accommodating chamber between the fixed plates at both ends.

[0007] According to the original rock stress level measuring device provided by the present invention, the elastic connector includes a return spring, one end of which is connected to the contact plate, and the other end of which is in contact with the fixed plate.

[0008] According to the original rock stress level measuring device provided by the present invention, the expansion component includes a flexible bladder and a medium filling and discharging component. The flexible bladder is disposed in the receiving cavity and communicates with the medium filling and discharging component. The medium filling and discharging component is configured to fill the flexible bladder with a medium to apply a force to the contact plate, causing the contact plate to move in a direction away from the main frame.

[0009] According to the original rock stress level measuring device provided by the present invention, the medium filling and discharging assembly includes a medium delivery pipe and a drive pump, wherein the output end of the drive pump is connected to the medium delivery pipe to drive the filling medium to be input into the flexible bladder.

[0010] The original rock stress level measuring device provided by the present invention further includes a protective box, which is disposed in the accommodating chamber and connected to the main frame; wherein, a protective groove is provided inside the protective box, and the telescopic detection element is disposed in the protective groove.

[0011] According to the original rock stress level measuring device provided by the present invention, the telescopic detection element includes a columnar main body, both ends of which are provided with telescopic ends. The two telescopic ends extend from the protective box and are connected to the contact plate on their respective sides. In a preferred embodiment, a welding hole is provided on the side wall of the contact plate, and the telescopic ends are connected to the contact plate through the welding hole.

[0012] According to the original rock stress level measuring device provided by the present invention, one end of the main frame is provided with a hollow transfer rod, and the transfer rod is fixedly connected to the main frame.

[0013] The original rock stress level measuring device provided by the present invention further includes a display, which is electrically connected to the telescopic detection element for displaying the measured data.

[0014] The present invention also provides a measurement method based on the aforementioned original rock stress level measuring device, comprising the following steps: Step S10: Use a transfer rod to send the measuring device to the depth to be measured in the preset borehole.

[0015] Step S20: Initiate the expansion assembly to expand, thereby applying a force to the contact plate, causing the contact plate to move away from the main frame; Step S30: While moving, the telescopic detection component acquires the displacement amount; Step S40: Calculate the original rock stress level based on the following formula: ; In the formula, δ represents the radial displacement of the rock wall; σ represents the stress level. This is related to the value of the elastic modulus E of the rock mass.

[0016] The present invention provides a device and method for measuring the stress level of original rock. The measuring device has a simple overall structure and is easy to operate. It also has data-driven and information-based features, which overcomes the problems of low measurement accuracy and high dependence on rock quality in traditional methods for measuring the stress level of original rock. The process is efficient and easy to repeat. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is one of the overall structural schematic diagrams of the original rock stress level measuring device provided by the present invention.

[0019] Figure 2 This is the second schematic diagram of the overall structure of the original rock stress level measuring device provided by the present invention.

[0020] Figure 3 This invention provides Figure 2 Cross-sectional view of the structure along the AA direction.

[0021] Figure 4 This invention provides Figure 2 A structural sectional view along the BB direction.

[0022] Figure 5 This is a schematic diagram of the overall structure of the expansion component in the original rock stress level measuring device provided by the invention.

[0023] Figure 6 This invention provides Figure 5 Cross-sectional view of the structure along the CC direction.

[0024] Figure 7 This is a top view of the expansion component in the original rock stress level measuring device provided by the invention.

[0025] Figure 8 This invention provides Figure 7 Cross-sectional view of the structure along the DD direction.

[0026] Figure 9 This is a schematic diagram of the overall structure of the main frame of the original rock stress level measuring device provided by the invention.

[0027] Figure 10 This is one of the exploded structural diagrams of the fixed disk in the original rock stress level measuring device provided by the invention.

[0028] Figure 11 This is the second of the exploded structural diagrams of the fixed disk in the original rock stress level measuring device provided by the invention.

[0029] Figure 12 This is a schematic diagram of the overall assembly and use of the original rock stress level measuring device provided by the invention.

[0030] Figure 13 This is a flowchart illustrating the measurement method based on the original rock stress level measuring device provided by the invention.

[0031] Figure 14 This is a finite element numerical model diagram of the measurement method of the present invention.

