Method for measuring loosening damage of anchoring interface of anchor rod in roadway circulating tunneling disturbance process

Abstract

The invention discloses a method for measuring loosening damage of an anchoring interface of an anchor rod in a roadway circulating tunneling disturbance process. A test drill hole is constructed in a top plate of a to-be-supported area; a tunneling vibration sensor is installed in the test drill hole; in the tunneling operation process, a tunneling vibration sensor is used for collecting vibration signals and storing the vibration signals; receiving and storing the vibration signal by using a wireless collector; receiving the vibration signal by using an industrial computer and analyzing and processing the vibration signal to obtain vibration excitation data; a steel pipe full-anchor test piece is manufactured under the laboratory condition; a low-frequency vibration simulation test system is adopted, vibration excitation is carried out on a steel pipe full-anchor test piece according to vibration excitation data, then an electro-hydraulic servo mechanical test system is used for carrying out a drawing test, drawing stress, displacement data and acoustic emission monitoring data in the drawing test process are integrated, and finally the loosening damage rule of the anchoring interface of the anchor rod is obtained through analysis. The method is accurate in monitoring and analysis result, and the loosening damage rule of the anchoring interface of the anchor rod can be accurately and effectively analyzed.

Description

Technical Field

[0001] The invention belongs to the technical field of intelligent mine safety monitoring, and specifically is a method for measuring the loosening damage of the anchoring interface of the anchor rod during the cyclic excavation disturbance of the tunnel. Background Art

[0002] Tunnel deformation begins in the excavation process and is caused by multiple disturbances during tunneling. The disturbance caused by head-on cyclic tunneling is the leading cause of initial damage and later instability of the anchoring system. The essence of this cyclic tunneling disturbance is the periodic loading and unloading of adjacent anchor bodies, which causes micro-cracks and small deformations in the anchoring system. These micro-cracks and small deformations will gradually evolve, which will have a significant impact on the long-term bearing capacity of the tunnel and become a major threat to mine safety production. Therefore, it is very important to clearly understand the loosening and damage law characteristics of the anchoring interface of the anchor rod during the head-on cyclic tunneling of the tunnel. This can not only help us understand and recognize the disturbance intensity of cyclic tunneling on the anchoring system, but also provide clear engineering guidance for strengthening and reinforcing support, which has important scientific significance and theoretical value.

[0003] At present, based on the application of engineering sites and related theoretical research, there are relatively few studies on the disturbance of the anchor bolt anchoring system caused by the head-on cyclic excavation of the tunnel. This disturbance is the leading cause of the progressive rupture and failure of the anchoring system and the deformation and instability of the surrounding rock. At the same time, there is a lack of effective monitoring methods and professional equipment for this disturbance at the engineering site. The existing mine pressure monitoring content during tunnel excavation mainly includes the surface displacement of the surrounding rock, the crack delamination of the rock mass inside the surrounding rock, and the working resistance of the anchor bolt cable. These conventional monitoring contents and equipment are difficult to accurately monitor and judge the loosening and damage laws of the anchor bolt anchoring interface, so they cannot provide effective guidance for the targeted strengthening of anchor bolt support in the cyclic excavation disturbance area. For this reason, it is urgent to provide an intelligent method for measuring the loosening and damage of the anchor bolt anchoring interface during the cyclic excavation disturbance of the tunnel, so as to provide a more solid guarantee for the safe production operation of the mine. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for determining the loosening damage of the anchor rod anchoring interface during the cyclic excavation disturbance of the tunnel. The method has accurate monitoring and analysis results, and can accurately and effectively analyze the loosening damage law of the anchor rod anchoring interface. It can provide strong support for accurately grasping the damage characteristics of the anchor rod anchoring system during the head-on cyclic excavation disturbance of the tunnel, and provides a reliable technical means for comprehensively comparing and analyzing the impact of cyclic excavation disturbance on rock masses in different layers, and has good application value.

[0005] In order to achieve the above-mentioned purpose, the present invention provides a method for determining the loosening damage of the anchor rod anchoring interface during the excavation disturbance process, adopting an intelligent monitoring system, the intelligent monitoring system includes an excavation vibration sensor and a wireless collector, the excavation vibration sensor includes a supporting steel pipe, an intelligent sensing module and a vibration signal pickup; the supporting steel pipe is divided into a free section, a sensing section and an anchoring section from the head end to the tail end, and a plurality of wire holes connected to the inner cavity of the supporting steel pipe are sequentially opened at intervals in the length direction of the sensing section; the intelligent sensing module includes a shell, a microprocessor, a storage module 1, a wireless communication module 1 and a power supply module 1; the shell is a box-type structure, and its top plate is fixedly installed on the head end of the supporting steel pipe, and a connecting hole connected to the inner cavity of the supporting steel pipe is opened on the top plate of the shell, and a signal transmission channel is opened on the bottom plate of the shell; the wireless communication module 1, the microprocessor The device, storage module one and power module one are all installed inside the shell; the microprocessor is connected to storage module one, wireless communication module one and power module one respectively; the number of the vibration signal pickers is multiple, and the multiple vibration signal pickers are fixedly installed on the pipe body of the supporting steel pipe in sequence and at intervals along the length direction of the sensing section, and the wires connected thereto are respectively penetrated into the interior of the supporting steel pipe through multiple wire holes, and are connected to the microprocessor after passing through the connecting hole; the wireless collector includes a casing, a wireless communication module two, a data processing module, a storage module two and a power module two; the wireless communication module two, the data processing module, the storage module two and the power module two are all installed in the inner cavity of the casing, and the wireless communication module two is connected to the wireless communication module one by wireless communication; the data processing module is respectively connected to the wireless communication module two, the storage module two and the power module two;

