Surrounding rock loose circle stress wave monitoring equipment and method

Abstract

The invention discloses a surrounding rock loose circle stress wave monitoring device and method, and the device comprises a monitoring device, a stress wave signal excitation device, a stress wave signal receiving device, and a stress wave signal analysis device. The stress wave signal excitation device is used for emitting stress waves into a test hole, and the stress wave signal receiving device comprises an acceleration sensor which is used for receiving stress wave signals and transmitting the received stress wave signals to the stress wave signal analysis device. And the stress wave signal analysis device is used for analyzing and processing the received stress wave signals and drawing an average speed table from the stress waves reflected by the sacs at different positions to the acceleration sensors at different positions. The range of the surrounding rock loose circle is determined according to the speed change of the average speed table, and the method has the advantages of simple operation and wider monitoring range; meanwhile, by reducing the distance between the acceleration sensor and the test hole, denser monitoring points are formed, and the measurement precision is improved.

Description

[Technical field] The present invention relates to the technical field of monitoring the loosened zone of surrounding rock in a tunnel, and in particular to a device and method for monitoring the stress wave of the loosened zone of surrounding rock. [Background technology] The accurate measurement of the loose zone of tunnel surrounding rock is the main basis for tunnel reinforcement and support design. After tunnel excavation, the original rock stress is redistributed, and the fracture zone of the tunnel excavation surface is called the loose zone of surrounding rock. It is very important to obtain the scope of the loose zone in a timely and accurate manner, so that a reasonable and effective support plan can be formulated to ensure the stability of tunnel surrounding rock.

[0003] The stress wave method of the loosening zone of the surrounding rock is a non-destructive testing method that uses stress waves to detect changes in the loosening zone of the surrounding rock. Compared with the destructive testing methods mainly based on the acoustic wave method, the test hole imaging method, the resistivity method and the seismic wave method, this method has the advantages of strong adaptability, simple operation, easy implementation and little damage to the surrounding environment. The traditional stress wave monitoring method is to place the acceleration sensor in the test hole, and calculate the average layer velocity at that position by changing the position of the acceleration sensor. This method can only measure the loosening zone of the surrounding rock of the layer and cannot achieve large-scale monitoring. It also has technical problems such as low measurement accuracy and complex operation. [Summary of the invention] In order to solve the current technical problems of low measurement accuracy, small monitoring range and complex operation of the loose zone of surrounding rock in tunnels, the present invention proposes a stress wave monitoring device and method for the loose zone of surrounding rock.

[0005] The present invention is achieved by the following technical solutions: A stress wave monitoring device for a surrounding rock loosening zone comprises a monitoring device, a stress wave signal excitation device, a stress wave signal receiving device and a stress wave signal analysis device. The monitoring device is arranged in a test hole pre-drilled in a tunnel. The monitoring device is provided with a plurality of bags for reflecting stress waves. The stress wave signal excitation device is used to emit stress waves into the test hole. The stress wave signal receiving device is provided with a plurality of groups on the left and right sides of the tunnel test hole. The stress wave signal receiving device comprises an acceleration sensor. The acceleration sensor is used to receive stress wave signals and transmit the received stress wave signals to the stress wave signal analysis device. The stress wave signal analysis device is used to analyze and process the received stress wave signals and draw an average velocity table between the stress waves reflected by bags at different positions and the acceleration sensors at different positions.

[0006] A stress wave monitoring device for the loosening zone of surrounding rock as described above, the monitoring device also includes a flexible bendable elastic rod and a flexible grouting pipe, at least 8 bags are fixed on the flexible bendable elastic rod, adjacent bags are spaced a certain distance apart, the slurry outlet of the flexible grouting pipe is connected to the bag, and the grouting port of the flexible grouting pipe is connected to a grouting machine for injecting slurry into the bag so that the bag expands to fit tightly against the wall of the test hole.

[0007] In the above-mentioned surrounding rock loosening zone stress wave monitoring device, the stress wave signal receiving device also includes a rivet for installing an acceleration sensor, and the rivet is provided with a strong magnetic magnet for adsorbing and fixing the acceleration sensor.

[0008] As described above, a stress wave monitoring device for the loosening zone of surrounding rock, the stress wave signal analysis device includes a data acquisition instrument and computer analysis software, a signal transmission cable for transmitting stress wave signals to the data acquisition instrument is connected between the data acquisition instrument and the acceleration sensor, and a USB data transmission cable for transmitting data to the computer analysis software is connected between the data acquisition instrument and the computer analysis software.

[0009] In the above-mentioned surrounding rock loosening zone stress wave monitoring device, the stress wave signal excitation device includes an exciting hammer, and the exciting hammer is connected to the data acquisition instrument via a signal transmission cable to transmit the exciting force signal to the data acquisition instrument.

