Real-time monitoring device for anchor bolt or anchor cable stress and method for assessing surrounding rock stability

Abstract

This invention discloses a real-time stress monitoring device for anchor bolts or anchor cables and a method for assessing surrounding rock stability, relating to the field of anchor bolt or anchor cable stress monitoring technology. The monitoring device includes a deformation-measuring shell, a deformation measuring mechanism, a deformation transmission mechanism, and a displacement-stress conversion display instrument. Used in conjunction with the anchor bolt or anchor cable, the device is positioned between the tray and nut of the anchor bolt or anchor cable. It contains four measuring stations. The deformation measuring mechanism measures the relative deformation between the top and bottom pressure-bearing shells. The deformation transmission mechanism then transmits the displacements of all four measuring stations to the displacement-stress conversion display instrument, which displays the stress at each of the four measuring stations. This allows for the determination of the maximum and minimum preload at each station, and enables real-time monitoring, improving the accuracy of anchor bolt or anchor cable stress measurement and providing a real-time, accurate display of anchor bolt stress.

Description

Technical Field

[0001] This invention relates to the field of anchor bolt or anchor cable stress monitoring technology, specifically to a real-time anchor bolt or anchor cable stress monitoring device and a method for assessing surrounding rock stability. Background Technology

[0002] In coal mine roadway support engineering, anchor bolts or cables are key components for maintaining the stability of the surrounding rock, and their stress state monitoring is crucial for preventing disasters such as roof falls and spalling. Most existing anchor bolt or cable stress detection devices are based on principles such as steel wire strain gauges, fiber Bragg grating sensors, foil strain gauges, and hydraulic force gauges, using electronic sensing technology to acquire and convert stress signals. These devices have already seen some application in underground coal mines. However, due to the unique environment of underground coal mines, these electronic component-dependent technical solutions face significant challenges: because underground gas is flammable and explosive, all electrical equipment must meet strict intrinsically safe explosion-proof standards, requiring additional explosion-proof structures and circuit protection measures for sensors and supporting systems, significantly increasing monitoring costs and limiting large-scale dense installation; at the same time, the complex working conditions of long-term high humidity, dust, and corrosive gases underground make integrated data transmission chips, signal conversion circuit boards, and other electronic components extremely susceptible to electrochemical corrosion or short circuits. Failures of core components caused by water vapor penetration in humid environments are difficult to eradicate, resulting in insufficient equipment stability and often creating safety blind spots due to data distortion or monitoring failures, failing to meet the needs of long-term reliable monitoring in underground coal mines.

[0003] The core contradiction of existing technologies lies in the reliance of electronic sensing principles on explosion-proof structures and precision electronic components, which clashes with the harsh environment of underground coal mines. This makes it difficult to balance the monitoring system's cost, reliability, and coverage. Therefore, there is an urgent need to invent a stress monitoring device for anchor bolts or cables that requires no complex electronic components and can adapt to the high humidity and dust environment of underground coal mines. This would overcome the technical bottlenecks of existing stress monitoring devices and provide a low-cost, highly reliable technical solution for large-scale stress monitoring of anchor bolts or cables in underground coal mines. Summary of the Invention

[0004] To address the aforementioned issues, this invention discloses a real-time stress monitoring device for anchor bolts or cables and a method for assessing surrounding rock stability. Based on the one-to-one correspondence between stress values ​​and deformation amounts in the linear elastic stage of an object under stress, real-time stress monitoring is achieved through a gear-rack transmission device that amplifies the stress, overcoming the reliance of traditional electronic sensing technology on explosion-proof circuits and precision components. The surrounding rock stability assessment employs a collaborative monitoring mode combining the monitoring device and a traditional roof delamination meter. The real-time stress monitoring device for anchor bolts or cables achieves regional coverage detection of the surrounding rock stress field through a large-area array layout, while the traditional roof delamination meter performs localized high-precision point displacement monitoring at key strata. The two devices, through data fusion, form a three-dimensional monitoring system combining point and surface data, providing dual-dimensional data support for surrounding rock stability assessment.

[0005] According to the present invention, a real-time stress monitoring device for anchor bolts or anchor cables includes a compression deformation shell, a deformation measuring mechanism, a deformation transmission mechanism, and a displacement-stress conversion display instrument.

[0006] The extrusion-deformable outer shell is disposed between the anchor rod or anchor cable tray and the nut, and is sleeved on the anchor rod or anchor cable. It includes a top pressure-bearing outer shell and a bottom pressure-bearing outer shell. The top pressure-bearing outer shell contacts the anchor rod tray and converts the axial tensile force of the anchor rod into pressure, which is pressed onto the top pressure-bearing outer shell. The bottom pressure-bearing outer shell is fitted with the top pressure-bearing outer shell at the top and contacts the nut at the bottom, which can provide support for the deformation of the top pressure-bearing outer shell under stress.

[0007] The deformation measuring mechanism includes a range extension guide hole, a displacement capturing rack, a displacement conversion gear, and a gear-coupled rotating shaft. The range extension guide hole is located inside the bottom pressure-bearing housing, but not through the bottom end. The displacement capturing rack is fixedly connected to the top pressure-bearing housing, with its free end placed inside the range extension guide hole. The displacement conversion gear is meshed with the displacement capturing rack and transmits the displacement to the deformation transmission mechanism via the gear-coupled rotating shaft. The gear-coupled rotating shaft is rotatably mounted on the bottom pressure-bearing housing, with one end fixedly connected to the displacement conversion gear and the other end fixedly connected to the deformation transmission mechanism.

[0008] The deformation transmission mechanism includes a straight bevel gear reversing transmission group; the straight bevel gear reversing transmission group includes a first bevel gear and a second bevel gear that are perpendicular to each other, the first bevel gear and the second bevel gear are in contact with each other, the first bevel gear is fixedly connected to the end of the gear joint rotation shaft away from the displacement conversion gear, and a transmission shaft is fixedly installed on the bottom surface of the second bevel gear, the transmission shaft is rotatably installed on the bottom pressure-bearing housing.

[0009] The displacement-stress conversion display instrument is mounted on the bottom pressure-bearing housing and includes a dial and a stress pointer; the dial is fixedly mounted on the outer surface of the bottom pressure-bearing housing, and the stress pointer is placed on the dial and can rotate under the drive of the transmission shaft.

