Soft rock tunnel surrounding rock compaction zone measuring device and method

Abstract

This invention discloses a device and method for measuring the compaction zone of surrounding rock in soft rock tunnels, relating to the field of surrounding rock compaction zone measurement technology. It includes a protective device and a detection device. The protective device comprises a protective shell that can extend into the tunnel's opening. The detection device includes a vibrator, a detector, and a measuring rod. The measuring rod extends into the protective shell, and both the vibrator and the detector are mounted on the measuring rod. The vibrator emits shock waves toward the tunnel's surrounding rock, and the detector receives the shock wave waveform. A detection port is also provided on the protective shell, corresponding to the detection device. This invention's method for measuring the compaction zone of surrounding rock in soft rock tunnels utilizes the aforementioned device. This invention can effectively suppress opening deformation and collapse, and can also achieve measurements of deeper rock layers with more accurate results.

Description

Technical Field

[0001] This invention relates to the field of surrounding rock compaction zone measurement technology, and in particular to a device and method for measuring the surrounding rock compaction zone of soft rock tunnels. Background Technology

[0002] The compaction zone of surrounding rock refers to the area where rock mass becomes compacted and dense under external pressure. The development of the compaction zone in tunnels with weak and fractured rock masses is influenced by the construction process, exhibiting significant spatiotemporal effects. Measuring the compaction zone can help determine if there is a risk of instability or deformation in the surrounding rock, thus improving engineering safety. Its development pattern is also an important basis for elucidating the mechanism of progressive failure of surrounding rock. The extent of the compaction zone and the loosened zone are both important parameters for determining tunnel support parameters, but current research on the measurement of the compaction zone is still limited.

[0003] Currently, single-hole acoustic methods are commonly used in China for testing compacted rock zones. During the test, water is used as a coupling agent, and the difference in the propagation velocity of acoustic waves (elastic waves) within the surrounding rock is measured to determine the extent of the compaction zone or loosening zone. Compacted zones have higher wave velocities due to the dense rock mass, while loosening zones have lower wave velocities due to the development of fissures. However, in weak and fractured rock masses, due to poor borehole wall stability and numerous fissures, borehole collapse occurs after a certain period, rendering the borehole unusable and resulting in poor water retention. Especially in tunnels with weak and fractured rock masses, the compacted rock zones are deep. Repeated drilling at the same location for testing would create significant cost and time constraints. Furthermore, using acoustic methods to measure deep surrounding rock requires low-frequency waves, which can probe deeper areas, but the resolution decreases, thus affecting test accuracy.

[0004] Therefore, a measuring device for the compaction zone of surrounding rock in soft rock tunnels is provided to solve the above-mentioned problems existing in the prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a device and method for measuring the compaction zone of surrounding rock in soft rock tunnels, so as to solve the problems existing in the prior art. It can effectively suppress hole deformation and collapse, and can also achieve measurement of deeper rock layers, and the results obtained are more accurate.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides a measuring device for the compaction zone of surrounding rock in soft rock tunnels, comprising a protective device and a detection device. The protective device includes a protective housing that can extend into the tunnel's opening. The detection device includes a vibrator, a detector, and a measuring rod. The measuring rod extends into the protective housing. Both the vibrator and the detector are mounted on the measuring rod. The vibrator emits shock waves toward the tunnel's surrounding rock, and the detector receives the shock wave waveform. The protective housing also has a detection port corresponding to the detection device.

[0008] Preferably, the protective housing is a cylindrical housing, and a cover is provided at the tail end of the protective housing. A through hole is provided in the middle of the cover, and the measuring rod passes through the through hole and can move along the axial direction of the protective housing; wherein, the detection port is provided along the axial length of the protective housing.

[0009] Preferably, the measuring rod is also provided with scale lines.

[0010] Preferably, it also includes a support device, which is disposed on the outside of the protective housing and is used to support the wall of the hole;

[0011] The supporting device is a deformable bladder, which surrounds the outer surface of the protective shell and can be filled with a medium to deform the bladder.

[0012] Preferably, the deformable bladder is a water bladder, which can be filled with water; wherein, the water bladder is also provided with a pressure sensor for detecting the water injection pressure.

