阅读说明：本技术 一种围岩中锚杆断裂状态现场监测系统及测试方法 (On-site monitoring system and testing method for fracture state of anchor rod in surrounding rock ) 是由 李凌峰 唐建园 毛盛泰 张恩桥 来荣国 李飞 魏磊 苏小敏 兰天仕 唐新华 刘飞 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种围岩中锚杆断裂状态现场监测系统及监测方法,该监测系统包括锚杆、波纹管和塑料定位件,所述塑料定位件套设在锚杆上,且所述锚杆通过塑料定位件与波纹管连接,所述波纹管内贯穿有第一信号线,所述波纹管的远端弯曲形成弯钩且通过连接组件与锚杆的远端连接,则第一信号线的一端与与锚杆的远端面连接,所述锚杆的近端面的中心部位与第二信号线的一端连接,形成锚杆监测装置,该锚杆监测装置被插入钻孔内,并在钻孔内注入浆液,所述第一信号线和第二信号线的另一端分别与万用表的负极和正极相连或者信号采集器相连。本发明将锚杆作为线路的一部分,通过线路的电阻阻值和其通断判断岩石锚杆的变形状态及其是否被拉断,操作简单方便。(The invention discloses an anchor rod fracture state on-site monitoring system and a monitoring method in surrounding rock, the monitoring system comprises an anchor rod, a corrugated pipe and a plastic positioning piece, the plastic positioning piece is sleeved on the anchor rod, the anchor rod is connected with the corrugated pipe through the plastic positioning piece, a first signal wire penetrates through the corrugated pipe, the far end of the corrugated pipe is bent to form a hook and is connected with the far end of the anchor rod through a connecting component, one end of the first signal wire is connected with the far end face of the anchor rod, the central part of the near end face of the anchor rod is connected with one end of a second signal wire to form an anchor rod monitoring device, the anchor rod monitoring device is inserted into a drill hole, grout is injected into the drill hole, and the other ends of the first signal wire and the second signal wire are respectively connected with a negative electrode and a positive electrode of a universal meter or a signal collector. The invention takes the anchor rod as a part of the circuit, judges the deformation state of the rock anchor rod and whether the rock anchor rod is broken or not through the resistance value and the on-off state of the circuit, and has simple and convenient operation.)

1. The utility model provides an anchor rod rupture state on-site monitoring system in country rock, its characterized in that, this monitoring system includes stock, bellows and plastics setting element, the plastics setting element cover is established on the stock, just the stock passes through the plastics setting element and is connected with the bellows, run through first signal line in the bellows, the distal end bending of bellows forms the crotch and is connected with the distal end of stock through coupling assembling, then the one end of first signal line with be connected with the distal end face of stock, the central point of the near-end face of stock is connected with the one end of second signal line, forms stock monitoring devices, and this stock monitoring devices is inserted in the drilling to inject the thick liquid in the drilling, the other end of first signal line and second signal line links to each other or signal collector with the negative pole and the positive pole of universal meter respectively.

2. The system for on-site monitoring of the fracture state of the anchor rod in the surrounding rock as claimed in claim 1, wherein the plastic positioning piece comprises a fixed column, an anchor rod positioning hole penetrating through the fixed column is formed in the horizontal axis of the fixed column, a plurality of connecting columns are arranged on the outer wall of the fixed column in the circumferential direction of the fixed column at equal intervals, a corrugated pipe positioning hole penetrating through the connecting columns is formed in the horizontal axis of the connecting columns, a supporting plate is connected to the outer wall of each connecting column through a supporting leg, and the supporting plate is parallel to the horizontal axis of the connecting columns.

3. The system for on-site monitoring of the fracture state of the anchor rod in the surrounding rock according to claim 2, wherein the thickness of the fixing column and the thickness of the connecting column are both 0.3 times of the respective diameters, the included angle between two adjacent supporting legs is 120 degrees, a chamfer angle is arranged at the joint of the supporting leg and the supporting plate for reinforcement, and the chamfer angle is 45 degrees.

4. The system of claim 1, wherein the corrugated pipe has a pipe body formed by alternately and continuously forming peaks and troughs, and both ends of the pipe body are smooth sections.