[0010] Preferably, the range extension guide holes are four circumferentially distributed holes, and the circle in which the four range extension guide holes are located includes the area with the largest radial span cross-section beam deflection; the deformation measurement mechanism and the deformation transmission mechanism are four sets corresponding to the range extension guide holes.

[0011] Preferably, there are four displacement-stress conversion display instruments corresponding to the deformation transmission mechanism, and the stress pointer in each displacement-stress conversion display instrument is fixedly connected to the end of the corresponding transmission shaft away from the second bevel gear.

[0012] Preferably, the four sets of deformation transmission mechanisms share a single displacement-stress conversion display instrument, which further includes pointer gears and pointer sleeves. Four pointer sleeves are provided, arranged from the inside out as a first-stage pointer sleeve, a second-stage pointer sleeve, a third-stage pointer sleeve, and a fourth-stage pointer sleeve. The first-stage pointer sleeve has the smallest diameter and the longest length; the diameters of the second-stage, third-stage, and fourth-stage pointer sleeves increase sequentially, while their lengths decrease sequentially. The second-stage pointer sleeve is fitted onto the first-stage pointer sleeve, the third-stage pointer sleeve is fitted onto the second-stage pointer sleeve, and the fourth-stage pointer sleeve is fitted onto the third-stage pointer sleeve. The four pointer sleeves are rotatable relative to each other. The fourth-stage pointer sleeve, with the largest diameter, is connected to a shaft... The bearing is rotatably connected to the bottom pressure-bearing outer shell; the pointer gear and stress pointer are four of each corresponding to the pointer sleeve, and are respectively fixedly connected to both ends of the pointer sleeve, and the four stress pointers are of different colors; the deformation transmission mechanism also includes a pointer drive gear, which is fixedly connected to the transmission shaft and is concentrically arranged with the second bevel gear; the height of the pointer drive gear in the deformation transmission mechanism is set according to the height of the corresponding pointer gear of the displacement-stress conversion display instrument, and meshes with the corresponding pointer gear to drive the stress pointer to rotate; the bottom pressure-bearing outer shell is also rotatably mounted with multiple transmission gears through bearings to realize the transmission connection between the pointer drive gear and the pointer gear.

[0013] Preferably, the first-stage pointer sleeve, the second-stage pointer sleeve, and the third-stage pointer sleeve are all provided with a shoulder and a C-shaped elastic retaining ring groove; the shoulder is fixedly installed on the pointer sleeve and located between the corresponding stress pointer and the adjacent pointer sleeve, and the outer diameter of the shoulder is larger than the inner diameter of the adjacent pointer sleeve; the C-shaped elastic retaining ring groove is provided between the corresponding pointer gear and the adjacent pointer sleeve, and an elastic retaining ring is installed in it, and the outer diameter of the elastic retaining ring is larger than the inner diameter of the adjacent pointer sleeve.

[0014] Another method disclosed in this invention for assessing surrounding rock stability using the aforementioned real-time stress monitoring device for anchor bolts or anchor cables includes the following steps:

[0015] Step 1: Design the bore diameter of the anchor bolt or anchor cable real-time stress monitoring device based on the diameter of the anchor bolt or anchor cable on site;

[0016] Step 2: Limit the range of materials to be selected for the real-time stress monitoring device for anchor bolts or anchor cables;

[0017] Step 3: Select the area in the underground roadway of the coal mine where anchor bolt or anchor cable stress monitoring is required, install real-time monitoring devices for anchor bolt or anchor cable stress on the roof and both sides of the roadway, apply the same preload, and number these real-time monitoring devices for anchor bolt or anchor cable stress. Install a roof separation meter on the roof every 30m to construct a "point-surface combined" regional stress-displacement monitoring system.

[0018] Step 4: Record and summarize the readings of the real-time stress monitoring device for anchor bolts or anchor cables and the amount of top slab delamination displacement at fixed intervals;

[0019] Step 5: Compare and analyze the collected data to determine the working conditions of the surrounding rock in the roadway corresponding to the abnormal data areas, and take corresponding measures accordingly.

[0020] Preferably, in step two, the method for limiting the material selection range of the anchor bolt or anchor cable stress real-time monitoring device includes the following steps:

[0021] S1. Calculate the maximum load F that the anchor bolt or anchor cable can withstand if it fails due to tensile failure. 拉断 :

[0022] Let the tensile strength σ of the anchor bolt or anchor cable be... b The cross-sectional area A of the anchor bolt or anchor cable s .

[0023] F 拉断 =σ b ×A s

[0024] In the formula:

[0025] σ b - The tensile strength of the anchor bolt or anchor cable, in Pa;

[0026] A s - Cross-sectional area of ​​the anchor bolt or anchor cable, in meters 2 ;

[0027] S2. Based on the maximum load F that the anchor bolt or anchor cable can withstand upon failure due to tensile strength. 拉断 Calculate the cross-sectional dimensions of the real-time stress monitoring device;

[0028] S21. Calculate the maximum load exerted by the nut on the real-time stress monitoring device when the anchor bolt or anchor cable breaks:

[0029]

[0030] In the formula:

[0031] D2 - The diameter of the real-time stress monitoring device minus the wall thickness t, in meters;

[0032] D3 - The diameter length of the real-time stress monitoring device, including the inner diameter and wall thickness t, in meters;

[0033] m - the width of the contact between the real-time stress monitoring device and the nut, in meters;

[0034] q max - The maximum load, in Pa, exerted by the nut on the real-time stress monitoring device when the anchor bolt or anchor cable breaks;

[0035] S22. Calculate the maximum bending moment that the real-time stress monitoring device will withstand when the anchor bolt or anchor cable breaks:

[0036]

[0037] In the formula:

[0038] M max - The maximum bending moment, N·m, that the stress monitoring device withstands when the anchor bolt or anchor cable breaks.

