An implantable rock mass structure deterioration monitoring pressure gauge and a monitoring method

Abstract

The application provides an implantable rock mass structure deterioration monitoring pressure gauge and a monitoring method, and relates to the technical field of underground engineering and rock mass engineering safety monitoring. The pressure gauge comprises a signal receiver, a signal transmission box, a display screen, a strain sensing box, a stress sensor and an anchoring structure. The pressure gauge is implanted in the rock mass, and the stress and strain response of the surrounding rock under the action of the engineering load are collected in real time, and the loading stress-strain curve of the surrounding rock is constructed. When cracks occur, expand or penetrate in the surrounding rock, the mechanical response curve will have a sudden change in slope or a large-angle inflection point feature. By identifying the inflection point position and amplitude change, the deterioration state and damage degree of the rock mass structure can be determined. The device can convert the evolution process of the surrounding rock structure into identifiable curve characteristic signals, and is suitable for the stability monitoring and early warning of the surrounding rock of slope engineering and other underground engineering.

Description

Technical Field

[0001] This invention relates to the field of safety monitoring technology for underground engineering and rock mass engineering, specifically to an implantable rock mass structure deterioration monitoring pressure gauge and monitoring method. Background Technology

[0002] In rock mass engineering projects such as tunnels, underground caverns, and steep slopes, the surrounding rock is continuously affected by in-situ stress, excavation disturbance, and environmental factors during long-term service. Its internal structure gradually evolves from a intact state to a damaged and deteriorated state. This evolution process is usually covert and gradual; once it reaches the instability stage, it is difficult to take timely and effective intervention measures, easily leading to engineering safety accidents. Existing rock mass structure monitoring technologies mainly focus on measuring single physical quantities, such as surrounding rock stress, displacement, or acoustic signals. While these monitoring methods can reflect the response state at a certain moment or in a certain area, they are difficult to reveal the overall mechanical evolution characteristics of the rock mass during loading, especially in accurately judging the timing and extent of structural deterioration. Furthermore, due to the significant heterogeneity and nonlinearity of rock mass materials, relying solely on threshold criteria for single physical quantities is easily affected by installation conditions, environmental noise, and differences in initial conditions, resulting in insufficient stability of monitoring results. Studies have shown that during loading, the macroscopic mechanical response of rock mass is not a continuous linear change, but rather accompanied by an internal structural reorganization process. When microcracks gradually initiate and interconnect, the overall stiffness of the rock mass undergoes a sudden change, and its mechanical response characteristics change accordingly. However, under engineering field conditions, there is still a lack of mature technical means to effectively convert this internal structural change into a signal that can be directly monitored and identified. Therefore, there is an urgent need for a monitoring device that can operate stably in engineering environments for a long period of time. This device should not only be able to acquire mechanical response information of the rock mass during loading, but also be able to identify and characterize the occurrence and development of rock mass structural deterioration based on the changing characteristics of the response curve, thus providing a new technical approach for safety assessment and risk warning in rock mass engineering.

[0003] Related experimental studies have shown that the stress-strain curve of the surrounding rock can intuitively reflect the structural evolution state during the loading process. When crack propagation occurs inside the surrounding rock, the slope of the curve will change abruptly, forming a breakpoint feature. Therefore, it is necessary to propose a monitoring device that can construct the stress-strain curve of the surrounding rock in real time on the engineering site and determine the deterioration of the surrounding rock structure through breakpoint identification. Summary of the Invention

[0004] Therefore, the present invention provides an implantable rock mass structure deterioration monitoring pressure gauge and monitoring method to solve the above problems. The device constructs stress-strain curves under surrounding rock loading conditions, analyzes the correspondence between the curve inflection point characteristics and the evolution of surrounding rock cracks, and clarifies the effectiveness of the inflection point as a sensing signal of surrounding rock structure deterioration and its engineering applicability.

[0005] Under external loads, the macroscopic mechanical response of surrounding rock can be characterized by the stress-strain relationship. When the surrounding rock is in a structurally intact stage, the stress-strain curve usually shows a continuous change. As the loading process progresses, microcracks gradually initiate, expand, and interconnect within the surrounding rock, resulting in a decrease in the equivalent stiffness of the surrounding rock. This leads to a sudden change in the slope of the stress-strain curve, forming a significant inflection point or turning point.

