Width measuring device for coal rock loosening circle of coal mine tunnel

Abstract

The utility model discloses a coal mine tunnel coal rock loosening circle width measuring device, and relates to the technical field of coal mine tunnel surrounding rock stability monitoring. Comprising an airbag, a measuring rod and a limiting mechanism, one end of the measuring rod is connected with an air bag; the measuring rod is provided with scales; the limiting mechanism comprises a limiting tray, and a through limiting hole is formed in the center of the limiting tray; inclined drill holes are formed in the sides of the roadway, and water is injected into the drill holes; one end, connected with the air bag, of the measuring rod extends into the drill hole, so that the air bag floats on the water surface, and the other end of the measuring rod extends out of a limiting hole in the limiting tray; the limiting tray is fixed on a roadway side and is positioned at an orifice of the drill hole, so that the measuring rod is parallel to the inclination angle of the drill hole; quantitative measurement of the width of the loose ring is achieved through the linkage relation between the water surface height displacement caused by water injection leakage and the air bag displacement, the structure is simple, cost is low, and higher applicability and safety are achieved.

Description

Technical Field

[0001] This utility model belongs to the field of coal mine roadway surrounding rock stability monitoring technology, specifically a coal mine roadway coal and rock loosening zone width measuring device. Background Technology

[0002] In coal mining operations, the surrounding rock deforms and loosens after tunnel excavation, and the loosened zone of the surrounding rock is a key parameter in support design. In recent years, many theoretical results on the calculation of the range of the loosened zone of the surrounding rock have emerged both domestically and internationally. However, due to the many complex factors in actual engineering projects, the calculation results have significant limitations.

[0003] The loosening zone test is an important technical means to verify the stability of the surrounding rock in a roadway. The extent of the loosening zone is an important indicator of the integrity of the surrounding rock after roadway excavation and is a crucial basis for determining roadway support parameters. After roadway excavation, the original rock stress is redistributed, and stress unloading zones and stress concentration zones form in the surrounding rock mass. Under the action of concentrated stress, the free-face rock mass formed in the excavated space forms a near-circular ring-shaped fracture zone, i.e., the loosening zone, in the surrounding rock mass. If not supported in time, there is a risk of sidewall spalling and roof collapse. The extent of the loosening zone is closely related to the lithology of the coal and rock strata in which the roadway is located and the level of in-situ stress. The higher the strength of the coal and rock mass and the lower the level of in-situ stress, the lower the concentrated stress of the surrounding rock mass, which is less than the strength of the rock itself, and the smaller the loosening zone.

[0004] In related technologies, methods for testing the extent of the loosened zone mainly include acoustic wave methods, ground-penetrating radar methods, seismic wave methods, multi-point displacement gauge methods, and borehole inspection methods. The first three methods primarily use specialized instruments to emit and collect ultrasonic and electromagnetic wave signals from the surrounding rock of the tunnel, analyzing their waveforms and propagation speeds in different media to infer the rock structure. However, these methods suffer from high testing costs and low measurement accuracy, especially when the surrounding rock structure varies significantly, leading to large measurement errors and compromising accuracy. The multi-point displacement gauge method requires installing multiple displacement monitoring devices on the tunnel roof and sides to monitor changes in distance between measuring points. This method is affected by factors such as the accuracy of the multi-point displacement gauge, installation quality, and monitoring depth, making measurement accuracy difficult. Furthermore, it suffers from long testing times and the inability to retrieve the equipment. The borehole inspection method involves visually inspecting the construction borehole to analyze the degree of fracture development at different depths to infer the extent of the loosened zone. This method relies heavily on operator experience, and the measurement results are only qualitative, unable to be accurately quantified.

[0005] The existing field measurement technologies mentioned above all suffer from problems such as high equipment costs, complex operation, and unsuitability for widespread adoption. Utility Model Content

[0006] This invention overcomes the shortcomings of existing technologies and proposes a device for measuring the width of the loosened zone of coal and rock in coal mine roadways. It achieves quantitative determination of the width of the loosened zone by means of the linkage between the water level displacement caused by water leakage and the airbag displacement. The device has a simple structure, low cost, and stronger applicability and safety.

[0007] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0008] A device for measuring the width of the loosened zone of coal and rock in a coal mine roadway includes an air bladder, a measuring rod, and a limiting mechanism. One end of the measuring rod is connected to the air bladder. The measuring rod is marked with a scale. The limiting mechanism includes a limiting tray with a through limiting hole at its center. An inclined borehole is drilled in the roadway wall, and water is filled into the borehole. One end of the measuring rod connected to the air bladder extends into the borehole, causing the air bladder to float on the water surface. The other end of the measuring rod extends out from the limiting hole on the limiting tray. The limiting tray is fixed to the roadway wall and located at the borehole opening, so that the measuring rod is parallel to the inclination angle of the borehole.