[0039] S23. Calculate the moment of inertia of the radial span of the stress-bearing section of the real-time stress monitoring device for anchor bolts or anchor cables:

[0040]

[0041] In the formula:

[0042] I z - Moment of inertia of radial span stress-bearing section of anchor bolt or anchor cable real-time stress monitoring device, m 4 ;

[0043] t - wall thickness of the real-time stress monitoring device, in meters;

[0044] S24. Calculate the maximum tensile or compressive stress in the cross-section of the slice from the real-time stress monitoring device for anchor bolts or anchor cables:

[0045]

[0046] In the formula:

[0047] σ max - The maximum tensile or compressive stress (Pa) on the cross-section of a slice from a real-time stress monitoring device for anchor bolts or anchor cables;

[0048] ymax - The ordinate of the farthest boundary stress point, in meters;

[0049] S25. Select materials based on the maximum tensile or compressive stress determined in S24. The material range is then selected as follows:

[0050] |σ max |≤[σ t ]

[0051] |σ max |≤[σ c ]

[0052] In the formula:

[0053] [σ t - The maximum tensile stress that the material can withstand, in Pa;

[0054] [σ c - The maximum compressive stress that the material can withstand, in Pa;

[0055] Preferably, in step five, targeted measures are taken based on the working conditions of the surrounding rock in the roadway, including:

[0056] Condition 1: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable is normal, and the amount of delamination monitored by the top plate delamination instrument is normal, the support condition is judged to be normal, and no measures need to be taken.

[0057] Condition 2: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable is normal, and the amount of delamination monitored by the top plate delamination instrument exceeds the normal range but does not reach the safety warning threshold, it is judged that the stress of the anchor bolt or anchor cable is normal, the top plate rock layer has delamination but is still stable, the number of anchor cables should be increased, the anchoring depth should be increased, the anchor cable support force should be strengthened, the amount of delamination displacement should be reduced, and the deformation of the surrounding rock should be controlled.

[0058] Condition 3: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable is normal, but the amount of delamination monitored by the top plate delamination instrument exceeds the safety warning threshold, the rock layer below the delamination should be stripped and then re-supported.

[0059] Condition 4: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable exceeds the set warning threshold, and the amount of delamination monitored by the roof delamination instrument is normal, it is judged that the support strength is insufficient and the anchor bolt or anchor cable is about to reach the yield limit. The density of anchor bolts should be increased and the number of anchor bolts should be increased. Consider adding individual props to assist in supporting the surrounding rock of the roadway and enhance the bearing capacity of the support structure.

[0060] Condition 5: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable exceeds the set warning threshold, and the amount of delamination monitored by the top plate delamination instrument exceeds the normal range but does not reach the safety warning threshold, the number of anchor bolts and anchor cables should be increased. The anchor cables are used to increase the suspension force, and the anchor bolts fully mobilize the strength of the surrounding rock itself to maintain the stability of the surrounding rock and increase the support strength.

[0061] Condition 6: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable exceeds the set warning threshold, and the amount of delamination monitored by the top plate delamination instrument exceeds the safety warning threshold, the rock layer below the delamination should be stripped and then re-supported.

[0062] Condition 7: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable is far below the normal working range or even close to zero, and the amount of delamination monitored by the top plate delamination instrument is normal, it is judged that the anchor bolt or anchor cable may have broken and failed. The anchor bolt or anchor cable at this location should be checked immediately. If it is confirmed to be broken, a new anchor bolt or anchor cable should be replaced in time, and the installation quality of the new anchor bolt or anchor cable should be ensured to meet the design requirements.

[0063] Condition 8: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable is far below the normal working range or even close to zero, and the amount of delamination monitored by the top plate delamination instrument exceeds the normal range but does not reach the safety warning threshold, it is necessary to check whether the anchor bolt or anchor cable is broken or failed, reinstall it, and also install additional anchor cables.

[0064] Condition 9: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable shows abnormal changes, such as a sudden drop, and the amount of delamination monitored by the top plate delamination instrument exceeds the safety warning threshold, it is judged that the surrounding rock is seriously unstable. The area should be immediately listed as a danger zone, a plan and safety measures should be formulated, the rock below the delamination should be stripped, and after the stripping is completed, the support design and construction should be re-carried out, and a high-strength support structure should be adopted.

[0065] Compared with existing technologies, the advantages of the real-time monitoring device for anchor bolt or anchor cable stress and the surrounding rock stability assessment method disclosed in this invention are:

[0066] (1) Based on the one-to-one correspondence between stress value and deformation of an object in the elastic stage of force line, the present invention realizes real-time stress monitoring through a gear-rack transmission device after transmission amplification. It is very sensitive, reacts immediately to pressure, and is a purely mechanical transmission with no circuit delay. With the help of pre-tightened backlash gears, it realizes synchronous response to load changes. At the same time, the stress real-time monitoring device only contains mechanical transmission and support components, without sensors, circuit boards and other electronic components, which is low cost. It breaks through the dependence of traditional electronic sensing technology on explosion-proof circuits and precision components, and avoids problems such as short circuits, signal interference and difficulty in replacing aging components in the harsh environment of underground coal mines. It has strong environmental adaptability and can operate stably for a long time in the high humidity and high dust environment of underground coal mines. It is suitable for large-scale real-time stress monitoring of anchor bolts or anchor cables in underground coal mine roadways.

[0067] (2) This invention employs a collaborative monitoring mode combining a monitoring device and a traditional roof delamination meter. The real-time monitoring device for anchor bolt or cable stress achieves regional coverage monitoring of the surrounding rock stress field through a large-area array layout, while the traditional roof delamination meter performs localized, high-precision point displacement monitoring at key strata. The two devices fuse data to form a three-dimensional monitoring system combining point and surface measurements, comprehensively capturing the stability characteristics of the surrounding rock, reducing monitoring blind spots, and forming a comprehensive, multi-dimensional assessment system. This method achieves stress monitoring through mechanical transmission principles. Combined with the point-surface collaborative monitoring mode, it effectively solves the problems of high cost, poor environmental adaptability, and monitoring blind spots of existing electronic monitoring devices, providing a low-cost, high-reliability technical solution for anchor bolt or cable stress monitoring and surrounding rock stability assessment in complex underground coal mine environments. Attached Figure Description

[0068] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0069] Figure 1 This is a schematic diagram of the interior of Example 1.