[0006] The method for determining the loosening damage of the anchor bolt anchoring interface during the excavation disturbance process includes the following steps:

[0007] Step 1: During the tunneling operation of the tunneling equipment, a test borehole is constructed on the top plate of the tunneling head near the tunneling head support area behind the tunneling head;

[0008] Step 2: Prepare an excavation vibration sensor that matches the size of the test borehole, wrap the resin anchoring agent in the anchoring section of the supporting steel pipe, and then place the anchoring section of the supporting steel pipe and the resin anchoring agent at the bottom of the test borehole. At the same time, make multiple vibration signal pickups correspondingly distributed within the height L2 range of the anchoring bonding section of the anchor rod anchored in the top plate, so that the shell is exposed outside the hole. After the resin anchoring agent solidifies, fix the excavation vibration sensor firmly in the test borehole;

[0009] Step 3: After the tunneling vibration sensor is installed, the tunneling operation begins. During the tunneling operation, the distance L from the tunneling vibration sensor to the tunneling head gradually increases. During the period when the tunneling head is within the tunneling disturbance sensing range of the tunneling vibration sensor, each tunneling will cause cyclic loading and unloading, and a cyclic vibration signal will be generated. Multiple vibration signal pickers are used to collect the cyclic vibration signal transmitted from the coal and rock mass to the supporting steel pipe body in real time, and send it to the microprocessor. After receiving the cyclic vibration signal, the microprocessor adds a time stamp to the cyclic vibration signal to form a time-series cyclic vibration signal with a time stamp, and sends the time-series cyclic vibration signal to the storage module 1 for storage;

[0010] The above process of collecting cyclic vibration signals is continued until the distance L between the tunneling vibration sensor and the tunneling head exceeds the sensing critical distance value, and the tunneling head is no longer within the sensing range of the tunneling vibration sensor, and the operation of collecting cyclic vibration signals is completed;

[0011] Step 4: Perform underground signal collection operations at the location of the tunneling vibration sensor by manually holding a wireless collector, and establish a wireless communication link between the wireless communication module 2 and the wireless communication module 1 within the effective transmission distance of the wireless signal. After the wireless communication link is established, the microprocessor reads the timing cycle vibration signal in the storage module 1 and sends it to the data processing module through the wireless communication link. After receiving the timing cycle vibration signal, the data processing module stores it in the storage module 2;

[0012] Step 5: After completing the downhole signal collection operation, the wireless collector is moved to the ground, and then a communication link is established between the wireless collector and the industrial computer by wireless communication. After the communication link is established, the wireless collector reads the timing cycle vibration signal in the storage module 2 and sends it to the industrial computer through the communication link. The industrial computer analyzes and processes the timing cycle vibration signal to obtain vibration frequency and vibration amplitude data, and uses the data as vibration excitation data. At the same time, the vibration excitation data is stored in the vibration signal database;

[0013] Step 6: Under laboratory conditions, use seamless steel pipes, ordinary steel pipes, vaseline, mortar concrete, left-handed threaded steel anchor rods commonly used in coal mines, and resin anchoring agents to make steel pipe full-anchor test pieces;

[0014] S61: prepare a seamless steel pipe with a length of 200-400 mm, an outer diameter of 50-55 mm, an inner diameter of 40-45 mm, and one end open and the other end closed; prepare an ordinary steel pipe with an outer diameter of 30 mm and a length of 300-550 mm, and apply vaseline on the outer wall of the ordinary steel pipe, then insert the ordinary steel pipe into the seamless steel pipe in the center, and expose the outer end of the ordinary steel pipe to the outside of the open end of the seamless steel pipe;

[0015] S62: According to the lithology of the rock mass within the height L2 of the anchoring bonding section of the anchor rod in the top plate, a similar ratio is used to formulate mortar concrete to simulate the lithology of the rock mass within the L2 range, and the mortar concrete is poured into the annular gap between the ordinary steel pipe and the seamless steel pipe, and cured for 28 days;

[0016] S63: The ordinary steel pipe is pulled out, that is, a mortar ring with a thickness of 10 to 15 mm and a test hole with a diameter of 30 mm are formed in the inner cavity of the seamless steel pipe;