5. The system for on-site monitoring of the fracture state of the anchor rod in the surrounding rock according to claim 4, wherein the connecting assembly comprises a hollow connecting part, one end face of the connecting part is connected with the far end face of the anchor rod, a through hole capable of passing through a first signal line is arranged at the end face, the other end face of the connecting part is provided with an opening for inserting the smooth section of the corrugated pipe into the inner cavity, the inner cavity of the connecting part is internally provided with a first inner cylinder, a second inner cylinder and a circular ring from inside to outside, one end of each of the first inner cylinder and the second inner cylinder is fixedly connected with the inner end face of the connecting part on the side close to the anchor rod, the inner side wall of the connecting part is provided with a sliding groove matched with the outer wall of the circular ring along the circumferential direction, the inner ring can rotate in the sliding groove, the outer wall of the connecting part is provided with a guide groove along the circumferential direction, the guide groove is communicated with the sliding groove, and a poking block is arranged in the guide groove, the inner end surface of the poking block is fixedly connected with the outer wall of the circular ring, the inner ring surface of the circular ring is provided with a plurality of wedge blocks at equal intervals along the circumferential direction, the inner end surface of the wedge block is an inclined surface, a plurality of through holes with equal intervals are arranged on the second inner cylinder along the circumferential direction of the second inner cylinder, a guide post is arranged in each through hole, one end of each guide post penetrates through the through hole to a position between the first inner cylinder and the second inner cylinder, and the end surface is provided with an arc-shaped snap-gauge, the other end of the guide post penetrates through the through hole to reach the position between the second sleeve and the circular ring, a stop block is arranged on the end surface of the guide post, a compression spring is sleeved on the outer side of the guide post, one end of the compression spring is connected with the inner end surface of the stop block, the other end of the wedge block is connected with the outer end face of the second sleeve, and the wedge block extrudes the stop block to fix the smooth section of the corrugated pipe on the outer wall of the first inner cylinder through the arc-shaped clamping plate when the smooth section of the corrugated pipe is inserted into the connecting part.

6. The system of claim 5, wherein an inner end surface of each arc-shaped clamping plate is provided with an arc-shaped clamping block, and a smooth section of the corrugated pipe is provided with a clamping groove matched with the arc-shaped clamping block.

7. The in-situ monitoring system for the fracture state of the anchor rod in the surrounding rock as claimed in claim 5, wherein a rubber gasket is respectively arranged on two symmetrical inner side walls of the guide groove, the two symmetrical rubber gaskets are arranged at one end in the guide groove, and the toggle block is limited between the two symmetrical rubber gaskets when the wedge block presses the stop block.

8. The system for on-site monitoring of the fracture state of the anchor rod in the surrounding rock according to claim 1, wherein the signal collector is further connected with a signal processing center through a signal transmission unit.

9. The test method of the anchor rod fracture state on-site monitoring system in the surrounding rock according to any one of claims 1 to 8, characterized by comprising the following steps:

step 1: drilling a borehole at a proper position of the surrounding rock, cleaning the borehole, and detecting the diameter, depth and pore-forming quality of the borehole;

step 2: installing a plastic positioning piece on the anchor rod at intervals, sleeving an anchor rod positioning hole of the plastic positioning piece on the anchor rod along the extension direction of the anchor rod during installation, and then adjusting the interval of each plastic positioning piece;

and step 3: the first signal wire penetrates through the corrugated pipe, then the corrugated pipe sequentially penetrates through corrugated pipe positioning holes in the plastic positioning pieces, and the distance between the plastic positioning pieces is adjusted again;

and 4, step 4: fixing a connecting part on the far end surface of the anchor rod through strong glue, bending the far end of the corrugated pipe, inserting the smooth section of the far end into the connecting part along an opening on the connecting part, penetrating one end of a first signal wire out of a through hole on the connecting part to be connected with the far end surface of the anchor rod, connecting one end of a second signal wire with the near end of the anchor rod, and adjusting the corrugated pipe to be parallel to the anchor rod to form the anchor rod monitoring device;

and 5: the well-installed anchor rod monitoring device is slowly inserted into a drilled hole, grout is injected, the first signal line is isolated from the grout by the corrugated pipe, the anchor rod and the corrugated pipe can deform along with the deformation of surrounding rock after the grout is solidified, but the first signal line in the corrugated pipe is in a non-stressed state, and the first signal line cannot be broken when the surrounding rock deforms;

step 6: after the slurry is solidified, the other ends of the first signal wire and the second signal wire are respectively connected with the negative electrode and the positive electrode of a universal meter, whether the circuits are communicated or not is detected, and whether the element is installed and survived or not is judged; after the circuit is detected to be normal, measuring the initial resistance value of the circuit;

and 7: after the group of anchor rod monitoring devices are installed, repeating the steps 1-7 to install and test the next group of anchor rods;

and 8: the signal transmission unit is connected with a signal processing center which is used for storing, processing and analyzing data to obtain a conclusion.