[0010] Another aspect of the present invention is a method for monitoring stress waves in a surrounding rock loosening zone implemented by the above-mentioned monitoring device; The monitoring method comprises the following steps: Step S1, using a drilling machine to drill a test hole of more than 10m in the upper or lower wall of the tunnel in advance; Step S2, assembling the monitoring device and inserting the monitoring device into the test hole; Step S3, using an exciting hammer to strike the center point of the end surface of the flexible bendable elastic rod to generate a stress wave signal and an exciting force signal, and at the same time, the acceleration sensor transmits the received stress wave signal and the exciting force signal generated by the exciting hammer to the data acquisition instrument; Step S4, importing the data stored in the data acquisition instrument into the computer analysis software; Step S5, after the computer analysis software reads the data, it draws the exciting force-time curve and the acceleration-time curve; Step S6, analyzing and processing the drawn exciting force-time curve and acceleration-time curve to determine the range of the surrounding rock loosening zone and whether there are cracks or fractures in the surrounding rock loosening zone within the range.

[0011] In the above-mentioned method for monitoring stress waves in the surrounding rock loosening zone, the step S6 further comprises the following steps: Step S61, the speed of stress wave propagation along the flexible bendable elastic rod is measured by experiment and the time it takes for the stress wave to reach each pocket ; Step S62, calculating the time it takes for the stress wave to be reflected from the bladder to the acceleration sensor ; Step S63, calculating the average velocity of the stress wave reflected from the bladder to the acceleration sensor ; Step S64, changing the position of the acceleration sensor, repeating steps S62 and S63, and calculating an average velocity table of the stress wave from the bladder at different positions to the acceleration sensors at different positions; Step S65, performing comparative analysis based on the average velocity table obtained in step S64 to determine the range of the surrounding rock loosening zone and whether there are cracks or fractures within the range.

[0012] In the above-mentioned method for monitoring stress waves in the surrounding rock loosening zone, the step S62 further includes the following steps: Step S621, obtaining the first arrival time of the exciting force signal to the acceleration sensor from the exciting force-time curve and the acceleration-time curve And the first arrival time of the stress wave signal generated by the bladder to the acceleration sensor ; Step S622, subtract the two first arrival times obtained in step S621 to obtain the total time for the stress wave signal to be reflected from the top of the flexible bendable elastic rod through the bladder to the acceleration sensor ; Step S623, the total time calculated according to step S622 , calculate the time it takes for the stress wave to be reflected from the bag to the acceleration sensor .

[0013] In the above-mentioned method for monitoring stress waves in the surrounding rock loosening zone, the step S63 further comprises the following steps: Step S631, calculating the distances from different capsules to the exposed end apex of the flexible bendable elastic rod , calculate the distance from the acceleration sensor at different positions to the center point of the exposed end of the flexible bendable elastic rod ; Step S632: Calculate the distance from the capsule to the acceleration sensor based on the data obtained in step S631. ; Step S633, based on the data obtained in step S632 and step S62, calculate the average velocity of the stress wave from the bladder to the acceleration sensor .

[0014] In the above-mentioned method for monitoring stress waves in the surrounding rock loosening zone, the step S65 further comprises the following steps: Step S651, comparing the average speeds of the stress wave to the acceleration sensors at different positions along the test hole direction to determine the range of the surrounding rock loosening zone; Step S652, based on the range obtained in step S651, compare the average speeds of the stress wave in the range along the tunnel direction to the acceleration sensors at different positions, and determine whether there are cracks or fractures in the range; Step S653, if the average speed along the lane direction in step S652 is the same, then there is no crack or breakage within this range; if the average speed along the lane direction in step S652 is different, then there is a crack or breakage within this range.

[0015] Compared with the prior art, the device and method for monitoring stress waves in the loosening zone of surrounding rock proposed by the present invention have the following beneficial effects: 1. The monitoring device proposed in the present invention includes a monitoring device and an acceleration sensor. A plurality of bags are fixed on the monitoring device. By changing the position of the acceleration sensor, the average velocity table of the stress wave reflected by the bags at different positions to the acceleration sensors at different positions is measured, so that the velocity change of the average velocity table can be compared to determine the range of the loosening zone of the surrounding rock. The device has the advantages of simple operation and wider monitoring range. At the same time, by reducing the distance between the acceleration sensor and the test hole or increasing the fixed number of bags, more dense monitoring points can be formed, which is helpful to more accurately analyze the propagation characteristics of the stress wave and improve the measurement accuracy.

[0016] 2. The monitoring device of the present invention forms a whole with the surrounding rock after the bag grouting is completely solidified, and can be installed in the test hole for a long time to achieve long-term monitoring of changes in the loose zone of the surrounding rock.

[0017] 3. The monitoring method proposed in the present invention can calculate the average speed of the stress wave reflected from the sac to the acceleration sensor through the exciting force-time curve and the acceleration-time curve, thereby obtaining an average speed table of the stress wave reflected from the sac at different positions to the acceleration sensors at different positions, which has the advantages of low calculation difficulty and high measurement accuracy; at the same time, the change of speed can be simply and clearly observed from the waveform through the exciting force-time curve and the acceleration-time curve, which is easy to observe and simple to operate.