[0017] S64: placing the resin anchoring agent and the left-hand threaded steel anchor rod with a length of 300 to 500 mm and a diameter of 22 mm in the test hole in turn to complete the production of the steel pipe full anchor test piece;

[0018] Step seven: Use a low-frequency vibration simulation test system, and perform vibration excitation on the prepared steel pipe full-anchor specimen according to the vibration excitation data in the vibration signal database. Then use the electro-hydraulic servo mechanical test system to perform a pull-out test on the steel pipe full-anchor specimen. Combine the pull-out stress and displacement data during the pull-out experiment and the acoustic emission monitoring data obtained by the acoustic emission monitoring system to obtain the anchor force change, rod wall relative displacement and rupture information of the steel pipe full-anchor specimen. Compare and analyze the weakening law of the bonding strength caused by the amplitude and vibration frequency, and then clarify the loosening damage characteristics of the bonding interface between the inner and outer rings of the anchor. According to the experimental test results, the loosening damage law of the anchor interface is analyzed.

[0019] Furthermore, in order to ensure a reliable connection between the shell and the supporting steel pipe, the shell is connected to the head end of the supporting steel pipe by welding.

[0020] As a preferred embodiment, the distance between two adjacent vibration signal pickups is 50 to 200 mm.

[0021] As a preference, in step three, the critical sensing distance value is 60-100 m.

[0022] Preferably, in step 2, the length of the supporting steel pipe is 300-600 mm longer than the anchor rod anchored in the top plate, and the diameter of the supporting steel pipe is 30-60 mm; the length of the vibration signal sensor is 30-60 mm, and the width is 20-40 mm.

[0023] Furthermore, in order to facilitate and smoothly install the excavation vibration sensor in the test borehole, in step 2, the length of the test borehole is adapted to the length of the supporting steel pipe, and its aperture is 6 to 10 mm larger than the sum of the diameter of the supporting steel pipe and the width of the vibration signal pickup.

[0024] The present invention adopts an intelligent monitoring system. For the intelligent monitoring system, by setting an anchoring section at the end of the supporting steel pipe, the end of the supporting steel pipe can be firmly fixed to the bottom of the borehole by using an anchoring agent during the installation process, thereby ensuring that the vibration signal can be obtained more stably during the continuous monitoring process. A plurality of vibration signal sensors are installed in sequence and at intervals in the length direction of the sensing section of the supporting steel pipe, which can effectively adapt to the sensing and picking requirements of rock strata at different levels within the length range of the sensing section for the head-on cycle excavation vibration signal, so that only one excavation vibration sensor is needed to simultaneously obtain the vibration signals of multiple rock strata at different levels. A plurality of wire holes are opened in sequence along the length direction on the sensing section of the supporting steel pipe, which can facilitate the wires connected to the plurality of vibration signal sensors to smoothly penetrate the interior of the pipe body and extend to the head end of the pipe body, so that it can be convenient to connect with the intelligent sensing module located at the head end of the pipe body. At the same time, this arrangement method is conducive to protecting the wires, thereby preventing the wires from being damaged by scratches from foreign objects, thereby ensuring the reliable reception of vibration signals. By setting the power module one, a stable supply of electricity can be provided for the excavation vibration sensor, so that it has the ability to work offline, and there is no need to lay a power supply line specifically for the excavation vibration sensor. The shell is fixedly installed at the head end of the supporting steel pipe. After the supporting steel pipe is installed in the borehole, the shell can be exposed to the outside of the hole, thereby ensuring the reliable transmission of the wireless signal. By setting a microprocessor in the intelligent sensing module, the intelligent sensing module can have a certain data processing capability. When receiving the vibration signal transmitted by the vibration signal sensor, the microprocessor can add a timestamp to it, thereby forming a time-series cyclic vibration signal with a timestamp. By setting the storage module one, it is convenient to store and read data. In this way, the microprocessor can not only conveniently store the processed data in the storage module one, but also conveniently read the data from the storage module one after the wireless communication link is established, and send it to the wireless collector through the wireless communication link. By setting the wireless communication module 1 in the intelligent sensing module and setting the wireless communication module 2 in the wireless collector, it is possible to form a wireless communication link between the excavation vibration sensor and the wireless collector through the wireless connection between the wireless communication module 1 and the wireless communication module 2, thereby ensuring reliable data transmission between the two. By setting the power module 2, the wireless collector can be supplied with electricity, thereby enabling the wireless collector to work offline, thereby improving the convenience of carrying. By setting the data processing module, the received data can be processed easily, and at the same time, it can be easy to realize interactive communication with the industrial computer, and then the received data can be sent to the industrial computer.The intelligent monitoring system has a high degree of integration and automation, and its monitoring results are accurate. Through the cooperation of excavation vibration sensors and wireless collectors, it can realize the simultaneous monitoring and collection of vibration signals of rock masses in different layers within the height range of the anchor bolt bonding section during excavation operations, providing reliable technical support for subsequent test processes under laboratory conditions.