[0032] Figure 15 This invention relates to a family of curves and mathematical fitting diagrams showing the relationship between geostress level and rock wall displacement.

[0033] Figure label: 1. Contact plate; 2. First protruding post; 3. Welding hole; 4. Telescopic detection component; 5. Return spring; 6. Support post; 7. Connecting plate; 8. Protective box; 801. Protective groove; 9. Second protruding post; 10. Protective cover; 101. Clearance groove; 11. Flexible bladder; 12. Medium delivery pipe; 13. Drive pump; 14. Delivery rod; 15. Data cable; 16. Display. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0035] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the purpose of clarifying the embodiments of 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 limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0037] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0038] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0039] There are generally two methods for obtaining rock mass stress levels: one is to directly obtain rock mass samples for testing, and the other is to use on-site local testing methods, such as borehole collapse and hydraulic fracturing. The measurement schemes in related technologies that directly obtain rock mass stress levels (such as stress relief methods) generally suffer from problems such as complex operation, high cost, and measurement accuracy being easily affected by rock mass disturbance.

[0040] To address the aforementioned problems, the technical solution of this application provides an indirect evaluation approach, which infers the stress state of the rock mass by observing its deformation response under load. Both theoretical analysis and engineering practice show that for rock masses with different elastic moduli, even under the same external load, the resulting displacement will significantly differ due to variations in their initial stress levels. The digital expansion device can efficiently and accurately acquire displacement data of the rock wall under external pressure. By establishing the relationship between rock wall displacement and stress level under different elastic moduli, the device can measure the original rock stress level.

[0041] The following is combined Figures 1-10 This invention describes a device for measuring the stress level of in-situ rock, comprising a main frame, contact plates 1, an expansion assembly, and a telescopic detection element 4. The main frame has an internal accommodating chamber. The contact plates 1 are connected to the main frame via elastic connectors and are evenly spaced around the outer periphery of the main frame. The expansion assembly is located within the accommodating chamber and drives each contact plate 1 to move simultaneously away from the main frame. The telescopic detection element 4 is located between two opposing contact plates 1 to sense the relative displacement of the opposing contact plates 1. In measuring the stress level of in-situ rock, drilling and sampling are typically required in the area to be measured. In this embodiment, the expansion assembly enables the driving of the contact plates 1, causing them to move. By detecting the displacement, the stress level can be indirectly measured. This measurement method improves measurement accuracy, and the overall structure of the measuring device is more compact.

[0042] Specifically, the main frame is cylindrical or columnar in shape, made of high-strength alloy (such as stainless steel), and hollow inside, forming an accommodating chamber. Contact plate 1 is an arc-shaped plate, with its outer arc curvature matching the nominal diameter of the target borehole to increase the contact area and improve coupling. An elastic connector limits the position of contact plate 1, allowing it to float. This enables the contact plate 1 to move when the expansion assembly is activated, preventing it from adhering to the inner wall of the borehole.

[0043] The expansion assembly enables simultaneous expansion of each contact plate 1, allowing for direct measurement of stress levels once the device reaches a designated position. The expansion assembly can be a mechanical expansion structure; for example, it could consist of a conical plug driven by a micro-motor positioned at the center of the accommodating chamber, with multiple radially sliding wedges surrounding the plug. When the conical plug moves axially, it pushes the wedges radially outward, thereby pushing against the contact plate 1. This mechanical self-locking structure offers the advantage of strong holding force. Alternatively, it could be a structure such as an air bladder or hydraulic bladder. See the following description for details.

[0044] The telescopic detection element 4 is laterally positioned between two opposing contact plates 1 along their diameter. Specifically, both ends of the telescopic detection element 4 are connected to the inner center points of the two opposing contact plates 1 via universal hinges or ball joints (not shown in the figure). The telescopic detection element 4 itself is a precision strain sensor, connected via an external connecting body. This connecting body has a telescopic function and can sense minute displacement changes through the precision strain sensor. When the device is expanded and fixed in the borehole by the expansion assembly, the rock wall inside the borehole undergoes radial elastic deformation under the action of the device. The amount of deformation is related to the elastic modulus (E) and the initial stress level (σ) of the rock mass. The device achieves real-time monitoring of the displacement of the contact plates 1 through the telescopic detection element, thereby enabling the establishment of a family of stress-displacement relationship curves under different elastic moduli and initial stress levels based on finite element numerical simulation (FLAC3D), achieving accurate measurement of rock wall stress.