[0006] The present invention provides an implantable rock mass structure deterioration monitoring pressure gauge, comprising: a stress housing, a strain sensing box disposed on the top of the stress housing, a signal transmission box disposed on the top of the strain sensing box, a threaded fixing end disposed on the bottom of the stress housing; a drill bit connected to the bottom of the threaded fixing end; and a stress sensor disposed on the surface of the stress housing.

[0007] Furthermore, an independent stress sensing guide rod is horizontally arranged inside the stress housing to connect to the stress sensor, and an independent strain sensing guide rod is vertically arranged to transmit strain to the signal transmission box.

[0008] Furthermore, a signal transmission box is provided on the top of the strain sensing box. The signal transmission box contains a signal relay structure including a signal convergence bar, a signal conditioning circuit board (PCB), and a physical fixing interface. A display screen, an embedded switch, a status indicator light, and a signal receiver are provided outside the signal transmission box. The two ends of the signal relay structure are fixed by anchor rods, and a high-endurance battery is fixed at the bottom of the shell for data transmission and signal reception. The signal relay structure is connected to the signal receiver, the display screen, and the high-endurance battery via wires, and the high-endurance battery is fixed at the bottom of the shell.

[0009] Furthermore, the threaded fixed end and the drill bit serve as the front-end anchoring structure, while the strain sensing box and the stress shell serve as the middle load-bearing structure. The front-end anchoring structure is used to form a stable embedment with the surrounding rock, so that the pressure gauge does not slip relative to the surrounding rock during loading.

[0010] Furthermore, the stress sensing unit and the strain sensing unit are arranged coaxially along the main force direction of the surrounding rock to ensure that the load of the surrounding rock is transmitted to the signal relay structure of the strain receiving unit along the axial and radial paths.

[0011] Furthermore, the strain sensing unit is mounted on the threaded fixed end of the force transmission structure with elastic deformation capability, and is used to convert the pressure change of the surrounding rock during the loading process into a measurable strain response.

[0012] Furthermore, the data processing unit is integrated inside the signal transmission box and is electrically connected to the stress sensor and strain sensing box via multiple data buses. The unit includes a high-precision A / D acquisition module, an ARM core processing chip, and a wireless LoRa communication module, used to synchronously process the stress and strain data continuously acquired during the surrounding rock loading process to form a continuous stress-strain curve. A dynamic sliding time window algorithm is introduced to calculate the real-time tangent modulus of the stress-strain curve. ;when When E0 is the initial modulus and λ is the degradation threshold, it is determined to be a feature inflection point.

[0013] Furthermore, the display screen and status indicator lights constitute a signal output unit for outputting information on the surrounding rock structure status or deterioration warning signals. It is connected to the output I / O port of the data processing unit through a built-in flexible circuit board (FPC), and the indicator lights and the display screen share the same set of signal demodulation driver chips. The status indicator lights are green as the normal state and red as the warning state. The signal relay structure receives the electrical signal transmitted back by the stress sensing guide rod, passes through the center hole of the strain sensing box via the signal transmission line, and enters the data processing unit in the signal transmission box for calculation. The calculation results drive the display screen to update the values ​​in real time and control the color switching of the status indicator lights.

[0014] The present invention also provides a method for monitoring the deterioration of surrounding rock structures based on the above-mentioned implanted rock mass structure deterioration monitoring pressure gauge, comprising the following steps:

[0015] (1) Prepare rock mass samples or surrounding rock similar material models according to the test requirements. Drill installation holes at predetermined positions and embed the implantable pressure gauge inside the sample, ensuring that the pressure transmission end is in close contact with the surrounding rock. Fix the pressure gauge with the threaded fixing end to ensure that the device does not slip relative to the surrounding rock during loading.

[0016] (2) Before loading, the pressure gauge is initially calibrated, and the strain reference value under no-load or low-load conditions is recorded as the initial reference state for the subsequent construction of stress-strain curves. At the same time, the stability of the signal acquisition system is checked to ensure that the stress and strain signals are continuously acquired without significant noise interference.