[0025] The method of measuring the loosening and damage of the anchor bolt anchoring interface during the cyclic excavation disturbance of the tunnel in the present invention is applicable to the field of geotechnical engineering or shaft and tunnel engineering. First, during the tunnel excavation process, a hole is drilled in the top plate construction immediately behind the tunnel head and a tunneling vibration sensor is installed. As the head continues to cyclically excavate forward, the tunneling vibration sensor will sense and receive the vibration signal of each cyclic excavation disturbance until the distance from the tunneling vibration sensor to the head exceeds a certain critical value, that is, the tunneling vibration sensor is no longer within the cyclic excavation disturbance range of the head. Then, the vibration signal data sensed and stored by the tunneling vibration sensor is collected by a wireless collector, and then the vibration signal data is sent to an industrial computer on the ground, so that the industrial computer obtains the vibration excitation data required for the subsequent low-frequency vibration simulation test based on the vibration signal data. The vibration excitation data is derived from the real operation process, and can effectively ensure the authenticity of the simulation effect in the subsequent simulation test. In the laboratory, the steel pipe full anchor specimens are made of seamless steel pipes, ordinary steel pipes, vaseline, mortar concrete, left-handed threaded steel anchors commonly used in coal mines, and resin anchors, which can effectively reduce the test cost. At the same time, it can be convenient to effectively simulate the anchor bolt anchoring interface in the real environment, which is conducive to completing the loosening damage simulation test of the anchor bolt anchoring interface in a low-cost and safer way under laboratory conditions. For the steel pipe full anchor specimen, a low-frequency vibration simulation test system is used, and vibration excitation is performed with reference to the vibration excitation data collected on site. After that, the pull-out test is performed using the electro-hydraulic servo mechanical test system. Further comprehensive experimental data such as stress, displacement and acoustic emission monitoring can be used to analyze the weakening law of the bonding strength of the anchor system by amplitude and vibration frequency, so as to clarify the loosening damage characteristics of the anchor bolt anchoring interface during the cyclic excavation disturbance process, and ensure the accuracy of the obtained damage characteristics.

[0026] This method combines on-site collection of vibration signals, preparation of steel pipe full-anchor specimens under laboratory conditions, vibration excitation using a low-frequency vibration simulation test system, pull-out testing using an electro-hydraulic servo mechanical test system, and acoustic emission monitoring using an acoustic emission monitoring system. The entire implementation process has a high degree of automation, which effectively reduces dependence on manual labor and reduces labor intensity. The monitoring and analysis results of this method are accurate, and can accurately and effectively analyze the loosening and damage laws of the anchor bolt anchoring interface. It can provide strong support for accurately grasping the damage characteristics of the anchor bolt anchoring system during the head-on cyclic excavation disturbance of the tunnel, and provides a reliable technical means for the overall comparative analysis of the impact of cyclic excavation disturbance on rock masses in different layers, and has good application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the present invention for measuring the loosening damage of the anchoring interface of the anchor bolt during the head-on cyclic excavation disturbance process;

[0028] Figure 2 It is a structural schematic diagram of the excavation vibration sensor in the present invention;

[0029] Figure 3 It is a structural schematic diagram of the wireless collector in the present invention;

[0030] Figure 4 It is a principle block diagram of the system part in the present invention.

[0031] In the figure: 1. Tunnel; 2. Excavation equipment; 3. Excavation head; 4. Roof; 5. Anchor rod; 6. Test borehole; 7. Resin anchor; 8. Excavation vibration sensor; 8-1. Support steel pipe; 8-2. Vibration signal pickup; 8-3. Wire; 8-4. Intelligent sensing module; 8-5. Shell; 9. Wireless collector; 9-1. Data processing module; 9-2. Storage module 2; 9-3. Wireless communication module 2; 9-4. Casing. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings.

[0033] like Figures 1 to 4As shown, the present invention provides a method for determining the loosening damage of the anchoring interface of the anchor rod during the excavation disturbance, adopting an intelligent monitoring system, the intelligent monitoring system includes an excavation vibration sensor 8 and a wireless collector 9, the excavation vibration sensor 8 includes a supporting steel pipe 8-1, an intelligent sensing module 8-4 and a vibration signal pickup 8-2; the supporting steel pipe 8-1 is divided into a free section, a sensing section and an anchoring section from the head end to the tail end, and a plurality of wire holes connected to the inner cavity of the supporting steel pipe 8-1 are sequentially opened in the length direction of the sensing section; the intelligent sensing module 8-4 includes a shell 8-5, a microprocessor, a storage module 1, a wireless communication module 1 and a power supply module 1; the shell 8-5 is a box-type structure, and its top plate is fixedly installed on the head end of the supporting steel pipe 8-1, and a connecting hole connected to the inner cavity of the supporting steel pipe 8-1 is opened on the top plate of the shell 8-5, and a signal transmission channel is opened on the bottom plate of the shell 8-5; the wireless communication module 1, the microprocessor, the storage module 1 and the power supply module 1 Blocks one are installed inside the shell 8-5; the microprocessor is connected to the storage module one, the wireless communication module one and the power module one respectively; the number of the vibration signal pickers 8-2 is multiple, and the multiple vibration signal pickers 8-2 are fixedly installed on the tube body of the supporting steel pipe 8-1 in sequence and at intervals along the length direction of the sensing section, and the wires 8-3 connected thereto are respectively penetrated into the interior of the supporting steel pipe 8-1 through multiple wire holes, and are connected to the microprocessor after passing through the connecting holes; the wireless collector 9 includes a housing 9-4, a wireless communication module two 9-3, a data processing module 9-1, a storage module two 9-2 and a power module two; the wireless communication module two 9-3, the data processing module 9-1, the storage module two 9-2 and the power module two are all installed in the inner cavity of the housing 9-4, and the wireless communication module two 9-3 is connected to the wireless communication module one by wireless communication; the data processing module 9-1 is respectively connected to the wireless communication module two 9-3, the storage module two 9-2 and the power module two;