[0045] The contact plate 1 is a rigid contact plate, which is made entirely of a hard material, such as metal or rigid plastic. In a preferred embodiment, the pressure-bearing capacity of the contact plate 1 needs to be greater than 70 MPa to meet the requirements of on-site operations.

[0046] It is understandable that, compared with the traditional method, this embodiment, through the coordinated arrangement of contact plate 1, expansion component and telescopic detection component 4, can realize the direct measurement of rock stress level. Moreover, this method can avoid the cumbersome procedures caused by sampling, and can directly perform in-situ measurement, which improves the measurement accuracy and can greatly shorten the measurement cycle.

[0047] In some embodiments, the original rock stress level measuring device further includes a processing module electrically connected to the telescopic detection element, which is used to receive the displacement signal collected by the telescopic detection element and perform data calculations based on a pre-stored finite element analysis model to obtain the original rock stress level.

[0048] Specifically, the processing module includes a storage unit and a computation unit. The storage unit pre-stores multiple elastic moduli corresponding to different rock masses. The corresponding stress-displacement fitting formula has the following general form: ; in, This indicates the radial displacement of the rock wall. Indicates the stress level of the original rock. , , , To match the elastic modulus of the rock mass Related fitting parameters The fitting formula is obtained based on the following finite element modeling and data fitting process: a finite element model of the measuring device applying lateral pressure to the borehole rock wall is established using numerical simulation software; different rock mass elastic moduli are set in the model. and initial ground stress level Calculate the radial displacement of the rock wall under a given lateral pressure. Through multiple groups The data is used to generate stress-displacement relationship curves corresponding to different elastic moduli; function fitting is performed on each curve to obtain the attenuation function expression as described above, and its parameters and elastic moduli are determined. The correspondence.

[0049] During actual measurement, the user inputs or selects the elastic modulus based on the characteristics of the rock mass at the site. The processing module automatically matches the corresponding fitting formula and parameters, combined with the displacement data collected in real time by the telescopic detection component. The stress level of the original rock is calculated by the computing unit. The results are then output to the monitor for display.

[0050] This embodiment integrates finite element analysis models with real-time data processing functions to achieve rapid, automatic, and accurate calculation of the original rock stress level, further enhancing the informatization and intelligence level of the measuring device.

[0051] In some embodiments, the main frame includes multiple support columns 6 and fixed plates at both ends of the support columns 6. The fixed plates are fixedly connected to the support columns 6, forming an accommodating chamber between the fixed plates at both ends. The main frame is used to support the entire device, and the device needs to be carried to the field for measurement. In this embodiment, the combination of multiple support columns 6 and fixed plates results in high overall structural strength, suitable for direct outdoor measurement. Furthermore, the use of support columns 6 makes the overall structure lighter and easier to carry.

[0052] Specifically, multiple support columns 6 are arranged circumferentially, and fixed plates are connected to both ends of the support columns 6 in the axial direction to form a cylindrical main frame. The fixed plates are connected to the support columns 6 by threaded connections, welding, or riveting, thereby enclosing an open and transparent accommodating chamber between the fixed plates at both ends. This design greatly facilitates the installation, wiring, and maintenance of other internal components.

[0053] In a specific configuration, there are four support columns 6, and four corresponding contact plates 1, located in the outer wall space between adjacent support columns 6. The arc length design of the contact plates 1 ensures that, in the retracted state, they can essentially cover the gap between adjacent support columns 6. The expansion assembly is preferably located at the center of the accommodating chamber formed by the support columns 6. The expansion assembly can adopt the form of any of the aforementioned embodiments (such as a hydraulic bladder or a mechanical cone plug mechanism). Since the accommodating chamber is open, the piping of the expansion assembly is more conducive to the assembly of piping and related components, and facilitates the connection of piping to an external power source.

[0054] Understandably, the way the support column 6 is connected to the fixed plate results in a large amount of open space in the main frame, which can effectively reduce the overall mass of the main frame. However, the connection through the support columns 6 at both ends can provide strong overall structural strength.