[0013] Preferably, it also includes a waterproof membrane, which is used to lay on the wall of the hole.

[0014] Preferably, it further includes a telescopic device and a top plate, the top plate being disposed at the detection port and capable of fitting against the wall of the hole; the telescopic device being fixedly connected to the measuring rod, and the top of the telescopic device being connected to the top plate, the telescopic device being capable of driving the top plate to rise and fall, so that the top plate fits against the top wall of the hole or detaches from the wall of the hole;

[0015] Both the vibrator and the detector are connected to the top plate via springs. The top plate is an arc-shaped plate that can fit snugly against the wall of the hole.

[0016] Preferably, the telescopic device includes an outer shell, a rotating tube, and a pushing part. A spiral slide is arranged around the outer shell. The rotating tube is rotatably disposed within the outer shell and is provided with a Z-shaped slide. The pushing part is disposed inside the rotating tube. The top of the pushing part is connected to the top plate via a support rod. A limit block is provided at the bottom of the pushing part. The limit block passes through the Z-shaped slide and is slidably disposed within the spiral slide. Rotating the rotating tube can drive the pushing part to rise and fall.

[0017] Preferably, the rotating tube is connected to a driving mechanism, which can drive the rotating tube to rotate;

[0018] The rotating tube has a gear connected to its bottom, and the driving mechanism includes a driving rod that is slidably connected to the measuring rod. The front end of the driving rod is provided with a rack that meshes with the gear. The tail end of the driving rod extends out of the protective housing. Pushing the driving rod can drive the gear to rotate.

[0019] Preferably, the telescopic device is slidably disposed within the protective housing;

[0020] The protective housing has a slide rail arranged along its length near the detection port, and the telescopic device is connected to a slider, which is slidably mounted on the slide rail.

[0021] The present invention also provides a method for measuring the compaction zone of surrounding rock in soft rock tunnels, which is implemented using the soft rock tunnel surrounding rock compaction zone measuring device described above, and includes the following steps:

[0022] S1. Install the measuring device for the compaction zone of the surrounding rock in the soft rock tunnel;

[0023] S2. A shock wave is emitted toward the surrounding rock of the tunnel through the exciter, and the waveform of the shock wave is received by the detector; wherein, the wave velocity change is measured and compared at different times to obtain the range of the compaction zone.

[0024] The present invention achieves the following technical effects compared to the prior art:

[0025] This invention features a protective shell that supports the borehole walls, preventing deformation and collapse. Furthermore, the detection device includes a vibrator, a detector, and a measuring rod. The measuring rod extends into the protective shell, and both the vibrator and the detector are mounted on the measuring rod. The vibrator emits shock waves towards the tunnel surrounding rock, and the detector receives the shock wave waveform to obtain the compaction status of the surrounding rock compaction zone. By using shock waves instead of conventional sound waves, measurements of deeper rock layers can be achieved, and the results are more accurate. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic diagram of the overall structure of the measuring device for the compaction zone of surrounding rock in a soft rock tunnel according to an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the telescopic device in an embodiment of the present invention;

[0029] Figure 3 A schematic diagram of the arc-shaped top plate configuration in an embodiment of the present invention;

[0030] Figure 4 The diagram shows the hole depth-wave velocity curves at different time points in the embodiments of the present invention.

[0031] In the diagram: 1-protective housing; 2-slide rail; 3-slider; 4-support rod; 5-telescopic device; 6-top plate; 7-spring; 8-gear; 9-drive rod; 10-vibrator; 11-measuring rod; 12-shell cover; 13-detector; 14-water bladder. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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] The purpose of this invention is to provide a device and method for measuring the compaction zone of surrounding rock in soft rock tunnels, so as to solve the problems existing in the prior art. It can effectively suppress hole deformation and collapse, and can also achieve measurement of deeper rock layers, and the results obtained are more accurate.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1

[0036] like Figures 1-4As shown, this embodiment provides a measuring device for the compaction zone of surrounding rock in a soft rock tunnel, mainly including a protective device and a detection device. The protective device includes a protective housing 1, which can extend into the tunnel cavity to support the cavity wall and prevent collapse. The detection device includes a vibrator 10, a detector 13, and a measuring rod 11. The measuring rod 11 extends into the protective housing 1. The vibrator 10 and the detector 13 are both mounted on the measuring rod 11. The vibrator 10 can emit shock waves toward the tunnel surrounding rock, and the detector 13 is used to receive the shock wave waveform to obtain the compaction status of the surrounding rock compaction zone. The protective housing 1 also has a detection port, which corresponds to the detection device to facilitate detection by the detection device.