[0070] Figure 2 This is a schematic diagram of the bottom pressure-bearing outer shell in Example 1.

[0071] Figure 3 This is a schematic diagram of the deformation transmission mechanism in Example 1.

[0072] Figure 4 This is a schematic diagram of the interior of Example 2.

[0073] Figure 5 This is a schematic diagram of the bottom pressure-bearing outer shell in Example 2.

[0074] Figure 6 This is a schematic diagram showing the combination of the deformation transmission mechanism and the displacement-stress conversion display instrument in Example 2.

[0075] Figure 7 This is a schematic diagram of the pointer sleeve in Example 2.

[0076] Figure 8 This is a three-dimensional schematic diagram of the pointer gear and stress pointer in Example 2 (the shoulder and elastic retaining ring are not shown).

[0077] Figure 9 This is a schematic diagram of the plane between the pointer gear and the stress pointer in Example 2 (the shoulder and elastic retaining ring are not shown).

[0078] Figure 10 A schematic diagram of the installation of a real-time stress monitoring device for anchor bolts or anchor cables.

[0079] Figure 11 This is a schematic diagram of the stress on a real-time stress monitoring device for anchor bolts or anchor cables.

[0080] Figure 12 for Figure 7 Simplified diagram of the stress on section I-I.

[0081] Figure 13 The simplified bending moment force diagram is shown for the cross-section.

[0082] Figure 14 This is a schematic diagram of the combined monitoring of real-time stress monitoring device for anchor bolts or anchor cables and delamination instrument for roof slab.

[0083] In the diagram: 1-Central hole; 2-Extrusion deformable outer shell; 21-Bottom pressure-bearing outer shell; 31-Range expansion guide hole; 32-Displacement conversion gear; 33-Displacement capture rack; 34-Bearing seat; 35-Gear combined rotation shaft; 41-Straight bevel gear reversing transmission group; 411-First bevel gear; 412-Second bevel gear; 42-Drive shaft; 43-Pointer drive gear; 5-Displacement-stress conversion display instrument; 51-Pointer gear; 52-First-stage pointer sleeve; 53-Second-stage pointer sleeve; 54-Third-stage pointer sleeve; 55-Fourth-stage pointer sleeve; 56-Stress pointer; 57-Shaft shoulder; 58-Elastic retaining ring; 6-Panel; 7-Nut; 8-Drive gear. Detailed Implementation

[0084] The specific embodiments of the present invention will be briefly described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0085] Figures 1-14 A preferred embodiment of the present invention is shown and analyzed in detail.

[0086] Example 1

[0087] like Figure 1 , Figure 2 , Figure 3 , Figure 10 The device shown is a real-time stress monitoring device for anchor bolts or anchor cables, comprising a compression deformation shell 2, a deformation measuring mechanism, a deformation transmission mechanism, and a displacement-stress conversion display instrument 5.

[0088] The extrusion-deformable outer shell 2 is disposed between the anchor rod or anchor cable tray 6 and the nut 7, and is fitted onto the anchor rod or anchor cable. It includes a top pressure-bearing outer shell and a bottom pressure-bearing outer shell 21. The top pressure-bearing outer shell contacts the anchor rod tray 6, converting the axial tensile force of the anchor rod into compressive force, which is applied to the top pressure-bearing outer shell. The top pressure-bearing outer shell 21 is fitted into the top pressure-bearing outer shell at the top and contacts the nut 7 at the bottom, providing support for the deformation of the top pressure-bearing outer shell under stress.

[0089] The deformation measurement mechanism includes a range extension guide hole 31, a displacement capturing rack 33, a displacement conversion gear 32, and a gear-connected rotating shaft 35. The range extension guide hole 31 is located within the bottom pressure-bearing housing 21, with no through-hole at the bottom. There are four range extension guide holes 31 evenly distributed circumferentially, and the circle containing these four holes encompasses the area of ​​maximum beam deflection in the radial span section (the span slice section between the two force points on the inner and outer diameters). The displacement capturing rack 33, displacement conversion gear 32, and gear-connected rotating shaft 35 are four corresponding to the range extension guide holes 31. One end of the displacement capturing rack 33 is fixedly connected to the top pressure-bearing housing, while the other end is free and placed within the corresponding range extension guide hole 31. The displacement conversion gear 32 meshes with the displacement capturing rack 33 and is connected to the deformation transmission mechanism via the gear-connected rotating shaft 35. The gear-connected rotating shaft 35 is rotatably mounted on the bottom pressure-bearing housing 21, with one end fixedly connected to the displacement conversion gear 32 and the other end fixedly connected to the deformation transmission mechanism. Specifically, four bearing seats 34 are fixedly installed on the bottom pressure-bearing housing 21 by bolts. Bearings are fixedly installed inside the bearing seats 34. The gear coupling rotating shaft 35 is rotatably installed on the bottom pressure-bearing housing 21 through the bearings, and the bearing seats 34 restrict the gear coupling rotating shaft 35.

[0090] The deformation transmission mechanism consists of four sets corresponding to the range extension guide hole 31. Each set of deformation transmission mechanism includes a straight bevel gear reversing transmission set 41. For example... Figure 3 As shown, the spur bevel gear reversing transmission assembly 41 includes a first bevel gear 411 and a second bevel gear 412 that are perpendicular to each other. The first bevel gear 411 and the second bevel gear 412 are in contact with each other. The first bevel gear 411 is fixedly connected to the end of the gear joint rotation shaft 35 away from the displacement conversion gear 32. The bottom surface of the second bevel gear 412 is fixedly mounted with a transmission shaft 42. The transmission shaft 42 is rotatably mounted on the bottom pressure-bearing housing 21 through a bearing.

[0091] like Figure 2As shown, four displacement-stress conversion display instruments 5 are installed on the bottom pressure-bearing housing 21, corresponding to the deformation transmission mechanism. Each displacement-stress conversion display instrument 5 includes a dial and a stress pointer 56. The dial is fixedly installed on the outer surface of the bottom pressure-bearing housing 21, and the stress pointer 56 is placed on the dial and fixedly connected to the end of the corresponding transmission shaft 42 away from the second bevel gear 412, and can rotate under the drive of the deformation transmission mechanism.