[0055] In conjunction with the above embodiments, the elastic connector includes a return spring 5, one end of which is connected to the contact plate 1, and the other end of which is in contact with the fixed disk. After the measurement is completed, the contact plate 1 needs to retract from its outward expanding state to its inward closing state. In this embodiment, the return spring 5 effectively enables the return of the contact plate 1.

[0056] Specifically, a return spring 5 is connected to the end face of each of the two axial ends of each contact plate 1. The return spring 5 is arranged radially, such that one end of the return spring 5 is connected to the contact plate 1 and the other end is connected to the fixed plate. When in the inward retracting state, the return spring 5 applies an inward pulling force to the contact plate 1, thereby driving each contact plate 1 to retract.

[0057] In a specific configuration, the fixed plate includes a connecting plate 7 and a protective cover 10. The connecting plate is fixedly connected to the support column 6. A first protruding column 2 for connecting the return spring 5 is provided on the connecting plate 7. The protective cover 10 is placed on the connecting plate 7 and has a clearance groove 101 for placing the return spring 5. The clearance groove 101 is arranged radially along the protective cover 10, so that the main body of the return spring 5 is located within the clearance groove 101. A second protruding column 9 is provided at the end of the contact plate 1. The two ends of the return spring 5 have connecting structures, which are correspondingly connected to the first protruding column 2 and the second protruding column 9, thereby achieving a fixed connection of the return spring 5.

[0058] It is understood that in this embodiment, the return spring 5 enables the contact plate 1 to retract quickly. Furthermore, the protective cover 10 effectively prevents the main body of the return spring 5 from being exposed, avoiding excessive corrosion from the external environment and improving the durability of the equipment.

[0059] In some embodiments, the expansion assembly includes a flexible bladder 11 and a media filling and discharging assembly. The flexible bladder 11 is disposed within a receiving cavity and communicates with the media filling and discharging assembly. The media filling and discharging assembly is configured to fill the flexible bladder 11 with a medium to apply a force to the contact plate 1, causing the contact plate 1 to move in a direction away from the main frame. During measurement, the expansion assembly needs to drive multiple contact plates 1 to move simultaneously to achieve the measurement. In this embodiment, the flexible bladder 11 improves the measurement quality.

[0060] Specifically, the flexible bladder 11, after being filled with the medium, takes on a cylindrical shape and is made of high-strength, high-elasticity, low-permeability rubber or polyurethane composite material, capable of withstanding high internal pressure and producing uniform radial expansion deformation. The medium filling and discharging assembly is connected to the flexible bladder 11 through at least one high-pressure pipeline, forming a closed-loop or open-loop pressure system. The main function of the medium filling and discharging assembly is to fill or discharge the working medium into the flexible bladder 11 to precisely control its internal pressure and volume, thereby controlling its thrust on the contact plate 1.

[0061] During operation, before the device is lowered to the predetermined drilling position, the flexible bladder 11 is in a relaxed, unpressurized state, and the contact plates 1 are retracted under the action of the elastic connector. The medium filling and discharging assembly is activated, and the pressure source within the assembly operates, pumping the working medium into the flexible bladder 11 through the pipeline. As the medium is injected, the internal pressure of the flexible bladder 11 increases, and its annular bladder expands radially and uniformly outward. The expanding outer wall of the flexible bladder 11 synchronously and uniformly compresses the inner sides of all the contact plates 1 surrounding it, driving all the contact plates 1 to overcome the resistance of the elastic connector and move away from the main frame until they are tightly pressed against the borehole wall. A pressure sensor can also be installed for pressure monitoring. When the pressure reaches the preset calibration coupling pressure, the control unit closes the filling valve, and the system enters a pressure-holding state. This state ensures that a constant and sufficient normal contact force is maintained between the contact plates 1 and the borehole wall throughout the measurement process, and data is acquired through the telescopic detection element 4 (precision strain sensor). After the measurement is completed, the pressure relief valve is opened, and the medium in the flexible bladder 11 is discharged back into the storage tank under the action of the rebound force of the contact plate 1. The bladder contracts, the contact plate 1 is reset under the action of the elastic connector, and the device returns to the retracted state, making it easy to pull out from the borehole.