[0017] (3) Apply load to the surrounding rock according to the preset loading path. The loading method can be monotonic loading, graded loading, or cyclic loading. Keep the loading rate stable during the loading process to allow sufficient time for the internal structure of the surrounding rock to respond and evolve. During the entire loading process, the implanted pressure gauge synchronously collects the strain response inside the surrounding rock and records the stress level under the corresponding loading conditions.

[0018] (4) Based on the collected stress and strain data, the stress-strain response curve of the surrounding rock is constructed in real time. By continuously recording the curve, the complete response evolution process of the surrounding rock from the initial intact state to the structural deterioration stage is obtained.

[0019] (5) Analyze the constructed stress-strain curves, identify the locations where the slope of the curve changes abruptly, and determine the stress and strain levels at the inflection points. When the curve shows the first obvious inflection point, it is determined that cracks have started or propagated inside the surrounding rock; as loading continues, if the amplitude of the inflection point gradually increases or the number of inflection points increases, it is determined that the deterioration of the surrounding rock structure continues to deepen.

[0020] (6) The degree of deterioration of the surrounding rock structure is graded and assessed based on the inflection point amplitude, slope change rate, or inflection point distribution density. The larger the inflection point amplitude, the more significant the reduction in the integrity of the surrounding rock structure, and the more severe the corresponding damage. When a large inflection point first appears in the stress-strain curve, it is determined that the initial stage of structural deterioration has occurred inside the surrounding rock; when the inflection point amplitude continues to increase with the loading process, it is determined that the degree of structural deterioration inside the surrounding rock continues to deepen; when the inflection point amplitude or the number of inflection points reaches a preset threshold, an early warning signal for the failure of the surrounding rock structure is output.

[0021] (7) After the test, the correlation between the stress-strain curve inflection point characteristics and the deterioration of the surrounding rock structure is verified by comparing and analyzing the crack distribution, failure mode or other observation methods of the sample, thereby confirming the reliability of the monitoring method.

[0022] The present invention has the following advantages over the prior art:

[0023] 1. This invention includes a signal receiver, a signal transmission box, a display screen, a strain sensing box, a stress sensor, and an anchoring structure. The pressure gauge, implanted inside the rock mass, collects the stress and strain responses of the surrounding rock in real time under engineering loads, constructing a stress-strain curve for the surrounding rock. When cracks initiate, propagate, or penetrate within the surrounding rock, its mechanical response curve exhibits abrupt changes in slope or large-angle inflection points. By identifying the location and amplitude changes of these inflection points, the deterioration state and degree of damage to the rock mass structure can be determined. This device can convert the evolution process of the surrounding rock structure into identifiable curve characteristic signals, making it suitable for monitoring and early warning of surrounding rock stability in slope engineering and other underground engineering projects.

[0024] 2. This invention transforms the evolution process of the internal structure of the surrounding rock into identifiable stress-strain curve characteristics; identifies signs of deterioration of the surrounding rock structure before macroscopic failure occurs; provides reliable experimental basis for the application of implantable pressure gauges in engineering sites; and provides new criteria for the quantitative evaluation of the degree of deterioration of the surrounding rock structure. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0027] Figure 2 This is a schematic diagram of the internal structure of the signal transmission box of the present invention.

[0028] Figure 3 This is the front view of the present invention;

[0029] Figure 4 This is a stress-strain curve diagram for monitoring the deterioration of surrounding rock according to the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Signal receiver; 2. Signal transmission box; 3. Display screen; 4. Built-in switch; 5. Status indicator light; 6. Strain sensor box; 7. Stress sensor; 8. Threaded fixing end; 9. Drill bit; 10. Stress sensing guide rod; 11. Strain sensing guide rod; 12. Wire; 13. Signal relay structure; 14. Anchor rod; 15. High-endurance battery; 16. Stress housing. Detailed Implementation

[0032] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] Reference Figures 1 to 3 The present invention provides an implantable rock mass structure deterioration monitoring pressure gauge, which includes a drill bit 9 and a threaded fixing end 8 for implanting the device inside the surrounding rock and forming a stable anchor; a stress sensor 7 and a strain sensing box 6 are set in the middle of the device for collecting the stress and strain response of the surrounding rock under engineering loads.