[0092] like Figure 10 As shown, the real-time stress monitoring device for anchor bolts or anchor cables is equipped with four measuring stations. When the anchor bolt or anchor cable tray 6 is pressed against the nut 7, the top pressure-bearing shell deforms. The deformation of the top pressure-bearing shell is measured by a deformation measuring mechanism. The deformation measuring mechanism transmits the deformation displacement to the displacement-stress conversion display instrument 5 via a deformation transmission mechanism. The displacement is converted into stress magnitude according to the existing displacement-stress conversion method and displayed by four stress pointers 56. After the real-time stress monitoring device for anchor bolts or anchor cables is assembled, it is filled halfway with silicone grease to provide shock absorption and lubrication.

[0093] Example 2

[0094] like Figures 4-9 As shown, the rest is the same as in Example 1, except that:

[0095] like Figure 4 and Figure 5 As shown, the four sets of deformation transmission mechanisms share a single displacement-stress conversion display instrument 5, which also includes a pointer gear 51 and a pointer sleeve. Figures 7-9 As shown, there are four pointer sleeves, from the inside out: primary pointer sleeve 52, secondary pointer sleeve 53, tertiary pointer sleeve 54, and quaternary pointer sleeve 55. Primary pointer sleeve 52 has the smallest diameter and the longest length. The diameters of secondary pointer sleeves 53, tertiary pointer sleeve 54, and quaternary pointer sleeve 55 increase sequentially, while their lengths decrease sequentially. Secondary pointer sleeve 53 is fitted onto primary pointer sleeve 52, tertiary pointer sleeve 54 is fitted onto secondary pointer sleeve 53, and quaternary pointer sleeve 55 is fitted onto tertiary pointer sleeve 54. The four pointer sleeves are rotatable relative to each other. The quaternary pointer sleeve 55, with the largest diameter, is rotatably connected to the bottom pressure-bearing housing 21 via a bearing. Four pointer gears 51 and four stress pointers 56 are provided corresponding to the pointer sleeves, and they are fixedly connected to the two ends of the four pointer sleeves respectively. The four stress pointers 56 are of different colors and are placed on the same dial. Figure 6As shown, the deformation transmission mechanism also includes a pointer drive gear 43, which is fixedly connected to the transmission shaft 42 and concentrically arranged with the second bevel gear 412. The height of the pointer drive gear 43 in the deformation transmission mechanism is set according to the height of the corresponding pointer gear 51 of the displacement-stress conversion display instrument 5, and meshes with the corresponding pointer gear 51 to drive the stress pointer 56 to rotate. Multiple transmission gears 8 are also rotatably mounted on the bottom pressure-bearing housing 21 via bearings to achieve the transmission connection between the pointer drive gear 43 and the pointer gear 51. The transmission gears 8 can, on the one hand, connect the pointer drive gear 43 and the pointer gear 51, allowing multiple deformation transmission mechanisms to share a single displacement-stress conversion display instrument 5; on the other hand, because the four displacement capturing racks 33 are divided into two symmetrically arranged groups, the corresponding displacement conversion gears 32 on the left and right sides rotate in opposite directions, thus causing the corresponding pointer drive gears 43 to rotate in opposite directions. The transmission gears 8 can change the rotation direction of the pointer drive gears 43, thereby ensuring that the four stress pointers 56 ultimately rotate in the same direction.

[0096] like Figure 7 As shown, the first-stage pointer sleeve 52, the second-stage pointer sleeve 53, and the third-stage pointer sleeve 54 are all provided with shoulders 57 and C-shaped elastic retaining ring grooves. The shoulders 57 are fixedly mounted on the pointer sleeves, located between the corresponding stress pointer 56 and the adjacent pointer sleeve, and the outer diameter of the shoulder 57 is larger than the inner diameter of the adjacent pointer sleeve. The C-shaped elastic retaining ring groove is provided between the corresponding pointer gear 51 and the adjacent pointer sleeve, and an elastic retaining ring 58 is installed inside it. The outer diameter of the elastic retaining ring 58 is larger than the inner diameter of the adjacent pointer sleeve. Lubricating grease is added between the pointer sleeves to ensure that the friction between the pointer sleeves is less than the contact force of the gear meshing, thus avoiding interference with their rotation.

[0097] like Figures 11-14 As shown, the present invention also discloses a method for assessing the stability of surrounding rock using the above-mentioned real-time stress monitoring device for anchor bolts or anchor cables, comprising the following steps:

[0098] Step 1: Design the diameter of the central hole 1 of the real-time stress monitoring device for anchor bolts or anchor cables based on the diameter of the anchor bolts or anchor cables on site. The diameter of the central hole 1 of the real-time stress monitoring device for anchor bolts or anchor cables should be slightly larger than the diameter of the anchor bolts or anchor cables. If the central hole 1 is too small, the real-time stress monitoring device for anchor bolts or anchor cables cannot be installed on the anchor bolts or anchor cables. If the central hole 1 is too large, resulting in a large gap, the nut 7 cannot generate stress along the same circle on the monitoring device, which will lead to uneven deformation and easily cause systematic errors.

[0099] Step 2: Limit the range of materials to be selected for the real-time stress monitoring device for anchor bolts or anchor cables;

[0100] S1. Calculate the maximum load F that the anchor bolt or anchor cable can withstand if it fails due to tensile failure. 拉断 :

[0101] Let the tensile strength σ of the anchor bolt or anchor cable be... b The cross-sectional area A of the anchor bolt or anchor cable s .

[0102] F 拉断 =σ b ×A s

[0103] In the formula:

[0104] σ b - The tensile strength of the anchor bolt or anchor cable, in Pa;

[0105] A s - Cross-sectional area of ​​the anchor bolt or anchor cable, in meters 2 ;

[0106] S2. Based on the maximum load F that the anchor bolt or anchor cable can withstand upon failure due to tensile strength. 拉断 Calculate the cross-sectional dimensions of the real-time stress monitoring device;

[0107] S21. Calculate the maximum load exerted by nut 7 on the real-time stress monitoring device when the anchor bolt or anchor cable breaks:

[0108]

[0109] In the formula:

[0110] D2 - The diameter of the real-time stress monitoring device minus the wall thickness t, in meters;

[0111] D3 - The diameter length of the real-time stress monitoring device, including the inner diameter and wall thickness t, in meters;

[0112] m - the width of the contact between the real-time stress monitoring device and nut 7, in meters;

[0113] q max - The maximum load, in Pa, applied by nut 7 to the real-time stress monitoring device when the anchor bolt or anchor cable breaks;

[0114] S22. Calculate the maximum bending moment that the real-time stress monitoring device will withstand when the anchor bolt or anchor cable breaks:

[0115]

[0116] In the formula:

[0117] M max - The maximum bending moment, N·m, that the stress monitoring device withstands when the anchor bolt or anchor cable breaks.