[0037] In this embodiment, a protective shell 1 is provided to support the hole wall and suppress hole deformation and collapse. Furthermore, the detection device includes a vibrator 10, a detector 13, and a measuring rod 11. The measuring rod 11 extends into the protective shell 1. Both the vibrator 10 and the detector 13 are mounted on the measuring rod 11. The vibrator 10 emits shock waves toward the tunnel surrounding rock, and the detector 13 receives the shock wave waveform to obtain the compaction status of the surrounding rock compaction zone. Using shock waves instead of conventional sound waves allows for the measurement of deeper rock layers, and the results are more accurate.

[0038] In this embodiment, the protective shell 1 is a cylindrical shell, and a shell cover 12 is provided at the tail end of the protective shell 1 (the end that does not extend into the hole). A through hole is provided in the middle of the shell cover 12, and the measuring rod 11 passes through the through hole and can move along the axial direction of the protective shell 1, so as to measure different positions of the hole. The waveform of the entire hole can be obtained by multiple measurements, and the surrounding rock compaction can be obtained by analyzing the waveform. The detection port on the protective shell 1 is set along its length to facilitate measurement at different positions.

[0039] Furthermore, the measuring rod 11 is also provided with scale lines for observing the position of the detector.

[0040] In this embodiment, a support device is also included. The support device is disposed on the outside of the protective housing 1 and is used to support the hole wall. The support device can be selected according to specific working needs. For example, it can be a deformable bladder. The deformable bladder is disposed around the outer surface of the protective housing 1 (and needs to be staggered from the detection port). By filling the deformable bladder with a medium, it deforms and expands, thereby supporting the hole wall.

[0041] In a preferred embodiment, the deformable bladder is a water bladder 14, which can be filled with water. The incompressibility of water is used to apply uniform radial pressure to the surrounding rock through the water bladder 14, thereby inhibiting the deformation of the hole. Moreover, by adjusting the water volume, the water bladder 14 can adjust its state according to the deformation of the surrounding rock, conform to the surface of the irregular hole, reduce the blind spot of the support, and provide a relatively more stable and uniform support for the hole wall.

[0042] Furthermore, the water bladder 14 is also equipped with a pressure sensor for detecting the water injection pressure.

[0043] It should be noted that other media, such as inert gases or other liquids, can also be injected into the deformable capsule, and are not limited to water.

[0044] In this embodiment, a waterproof membrane is also included, which is used to lay on the hole wall of the hole to prevent the water bag 14 from leaking and softening the surrounding rock, thus preventing the hole from collapsing.

[0045] In this embodiment, a telescopic device 5 and a top plate 6 are also included. The top plate 6 is disposed at the detection port and can fit against the hole wall to provide support and improve stability. The telescopic device 5 is fixedly connected to the measuring rod 11, and the top of the telescopic device 5 is connected to the top plate 6. The telescopic device 5 can drive the top plate 6 to rise and fall so that the top plate 6 fits against the top wall of the hole or detaches from the hole wall.

[0046] In this embodiment, both the exciter 10 and the detector 13 are connected to the top plate 6 via springs 7, which provide damping and facilitate the reset of the top plate 6; wherein, as Figure 3 As shown, the top plate 6 is preferably an arc-shaped top plate, which can better fit the top wall of the hole.

[0047] In this embodiment, the telescopic device 5 includes an outer shell, a rotating tube, and a pushing part. A spiral slide is arranged around the outer shell. The rotating tube is rotatably disposed within the outer shell and is provided with a Z-shaped slide. The pushing part is disposed inside the rotating tube. The top of the pushing part is connected to the top plate 6 via a support rod 4. A limit block is provided at the bottom of the pushing part. The limit block passes through the Z-shaped slide and is slidably disposed within the spiral slide. By rotating the rotating tube, the pushing part can be driven to rise and fall, thereby driving the top plate 6 to rise and fall.