[0035] The acquired signals are processed by signal transmission box 2 to construct the stress-strain response curve of the surrounding rock under load, and the changes in the slope of the curve are analyzed. When a breakpoint appears in the curve, it is determined that crack propagation or structural deterioration has occurred inside the surrounding rock, and the amplitude of the breakpoint is used to characterize the degree of damage.

[0036] The signal processing results are output through the signal receiver 1 and can be displayed on the display screen 3 to show the current surrounding rock status. When the degree of surrounding rock deterioration reaches the preset threshold, the status indicator light 5 issues an early warning signal to realize real-time monitoring of the stability of the surrounding rock of the tunnel or slope.

[0037] Example 2

[0038] This embodiment provides an application principle for monitoring the deterioration of surrounding rock in deeply buried tunnels, demonstrating the real-time response of a pressure gauge after it is implanted in the surrounding rock as the load continues to increase.

[0039] Initial stiffness assessment: In the initial loading stage, strain ε∈[0,0.02], stress and strain exhibit a good linear relationship. The initial elastic modulus calculated by the data processing unit... ≈590.40MPa. At this time, the internal structure of the surrounding rock is intact, and the status indicator light 5 on the signal transmission box remains green.

[0040] Inflection point feature identification: When the strain reaches 0.02 MPa and the stress level reaches 12.15 MPa, a significant abrupt change in the slope of the monitoring curve occurs. Algorithm determination: The data processing unit calculates the tangent modulus in real time using a sliding time window. Amplitude of abrupt change: Tangent modulus after the inflection point The stiffness decreased to approximately 174.51 MPa, a reduction of about 70.4% compared to the initial stiffness. Physical significance: This inflection point characteristic signal indicates that cracks have initiated and begun to propagate within the surrounding rock, resulting in damage and deterioration of the rock mass's equivalent stiffness.

[0041] Conclusion and Early Warning Output Monitoring Judgment: The system identified the first significant inflection point, determining that the surrounding rock had entered the "initial stage of structural deterioration." Hardware Response: Based on the calculation results, the signal transmission box immediately drove the status indicator light 5 to switch from green to flashing red, and locked the critical stress value of 12.15 MPa at the time of the inflection point on the display screen 3. Engineering Recommendations: Due to the large amplitude of the inflection point, it indicates a deep degree of structural deterioration of the surrounding rock. It is recommended to take timely intervention measures such as anchor bolt reinforcement or shotcrete to prevent further crack penetration and macroscopic instability. As shown in Table 1 below, the real-time monitoring status of this embodiment can be seen. Figure 4 As can be seen in the stress-strain curve diagram for monitoring the deterioration of the surrounding rock in this embodiment.

[0042] Table 1: Data collected and generated in real time by the monitoring device

[0043] Monitoring time points strain Stressσ(MPa) Remark 0 0 0 initial state 10 0.01 5.9 Stable loading period 20 0.02 12.15 Inflection point identified 30 0.03 13.89 Deterioration and development period 50 0.05 17.38 Severe injury period

[0044] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An implantable rock mass structure deterioration monitoring pressure gauge, characterized in that, It includes a stress housing (16), a strain sensing box (6) on its top, a signal transmission box (2) on the top of the strain sensing box (6), a threaded fixing end (8) on the bottom of the stress housing (16); a drill bit (9) is connected to the bottom of the threaded fixing end (8); and a stress sensor (7) is provided on the surface of the stress housing (16).

2. The implantable rock mass structure deterioration monitoring pressure gauge according to claim 1, characterized in that, The stress housing (16) has an independent stress sensing guide rod (10) arranged horizontally inside to connect to the stress sensor (7), and an independent strain sensing guide rod (11) arranged vertically to transmit strain to the signal transmission box (2).