[0062] In addition to liquids, the working medium can also be a gas (such as nitrogen), in which case the system becomes a pneumatic system with a faster response. In the preferred embodiment, the working medium is a liquid.

[0063] Understandably, the flexible bladder 11 ensures that the force applied to each contact plate 1 in the circumferential direction is highly uniform and synchronized. This is the basis for achieving isotropic initial coupling conditions and greatly reduces system errors. Furthermore, the flexible bladder 11 is in surface contact with the inner side of the contact plate 1, which can adapt to the slight unevenness of the inner surface of the contact plate 1 to a certain extent, making the pressure distribution more uniform.

[0064] In conjunction with the above embodiments, the media filling and discharging assembly includes a media delivery pipe and a drive pump 13. The output end of the drive pump 13 is connected to the media delivery pipe to drive the filling media into the flexible bladder 11. The drive pump 13 and the media delivery pipe enable efficient and precise delivery of the media.

[0065] Specifically, the drive pump 13 is a miniature, high-pressure positive displacement pump. Preferably, a miniature plunger pump or gear pump is used, characterized by high output pressure, precise flow control, and strong self-priming capability, making it suitable for operation in confined spaces and outdoor environments. The drive pump 13 is located externally and connected to the flexible bladder 11 inside the device via piping.

[0066] In some embodiments, a protective box 8 is also included, which is disposed in the accommodating cavity and connected to the main frame; wherein, the protective box 8 is provided with a protective groove 801, and the telescopic detection component 4 is disposed in the protective groove 801. The telescopic detection component 4 is located in the accommodating cavity. In this embodiment, the telescopic detection component 4 is isolated by the protective box, which effectively avoids the flexible bladder 11 from affecting the telescopic detection component 4.

[0067] Specifically, the protective box is located at the axial center of the main frame, and the telescopic detection component is located inside the protective box and connected to two opposing contact plates 1. The protective box divides the accommodating chamber into an upper chamber and a lower chamber, and a flexible bladder 11 is provided in both the upper and lower chambers.

[0068] It is understandable that by setting up the protective box, the exposure of the telescopic detection component 4 can be effectively avoided, thus providing effective protection for the telescopic detection component 4 and preventing the flexible bag 11 from contacting the telescopic detection component 4 and affecting the detection of the telescopic detection component 4.

[0069] In conjunction with the above embodiments, the telescopic detection component 4 includes a columnar main body, with telescopic ends at both ends. The two telescopic ends extend from the protective box 8 and are connected to a contact plate 1 on their respective sides. The accuracy of the measurement is improved by measuring the minute displacement of the telescopic ends.

[0070] Specifically, the main body contains a precision strain sensor, which is coupled to the telescopic ends at both ends, so that the sensor can sense the displacement change when the telescopic ends extend and retract, thereby realizing the measurement of the stress level of the original rock.

[0071] In the specific implementation, the telescopic detection element 4 is a dual-output high-precision displacement sensor. The telescopic ends extend or retract coaxially from both ends of the main body. Each telescopic end is equipped with a universal ball joint connector for hinged connection to the inner side of the corresponding contact plate 1. This connection method ensures that even if the movement direction of the contact plate 1 deviates slightly from the axis of the telescopic detection element 4, no lateral force will be generated that could cause jamming or affect measurement accuracy. A precision strain sensor assembly is integrated inside the main body, which can sense the movement of the contact plate 1 and measure the amount of movement.

[0072] In some embodiments, a hollow transfer rod 14 is provided at one end of the main frame, and the transfer rod 14 is fixedly connected to the main frame. The device needs to be inserted into the borehole during measurement; in this embodiment, the transfer rod 14 enables this insertion, and the hollow structure facilitates the management of wires and media delivery pipes.

[0073] Specifically, the transfer rod 14 is a long tubular structure. One end of the transfer rod 14 is connected to the fixed plate on the main frame, and the other end extends freely. Because the transfer rod 14 has a hollow structure inside, the wires and media conveying pipes can pass through the hollow, thereby realizing the connection with external equipment. This makes the pipeline more standardized and avoids the situation of pipelines crossing and messing.