10. The test method of the anchor rod fracture state on-site monitoring system in the surrounding rock according to claim 9, wherein the anchor rod fracture state monitoring process is as follows:

step 801: firstly, detecting whether the connection of a signal monitoring system is smooth or not and whether the operation is normal or not, synchronously observing the change of test data, determining that a data acquisition system works normally, and initializing the system to prepare for testing after all the data acquisition system works normally;

step 802: according to the method for judging the state of the anchor rod, the anchor rod is stretched along with the deformation of surrounding rocks when the anchor rod enters a working state, the resistance value of the anchor rod is increased, if the anchor rod is stressed to exceed the strength of the anchor rod, one or more parts in the anchor rod are broken, the resistance value of the anchor rod is greatly increased and even reaches infinity, and whether the anchor rod is broken or not can be judged by measuring the resistance value of the anchor rod; step 803: judging and alarming the state of the anchor rod, storing, processing and analyzing data in real time by a signal processing center, and when the monitored change rate of the resistance of the anchor rod exceeds a warning threshold value, indicating that the anchor rod is rapidly stretched and deformed and is damaged, sending an early warning signal by the signal processing center; when the resistance of the anchor rod reaches the fracture resistance threshold value, one or more parts of the anchor rod are judged to be broken, and an anchor rod damage alarm signal is sent out by the signal processing center.

Technical Field

The invention belongs to the technical field of anchor rod monitoring, and particularly relates to an anchor rod fracture state on-site monitoring system and a test method in surrounding rock.

Background

With the rapid development of tunnel and mining engineering, the anchor rod is widely applied to underground engineering as an effective surrounding rock deformation control measure. However, in high ground stress and large deformation surrounding rocks, the anchor rod is subjected to huge tensile stress, and when the stress applied to the anchor rod exceeds the strength of the anchor rod, the anchor rod is pulled apart. After the anchor rod is broken, the surrounding rock is out of restraint, and large deformation and even collapse can occur, so that the safe construction and operation of the engineering are threatened. Because the anchor rod is buried in the surrounding rock when working, after the anchor rod is stressed and broken, the stress condition of the anchor rod is difficult to judge from the outside of the surrounding rock, correct judgment and reinforcement measures cannot be made, and further, a proper remediation opportunity is missed, so that engineering safety accidents are caused.

At present, some methods for detecting the fracture state of the anchor rod exist, and the end head and the base plate of the anchor rod can be directly determined by visual observation if the anchor rod is broken and the anchor rod and the base plate fall off or even fly out. The condition of some anchor rods internal fracture can not be judged by observation. In this situation, some scholars have designed external detection instruments, for example, chinese patent No. CN201320733527.6 discloses a broken anchor rod detector, which utilizes the capacitance characteristic of the rock between two anchor rods in the roadway support, and determines whether the anchor rod is broken by measuring the instantaneous current value between the two anchor rods and comparing the measured instantaneous current value with the standard instantaneous current. The device principle is complicated, and the fracture state of specific stock can't real-time supervision needs to carry out the comprehensive measurement to many stocks, combines logical analysis just can judge. At present, no system for monitoring and determining the fracture state of the anchor rod in real time exists.

Disclosure of Invention

The invention aims to overcome the defects and shortcomings of the prior art, according to the fact that the resistance of a metal conductor is in direct proportion to the length of the metal conductor and in inverse proportion to the section of the metal conductor, if one or more parts inside an anchor rod are broken, the resistance value of the metal conductor can be greatly increased, and even infinite characteristics are achieved. The invention provides a set of on-site monitoring system for judging the fracture state of the anchor rod in the surrounding rock by measuring the resistance value of the anchor rod, and the deformation state of the anchor rod in the surrounding rock is judged by measuring the resistance value of the anchor rod, so that a certain basis is provided for judging whether the anchor rod of the surrounding rock is fractured.

In order to achieve the purpose, the invention adopts the technical scheme that:

the utility model provides an anchor rod rupture state on-site monitoring system in country rock, this monitoring system includes anchor rod, bellows and plastics setting element, the plastics setting element cover is established on the anchor rod, just the anchor rod passes through the plastics setting element and is connected with the bellows, it has first signal line to run through in the bellows, the distal end bending of bellows forms the crotch and is connected with the distal end of anchor rod through coupling assembling, then the one end of first signal line is connected with the distal end face of anchor rod, the central point of the near-end face of anchor rod is connected with the one end of second signal line, forms anchor rod monitoring devices, and this anchor rod monitoring devices is inserted in the drilling to inject the thick liquid in the drilling, the other end of first signal line and second signal line links to each other or signal collector with the negative pole and the positive pole of universal meter respectively.