[0118] S23. Calculate the moment of inertia of the radial span of the stress-bearing section of the real-time stress monitoring device for anchor bolts or anchor cables:

[0119]

[0120] In the formula:

[0121] I z - Moment of inertia of radial span stress-bearing section of anchor bolt or anchor cable real-time stress monitoring device, m 4 ;

[0122] t - wall thickness of the real-time stress monitoring device, in meters;

[0123] S24. Calculate the maximum tensile or compressive stress in the cross-section of the slice from the real-time stress monitoring device for anchor bolts or anchor cables:

[0124]

[0125] In the formula:

[0126] σ max - The maximum tensile or compressive stress (Pa) on the cross-section of a slice from a real-time stress monitoring device for anchor bolts or anchor cables;

[0127] y max - The ordinate of the farthest boundary stress point, in meters;

[0128] S25. Select materials based on the maximum tensile or compressive stress determined in S24. The material range is then selected as follows:

[0129] |σ max |≤[σ t ]

[0130] |σ max |≤[σ c ]

[0131] In the formula:

[0132] [σ t - The maximum tensile stress that the material can withstand, in Pa;

[0133] [σ c - The maximum compressive stress that the material can withstand, in Pa;

[0134] Step 3, as follows Figure 14 As shown, in the underground roadway of the coal mine, the area where anchor bolt or anchor cable stress monitoring needs to be carried out is selected, and real-time monitoring devices for anchor bolt or anchor cable stress are installed on the roof and both sides of the roadway. The same preload is applied, and these real-time monitoring devices for anchor bolt or anchor cable stress are numbered. A roof separation meter is installed on the roof every 30m to construct a "point-surface combined" regional stress-displacement monitoring system.

[0135] Step 4: Record and summarize the readings of the real-time stress monitoring device for anchor bolts or anchor cables and the amount of top slab delamination displacement at fixed intervals;

[0136] Step 5: Compare and analyze the collected data to determine the working conditions of the surrounding rock in the roadway corresponding to the data anomalies, and take targeted measures accordingly.

[0137] Condition 1: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable is normal, and the amount of delamination monitored by the top plate delamination instrument is normal, the support condition is judged to be normal, and no measures need to be taken.

[0138] Condition 2: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable is normal, and the amount of delamination monitored by the top plate delamination instrument exceeds the normal range but does not reach the safety warning threshold, it is judged that the stress of the anchor bolt or anchor cable is normal, the top plate rock layer has delamination but is still stable, the number of anchor cables should be increased, the anchoring depth should be increased, the anchor cable support force should be strengthened, the amount of delamination displacement should be reduced, and the deformation of the surrounding rock should be controlled.

[0139] Condition 3: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable is normal, but the amount of delamination monitored by the top plate delamination instrument exceeds the safety warning threshold, the rock layer below the delamination should be stripped and then re-supported.

[0140] Condition 4: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable exceeds the set warning threshold, and the amount of delamination monitored by the roof delamination instrument is normal, it is judged that the support strength is insufficient and the anchor bolt or anchor cable is about to reach the yield limit. The density of anchor bolts should be increased and the number of anchor bolts should be increased. Consider adding individual props to assist in supporting the surrounding rock of the roadway and enhance the bearing capacity of the support structure.

[0141] Condition 5: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable exceeds the set warning threshold, and the amount of delamination monitored by the top plate delamination instrument exceeds the normal range but does not reach the safety warning threshold, the number of anchor bolts and anchor cables should be increased. The anchor cables are used to increase the suspension force, and the anchor bolts fully mobilize the strength of the surrounding rock itself to maintain the stability of the surrounding rock and increase the support strength.

[0142] Condition 6: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable exceeds the set warning threshold, and the amount of delamination monitored by the top plate delamination instrument exceeds the safety warning threshold, the rock layer below the delamination should be stripped and then re-supported.

[0143] Condition 7: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable is far below the normal working range or even close to zero, and the amount of delamination monitored by the top plate delamination instrument is normal, it is judged that the anchor bolt or anchor cable may have broken and failed. The anchor bolt or anchor cable at this location should be checked immediately. If it is confirmed to be broken, a new anchor bolt or anchor cable should be replaced in time, and the installation quality of the new anchor bolt or anchor cable should be ensured to meet the design requirements.

[0144] Condition 8: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable is far below the normal working range or even close to zero, and the amount of delamination monitored by the top plate delamination instrument exceeds the normal range but does not reach the safety warning threshold, it is necessary to check whether the anchor bolt or anchor cable is broken or failed, reinstall it, and also install additional anchor cables.

[0145] Condition 9: When the stress value monitored by the real-time stress monitoring device of the anchor bolt or anchor cable shows abnormal changes, such as a sudden drop, and the amount of delamination monitored by the top plate delamination instrument exceeds the safety warning threshold, it is judged that the surrounding rock is seriously unstable. The area should be immediately listed as a danger zone, a plan and safety measures should be formulated, the rock below the delamination should be stripped, and after the stripping is completed, the support design and construction should be re-carried out, and a high-strength support structure should be adopted.