[0048] The telescopic device 5 can be provided in multiple ways, for example, four, to provide support at the four corners of the top plate 6, thereby improving the overall stability.

[0049] In this embodiment, the rotating tube is connected to a driving mechanism, which can drive the rotating tube to rotate. A gear 8 is connected to the bottom of the rotating tube. The driving mechanism includes a driving rod 9, which is slidably connected to the measuring rod 11. A rack is provided at the front end of the driving rod 9, and the rack meshes with the gear 8. The tail end of the driving rod 9 extends out of the protective housing 1. By pushing the driving rod 9, the gear 8 can be driven to rotate, thereby driving the rotating tube to rotate.

[0050] In this embodiment, the telescopic device 5 can be manually driven to raise and lower the top plate 6 via the drive rod 9, rack, and gear 8, without the need for a pneumatic or electric drive mechanism. The structure is simple and easy to operate.

[0051] Furthermore, it should be noted that the telescopic device 5 is not limited to the above structure, and can also be equipped with pneumatic or electric lifting structures such as hydraulic rods or electric push rods as needed.

[0052] In this embodiment, the telescopic device 5 is slidably disposed within the protective housing 1; specifically, a slide rail 2 is provided along its length direction near the detection port within the protective housing 1, the telescopic device 5 is connected to a slider 3, and the slider 3 is slidably disposed on the slide rail 2. While enabling the telescopic device 5 and the connected measuring rod 11 to slide, the slide rail 2 can effectively support both and improve stability.

[0053] In this embodiment, the method of using the soft rock tunnel surrounding rock compaction zone measuring device is as follows:

[0054] 1. Drill holes at the monitoring points in the tunnel where monitoring is required;

[0055] 2. After drilling, clean the inside of the hole and smooth the opening and surrounding area to prevent any protruding sharp stones from tearing the water bag 14;

[0056] 3. After cleaning the hole, lay a waterproof membrane to prevent water leakage from water bag 14 from softening the surrounding rock and causing the hole to collapse;

[0057] 4. Secure the empty water bladder 14 completely to the surface of the protective shell 1, and push them into the hole together;

[0058] 5. Determine the pressure required for borehole wall stability based on the test depth, surrounding rock fracturing condition, and ground stress.

[0059] 6. Slowly and gradually inject water into the water bladder 14 and pressurize it to the design pressure value to support the hole;

[0060] 7. Regularly monitor the pressure of the water bladder 14. When the water pressure is less than 90% of the required water pressure, inject water to pressurize it in time.

[0061] The process of a single test is as follows:

[0062] (1) Assemble the equipment by installing the detector and the telescopic device 5 connected to it onto the slide rail 2 via the slider 3;

[0063] (2) Control the measuring rod 11 and determine the measurement position according to the scale on the measuring rod 11;

[0064] (3) After fixing the position, move the drive rod 9 back and forth to drive the gear 8 to rotate the support rod 4 in the telescopic device 5 and push the top plate 6 to contact the hole wall;

[0065] (4) After adjustment, the exciter 10 is activated and the shock wave waveform at that position is collected by the detector 13;

[0066] (5) After completion, the support rod 4 and the top plate 6 are screwed back in by the drive rod 9, and the position of the detector is adjusted again.

[0067] (6) Repeat the above operation multiple times to obtain the waveform of the entire hole. The surrounding rock compaction can be obtained by analyzing the waveform.

[0068] Multiple tests:

[0069] Based on the construction process and time, the surrounding rock compaction zone of the borehole was repeatedly tested.

[0070] The specific principle of measuring the compacted zone of surrounding rock in this embodiment is as follows:

[0071] Among them, the faster the wave velocity, the better the rock mass integrity; affected by the support force on the side and the pressure of the deep surrounding rock, after a period of time after the support is completed, the originally loose surrounding rock will be compressed and compacted into a ring-shaped area under the action of concentrated stress. For example Figure 4 As shown in the image analysis, time point 1 represents the construction process from the upper to the lower bench of the tunnel; time point 2 represents the initial support closure; and time point 3 represents the time approximately 40m from the tunnel face after the initial support closure. The overall slower wave velocity at time point 2 compared to time point 1 indicates that the surrounding rock became more fractured after excavation. However, at time point 3, compared to time point 2, the wave velocity actually began to increase within the 0m-1.4m depth range from the support side, suggesting that this area represents the rock compaction zone.