Preferably, the plastic positioning piece comprises a fixing column, an anchor rod positioning hole penetrating through the fixing column is formed in the horizontal axis of the fixing column, a plurality of connecting columns which are equidistant are arranged on the outer wall of the fixing column in the circumferential direction of the outer wall of the fixing column, a corrugated pipe positioning hole penetrating through the connecting columns is formed in the horizontal axis of the connecting columns, a supporting plate is connected to the outer wall of the connecting columns through supporting legs, and the supporting plate is parallel to the horizontal axis of the connecting columns.

Preferably, the thickness of the fixed column and the thickness of the connecting column are 0.3 times of the respective diameter, the included angle between two adjacent supporting legs is 120 degrees, a chamfer angle is arranged at the joint of the supporting leg and the supporting plate for reinforcement, and the chamfer angle is 45 degrees.

Preferably, the tube body of the corrugated tube is formed by alternately and continuously forming wave crests and wave troughs, and both ends of the tube body are smooth sections.

Preferably, the connecting assembly comprises a hollow connecting part, one end face of the connecting part is connected with the far end face of the anchor rod, a through hole capable of passing through a first signal line is arranged at the end face, the other end face of the connecting part is provided with an opening for inserting the smooth section of the corrugated pipe into the inner cavity, a first inner cylinder, a second inner cylinder and a circular ring from inside to outside are arranged in the inner cavity of the connecting part, one end of each of the first inner cylinder and the second inner cylinder is fixedly connected with the inner end face, close to one side of the anchor rod, on the connecting part, a sliding groove matched with the outer wall of the circular ring is arranged on the inner side wall of the connecting part along the circumferential direction of the inner cylinder, the inner ring can rotate in the sliding groove, a guide groove is arranged on the outer wall of the connecting part along the circumferential direction of the outer wall of the connecting part, the guide groove is communicated with the sliding groove, a shifting block is arranged in the guide groove, the inner end face of the shifting block is fixedly connected with the outer wall of the circular ring, and a plurality of uniformly spaced wedges are arranged on the inner ring along the circumferential direction of the circular ring, the inner end face of the wedge block is an inclined plane, a plurality of through holes which are equidistant are formed in the second inner cylinder in the circumferential direction, a guide post is arranged in each through hole, one end of each guide post penetrates through the through hole to the position between the first inner cylinder and the second inner cylinder, an arc-shaped clamping plate is arranged on the end face of each guide post, the other end of each guide post penetrates through the through hole to the position between the second sleeve and the circular ring, a stop block is arranged on the end face of each guide post, a compression spring is sleeved on the outer side of each guide post, one end of each compression spring is connected with the inner end face of each stop block, the other end of each compression spring is connected with the outer end face of each second sleeve, and the wedge block extrudes each stop block to fix the smooth section of the corrugated pipe on the outer wall of the first inner cylinder through the arc-shaped clamping plates when the smooth section of the corrugated pipe is inserted into the connecting portion.

Preferably, the inner end face of each arc-shaped clamping plate is provided with an arc-shaped clamping block, and the smooth section of the corrugated pipe is provided with a clamping groove matched with the arc-shaped clamping block.

Preferably, two symmetrical inner side walls of the guide groove are respectively provided with a rubber gasket, the two symmetrical rubber gaskets are positioned at one end in the guide groove, and the poking block is limited between the two symmetrical rubber gaskets when the wedge block extrudes the check block.

Preferably, the signal collector is further connected with the signal processing center through a signal transmission unit.

A test method of an anchor rod fracture state field monitoring system in surrounding rock comprises the following steps:

step 1: drilling a borehole at a proper position of the surrounding rock, cleaning the borehole, and detecting the diameter, depth and pore-forming quality of the borehole;

step 2: installing a plastic positioning piece on the anchor rod at intervals, sleeving an anchor rod positioning hole of the plastic positioning piece on the anchor rod along the extension direction of the anchor rod during installation, and then adjusting the interval of each plastic positioning piece;

and step 3: the first signal wire penetrates through the corrugated pipe, then the corrugated pipe sequentially penetrates through corrugated pipe positioning holes in the plastic positioning pieces, and the distance between the plastic positioning pieces is adjusted again;

and 4, step 4: fixing a connecting part on the far end surface of the anchor rod through strong glue, bending the far end of the corrugated pipe, inserting the smooth section of the far end into the connecting part along an opening on the connecting part, penetrating one end of a first signal wire out of a through hole on the connecting part to be connected with the far end surface of the anchor rod, connecting one end of a second signal wire with the near end of the anchor rod, and adjusting the corrugated pipe to be parallel to the anchor rod to form the anchor rod monitoring device;