[0146] The above description of the disclosed embodiments enables those skilled in the art to make and use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit and scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A real-time monitoring device for stress in an anchor rod or cable, characterized in that, The device comprises an extrusion deformation shell (2), a deformation measuring mechanism, a deformation transmission mechanism, and a displacement-stress conversion display instrument (5). The extrusion deformation shell (2) is arranged between an anchor rod or anchor cable tray (6) and a nut (7), and is sleeved on the anchor rod or anchor cable, and comprises a top pressure-bearing shell and a bottom pressure-bearing shell (21); the top pressure-bearing shell is in contact with the anchor rod tray (6), converts the axial tension of the anchor rod into pressure, and is pressed on the top pressure-bearing shell; the bottom pressure-bearing shell (21) is embedded with the top pressure-bearing shell above and is in contact with the nut (7) below, and can provide support force for the force deformation of the top pressure-bearing shell. The deformation measuring mechanism comprises a range expansion guide hole (31), a displacement capture rack (33), a displacement conversion gear (32), and a gear joint rotating shaft (35); the range expansion guide hole (31) is arranged in the bottom pressure-bearing shell (21) and is not penetrated at the bottom end; the displacement capture rack (33) is fixedly connected to the top pressure-bearing shell, and the free end thereof is placed in the range expansion guide hole (31); the displacement conversion gear (32) is meshingly connected to the displacement capture rack (33) and is transmitted to the deformation transmission mechanism through the gear joint rotating shaft (35); and the gear joint rotating shaft (35) is rotatably installed on the bottom pressure-bearing shell (21), one end of the gear joint rotating shaft (35) is fixedly connected with the displacement conversion gear (32), and the other end is fixedly connected with the deformation transmission mechanism. The deformation transmission mechanism comprises a straight bevel gear reversing transmission group (41); the straight bevel gear reversing transmission group (41) comprises a first bevel gear (411) and a second bevel gear (412) perpendicular to each other, the first bevel gear (411) and the second bevel gear (412) are in contact connection, the first bevel gear (411) is fixedly connected to one end of the gear joint rotating shaft (35) away from the displacement conversion gear (32), and the second bevel gear (412) is fixedly installed with a transmission shaft (42) on the bottom surface, and the transmission shaft (42) is rotatably installed on the bottom pressure-bearing shell (21). The displacement-stress conversion display instrument (5) is installed on the bottom pressure-bearing shell (21) and comprises a dial and a stress pointer (56); the dial is fixedly installed on the outer surface of the bottom pressure-bearing shell (21), and the stress pointer (56) is placed on the dial and can rotate under the driving of the transmission shaft (42).

2. The real-time monitoring device for bolt or anchor stress according to claim 1, characterized in that, The range expansion guide hole (31) is circumferentially and uniformly distributed in four, and the circle containing the four range expansion guide holes (31) contains the area with the maximum radial span cross-section beam deflection; the deformation measuring mechanism and the deformation transmission mechanism are four groups corresponding to the range expansion guide holes (31).

3. The real-time monitoring device for stress in rock bolts or rock anchors according to claim 2, characterized in that, The displacement-stress conversion display instrument (5) is four corresponding to the deformation transmission mechanism, and the stress pointer (56) in each displacement-stress conversion display instrument (5) is fixedly connected to one end of the corresponding transmission shaft (42) away from the second bevel gear (412).

4. The real-time monitoring device for bolt or anchor stress according to claim 2, characterized in that, Four groups of deformation transmission mechanisms share one displacement-stress conversion display instrument (5), which also comprises a pointer gear (51) and a pointer sleeve; the pointer sleeve is provided with four, from inside to outside, they are a first-level pointer sleeve (52), a second-level pointer sleeve (53), a third-level pointer sleeve (54) and a fourth-level pointer sleeve (55), the first-level pointer sleeve (52) has the smallest diameter and the longest length, the second-level pointer sleeve (53), the third-level pointer sleeve (54) and the fourth-level pointer sleeve (55) have diameters increasing in turn and lengths shortening in turn, the second-level pointer sleeve (53) is sleeved on the first-level pointer sleeve (52), the third-level pointer sleeve (54) is sleeved on the second-level pointer sleeve (53), the fourth-level pointer sleeve (55) is sleeved on the third-level pointer sleeve (54), and the four pointer sleeves can rotate relative to each other; the fourth-level pointer sleeve (55) with the largest diameter is rotatably connected to the bottom pressure shell (21) through a bearing; the pointer gear (51) and the stress pointer (56) are both provided with four corresponding to the pointer sleeves, and are fixedly connected to two ends of the pointer sleeves respectively, and the four stress pointers (56) are different in color; the deformation transmission mechanism further comprises a pointer driving gear (43), which is fixedly connected to the transmission shaft (42) and is concentrically arranged with the second bevel gear (412); the height of the pointer driving gear (43) in the deformation transmission mechanism is set according to the height of the corresponding pointer gear (51) of the displacement-stress conversion display instrument (5), and the pointer driving gear (43) is in meshing transmission with the corresponding pointer gear (51), so as to drive the stress pointer (56) to rotate; a plurality of transmission gears (8) for realizing the transmission connection between the pointer driving gear (43) and the pointer gear (51) are also rotatably installed on the bottom pressure shell (21) through bearings.

5. The real-time monitoring device for bolt or anchor stress according to claim 4, characterized in that, The first-level pointer sleeve (52), the second-level pointer sleeve (53) and the third-level pointer sleeve (54) are all provided with an axle shoulder (57) and a C-shaped elastic retainer groove; the axle shoulder (57) is fixedly installed on the pointer sleeve and located between the corresponding stress pointer (56) and the adjacent pointer sleeve, and the outer diameter of the axle shoulder (57) is larger than the inner diameter of the adjacent pointer sleeve; the C-shaped elastic retainer groove is arranged between the corresponding pointer gear (51) and the adjacent pointer sleeve, and an elastic retainer (58) is installed in the C-shaped elastic retainer groove, and the outer diameter of the elastic retainer (58) is larger than the inner diameter of the adjacent pointer sleeve.

6. A method for evaluating the stability of surrounding rock using the real-time monitoring device for bolt or anchor stress according to claim 1, characterized in that, The method comprises the following steps: Step one, design the hole diameter of the anchor rod or anchor cable stress real-time monitoring device according to the diameter of the anchor rod or anchor cable on site; Step two, limit the material selection range of the anchor rod or anchor cable stress real-time monitoring device; Step three, select the area where the anchor rod or anchor cable stress needs to be monitored in the coal mine roadway, install the anchor rod or anchor cable stress real-time monitoring device on the roadway roof and two sides, apply the same pre-tightening force, and number these anchor rod or anchor cable stress real-time monitoring devices; Step four, every fixed time to anchor rod or anchor cable stress real-time monitoring device show and roof separation displacement amount are recorded and summarized; Step five, comparative analysis of the collected data, determine the abnormal data area corresponding to the roadway surrounding rock working condition, take corresponding measures.