[0009] Furthermore, the airbag is a double-layered airbag, consisting of inner and outer layers. The inner layer is a buoyancy airbag, and the outer layer is a wear-resistant rubber protective layer.

[0010] Furthermore, the buoyancy airbag is filled with helium.

[0011] Furthermore, the top of the airbag is fitted with a universal joint, which connects to the measuring rod.

[0012] Furthermore, the measuring rod is made of carbon fiber.

[0013] Furthermore, the limiting tray has a circular plate structure, and two handles are symmetrically arranged on the limiting tray; the limiting hole is located in the middle of the two handles.

[0014] Furthermore, fluorescent scales and reflective ring markings are set on the surface of the measuring rod.

[0015] Furthermore, the center of the limiting hole corresponds to the center of the drill hole.

[0016] The beneficial effects of this utility model compared to the prior art are as follows:

[0017] Before measuring the loosened zone of coal and rock, a borehole is drilled at a 30° downward angle to the sidewall of the roadway. Water is injected into the borehole until it overflows. Water within the loosened zone leaks out due to fissures, while water outside the zone remains at the bottom of the borehole due to gravity. The device for measuring the width of the loosened zone involves placing an airbag device into the borehole. The airbag floats on the water surface due to buoyancy. At this time, a lightweight measuring rod connected to the airbag device extends out of the borehole through a limiting device. After the airbag stabilizes, the scale of the measuring rod is read. Based on the reading of the measuring rod and the actual angle of the borehole, the depth of the loosened zone within the borehole can be calculated. This device for measuring the width of the loosened zone of coal and rock can realize the measurement of the loosened zone of coal and rock under different surrounding rock conditions, providing a basis for the design of roadway support. At the same time, because the airbag device has a double-layer airbag structure, it prevents scratches from sharp rock walls and facilitates the removal of the device from the borehole, allowing the invention to be reused multiple times. The design principle of this invention is simple, easy to operate, and economical. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the coal mine roadway coal loosening zone width measuring device described in this utility model.

[0019] Figure 2 This is a schematic diagram of the limiting mechanism.

[0020] Figure 3 This is a schematic diagram illustrating the working principle of the coal mine roadway coal loosening zone width measuring device described in this utility model.

[0021] The labels in the diagram indicate:

[0022] 1-Airbag, 2-Measuring rod, 3-Limiting tray, 4-Handle, 5-Limiting hole, 6-Roadside rock, 7-Rock loosening zone, 8-Drill hole. Detailed Implementation

[0023] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, this utility model will be further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of this utility model and are not intended to limit it. The technical solution of this utility model will be described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

[0024] See Figures 1 to 3 This embodiment proposes a coal mine roadway coal loosening zone width measuring device, including an airbag 1 that can float on the water surface, a measuring rod 2 connected to the airbag 1, and a limiting mechanism.

[0025] The airbag 1 is a double-layered structure, consisting of inner and outer layers. The inner layer is a buoyancy airbag filled with helium. The outer layer of airbag 1 is a wear-resistant rubber protective layer to prevent scratches from sharp rock walls. A universal joint is connected to the top of airbag 1, which is then connected to the measuring rod 2. To avoid the influence of gravity on the center of gravity of airbag 1, the measuring rod 2 is made of lightweight materials, such as carbon fiber. The surface of the measuring rod 2 is equipped with fluorescent scales and reflective ring markings for easy reading in dark environments, thus enabling it to be used to measure the width of loose rings.

[0026] The limiting mechanism mainly consists of a limiting tray 3, handles 4, and limiting holes 5. The limiting tray 3 is a circular plate structure with two handles symmetrically arranged. A limiting hole 5 is located at the center of the limiting tray 3, between the two handles 4. The limiting tray 3 can be fixed to the tunnel wall using the handles 4. When the measuring rod 2 is passed through the limiting hole 5, the limiting tray 3 ensures that the measuring rod 2 is parallel to the borehole 8, preventing the measuring rod 2 from contacting the borehole wall and causing inaccurate measurement results.