and 5: the well-installed anchor rod monitoring device is slowly inserted into a drilled hole, grout is injected, the first signal line is isolated from the grout by the corrugated pipe, the anchor rod and the corrugated pipe can deform along with the deformation of surrounding rock after the grout is solidified, but the first signal line in the corrugated pipe is in a non-stressed state, and the first signal line cannot be broken when the surrounding rock deforms;

step 6: after the slurry is solidified, the other ends of the first signal wire and the second signal wire are respectively connected with the negative electrode and the positive electrode of a universal meter, whether the circuits are communicated or not is detected, and whether the element is installed and survived or not is judged; after the circuit is detected to be normal, measuring the initial resistance value of the circuit;

and 7: after the group of anchor rod monitoring devices are installed, repeating the steps 1-7 to install and test the next group of anchor rods;

and 8: the signal transmission unit is connected with a signal processing center which is used for storing, processing and analyzing data to obtain a conclusion.

Preferably, the bolt fracture state monitoring process is as follows:

step 801: firstly, detecting whether the connection of a signal monitoring system is smooth or not and whether the operation is normal or not, synchronously observing the change of test data, determining that a data acquisition system works normally, and initializing the system to prepare for testing after all the data acquisition system works normally;

step 802: according to the method for judging the state of the anchor rod, the anchor rod is stretched along with the deformation of surrounding rocks when the anchor rod enters a working state, the resistance value of the anchor rod is increased, if the anchor rod is stressed to exceed the strength of the anchor rod, one or more parts in the anchor rod are broken, the resistance value of the anchor rod is greatly increased and even reaches infinity, and whether the anchor rod is broken or not can be judged by measuring the resistance value of the anchor rod;

step 803: judging and alarming the state of the anchor rod, storing, processing and analyzing data in real time by a signal processing center, and when the monitored change rate of the resistance of the anchor rod exceeds a warning threshold value, indicating that the anchor rod is rapidly stretched and deformed and is damaged, sending an early warning signal by the signal processing center; when the resistance of the anchor rod reaches the fracture resistance threshold value, one or more parts of the anchor rod are judged to be broken, and an anchor rod damage alarm signal is sent out by the signal processing center.

The invention has the beneficial effects that: the invention takes the anchor rod as a part of the circuit, directly measures the resistance of the circuit, judges the deformation state of the rock anchor rod and whether the rock anchor rod is broken or not through the resistance value of the circuit and the on-off state of the circuit, has simple and convenient operation, clear and understandable test result and is convenient to implement on site.

The output signals are electric signals, and the signals are easy to transmit and receive; a data collection system can be established to automatically monitor and collect signals, and monitoring automation is realized.

The connecting component is made of an insulating material and is bonded with the far end of the anchor rod by using strong glue, the smooth section at the far end of the corrugated pipe is inserted into the connecting part, the corrugated pipe is separated from a first signal wire by the first inner cylinder, the first signal wire is connected with the far end surface of the anchor rod, and the stop block is extruded by the wedge block, so that the arc-shaped clamping plate is driven by the guide column to extrude the outer wall of the corrugated pipe, the inner wall of the corrugated pipe is tightly contacted with the outer wall of the first inner cylinder and is clamped into the clamping groove on the corrugated pipe by the arc-shaped clamping block, the corrugated pipe is fixed, the corrugated pipe can be fixed by stirring the stirring block, and the grouting slurry of the connecting part is isolated from the first signal wire, so that the sealing performance of the far end of the corrugated pipe and the far end of the anchor rod is ensured.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of an anchor rod fracture state on-site monitoring system in surrounding rock according to the embodiment;

fig. 2 is a schematic structural diagram of a plastic positioning element in the in-situ monitoring system for the fracture state of the anchor rod in the surrounding rock according to the embodiment;

fig. 3 is a schematic structural view of a bellows in the anchor rod fracture state on-site monitoring system in the surrounding rock according to the embodiment.

Fig. 4 is a partial view showing that the far end of the anchor rod is connected with the corrugated pipe through the connecting part in the anchor rod fracture state on-site monitoring system in the surrounding rock according to the embodiment;

fig. 5 is a schematic internal view of a connecting part in the anchor rod fracture state on-site monitoring system in the surrounding rock according to the embodiment.

FIG. 6 is a side cross-sectional view of the connecting portion of the in-situ anchor bolt fracture status monitoring system in the surrounding rock according to the present embodiment;

fig. 7 is a side cross-sectional view of a connecting part fixing corrugated pipe in the anchor rod fracture state on-site monitoring system in the surrounding rock according to the embodiment.