3. The implantable rock mass structure deterioration monitoring pressure gauge according to claim 2, characterized in that, The strain sensing box (6) is equipped with a signal transmission box (2) on top. The signal transmission box (2) is equipped with a signal relay structure (13) with both ends fixed by anchor rods (14) and connected to the signal receiver (1), display screen (3) and high-endurance battery (15) by wires (12). The high-endurance battery (15) is fixed at the bottom of the shell. The signal transmission box (2) is equipped with a display screen (3), an embedded switch (4), a status indicator light (5), and a signal receiver (1).

4. The implantable rock mass structure deterioration monitoring pressure gauge according to claim 3, characterized in that, The threaded fixed end (8) and the drill bit (9) serve as the front anchoring structure, while the strain sensing box (6) and the stress shell (16) serve as the middle bearing structure. The front anchoring structure is used to form a stable embedment with the surrounding rock.

5. The implantable rock mass structure deterioration monitoring pressure gauge according to claim 4, characterized in that, The stress sensor (7) of the stress sensing unit and the strain sensing rod (11) of the strain sensing unit are arranged coaxially along the main force direction of the surrounding rock to ensure that the load of the surrounding rock is transmitted to the signal relay structure (13) of the strain receiving unit along the axial and radial paths.

6. The implantable rock mass structure deterioration monitoring pressure gauge according to claim 5, characterized in that, The strain sensing unit is set on the threaded fixed end (8) of the force transmission structure with elastic deformation capability, and is used to convert the pressure change of the surrounding rock during the loading process into a measurable strain response.

7. The implantable rock mass structure deterioration monitoring pressure gauge according to claim 6, characterized in that, The data processing unit is integrated inside the signal transmission box (2) and is electrically connected to the stress sensor (7) and strain sensing box (6) respectively through a multi-channel data bus. The data unit includes a high-precision A / D acquisition module, an ARM core processing chip and a wireless LoRa communication module, which are used to synchronously process the stress and strain data continuously acquired during the surrounding rock loading process to form a continuous stress-strain curve. A dynamic sliding time window algorithm is introduced to calculate the real-time tangent modulus of the stress-strain curve. ;when When E0 is the initial modulus and λ is the degradation threshold, it is determined to be a feature inflection point.

8. The implantable rock mass structure deterioration monitoring pressure gauge according to claim 7, characterized in that, The display screen (3) and the status indicator light (5) constitute a signal output unit, which is used to output the status information of the surrounding rock structure or the deterioration warning signal. It is connected to the output I / O port of the data processing unit through the built-in flexible circuit board. The indicator light (5) and the display screen (4) share the same set of signal demodulation driving chips. The status indicator light (5) is green as normal and red as warning. The signal relay structure (13) receives the electrical signal transmitted back by the stress sensing guide rod (10), passes through the center hole of the strain sensing box (6) via the signal transmission line (12), and enters the data processing unit in the signal transmission box (2) for calculation. The calculation result drives the display screen (4) to update the value in real time and controls the color switching of the status indicator light (5).

9. A method for monitoring the deterioration of surrounding rock structure using an implantable rock mass structure deterioration monitoring pressure gauge according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1: The pressure gauge is implanted inside the surrounding rock to form a mechanical coupling with the surrounding rock; S2: During the loading process of the surrounding rock, the stress and strain response of the surrounding rock are collected; S3: Construct the surrounding rock loading stress-strain response curve based on the collected data; S4: Identify the inflection point features in the stress-strain response curve. When there is a sudden change in the slope or a significant change in the curve shape in the stress-strain curve, the location of the change is identified as an inflection point. S5: Determine the deterioration state of the surrounding rock structure based on the inflection point characteristics. The strain change amplitude corresponding to the inflection point is used to characterize the degree of deterioration of the surrounding rock structure. The larger the inflection point amplitude, the more severe the deterioration of the surrounding rock structure.

10. The method according to claim 9, characterized in that, In step S5, when a large inflection point first appears in the stress-strain curve, it is determined that the initial stage of structural deterioration has occurred inside the surrounding rock; when the amplitude of the inflection point continues to increase with the loading process, it is determined that the degree of structural deterioration inside the surrounding rock continues to deepen; when the amplitude of the inflection point or the number of inflection points reaches a preset threshold, a warning signal for the failure of the surrounding rock structure is output.

Images