Brief Description of the Drawings

[0019] Figure 1 It is a structural schematic diagram of the surrounding rock loosening zone stress wave monitoring device of the present invention; Figure 2 It is a schematic diagram of the acceleration sensor and the strong magnetic magnet structure of the present invention; Figure 3 It is a flow chart of the method for monitoring stress waves in the loosening zone of surrounding rock of the present invention; Figure 4 is a detailed flow chart of step S5 of the present invention; Figure 5 is a detailed flow chart of step S6 of the present invention; Figure 6 is a detailed flow chart of step S62 of the present invention; Figure 7 is a detailed flow chart of step S63 of the present invention; Figure 8 is a detailed flow chart of step S65 of the present invention; Fig. 9 It is the exciting force-time curve diagram of the present invention; Fig.10 is an acceleration-time curve diagram of the present invention; Fig.11 It is a partial schematic diagram of the surrounding rock loosening zone stress wave monitoring method of the present invention. [Specific implementation method] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] First embodiment: Please refer to Figure 1 to Figure 2As shown, this embodiment proposes a stress wave monitoring device for a surrounding rock loosening zone, comprising a monitoring device 10, a stress wave signal excitation device 20, a stress wave signal receiving device 30 and a stress wave signal analysis device 40. The monitoring device 10 is arranged in a test hole pre-drilled in a tunnel, and the monitoring device 10 is provided with a plurality of bags 13 for reflecting stress waves. The stress wave signal excitation device 20 is used to emit stress waves into the test hole. The stress wave signal receiving device 30 is provided with a plurality of groups on the left and right sides of the tunnel test hole. The stress wave signal receiving device 30 comprises an acceleration sensor 31, and the acceleration sensor 31 is used to receive stress wave signals and transmit the received stress wave signals to the stress wave signal analysis device 40. The stress wave signal analysis device 40 is used to analyze and process the received stress wave signals, and draw an average velocity table between the stress waves reflected by the bags 13 at different positions and the acceleration sensors 31 at different positions, so as to judge the range of the surrounding rock loosening zone and whether there are cracks or fractures in the surrounding rock loosening zone within the range. A plurality of bags 13 are fixed on the monitoring device 10 of the monitoring equipment. By changing the position of the acceleration sensor 31, the average velocity table of the stress wave reflected by the bags 13 at different positions to the acceleration sensors 31 at different positions is measured, so that the velocity change of the average velocity table can be compared to determine the range of the loosening zone of the surrounding rock, and the operation is simple and the monitoring range is wider. At the same time, by reducing the distance between the acceleration sensor and the test hole or increasing the fixed number of bags, more dense monitoring points can be formed, which is helpful to more accurately analyze the propagation characteristics of the stress wave and improve the measurement accuracy.

[0022] Furthermore, as a preferred embodiment of the present scheme but not a limitation, the monitoring device 10 includes a flexible bendable elastic rod 11 and a flexible slurry delivery pipe 12, at least 8 bags 13 are fixed to the top of the flexible bendable elastic rod 11, the slurry outlet of the flexible slurry delivery pipe 12 is connected to the bag 13, and the slurry inlet of the flexible slurry delivery pipe 12 is connected to a grouting machine 14 for injecting slurry into the bag 13 so that the bag 13 expands to fit tightly against the wall of the test hole.

[0023] In this embodiment, the monitoring device forms a whole with the surrounding rock after the bladder grouting is completely solidified, and can be installed in the test hole for a long time to achieve long-term monitoring of changes in the loosening zone of the surrounding rock; at the same time, when the stress wave propagates into the test hole and encounters the bladder, it will be reflected to generate a stress wave signal. At the same time, the bladder expands to fit tightly with the wall of the test hole, which can reduce interference from external factors, so that the generated stress wave signal can be used to more accurately monitor and evaluate the conditions of the surrounding formations.

[0024] Furthermore, as a preferred implementation of the present solution but not a limitation, the length of the flexible bendable elastic rod 11 is 9m-11m, preferably, the length of the flexible bendable elastic rod 11 is 10m, and adjacent pouches 13 fixed on the flexible bendable elastic rod 11 are spaced a certain distance apart, and the distance between adjacent pouches is preferably 0.9m, and the length of the pouch 13 is 30cm.

[0025] In this embodiment, the bag is provided with multiple monitoring points that can provide more monitoring points for the monitoring device, which helps to improve the accuracy and coverage of monitoring; the length of the flexible bendable elastic rod is preferably 10m, which can ensure that the monitoring device can adapt to the depth of most test holes and is not too long to cause inconvenience in operation and increased cost.

[0026] Furthermore, as a preferred implementation mode of the present invention but not a limitation, the flexible slurry delivery pipe 12 has a length greater than 10 m, an outer diameter of 12 mm, and an inner diameter of 8 mm. The flexible slurry delivery pipe 12 is laid on a flexible bendable elastic rod 11. The flexible slurry delivery pipe 12 has a slurry discharge hole reserved at the bag 13, and the number of the slurry discharge hole is preferably one.

[0027] Furthermore, as a preferred implementation mode of the present invention but not limitation, after the grouting is completed, the excess flexible grouting pipe 12 exposed outside the test hole is cut off, and the flexible grouting pipe 12 at the break is fastened with a thin iron wire.

[0028] In this embodiment, the flexible slurry delivery pipe is provided with slurry discharge holes, so that the grouting liquid can be quickly and evenly distributed to the area requiring grouting, thereby improving the efficiency of grouting; at the same time, the slurry discharge holes can also be used as inspection points to help detect and prevent blockage problems in the flexible slurry delivery pipe.