[0034] The method for determining the loosening damage of the anchor bolt anchoring interface during the excavation disturbance process includes the following steps:

[0035] Step 1: During the excavation operation of the excavation equipment 2 in the tunnel 1, a test borehole 6 is constructed on the top plate 4 behind the excavation head 3 and close to the area to be supported by the excavation head 3;

[0036] Step 2: Prepare a tunneling vibration sensor 8 that matches the size of the test borehole 6, wrap the resin anchor 7 in the anchor section of the support steel pipe 8-1, and then place the anchor section of the support steel pipe 8-1 and the resin anchor 7 together at the bottom of the test borehole 6. At the same time, make multiple vibration signal pick-ups 8-2 correspondingly distributed within the height L2 range of the anchor bonding section of the anchor rod 5 anchored in the top plate 4, such as Figure 1As shown, the height L1 is the height of the unbonded section, so that the housing 8-5 is exposed outside the hole, and after the resin anchor 7 solidifies, the excavation vibration sensor 8 is firmly fixed in the test borehole 6;

[0037] As a preference, the number of vibration signal pickers 8-2 may be two, three, four, five or more, so as to meet the requirements of sensing and picking up vibration signals of head-on cyclic tunneling in rock masses of different layers within the height L2 range.

[0038] Step 3: After the excavation vibration sensor 8 is installed, the excavation operation begins. During the excavation operation, the distance L between the excavation vibration sensor 8 and the excavation head 3 gradually increases. During the period when the excavation head 3 is within the excavation disturbance sensing range of the excavation vibration sensor 8, each excavation will cause cyclic loading and unloading, and a cyclic vibration signal will be generated. The cyclic vibration signal transmitted from the coal and rock mass to the pipe body of the supporting steel pipe 8-1 is collected in real time by multiple vibration signal pickers 8-2 simultaneously, and sent to the microprocessor. After receiving the cyclic vibration signal, the microprocessor adds a time stamp to the cyclic vibration signal to form a time-series cyclic vibration signal with a time stamp, and sends the time-series cyclic vibration signal to the storage module 1 for storage;

[0039] The above process of collecting cyclic vibration signals is continued until the distance L between the tunneling vibration sensor 8 and the tunneling head 3 exceeds the sensing critical distance value, and the tunneling head 3 is no longer within the sensing range of the tunneling vibration sensor 8, and the operation of collecting cyclic vibration signals is completed;

[0040] Step 4: Perform underground signal collection operations at the location of the tunneling vibration sensor 8 by manually holding the wireless collector 9. A wireless communication link is established between the wireless communication module 2 9-3 and the wireless communication module 1 within the effective transmission distance of the wireless signal. After the wireless communication link is established, the microprocessor reads the timing cycle vibration signal in the storage module 1 and sends it to the data processing module 9-1 through the wireless communication link. After receiving the timing cycle vibration signal, the data processing module 9-1 stores it in the storage module 2 9-2;

[0041] Step 5: After completing the downhole signal acquisition operation, the wireless collector 9 is moved to the ground, and then a communication link is established between the wireless collector 9 and the industrial computer by wireless communication. After the communication link is established, the wireless collector 9 reads the timing cycle vibration signal in the storage module 2 9-2 and sends it to the industrial computer through the communication link. The industrial computer analyzes and processes the timing cycle vibration signal to obtain vibration frequency and vibration amplitude data, and uses the data as vibration excitation data. At the same time, the vibration excitation data is stored in the vibration signal database;

[0042] Step 6: Under laboratory conditions, use seamless steel pipes, ordinary steel pipes, vaseline, mortar concrete, left-handed threaded steel anchor rods commonly used in coal mines, and resin anchoring agents to make steel pipe full-anchor test pieces;

[0043] S61: prepare a seamless steel pipe with a length of 200-400 mm, an outer diameter of 50-55 mm, an inner diameter of 40-45 mm, and one end open and the other end closed; prepare an ordinary steel pipe with an outer diameter of 30 mm and a length of 300-550 mm, and apply vaseline on the outer wall of the ordinary steel pipe, then insert the ordinary steel pipe into the seamless steel pipe in the center, and expose the outer end of the ordinary steel pipe to the outside of the open end of the seamless steel pipe;

[0044] The length of the ordinary steel pipe is 300-550 mm, which can ensure that the length of the exposed section is 100-150 mm, and can facilitate the subsequent pulling-out operation.