Fig. 8 is a schematic cross-sectional view of the anchor rod monitoring device before the anchor rod is broken in the anchor rod fracture state on-site monitoring system in the surrounding rock according to the embodiment;

fig. 9 is a schematic cross-sectional view of the anchor rod monitoring device after the anchor rod is broken in the in-situ anchor rod fracture state monitoring system in the surrounding rock according to the embodiment;

fig. 10 is a schematic diagram of a signal management system in the field monitoring system for the fracture state of the anchor rod in the surrounding rock according to the embodiment.

Wherein, 1, surrounding rock; 2. drilling; 3. an anchor rod; 4. grouting; 5. a plastic positioning member; 501. supporting legs; 502. a support plate; 503. positioning holes of the anchor rods; 504. a corrugated pipe positioning hole; 6. a bellows; 601. wave crest; 602. a trough of a wave; 603. hooking; 7. a first signal line; 8. a second signal line; 9. a universal meter; 10. breaking; 11. a connecting portion; 1101. an opening; 1102. perforating; 12. a first inner cylinder; 13. a second inner barrel; 14. a circular ring; 15. an arc-shaped clamping plate; 16. a guide post; 17. an arc-shaped fixture block; 18. a compression spring; 19. a stopper; 20. a guide groove; 21. a wedge block; 22. a shifting block; 23. a rubber gasket; 24. a signal collector; 25. A signal transmission unit; 26. and a signal processing center.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention is made according to the relationship between the resistance of the conductive metal rod and the length, the sectional area and the fracture condition of the conductive metal rod. When the anchor rod is not broken, the resistance value of the anchor rod meets the following formula:

in the formula: r is the resistance of the material

ρ is an inherent property of metal and can be considered as a fixed value;

l is the length of the metal rod;

s is the sectional area of the metal rod.

When one or more parts in the anchor rod are broken due to overlarge stress, the resistance value of the anchor rod can be greatly increased, even the monitoring circuit is broken, and the resistance value tends to infinity.

According to the above formula, the resistance of a metal conductor is proportional to its length and inversely proportional to its cross-section. In the invention, after the length and the diameter of the anchor rod are determined, in an initial state, the anchor rod and the line have determined initial resistance values, the anchor rod can be stretched along with the deformation of surrounding rocks when the anchor rod enters a working state, the sectional area is reduced, the resistance value of the anchor rod can be increased, and if one or more parts in the anchor rod are broken by being subjected to overlarge stress, the resistance value of the anchor rod can be greatly increased and even reaches infinity. The fracture state of the anchor rod in the surrounding rock can be judged by measuring the resistance value of the anchor rod.

Referring to fig. 1-10, the present embodiment provides a system for on-site monitoring of bolt fracture status in surrounding rock, the monitoring system comprises an anchor rod 3, a corrugated pipe 6 and a plastic positioning piece 5, wherein the plastic positioning piece 5 is sleeved on the anchor rod 3, the anchor rod 3 is connected with a corrugated pipe 6 through a plastic positioning piece 5, a first signal wire 7 penetrates through the corrugated pipe 6, the distal end of the bellows 6 is bent to form a hook 603 and connected to the distal end of the anchor rod 3 by a connecting member, one end of the first signal wire 7 is connected with the far end surface of the anchor rod 3, the central part of the near end surface of the anchor rod 3 is connected with one end of the second signal wire 8, so as to form the anchor rod monitoring device, the anchor rod monitoring device is inserted into a drill hole 2, grout 4 is injected into the drill hole 2, and the other ends of the first signal line 7 and the second signal line 8 are respectively connected with the negative pole and the positive pole of a multimeter 9 or a signal collector 24.

In this embodiment, the plastic positioning member 5 is as shown in fig. 2, the plastic positioning member 5 includes a fixing column, an anchor rod positioning hole 503 penetrating through the fixing column is provided along a horizontal axis of the fixing column, a plurality of connecting columns are provided on an outer wall of the fixing column along a circumferential direction thereof at equal intervals, a bellows positioning hole 504 penetrating through the connecting columns is provided along the horizontal axis of the connecting columns, the outer wall of the connecting columns is connected with a supporting plate 502 through a supporting leg 501, and the supporting plate 502 is parallel to the horizontal axis of the connecting columns. The thickness of the fixing column and the thickness of the connecting column are 0.3 times of the respective diameters, the included angle between every two adjacent supporting legs 501 is 120 degrees, a chamfer angle is arranged at the joint of each supporting leg 501 and the corresponding supporting plate 502 for reinforcement, and the chamfer angle is 45 degrees.

In this embodiment, the anchor rod positioning hole 503 is located at the center of the plastic positioning member 5, and has a diameter slightly larger than that of the anchor rod 3. The diameter of the 3 bellows positioning holes 504 is slightly larger than the diameter of the bellows 6.