[0029] Furthermore, as a preferred implementation of the present scheme but not a limitation, the stress wave signal receiving device 30 also includes a rivet 32 ​​for installing the acceleration sensor 31, and the rivet 32 ​​is provided with a ferromagnetic magnet 33 for adsorbing and fixing the acceleration sensor 31. The stress wave signal receiving device 30 is preferably provided with 4 groups on the left and right sides of the tunnel test hole, the acceleration sensor 31 is an internal thread structure, and the ferromagnetic magnet 33 is an external thread structure.

[0030] In this embodiment, the magnetic adsorption characteristics of strong magnetic magnets are utilized so that the acceleration sensor can be quickly installed and disassembled and reused, which simplifies the installation and disassembly process and improves the reusability of the equipment; the magnetic fixation method can reduce the vibration interference caused by mechanical fixation and improve the accuracy of monitoring data; at the same time, multiple groups of stress wave receiving devices are arranged on the left and right sides of the tunnel test hole, which helps to uniformly monitor the test hole area and improve the monitoring coverage.

[0031] Furthermore, as a preferred implementation mode of the present invention but not a limitation, the stress wave signal analysis device 40 includes a data acquisition instrument 41 and a computer analysis software 42, a signal transmission cable 43 for transmitting stress wave signals to the data acquisition instrument 41 is connected between the data acquisition instrument 41 and the acceleration sensor 31, a USB data transmission cable 44 for transmitting data to the computer analysis software 42 is connected between the data acquisition instrument 41 and the computer analysis software 42, and the computer analysis software is MATLAB software.

[0032] In this embodiment, MATLAB software, as a high-level programming language and interactive environment widely used in engineering calculations, data analysis and visualization, has powerful data processing and analysis functions, and can perform in-depth analysis of stress wave signals; MATLAB software also provides a variety of data visualization tools, which can help staff members intuitively understand the characteristics and change trends of stress wave signals, and help staff members better understand monitoring results; data transmission is carried out through signal transmission cables and USB data transmission cables, which ensures the stability and reliability of data transmission and is also helpful for real-time monitoring and analysis; The data acquisition instrument can ensure the complete recording of the exciting force signal and stress wave signal, avoiding data inaccuracy caused by signal distortion or loss; at the same time, it can also record the exciting force signal generated by the exciting hammer in real time, which is helpful for subsequent data analysis and processing.

[0033] Further, as a preferred implementation mode of the present invention but not a limitation, the stress wave signal excitation device 20 includes an exciting hammer 21, and the exciting hammer 21 is connected to the data acquisition instrument 41 via a signal transmission cable 43 for transmitting an exciting force signal to the data acquisition instrument 41, and the exciting hammer 21 is a rubber exciting hammer.

[0034] In this embodiment, the signal transmission cable between the excitation hammer and the data acquisition instrument can ensure the accurate transmission of the signal and reduce the possibility of signal loss or interference; The rubber vibrating hammer has good sealing and durability and can work in a variety of environments. Compared with metal or other hard materials, rubber materials are less likely to damage the equipment and also reduce the risk of injury to operators during operation.

[0035] The working principle of this embodiment is as follows: The present invention proposes a surrounding rock loosening zone stress wave monitoring device, and the specific monitoring process is as follows: First, the flexible bendable elastic rod 11 is inserted into the pre-drilled test hole, and then the grouting machine 14 injects slurry into the bag 13 fixed on the flexible bendable elastic rod 11 through the flexible grouting pipe 12, so that the bag 13 expands to fit tightly with the wall of the test hole. After the grouting liquid is completely solidified so that the monitoring device and the surrounding rock form a whole, the acceleration sensor 31 is installed on the rivet 32 ​​near the test hole; An exciting hammer 21 is used to strike the center point of the end face of the flexible bendable elastic rod 11 to generate a stress wave signal and an exciting force signal. At the same time, the acceleration sensor 31 saves the received stress wave signal and the exciting force signal generated by the exciting hammer 21 into the data acquisition instrument 41 through the signal transmission cable 43. The computer analysis software 42 reads the .dat file saved in the data acquisition instrument 41 through the USB data transmission line 44, thereby drawing an exciting force-time curve and an acceleration-time curve. Then, based on the exciting force-time curve and the acceleration-time curve, the average velocity table of the stress wave reflected by the bag at different positions to the acceleration sensors at different positions is calculated, the range of the surrounding rock loosening circle is determined based on the vertical average velocity table of the average velocity table, and then the horizontal average velocity table of the average velocity table is used to determine whether there are cracks or damage in the surrounding rock loosening circle within the range.

[0036] Second embodiment: Please refer to Figures 3 to 11 As shown, this embodiment proposes a method for monitoring stress waves in a surrounding rock loosening zone, including steps S1-S6, wherein: S1. Use a drilling rig to drill a test hole of more than 10m in the upper or lower side of the tunnel in advance.