[0045] S62: according to the lithology of the rock mass within the height L2 of the anchoring bonding section of the anchor rod 5 in the top plate 4, a similar ratio is used to prepare mortar concrete to simulate the lithology of the rock mass within the L2 range, and the mortar concrete is poured into the annular gap between the ordinary steel pipe and the seamless steel pipe, and cured for 28 days;

[0046] S63: Pull out the ordinary steel pipe, that is, form a mortar ring with a thickness of 10 to 15 mm and a test hole with a diameter of 30 mm in the inner cavity of the seamless steel pipe; wherein the mortar ring is used to simulate the rock mass within the height L2 of the anchoring bonding section.

[0047] S64: Place the resin anchor and the left-handed threaded steel anchor rod with a length of 300-500 and a diameter of 22mm in the test hole in turn to complete the production of the steel pipe full-anchor test piece; the length of the left-handed threaded steel anchor rod is 300-500, which can ensure that the length of the exposed section is 100-150mm, so that it is convenient for subsequent pull-out tests.

[0048] Step seven: Use a low-frequency vibration simulation test system, and perform vibration excitation on the prepared steel pipe full-anchor specimen according to the vibration excitation data in the vibration signal database. Then use the electro-hydraulic servo mechanical test system to perform a pull-out test on the steel pipe full-anchor specimen. Combine the pull-out stress and displacement data during the pull-out experiment and the acoustic emission monitoring data obtained by the acoustic emission monitoring system to obtain the anchor force change, rod wall relative displacement and rupture information of the steel pipe full-anchor specimen. Compare and analyze the weakening law of the bonding strength caused by the amplitude and vibration frequency, and then clarify the loosening damage characteristics of the bonding interface between the inner and outer rings of the anchor. According to the experimental test results, the loosening damage law of the anchor interface is analyzed.

[0049] In order to ensure a reliable connection between the shell and the supporting steel pipe, the shell 8-5 is connected to the head end of the supporting steel pipe 8-1 by welding.

[0050] As a preferred embodiment, the distance between two adjacent vibration signal pickups 8 - 2 is 50 to 200 mm.

[0051] As a preference, in step three, the critical sensing distance value is 60-100 m.

[0052] As a preference, in step 2, the length of the support steel pipe 8-1 is 300 to 600 mm longer than the anchor rod 5 anchored in the top plate 4, and the diameter of the support steel pipe 8-1 is 30 to 60 mm; the length of the vibration signal sensor 8-2 is 30 to 60 mm, and the width is 20 to 40 mm.

[0053] In order to conveniently and smoothly install the excavation vibration sensor 8 in the test borehole 6, in step 2, the length of the test borehole 6 is adapted to the length of the support steel pipe 8-1, and its aperture is 6 to 10 mm larger than the sum of the diameter of the support steel pipe 8-1 and the width of the vibration signal pickup 8-2.

[0054] The present invention adopts an intelligent monitoring system. For the intelligent monitoring system, by setting an anchoring section at the end of the supporting steel pipe, the end of the supporting steel pipe can be firmly fixed to the bottom of the borehole by using an anchoring agent during the installation process, thereby ensuring that the vibration signal can be obtained more stably during the continuous monitoring process. A plurality of vibration signal sensors are installed in sequence and at intervals in the length direction of the sensing section of the supporting steel pipe, which can effectively adapt to the sensing and picking requirements of rock strata at different levels within the length range of the sensing section for the head-on cycle excavation vibration signal, so that only one excavation vibration sensor is needed to simultaneously obtain the vibration signals of multiple rock strata at different levels. A plurality of wire holes are opened in sequence along the length direction on the sensing section of the supporting steel pipe, which can facilitate the wires connected to the plurality of vibration signal sensors to smoothly penetrate the interior of the pipe body and extend to the head end of the pipe body, so that it can be convenient to connect with the intelligent sensing module located at the head end of the pipe body. At the same time, this arrangement method is conducive to protecting the wires, thereby preventing the wires from being damaged by scratches from foreign objects, thereby ensuring the reliable reception of vibration signals. By setting the power module one, a stable supply of electricity can be provided for the excavation vibration sensor, so that it has the ability to work offline, and there is no need to lay a power supply line specifically for the excavation vibration sensor. The shell is fixedly installed at the head end of the supporting steel pipe. After the supporting steel pipe is installed in the borehole, the shell can be exposed to the outside of the hole, thereby ensuring the reliable transmission of the wireless signal. By setting a microprocessor in the intelligent sensing module, the intelligent sensing module can have a certain data processing capability. When receiving the vibration signal transmitted by the vibration signal sensor, the microprocessor can add a timestamp to it, thereby forming a time-series cyclic vibration signal with a timestamp. By setting the storage module one, it is convenient to store and read data. In this way, the microprocessor can not only conveniently store the processed data in the storage module one, but also conveniently read the data from the storage module one after the wireless communication link is established, and send it to the wireless collector through the wireless communication link. By setting the wireless communication module 1 in the intelligent sensing module and setting the wireless communication module 2 in the wireless collector, it is possible to form a wireless communication link between the excavation vibration sensor and the wireless collector through the wireless connection between the wireless communication module 1 and the wireless communication module 2, thereby ensuring reliable data transmission between the two. By setting the power module 2, the wireless collector can be supplied with electricity, thereby enabling the wireless collector to work offline, thereby improving the convenience of carrying. By setting the data processing module, the received data can be processed easily, and at the same time, it can be easy to realize interactive communication with the industrial computer, and then the received data can be sent to the industrial computer.The intelligent monitoring system has a high degree of integration and automation, and its monitoring results are accurate. Through the cooperation of excavation vibration sensors and wireless collectors, it can realize the simultaneous monitoring and collection of vibration signals of rock masses in different layers within the height range of the anchor bolt bonding section during excavation operations, providing reliable technical support for subsequent test processes under laboratory conditions.