[0072] In this embodiment, when measuring the compaction zone of the surrounding rock, it is necessary to measure and compare the changes in wave velocity at different times to obtain the range of the compaction zone.

[0073] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A measuring device for the compaction zone of surrounding rock in soft rock tunnels, characterized in that: The device includes a protective device and a detection device. The protective device includes a protective housing that can extend into the tunnel opening. The detection device includes a vibrator, a detector, and a measuring rod. The measuring rod extends into the protective housing. The vibrator and the detector are both mounted on the measuring rod. The vibrator can emit shock waves toward the tunnel surrounding rock. The detector is used to receive the shock wave waveform. The protective housing also has a detection port corresponding to the detection device. It also includes a support device, which is disposed on the outside of the protective shell and is used to support the hole wall of the hole; wherein, the support device is a deformable bladder, which surrounds the outer surface of the protective shell and can be filled with a medium to deform the deformable bladder. It also includes a telescopic device and a top plate. The top plate is disposed at the detection port and can fit against the wall of the hole. The telescopic device is fixedly connected to the measuring rod, and the top of the telescopic device is connected to the top plate. The telescopic device can drive the top plate to rise and fall so that the top plate fits against the top wall of the hole or detaches from the hole wall. The vibrator and the detector are both connected to the top plate via springs. The top plate is an arc-shaped plate that can fit against the wall of the hole. The telescopic device is slidably disposed within the protective housing; wherein, a slide rail is provided along the length direction of the protective housing near the detection port, the telescopic device is connected to a slider, and the slider is slidably disposed on the slide rail.

2. The measuring device for the compaction zone of surrounding rock in soft rock tunnels according to claim 1, characterized in that: The protective housing is a cylindrical housing, and a cover is provided at the tail end of the protective housing. A through hole is provided in the middle of the cover. The measuring rod passes through the through hole and can move along the axial direction of the protective housing. The detection port is provided along the axial length of the protective housing.

3. The measuring device for the compaction zone of surrounding rock in soft rock tunnels according to claim 2, characterized in that: The measuring rod is also equipped with scale lines.

4. The measuring device for the compaction zone of surrounding rock in soft rock tunnels according to claim 1, characterized in that: The deformable bladder is a water bladder, which can be filled with water; a pressure sensor is also provided on the water bladder to detect the water injection pressure. It also includes a waterproof membrane, which is used to lay on the walls of the hole.

5. The measuring device for the compaction zone of surrounding rock in soft rock tunnels according to claim 1, characterized in that: The telescopic device includes an outer shell, a rotating tube, and a pushing part. A spiral slide is arranged around the outer shell. The rotating tube is rotatably disposed within the outer shell and is provided with a Z-shaped slide. The pushing part is disposed inside the rotating tube. The top of the pushing part is connected to the top plate via a support rod. A limit block is provided at the bottom of the pushing part. The limit block passes through the Z-shaped slide and is slidably disposed within the spiral slide. Rotating the rotating tube can drive the pushing part to rise and fall.

6. The measuring device for the compaction zone of surrounding rock in soft rock tunnels according to claim 5, characterized in that: The rotating tube is connected to a driving mechanism, which can drive the rotating tube to rotate. The rotating tube has a gear connected to its bottom, and the driving mechanism includes a driving rod that is slidably connected to the measuring rod. The front end of the driving rod is provided with a rack that meshes with the gear. The tail end of the driving rod extends out of the protective housing. Pushing the driving rod can drive the gear to rotate.

7. A method for measuring the compaction zone of surrounding rock in soft rock tunnels, characterized in that: The method employs the soft rock tunnel surrounding rock compaction zone measuring device as described in any one of claims 1-6, and includes the following steps: S1. Install the measuring device for the compaction zone of the surrounding rock in the soft rock tunnel; S2. A shock wave is emitted toward the surrounding rock of the tunnel through the exciter, and the waveform of the shock wave is received by the detector; wherein, the wave velocity change is measured and compared at different times to obtain the range of the compaction zone.

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