[0037] Specifically, a drilling rig is used to drill a test hole of more than 10m in the upper or lower wall of the tunnel, so that a monitoring device can be installed for long-term monitoring of the stability of the tunnel and subsequent evaluation of safety risks during tunnel construction and use. Drilling test holes in advance can also facilitate subsequent construction and monitoring work and reduce interference during the construction process.

[0038] S2. Assemble the monitoring device and insert the monitoring device into the test hole.

[0039] Specifically, a bag is fixed at a certain distance from the top of the flexible bendable elastic rod, a flexible grouting pipe is laid on the flexible bendable elastic rod, a grouting port thereof is connected to each bag, and a grouting port thereof is connected to a grouting machine. After the monitoring device is inserted into the test hole, grouting liquid is injected into each bag through the grouting machine, so that each bag expands to fit closely with the wall of the test hole. After the grouting liquid is completely solidified so that the monitoring device and the surrounding rock form a whole, a rivet is fixed at a certain distance on the left and right sides of the test hole; Among them, the spacing distance between each bag is preferably 0.9m, the number of fixed bags is preferably 8, the spacing distance between each rivet on the left and right sides of the test hole is preferably 1.0m, and the number of fixed rivets on the left and right sides of the test hole is preferably 4.

[0040] S3. Use an exciting hammer to strike the center point of the end surface of the flexible bendable elastic rod to generate a stress wave signal and an exciting force signal. At the same time, the acceleration sensor transmits the received stress wave signal and the exciting force signal generated by the exciting hammer to the data acquisition instrument.

[0041] Specifically, an exciting hammer is used to longitudinally strike the center point of the end face of the flexible bendable elastic rod to generate an exciting force signal and a stress wave signal. The stress wave propagates along the flexible bendable elastic rod toward the inside of the test hole. When encountering a wave impedance interface during the propagation process, scattered waves and transmitted waves are excited. After the acceleration sensor receives the stress wave reflected by the wave impedance interface, it transmits it to the data acquisition instrument. Wherein, the wave impedance interface is the surface of the bladder, and the exciting force signal and the stress wave signal are transmitted to the data acquisition instrument in the form of electrical signals.

[0042] In this embodiment, both the exciting force signal and the stress wave signal are stored by the data acquisition device, providing more comprehensive monitoring data. Through these monitoring data, the propagation characteristics of the stress wave can be analyzed and the geological conditions of the surrounding rock layer can be evaluated.

[0043] S4. Import the data saved by the data acquisition instrument into the computer analysis software.

[0044] Specifically, the data stored in the data acquisition instrument is imported into the computer analysis software installed on the computer via a USB data transmission line.

[0045] S5. After the computer analysis software reads the data, it draws the exciting force-time curve and the acceleration-time curve.

[0046] Specifically, the computer analysis software analyzes and processes the excited force signal and the stress wave signal read out, and draws the corresponding time curve; Wherein, the computer analysis software is MATLAB software.

[0047] Further, as a preferred implementation of this solution but not limiting, step S5 includes steps S51-S52, wherein: S51, computer analysis software reads the .dat file of the data acquisition instrument; S52. Analyze and process the read .dat file, and draw the exciting force-time curve and the acceleration-time curve.

[0048] In this embodiment, the powerful data processing capability of MATLAB software is used to analyze and process the .dat file saved in the data acquisition instrument, so as to draw a corresponding time curve, so that the staff can intuitively observe the monitoring results of the stress wave in the surrounding rock layer.

[0049] S6. Analyze and process the drawn exciting force-time curve and acceleration-time curve to determine the range of the surrounding rock loosening zone and whether there are cracks or breakages in the surrounding rock loosening zone within the range.

[0050] Specifically, the exciting force-time curve and acceleration-time curve are processed and analyzed to calculate the wave velocity of the stress wave. According to the change of wave velocity, the range of the surrounding rock loosening zone and whether there are cracks or breakages in the surrounding rock loosening zone within the range are determined; The wave velocity change refers to the average velocity at which the stress waves reflected by each bag reach the acceleration sensor.

[0051] In this embodiment, the changes in velocity can be observed simply and clearly from the waveform by drawing the exciting force-time curve and the acceleration-time curve, so that the staff can perform corresponding calculations based on the changes in the waveform and velocity to determine the range of the surrounding rock loosening zone, which is easy to observe and simple to operate.

[0052] Further, as a preferred implementation of this solution but not limiting, step S6 includes steps S61-S65, wherein: S61. Experimental measurement of the speed at which stress waves propagate along a flexible, bendable elastic rod and the time it takes for the stress wave to reach each pocket ; S62, calculating the time it takes for the stress wave to be reflected from the bladder to the acceleration sensor ; S63. Calculate the average velocity of the stress wave reflected from the bladder to the acceleration sensor ; S64, changing the position of the acceleration sensor, repeating steps S62 and S63, and calculating an average velocity table of the stress wave reflected from the bladder at different positions to the acceleration sensors at different positions; S65. Compare and analyze the average velocity table obtained in step S64 to determine the range of the surrounding rock loosening zone and whether there are cracks or fractures in the range.