[0074] In specific configurations, the delivery rod 14 can be a steel pipe or a rigid plastic pipe.

[0075] In some embodiments, a display 16 is also included, which is electrically connected to the telescopic detection element 4 for displaying the measured data. The display 16 makes the measurement results more intuitive and facilitates the direct recording and observation of multiple sets of data.

[0076] Specifically, the display 16 is located externally and is connected to the telescopic detection component 4 inside the device via a wire or data cable 15. The display 16 enables real-time feedback of the internal detection status.

[0077] The present invention also provides a measurement method based on the above-mentioned original rock stress level measuring device, comprising the following steps: Step S10: Deliver the measuring device to the depth to be measured within a preset borehole. Specifically, a borehole is preset in the area to be measured, and the device is delivered to the depth to be measured within the borehole using the transfer rod 14.

[0078] Step S20: Initiate the expansion assembly to expand, thereby applying a force to the contact plate 1, causing the contact plate 1 to move away from the main frame.

[0079] Specifically, starting the oil pump allows oil to be transported to the oil bladder through the medium delivery pipe. The oil bladder expands, the contact plate 1 moves outward, and the rock wall inside the borehole is compressed, resulting in radial displacement.

[0080] Step S30: While moving, the telescopic detection element 4 acquires the displacement. Specifically, the precision strain sensor acquires the measured displacement and processes it through a processor to obtain the stress level of the original rock.

[0081] Step S40: Calculate the original rock stress level based on the following formula: ; In the formula, δ is the radial displacement of the rock wall, in mm; σ is the stress level, in MPa. To establish a correspondence with the elastic modulus E of the rock mass, the processor stores the aforementioned calculation model. Calculations are performed using this model to obtain the stress level σ of the original rock.

[0082] Specifically, the original rock stress level measuring device includes a processor that processes data according to a preset processing model to obtain the original rock stress level. Specifically, the processor integrates a storage unit containing the aforementioned calculation model, so that after acquiring the measurement data of the expansion joint, the calculation model can be invoked to perform calculations and obtain the original rock stress level measuring device.

[0083] To obtain the above formula reflecting the relationship between stress level and rock wall displacement, the following numerical simulation and data fitting steps were adopted: A finite element numerical model of the process by which the measuring device applies lateral pressure to the rock wall was constructed using FLAC3D software, such as... Figure 14 As shown in the figure. In this model, different elastic moduli (E) of the rock mass are set to characterize the changes in its mechanical properties, and different original geostress levels (σ) are simulated by adjusting the model boundary conditions.

[0084] Based on the model, a series of simulation calculations are performed: for each set of elastic modulus (E) and original geostress level (σ), the displacement value (δ) generated by the rock wall after applying the same horizontal lateral pressure is calculated. By systematically changing the combination of values ​​of E and σ, multiple sets of data points can be obtained. Each set of data points represents the correspondence between stress level (σ) and rock wall displacement (δ) under a specific elastic modulus.

[0085] The datasets obtained from the series of simulations were then analyzed. Using stress level (σ) as the abscissa and rock wall displacement (δ) as the ordinate, a family of stress level-displacement relationship curves corresponding to different elastic moduli can be plotted, such as... Figure 15 As shown.

[0086] Finally, a mathematical fit is performed on the family of curves, such as... Figure 15 As shown. Analysis indicates that its variation follows a decay function form. Through fitting, the formula is determined. The specific expression, where the parameters of the formula It has a corresponding relationship with the value of the elastic modulus E of the rock mass.

[0087] Specifically, step S10 includes: selecting the depth to be measured according to engineering requirements, assembling the delivery rod 14 and the underground measuring device, holding the end of the delivery rod 14 and placing it into the borehole while keeping it vertical, and using the delivery rod 14 to send the underground measuring device to the depth to be measured in the borehole.

[0088] Step S20 includes: starting the oil pump to pressurize, setting the oil pump pressure so that the oil bladder gradually expands and squeezes the contact plate 1, causing the contact plate 1 to generate radial displacement until it touches the rock wall, setting the oil pump pressure so that the contact plate 1 continues to generate radial displacement and squeezes the rock wall, and then the rock wall generates radial displacement.