As shown in fig. 3, in the present embodiment, the bellows 6 has a tube body formed by alternately and continuously forming peaks 601 and valleys 602, and the tube body can be stretched and bent. Both ends of the tube body are smooth sections. The pipe shaft can stretch out and draw back along with the country rock deformation after the slip casting, and the first signal line in the protection pipe prevents that first signal line 7 from being broken by the stretch.

As shown in fig. 4-7, in the present embodiment, the coupling assembly is made of an insulating material, and may be made of plastic, and includes a hollow connecting portion 11, one end surface of the connecting portion 11 is connected to the distal end surface of the anchor rod 3 through a strong adhesive, a through hole 1102 is provided at the end surface for passing through the first signal line 7, the other end surface is provided with an opening 1101 for inserting the smooth section of the corrugated tube 6 into the inner cavity, the inner cavity of the connecting portion 11 is provided with a first inner cylinder 12, a second inner cylinder 13 and a ring 14 from inside to outside, one end of each of the first inner cylinder 12 and the second inner cylinder 13 is fixedly connected to the inner end surface of the connecting portion 11 on the side close to the anchor rod, the inner side wall of the connecting portion 11 is provided with a sliding groove (not shown in the figure) adapted to the outer wall of the ring 14 along the circumferential direction thereof, the inner ring 14 is rotatable in the sliding groove (the present embodiment improves the shape of the sliding groove and the outer wall of the ring, the connecting part is designed into a T-shaped structure to prevent an inner ring from separating from a sliding groove), a guide groove 20 is arranged on the outer wall of the connecting part 11 along the circumferential direction, the guide groove 20 is communicated with the sliding groove, a poking block 22 is arranged in the guide groove 20, the inner end surface of the poking block 22 is fixedly connected with the outer wall of a circular ring 14, 4 wedges 21 with equal intervals are arranged on the inner ring surface of the circular ring 14 along the circumferential direction, the inner end surface of each wedge is an inclined surface, 4 through holes with equal intervals are arranged on the second inner cylinder 13 along the circumferential direction, a guide column 16 is arranged in each through hole, one end of each guide column 16 penetrates through the through hole to be arranged between the first inner cylinder 12 and the second inner cylinder 13, an arc-shaped clamping plate 15 is arranged on the end surface of each guide column 16, the other end of each guide column 16 penetrates through the through hole to be arranged between the second sleeve 13 and the circular ring 14, a stop 19 is arranged on the end surface of each guide column 16, a compression spring 18 is sleeved on the outer side of each guide column, one end of the compression spring 18 is connected with the inner end face of the stop block 19, the other end of the compression spring is connected with the outer end face of the second sleeve 13, and the wedge 21 extrudes the stop block 19 to fix the smooth section of the corrugated pipe 6 on the outer wall of the first inner cylinder 12 through the arc-shaped clamping plate 15 when the smooth section of the corrugated pipe 6 is inserted into the connecting part 11.

In this embodiment, the interior terminal surface of every arc cardboard 15 is provided with arc fixture block 17, be provided with the draw-in groove with arc fixture block 17 matched with in the smooth section of bellows 6, when the smooth section laminating of bellows 6 is laminated on the outer wall of first inner tube 12 at arc cardboard 17, draw-in groove on the bellows 6 is gone into through arc fixture block 17 card, realize the fixed of bellows 6, stir the piece 22 (be provided with the tooth socket at the terminal surface of stirring the piece in this embodiment, be convenient for stir the piece) through stirring and can realize the fixed of bellows, it is isolated with slip casting thick liquid 4 and first signal line 7 through connecting portion 11, guarantee the leakproofness that the distal end of bellows 6 and the distal end of stock are linked.

In order to ensure that the shifting block 22 does not move along the guide groove 20 when being shifted to the bottommost part, two symmetrical inner side walls of the guide groove 20 are respectively provided with a rubber gasket 23, the two symmetrical rubber gaskets 23 are positioned at one end in the guide groove 20, and the shifting block 22 is limited between the two symmetrical rubber gaskets 23 when the wedge block 21 presses the stop block 19.

As shown in fig. 10, in this embodiment, the first signal line 7 and the second signal line 8 of the monitoring assembly of the multiple groups of anchor rods 3 are connected to a signal collector 24, the signal collector 24 is used for receiving and collecting signals, the other end of the signal collector is connected to a signal transmission unit 25, the signal transmission unit 25 transmits the signals to a signal processing center 26 through a wireless network, and the signal processing center 26 stores, processes and analyzes the data to obtain a conclusion.