[0055] The method of measuring the loosening and damage of the anchor bolt anchoring interface during the cyclic excavation disturbance of the tunnel in the present invention is applicable to the field of geotechnical engineering or shaft and tunnel engineering. First, during the tunnel excavation process, a hole is drilled in the top plate construction immediately behind the tunnel head and a tunneling vibration sensor is installed. As the head continues to cyclically excavate forward, the tunneling vibration sensor will sense and receive the vibration signal of each cyclic excavation disturbance until the distance from the tunneling vibration sensor to the head exceeds a certain critical value, that is, the tunneling vibration sensor is no longer within the cyclic excavation disturbance range of the head. Then, the vibration signal data sensed and stored by the tunneling vibration sensor is collected by a wireless collector, and then the vibration signal data is sent to an industrial computer on the ground, so that the industrial computer obtains the vibration excitation data required for the subsequent low-frequency vibration simulation test based on the vibration signal data. The vibration excitation data is derived from the real operation process, and can effectively ensure the authenticity of the simulation effect in the subsequent simulation test. In the laboratory, the steel pipe full anchor specimens are made of seamless steel pipes, ordinary steel pipes, vaseline, mortar concrete, left-handed threaded steel anchors commonly used in coal mines, and resin anchors, which can effectively reduce the test cost. At the same time, it can be convenient to effectively simulate the anchor bolt anchoring interface in the real environment, which is conducive to completing the loosening damage simulation test of the anchor bolt anchoring interface in a low-cost and safer way under laboratory conditions. For the steel pipe full anchor specimen, a low-frequency vibration simulation test system is used, and vibration excitation is performed with reference to the vibration excitation data collected on site. After that, the pull-out test is performed using the electro-hydraulic servo mechanical test system. Further comprehensive experimental data such as stress, displacement and acoustic emission monitoring can be used to analyze the weakening law of the bonding strength of the anchor system by amplitude and vibration frequency, so as to clarify the loosening damage characteristics of the anchor bolt anchoring interface during the cyclic excavation disturbance process, and ensure the accuracy of the obtained damage characteristics.

[0056] This method combines on-site collection of vibration signals, preparation of steel pipe full-anchor specimens under laboratory conditions, vibration excitation using a low-frequency vibration simulation test system, pull-out testing using an electro-hydraulic servo mechanical test system, and acoustic emission monitoring using an acoustic emission monitoring system. The entire implementation process has a high degree of automation, which effectively reduces dependence on manual labor and reduces labor intensity. The monitoring and analysis results of this method are accurate, and can accurately and effectively analyze the loosening and damage laws of the anchor bolt anchoring interface. It can provide strong support for accurately grasping the damage characteristics of the anchor bolt anchoring system during the head-on cyclic excavation disturbance of the tunnel, and provides a reliable technical means for the overall comparative analysis of the impact of cyclic excavation disturbance on rock masses in different layers, and has good application value.