[0089] Step S30 includes: the telescopic detection element 4 (precision strain sensor) acquires the relative displacement of the two contact plates 1 at the relative position when the oil pump pressure is applied, and the radial displacement of each contact plate 1 can be obtained (the radial displacement of the contact plates 1 at opposite positions is the same), that is, the displacement of the contact plates is collected, and the displacement data is stored in the memory card or the processor's memory unit.

[0090] Step S40 includes: based on the acquired displacement data, for example, during a single measurement process, the displacement of the rock wall under pressure deformation is 0.75 mm, and the elastic modulus is 5 GPa, its fitting curve is as follows: The calculated original rock stress level is 24.05 MPa. After processing in the background, the relevant parameters are recorded into the memory card or processor's storage unit and displayed on the monitor 15. After the test, the drill bit measuring device is removed from the borehole and the power is turned off.

[0091] In summary, the device of the present invention has a simple structural design, a clear mechanical action process, and is easy to operate. It also features data-driven and information-based characteristics, automatically calculating the stress level of the original rock. It overcomes the problems of low measurement accuracy and high dependence on rock quality in traditional methods for determining the stress level of the original rock. The process is efficient and easy to repeat. Furthermore, its high degree of digitalization avoids the influence of subjective human factors, thus making the evaluation results more reliable. Moreover, the device does not require cooperation with large equipment, making it easy to carry and measure on-site, and enabling its widespread application and promotion in engineering.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for measuring the level of stress in original rock, characterized in that, include: The main frame has internal accommodating chambers; The contact plates are connected to the main frame via elastic connectors and are evenly spaced on the outer periphery of the main frame. An expansion assembly is disposed within the receiving cavity and is used to drive each of the contact plates to move simultaneously in a direction away from the main frame. A telescopic detection element is disposed between two opposing contact plates to sense the relative displacement of the opposing contact plates.

2. The original rock stress level measuring device according to claim 1, characterized in that, The main frame includes multiple support columns and fixed plates at both ends of the support columns. The fixed plates are fixedly connected to the support columns and form the accommodating chamber between the fixed plates at both ends.

3. The original rock stress level measuring device according to claim 2, characterized in that, The elastic connector includes a return spring, one end of which is connected to the contact plate, and the other end of which is in contact with the fixed plate.

4. The original rock stress level measuring device according to claim 1, characterized in that, The expansion assembly includes a flexible bladder and a media filling and discharging assembly. The flexible bladder is disposed within the accommodating cavity and communicates with the media filling and discharging assembly. The media filling and discharging assembly is configured to fill the flexible bladder with a media to apply a force to the contact plate, causing the contact plate to move away from the main frame.

5. The original rock stress level measuring device according to claim 4, characterized in that, The medium filling and discharging assembly includes a medium delivery pipe and a drive pump. The output end of the drive pump is connected to the medium delivery pipe to drive the filling medium to be input into the flexible bladder.

6. The original rock stress level measuring device according to claim 1 or 4, characterized in that, It also includes a protective box, which is located in the accommodating chamber and connected to the main frame; wherein, the protective box is provided with a protective groove, and the telescopic detection component is located in the protective groove.

7. The original rock stress level measuring device according to claim 6, characterized in that, The telescopic detection component includes a columnar main body, with telescopic ends at both ends of the main body. The two telescopic ends extend from the protective box and are connected to the contact plate on their respective sides.

8. The original rock stress level measuring device according to claim 1, characterized in that, One end of the main frame is provided with a hollow delivery rod, which is fixedly connected to the main frame.

9. The original rock stress level measuring device according to claim 1, characterized in that, It also includes a display, which is electrically connected to the telescopic detection element for displaying the measured data.

10. A measurement method based on the original rock stress level measuring device according to any one of claims 1-9, characterized in that, Includes the following steps: Step S10: Use a transfer rod to send the measuring device to the depth to be measured in the preset borehole. Step S20: Initiate the expansion assembly to expand, thereby applying a force to the contact plate, causing the contact plate to move away from the main frame; Step S30: While moving, the telescopic detection component acquires the displacement amount; Step S40: Calculate the original rock stress level based on the following formula: ； In the formula, δ represents the radial displacement of the rock wall; σ represents the stress level. This is related to the value of the elastic modulus E of the rock mass.

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