[0027] The operating principle of the coal mine roadway loosening zone width measuring device proposed in this embodiment is as follows:

[0028] Before measuring the loosened coal and rock zone 7, a borehole is drilled at a 30° downward angle into the roadway sidewall. Water is injected into the borehole 8 until it overflows. Water within the loosened coal and rock zone 7 leaks out due to fissures, while water outside the zone remains at the bottom of the borehole due to gravity. An airbag 1 is placed in the borehole 8. The airbag 1 floats on the water surface due to buoyancy. At this time, a measuring rod 2 connected to the airbag 1 extends out of the borehole 8 through a limiting tray 3. After the airbag 1 stabilizes, the scale of the measuring rod 2 is read. Based on the reading of the measuring rod 2 and the actual angle of the borehole 8, the depth of the loosened coal and rock zone 7 within the borehole 8 can be calculated. This device for measuring the width of the loosened coal and rock zone 7 can achieve data measurement of the loosened coal and rock zone 7 under different surrounding rock conditions, providing a basis for the support design of the roadway surrounding rock 6. Furthermore, because the airbag 1 has a double-layered structure, it prevents scratches from sharp rock walls and facilitates the removal of the device from the borehole 8, allowing for repeated use. This invention has a simple design principle, is easy to operate, and is economical and practical.

[0029] The following is a detailed description of the installation and measurement procedures for the coal and rock loosening zone measuring device in coal mine roadways, with reference to the attached diagram:

[0030] Step 1: Drill a hole 8 with a diameter of at least 50mm and a downward inclination of 30° in the sidewall of the tunnel, at a depth 2m beyond the estimated loose coal and rock zone 7.

[0031] Step 2: Inject water into borehole 8 through the water injection pipe until the borehole is full, and let it stand for 5 minutes to allow the water to fully penetrate.

[0032] Step 3: Release the coal and rock loosening zone width measuring device, lower the airbag 1 to the water surface, and observe the displacement of the measuring rod 2 as the water level drops to ensure that the airbag 1 floats completely.

[0033] Step 4: Pass the measuring rod 2 through the limiting hole 5 on the limiting tray 3. The center of the limiting hole 5 corresponds to the center of the drill hole 8. Use the handle 4 on the limiting tray 3 to fix the limiting tray 3 to the roadway side.

[0034] Step 4: After the measuring rod 2 stabilizes and stops floating, read the scale change ΔH, and calculate the loosening ring width L according to the formula L=ΔH / sin30°.

[0035] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the present invention, and all such deductions or substitutions should be considered to fall within the scope of patent protection determined by the submitted claims.

Claims

1. A device for measuring the width of the loosened zone of coal and rock in a coal mine roadway, characterized in that, The system includes an airbag (1), a measuring rod (2), and a limiting mechanism. One end of the measuring rod (2) is connected to the airbag (1). The measuring rod (2) is equipped with a scale. The limiting mechanism includes a limiting tray (3), and the center of the limiting tray (3) is provided with a through limiting hole (5). An inclined borehole (8) is opened on the sidewall of the roadway, and water is filled in the borehole (8). One end of the measuring rod (2) connected to the airbag (1) extends into the borehole (8), so that the airbag (1) floats on the water surface. The other end of the measuring rod (2) extends out from the limiting hole (5) on the limiting tray (3). The limiting tray (3) is fixed on the sidewall and located at the opening of the borehole (8), so that the measuring rod (2) is parallel to the inclined angle of the borehole (8).

2. The device for measuring the width of the loosened zone of coal and rock in a coal mine roadway according to claim 1, characterized in that, The airbag (1) is a double-layer structure airbag, consisting of inner and outer layers. The inner layer is a buoyancy airbag, and the outer layer of the airbag (1) is a wear-resistant rubber protective layer.

3. The device for measuring the width of the loosened coal and rock zone in a coal mine roadway according to claim 2, characterized in that, The buoyancy airbag is filled with helium.

4. The device for measuring the width of the loosened zone of coal and rock in a coal mine roadway according to claim 1, characterized in that, The top of the airbag (1) is connected to a universal joint, which is connected to the measuring rod (2) through the universal joint.

5. The device for measuring the width of the loosened zone of coal and rock in a coal mine roadway according to claim 1, characterized in that, The measuring rod (2) is made of carbon fiber.

6. The device for measuring the width of the loosened zone of coal and rock in a coal mine roadway according to claim 1, characterized in that, The limiting tray (3) is a circular plate structure, and the limiting tray (3) is symmetrically provided with two handles (4); the limiting hole (5) is located in the middle of the two handles (4).

7. The device for measuring the width of the loosened zone of coal and rock in a coal mine roadway according to claim 1, characterized in that, Fluorescent scales and reflective ring markings are set on the surface of the measuring rod (2).

8. The device for measuring the width of the loosened coal and rock zone in a coal mine roadway according to claim 1, characterized in that, The center of the limiting hole (5) corresponds to the center of the drill hole (8).

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