7. The method of assessing the stability of surrounding rock according to claim 6, characterized in that, In step two, the method for limiting the material selection range of the anchor rod or anchor cable stress real-time monitoring device, comprising the following steps: S1, calculating the maximum load that the anchor rod or cable can withstand in the event of a pull-out failure F 拉断 : Tensile strength of the anchor rod or cable σ b Cross-sectional area A of the anchor rod or cable s ; F 拉断 = σ b ×A s In the formula: σ b - Tensile strength of the anchor rod or cable, in Pa; A s - cross-sectional area of the anchor rod or cable, in m 2 ; S2, the maximum load that can be sustained by the anchor rod or cable breakage failure F 拉断 The calculation stress real-time monitoring device section size; S21, calculate the maximum load exerted by the nut (7) on the stress real-time monitoring device when the anchor rod or anchor cable is pulled off: In the formula: D 2 - Diameter of the stress real-time monitoring device minus the wall thickness t in m; D 3 - Diameter of the inner part of the real-time stress monitoring device plus the wall thickness t in m; m - the width of the real-time stress monitoring device in contact with the nut (7), in m; q max - the maximum load, in Pa, exerted by the nut (7) on the real-time stress monitoring device when the anchor rod or cable is broken; S22, calculate the maximum bending moment borne by the stress real-time monitoring device when the anchor rod or anchor cable is pulled off: In the formula: M max - the maximum bending moment, in N.m, to which the real-time monitoring device of the stress at the time of the anchoring rod or cable breakage is subjected; S23, calculate the radial span stress section moment of inertia of the anchor rod or anchor cable stress real-time monitoring device: In the formula: I z - Radial span force section moment of inertia of the anchoring rod or cable real-time monitoring device, in m 4 ; t - wall thickness of the stress real-time monitoring device, in m; S24, calculate the maximum tensile stress or compressive stress of the anchor rod or anchor cable stress real-time monitoring device cross section: In the formula: σ max - Maximum tensile or compressive stress in the cross section of the anchor rod or cable stress real-time monitoring device, in Pa. y max - the ordinate of the farthest boundary stress point, in m; S25, select the material according to the maximum tensile stress or compressive stress determined in S24, and select the material range: In the formula: [ σ t - maximum tensile stress the material can withstand, in Pa; [ σ c - Maximum compressive stress the material can withstand, in Pa.

8. The method of assessing the stability of surrounding rock according to claim 6, characterized by, In step five, according to the working condition of the surrounding rock of the roadway, corresponding measures are taken, including: Working condition one: when the stress value monitored by the anchor rod or anchor cable stress real-time monitoring device is normal, and the separation amount monitored by the roof separation instrument is normal, it is judged that the support state is normal, and no measures need to be taken; Working condition two: when the stress value monitored by the anchor rod or anchor cable stress real-time monitoring device is normal, and the separation amount monitored by the roof separation instrument exceeds the normal range but does not reach the safety warning threshold, it is judged that the anchor rod or anchor cable stress is normal, the roof rock layer has separated but is still stable, the number of anchor cables should be increased, the anchoring depth should be increased, the anchor support force should be increased, and the displacement of the separation should be reduced to control the deformation of the surrounding rock; Working condition three: when the stress value monitored by the anchor rod or anchor cable stress real-time monitoring device is normal, and the separation amount monitored by the roof separation instrument exceeds the safety warning threshold, the rock layer below the separation should be stripped and supported again; Working condition four: when the stress value monitored by the anchor rod or anchor cable stress real-time monitoring device exceeds the set warning threshold, and the separation amount monitored by the roof separation instrument is normal, it is judged that the support strength is insufficient, and the anchor rod or anchor cable will soon reach the yield limit, the anchor rod layout density should be increased, and the number of anchor rods should be increased; single props can be considered to be added to assist in supporting the surrounding rock of the roadway and to increase the bearing capacity of the support structure; Working condition five: when the stress value monitored by the anchor rod or anchor cable stress real-time monitoring device exceeds the set warning threshold, and the separation amount monitored by the roof separation instrument exceeds the normal range but does not reach the safety warning threshold, the number of anchor rods and anchor cables should be increased, the anchor cables should be used to increase the suspension force, and the anchor rods should be used to fully mobilize the strength of the surrounding rock to maintain the stability of the surrounding rock, and the support strength should be increased; Working condition six: when the stress value monitored by the anchor rod or anchor cable stress real-time monitoring device exceeds the set warning threshold, and the separation amount monitored by the roof separation instrument exceeds the safety warning threshold, the rock layer below the separation should be stripped and supported again; Working condition seven: when the stress value monitored by the anchor rod or anchor cable stress real-time monitoring device is far below the normal working range or even tends to zero, and the roof separation amount monitored by the roof separation instrument is normal, it is judged that the anchor rod or anchor cable may have been broken and failed, and the anchor rod or anchor cable should be immediately checked. If it is confirmed to be broken, a new anchor rod or anchor cable should be replaced in time, and the installation quality of the new anchor rod or anchor cable should be ensured to meet the design requirements; Working condition eight: when the stress value monitored by the anchor rod or anchor cable stress real-time monitoring device is far below the normal working range or even tends to zero, and the roof separation amount monitored by the roof separation instrument exceeds the normal range but does not reach the safety warning threshold, it is necessary to check whether the anchor rod or anchor cable is broken and failed, to reinstall, and to supplement the anchor cable; Working condition nine: when the stress value monitored by the anchor rod or anchor cable stress real-time monitoring device appears abnormal change, such as sudden drop, and the roof separation amount monitored by the roof separation instrument exceeds the safety warning threshold, it is judged that the surrounding rock is seriously unstable, and the area should be immediately listed as a dangerous area. A scheme and safety measures should be developed, the rock below the separation should be stripped, and after the stripping is completed, the support design and construction should be re-performed, and high-strength support structure should be adopted.

Images