[0053] Specifically, the number of the pouches from near to far is k (k=1, 2, 3, 4, 5, 6, 7, 8...m), the number of the rivets from left to right is b (b=1, 2, 3, 4, 5, 6, 7, 8...j), and the distance from the pouch to the exposed top of the bendable flexible elastic rod from near to far is (k=1, 2, 3, 4, 5, 6, 7, 8...m), the distance from the rivet to the center point of the exposed top of the flexible elastic rod is (b=1, 2, 3, 4, 5, 6, 7, 8...j); In step S61, the acceleration sensor is first set to the top of the flexible elastic rod, and then the time for the stress wave to reach each bladder is measured. , and then the speed of stress wave propagation along the flexible elastic rod can be measured .

[0054] Further, as a preferred implementation of this solution but not limiting, step S62 includes steps S621-S623, wherein: S621. Obtain the first arrival time of the exciting force signal to the acceleration sensor from the exciting force-time curve and the acceleration-time curve And the first arrival time of the stress wave signal generated by the bladder to the acceleration sensor ; S622: Subtract the two first arrival times obtained in step S621 to obtain the total time for the stress wave signal to be reflected from the top of the flexible elastic rod through the bag to the acceleration sensor. ; S623: Total time calculated according to step S622 , calculate the time it takes for the stress wave to be reflected from the bag to the acceleration sensor .

[0055] Specifically, by analyzing the exciting force-time curve, the first arrival time of the exciting force signal to the acceleration sensor can be obtained. (i.e., the time corresponding to the surge in the exciting force-time curve from 0). By analyzing the acceleration-time curve, the first arrival time of the stress wave signal reflected from the top of the flexible bendable elastic rod through the bag to the acceleration sensor can be obtained. (i.e. the time when the acceleration-time curve begins to fluctuate); Among them, the two first arrival times obtained are subtracted to calculate the total time it takes for the stress wave signal to reach the acceleration sensor from the top of the flexible bendable elastic rod through the bag reflection. ,Right now , and then the time it takes for the stress wave to be reflected from the bag to the acceleration sensor can be obtained ,Right now .

[0056] In this embodiment, the time it takes for the stress wave to travel from the bladder to the acceleration sensor can be calculated using the exciting force-time curve and the acceleration-time curve, which reduces the difficulty of calculation and facilitates staff to monitor the geological conditions of the surrounding rock layer. At the same time, this analysis method can also be applied to dynamic monitoring and real-time evaluation of the structural status of the surrounding rock layer.

[0057] Further, as a preferred implementation manner of this solution but not limiting, step S63 includes steps S631-S633, wherein: S631. Calculate the distance from different bladders to the vertex of the exposed end of the flexible bendable elastic rod , calculate the distance from the acceleration sensor at different positions to the center point of the exposed end of the flexible bendable elastic rod ; S632: Calculate the distance from the capsule to the acceleration sensor based on the data obtained in step S631. ; S633: Calculate the average velocity of the stress wave from the bladder to the acceleration sensor based on the data obtained in step S632 and step S62. .

[0058] Specifically, the distance from the sac to the vertex of the exposed end of the flexible bendable elastic rod is expressed as , the distance from the acceleration sensor to the center point of the exposed end of the flexible bendable elastic rod is expressed as ; Among them, the distance from the bag to the acceleration sensor is The average velocity of the stress wave from the bladder to the accelerometer is ; Where k represents the position number of the bag from near to far, and b represents the position number of the rivet from left to right.

[0059] Further, as a preferred implementation of the present solution but not a limitation, step S64 can obtain an average velocity table of stress waves from bladders at different positions to acceleration sensors at different positions.

[0060] Specifically, a bag is fixed at every 0.9m interval from the top of the flexible bendable elastic rod, and a plurality of bags can be fixed. Preferably, 8 bags are fixed, and the bag numbers are as follows from the bag's distance from the exposed top of the flexible bendable elastic rod to the farthest: , , , , , , and A rivet is fixed at every 1.0m interval on the left and right sides of the test hole. The rivets can be fixed in multiple numbers. Preferably, 4 rivets are fixed on the left and right sides of the test hole. The rivets are numbered from the distance from the rivet to the center point of the outer end of the flexible bendable elastic rod from near to far. , , , , , , and ; First, place the stress wave monitoring device in the test hole. After the grouting is completely solidified, fix the acceleration sensor on the exposed top of the flexible elastic rod to measure the time it takes for the stress wave to reach each pocket. , , , , , , and , and then fix the acceleration sensor on The data is then imported into the computer analysis software for analysis and processing. According to the above steps, the first arrival time of the first capsule can be obtained. and , thus the total time for the force wave to be reflected from the top of the flexible elastic rod through the bag and reach the acceleration sensor can be calculated , and then the time it takes for the stress wave to be reflected from the bag to the acceleration sensor can be calculated , and the distance from the capsule to the acceleration sensor is , so the average velocity of the stress wave from the bladder to the accelerometer is Similarly, according to the above steps, the distance from other capsules to the acceleration sensor can be obtained in turn. The average stress wave velocity at , , , , , and ; Similarly, fix the acceleration sensor on When the above steps are followed, the distances from other capsules to the acceleration sensor can be obtained in turn. The average stress wave velocity at , , , , , , and , Similarly, according to this calculation principle, a total of 8 groups of stress wave average velocities from different bladders to acceleration sensors at different positions can be obtained. These 8 groups of data together constitute the average velocity table; The average speed table is:

[0061] Further, as a preferred implementation manner of this solution but not limiting, step S65 includes steps S651-S653, wherein: S651, comparing the average speeds of the stress wave to the acceleration sensors at different positions along the test hole direction b, and determining the range of the surrounding rock loosening zone; S652, according to the range obtained in step S651, compare the average speeds of the stress wave in the range along the tunnel direction a to the acceleration sensors at different positions, and determine whether there are cracks or fractures in the range; S653. If the average speeds along the lane direction a in step S652 are the same, there are no cracks or breakages within this range; if the average speeds along the lane direction a in step S652 are different, there are cracks or breakages within this range.