The embodiment also provides a test method of the anchor rod fracture state on-site monitoring system in the surrounding rock, which comprises the following steps:

step 1: drilling a borehole 2 at a proper position of the surrounding rock 1, cleaning the borehole 2, and detecting the diameter, depth and pore-forming quality of the borehole 2;

step 2: installing plastic positioning pieces 5 on the anchor rod 3 at intervals, sleeving anchor rod positioning holes 503 of the plastic positioning pieces 5 on the anchor rod 3 along the extension direction of the anchor rod 3 during installation, and then adjusting the intervals of the plastic positioning pieces 5;

and step 3: the first signal wire 7 penetrates through the corrugated pipe 6, then the corrugated pipe 6 sequentially penetrates through the corrugated pipe positioning holes 504 on the plastic positioning pieces 5, and the distance between the plastic positioning pieces 5 is adjusted again;

and 4, step 4: fixing a connecting part 11 on the far end surface of the anchor rod 3 through strong glue, bending the far end of the corrugated pipe 6, inserting the smooth section of the far end into the connecting part 11 along an opening 1101 on the connecting part 11, penetrating one end of a first signal wire 7 out of a through hole 1102 on the connecting part to be connected with the far end surface of the anchor rod 3, connecting one end of a second signal wire 8 with the near end of the anchor rod 3, and adjusting the corrugated pipe 6 to be parallel to the anchor rod 3 to form the anchor rod monitoring device;

and 5: the installed anchor rod monitoring device is slowly inserted into the drill hole 2, grout 4 is injected, the first signal line 7 is isolated from the grout 4 by the corrugated pipe 6, after the grout 4 is solidified, the anchor rod 3 and the corrugated pipe 6 can deform along with the deformation of the surrounding rock 1, but the first signal line 7 in the corrugated pipe 6 is in an unstressed state, and the first signal line 7 cannot be broken when the surrounding rock 1 deforms;

step 6: after the slurry 4 is solidified, the other ends of the first signal line 7 and the second signal line 8 are respectively connected with the negative electrode and the positive electrode of a universal meter 9, whether the circuits are communicated or not is detected, and whether the elements are installed and live or not is judged; after the circuit is detected to be normal, measuring the initial resistance value of the circuit;

and 7: after the group of anchor rod monitoring devices are installed, repeating the steps 1-7 to install and test the next group of anchor rods 3;

and 8: the signal lines of a plurality of groups of anchor rods 3 are connected to a signal collector 24 to realize automatic real-time monitoring of signals, a signal transmission unit 25 stores, processes and analyzes data in a signal processing center 26 collected by the signal collector and the signal processing center 26 to obtain a conclusion.

The anchor rod fracture state monitoring process is as follows:

step 801: firstly, monitoring whether the connection of a signal management system is smooth or not and whether the operation is normal or not, synchronously observing the change of test data, determining that a data acquisition system works normally, and initializing the system to prepare for testing after all the data acquisition systems are normal;

step 802: according to the method for judging the anchor rod state, as the anchor rod 3 enters the working state, the anchor rod 3 can be stretched along with the deformation of the surrounding rock 1, the resistance value of the anchor rod 3 can be increased, if the stress of the anchor rod 3 exceeds the strength of the anchor rod, one or more parts inside the anchor rod 3 are broken 10, the resistance value of the anchor rod 3 can be greatly increased and even reaches infinity, and whether the anchor rod 3 is broken or not can be judged by measuring the resistance value of the anchor rod 3;

step 803: judging and alarming the state of the anchor rod 3, storing, processing and analyzing the data in real time by the signal processing center 26, and when the monitored change rate of the resistance of the anchor rod 3 exceeds a warning threshold value, indicating that the anchor rod 3 is rapidly stretched and deformed and is damaged, sending an early warning signal by the signal processing center 26; when the resistance of the anchor rod reaches the fracture resistance threshold value, it is judged that one or more parts of the anchor rod 3 are broken, and an anchor rod damage alarm signal is sent out by the signal processing center 26.

The device is improved on the basis of the existing various metal rock anchor rods, has simple improved structure and easy manufacture, and can be conveniently applied to various anchor rods. The working principle is clear, the operation is simple and convenient, the specific anchor rod can be monitored, and the test result is clear and understandable. The output signals are electric signals and are easy to transmit and receive. A data collection system can be established to automatically monitor and collect signals, and monitoring automation is realized. The monitoring system can monitor the fracture state of the anchor rod in real time, give early warning to the anchor rod which is likely to be damaged, and give a report to the anchor rod which is damaged. And guarantee is provided for the stability of the surrounding rock.

The above description is only for the purpose of illustrating the technical solutions of the present invention and not for the purpose of limiting the same, and other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention should be covered within the scope of the claims of the present invention without departing from the spirit and scope of the technical solutions of the present invention.