[0062] Specifically, first compare the average speed of the stress wave along the test hole direction b to the acceleration sensors at different positions (i.e., the vertical average speed table of the average speed table in step S64) to determine the area where the surrounding rock loosening zone is located. For example, if > < In the case of and between; Then, the average speeds of the stress wave from the acceleration sensors at different positions along the tunnel direction a are compared (i.e., the lateral average speed table of the average speed table in step S64), to determine whether there are cracks or damages in the surrounding rock loosening zone in the area. The judgment standard is: the average speeds of the surrounding rock loosening zones in the same rock at the same horizontal plane and the same depth are the same. If they are different, the surrounding rock loosening zone in the area may have cracks or damages. The surrounding rock loose zone exists in and For example, if ≈ ≈ > or ≈ ≈ or ≈ ≈ > or ≈ ≈ In such cases, the cracks or damage in the loose zone of the surrounding rock in this area exist and If there is ≈ ≈ ≈ ≈ ≈ ≈ ≈ and ≈ ≈ ≈ ≈ ≈ ≈ ≈ When the situation is as follows, there are no cracks or damages in the loosened zone of surrounding rock in the area; Among them, since the bag at H1 is relatively close to the tunnel, the average velocity of the stress wave between the bag at H1 and the acceleration sensor along the test hole direction is generally lower than the normal average velocity value, so there will be a loose rock zone in the area between the bag at H1 and the outer end of the test hole. Therefore, the above judgment method is only applicable to judging whether there is a loose rock zone in the area between other bags and the acceleration sensor except the bag at H1.

[0063] In this embodiment, based on the average velocity table, by comparing the average velocities of stress waves recorded by acceleration sensors at different positions, the range of the loosened surrounding rock zone can be accurately located, and by comparing and analyzing the average velocity of the stress wave in the tunnel direction, it can be determined whether there are cracks or damage in the loosened surrounding rock zone within this range. This analysis result based on quantitative data can provide a more scientific and objective basis, and achieve a more accurate assessment of the stability and potential risks of the loosened surrounding rock zone.

[0064] Furthermore, as a preferred implementation mode of the present invention but not a limitation, in order to achieve more accurate monitoring of the loosening zone of the surrounding rock, the distance between the acceleration sensor and the test hole can be increased or the number of bags can be increased to achieve a wider range of monitoring, or the spacing between the bags can be reduced or the spacing between the rivets can be reduced.

[0065] In this embodiment, a wider monitoring range and more dense monitoring points can help to more accurately analyze the propagation characteristics of stress waves and achieve a more comprehensive assessment of the stability and looseness of the surrounding rock layer.

[0066] Ordinary technicians in the relevant field should understand that the above is an implementation method provided in combination with specific content, and it is not considered that the specific implementation of the present invention is limited to these descriptions. At the same time, due to different industry naming, it is not limited to the above naming, nor is it limited to English naming. Any similarity or similarity with the method, structure, etc. of the present invention, or a number of technical deductions or substitutions made on the premise of the concept of the present invention, should be regarded as the protection scope of the present invention.

Claims

1. A surrounding rock loosening zone stress wave monitoring device, characterized in that: It comprises a monitoring device (10), a stress wave signal exciting device (20), a stress wave signal receiving device (30) and a stress wave signal analyzing device (40); The monitoring device (10) is arranged in a test hole pre-drilled in the tunnel, and the monitoring device (10) is provided with a plurality of bags (13) for reflecting stress waves; The stress wave signal excitation device (20) is used to emit stress waves into the test hole; The stress wave signal receiving device (30) is provided in multiple groups on the left and right sides of the tunnel test hole, and the stress wave signal receiving device (30) comprises an acceleration sensor (31), and the acceleration sensor (31) is used to receive the stress wave signal and transmit the received stress wave signal to the stress wave signal analysis device (40); The stress wave signal analysis device (40) is used to analyze and process the received stress wave signal, and to draw an average velocity table between the stress wave reflected by the bladder (13) at different positions and the acceleration sensors (31) at different positions.

2. The surrounding rock loosening zone stress wave monitoring device according to claim 1 is characterized in that: The monitoring device (10) further comprises a flexible bendable elastic rod (11) and a flexible slurry delivery pipe (12); at least eight bags (13) are fixed on the flexible bendable elastic rod (11); adjacent bags (13) are spaced a certain distance apart; a slurry outlet of the flexible slurry delivery pipe (12) is connected to the bag (13); a grouting port of the flexible slurry delivery pipe (12) is connected to a grouting machine (14) for injecting slurry into the bag (13) so that the bag (13) expands to fit tightly against the wall of the test hole.

3. The device for monitoring stress waves in surrounding rock loosening zone according to claim 1 is characterized in that: The stress wave signal receiving device (30) further comprises a rivet (32) for mounting the acceleration sensor (31), wherein the rivet (32) is provided with a strong magnetic magnet (33) for adsorbing and fixing the acceleration sensor (31).

4. The device for monitoring stress waves in surrounding rock loosening zone according to claim 1 is characterized in that: The stress wave signal analysis device (40) comprises a data acquisition instrument (41) and computer analysis software (42); a signal transmission cable (43) for transmitting stress wave signals to the data acquisition instrument (41) is connected between the data acquisition instrument (41) and the acceleration sensor (31); and a USB data transmission cable (44) for transmitting data to the computer analysis software (42) is connected between the data acquisition instrument (41) and the computer analysis software (42).

5. The device for monitoring stress waves in surrounding rock loosening zone according to claim 4 is characterized in that: The stress wave signal excitation device (20) comprises an exciting hammer (21), and the exciting hammer (21) is connected to a data acquisition instrument (41) via a signal transmission cable (43) for transmitting an exciting force signal to the data acquisition instrument (41).

6. A method for monitoring stress waves in a surrounding rock loosening zone, characterized in that: The monitoring method is implemented by the monitoring device according to any one of claims 1 to 5; The monitoring method comprises the following steps: Step S1, using a drilling machine to drill a test hole of more than 10m in the upper or lower wall of the tunnel in advance; Step S2, assembling the monitoring device and inserting the monitoring device into the test hole; Step S3, using an exciting hammer to strike the center point of the end surface of the flexible bendable elastic rod to generate a stress wave signal and an exciting force signal, and at the same time, the acceleration sensor transmits the received stress wave signal and the exciting force signal generated by the exciting hammer to the data acquisition instrument; Step S4, importing the data stored in the data acquisition instrument into the computer analysis software; Step S5, after the computer analysis software reads the data, it draws the exciting force-time curve and the acceleration-time curve; Step S6, analyzing and processing the drawn exciting force-time curve and acceleration-time curve to determine the range of the surrounding rock loosening zone and whether there are cracks or fractures in the surrounding rock loosening zone within the range.

7. A method for monitoring stress waves in surrounding rock loosening zones according to claim 6, characterized in that: The step S6 further comprises the following steps: Step S61, the speed of stress wave propagation along the flexible bendable elastic rod is measured by experiment and the time it takes for the stress wave to reach each pocket ; Step S62, calculating the time it takes for the stress wave to be reflected from the bladder to the acceleration sensor ; Step S63, calculating the average velocity of the stress wave reflected from the bladder to the acceleration sensor ; Step S64, changing the position of the acceleration sensor, repeating steps S62 and S63, and calculating an average velocity table of the stress wave reflected from the bladder at different positions to the acceleration sensors at different positions; Step S65, performing comparative analysis based on the average velocity table obtained in step S64 to determine the range of the surrounding rock loosening zone and whether there are cracks or fractures within the range.

8. The method for monitoring stress waves in surrounding rock loosening zone according to claim 7 is characterized in that: The step S62 further comprises the following steps: Step S621, obtaining the first arrival time of the exciting force signal to the acceleration sensor from the exciting force-time curve and the acceleration-time curve And the first arrival time of the stress wave signal generated by the bladder to the acceleration sensor ; Step S622, subtract the two first arrival times obtained in step S621 to obtain the total time for the stress wave signal to be reflected from the top of the flexible bendable elastic rod through the bladder to the acceleration sensor ; Step S623, the total time calculated according to step S622 , calculate the time it takes for the stress wave to be reflected from the bag to the acceleration sensor .

9. The method for monitoring stress waves in surrounding rock loosening zone according to claim 7, characterized in that: The step S63 further comprises the following steps: Step S631, calculating the distances from different capsules to the vertex of the exposed end of the flexible bendable elastic rod , calculate the distance from the acceleration sensor at different positions to the center point of the exposed end of the flexible bendable elastic rod ; Step S632: Calculate the distance from the capsule to the acceleration sensor based on the data obtained in step S631. ; Step S633, based on the data obtained in step S632 and step S62, calculate the average velocity of the stress wave from the bladder to the acceleration sensor .

10. The method for monitoring stress waves in surrounding rock loosening zone according to claim 7, characterized in that: The step S65 further comprises the following steps: Step S651, comparing the average speeds of the stress wave along the test hole direction (b) to the acceleration sensors at different positions to determine the range of the surrounding rock loosening zone; Step S652, based on the range obtained in step S651, compare the average speeds of the stress wave in the range along the tunnel direction (a) to the acceleration sensors at different positions to determine whether there are cracks or fractures in the range; Step S653, if the average speeds along the lane direction (a) in step S652 are the same, then there are no cracks or breakages within this range; if the average speeds along the lane direction (a) in step S652 are different, then there are cracks or breakages within this range.

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