Claims

1. A method for determining the loosening damage of the anchoring interface of an anchor rod during a tunneling disturbance, using an intelligent monitoring system, the intelligent monitoring system comprising a tunneling vibration sensor (8) and a wireless collector (9), the tunneling vibration sensor (8) comprising a supporting steel pipe (8-1), an intelligent sensing module (8-4) and a vibration signal pick-up (8-2); the supporting steel pipe (8-1) is divided into a free section, a sensing section and an anchoring section from the head end to the tail end, and the sensing section is provided with a plurality of connecting sections connected to the supporting steel pipe (8-1) at intervals in the length direction thereof. ) inner cavity; the intelligent sensing module (8-4) comprises a shell (8-5), a microprocessor, a storage module 1, a wireless communication module 1 and a power module 1; the shell (8-5) is a box-type structure, the top plate of which is fixedly mounted on the head end of the supporting steel pipe (8-1), and a connecting hole communicating with the inner cavity of the supporting steel pipe (8-1) is opened on the top plate of the shell (8-5), and a signal transmission channel is opened on the bottom plate of the shell (8-5); the wireless communication module 1, the microprocessor, the storage module 1 and the power module 1 are all mounted on the shell The microprocessor is connected to a storage module 1, a wireless communication module 1 and a power module 1 respectively; the number of the vibration signal pickers (8-2) is multiple, and the multiple vibration signal pickers (8-2) are fixedly installed on the tube body of the supporting steel tube (8-1) in sequence and at intervals along the length direction of the sensing section, and the wires (8-3) connected thereto are respectively inserted into the interior of the supporting steel tube (8-1) through multiple wire holes, and are connected to the microprocessor after passing through the connecting hole; the wireless collector (9) includes a housing (9-4) , wireless communication module 2 (9-3), data processing module (9-1), storage module 2 (9-2) and power module 2; the wireless communication module 2 (9-3), data processing module (9-1), storage module 2 (9-2) and power module 2 are all installed in the inner cavity of the housing (9-4), and the wireless communication module 2 (9-3) is connected to the wireless communication module 1 by wireless communication; the data processing module (9-1) is respectively connected to the wireless communication module 2 (9-3), storage module 2 (9-2) and power module 2; It is characterized by: The method for determining the loosening damage of the anchor bolt anchoring interface during the excavation disturbance process includes the following steps: Step 1: During the excavation operation of the excavation equipment (2) in the tunnel (1), a test borehole (6) is constructed on the top plate (4) behind the excavation head (3) and close to the area to be supported of the excavation head (3); Step 2: prepare an excavation vibration sensor (8) that matches the size of the test borehole (6), wrap the resin anchor (7) in the anchor section of the support steel pipe (8-1), and then place the anchor section of the support steel pipe (8-1) and the resin anchor (7) together at the bottom of the test borehole (6). At the same time, make a plurality of vibration signal pick-ups (8-2) correspondingly distributed within the height L2 range of the anchor bonding section of the anchor rod (5) anchored in the top plate (4), so that the shell (8-5) is exposed outside the hole. After the resin anchor (7) solidifies, the excavation vibration sensor (8) is firmly fixed in the test borehole (6); Step 3: After the tunneling vibration sensor (8) is installed, the tunneling operation begins. During the tunneling operation, the distance L between the tunneling vibration sensor (8) and the tunneling head (3) gradually increases. During the period when the tunneling head (3) is within the tunneling disturbance sensing range of the tunneling vibration sensor (8), each tunneling operation will cause cyclic loading and unloading, and generate a cyclic vibration signal. The cyclic vibration signal transmitted from the coal and rock mass to the pipe body of the supporting steel pipe (8-1) is collected in real time by using multiple vibration signal pickers (8-2) in a synchronous manner, and sent to the microprocessor. After receiving the cyclic vibration signal, the microprocessor adds a time stamp to the cyclic vibration signal to form a time-series cyclic vibration signal with a time stamp, and sends the time-series cyclic vibration signal to the storage module 1 for storage; The above process of collecting cyclic vibration signals is continued until the distance L between the tunneling vibration sensor (8) and the tunneling head (3) exceeds the sensing critical distance value, and the tunneling head (3) is no longer within the sensing range of the tunneling vibration sensor (8), thus completing the operation of collecting cyclic vibration signals; Step 4: Perform underground signal collection operations at the location of the tunneling vibration sensor (8) by manually holding a wireless collector (9), and establish a wireless communication link between the wireless communication module 2 (9-3) and the wireless communication module 1 within the effective transmission distance of the wireless signal. After the wireless communication link is established, the microprocessor reads the timing cycle vibration signal in the storage module 1 and sends it to the data processing module (9-1) through the wireless communication link. After receiving the timing cycle vibration signal, the data processing module (9-1) stores it in the storage module 2 (9-2); Step 5: After the underground signal collection operation is completed, the wireless collector (9) is moved to the surface, and a communication link is established between the wireless collector (9) and the industrial computer by wireless communication. After the communication link is established, the wireless collector (9) reads the time-series cyclic vibration signal in the storage module 2 (9-2) and sends it to the industrial computer through the communication link. The industrial computer analyzes and processes the time-series cyclic vibration signal to obtain vibration frequency and vibration amplitude data, and uses the data as vibration excitation data. At the same time, the vibration excitation data is stored in the vibration signal database; Step 6: Under laboratory conditions, use seamless steel pipes, ordinary steel pipes, vaseline, mortar concrete, left-handed threaded steel anchor rods commonly used in coal mines, and resin anchoring agents to make steel pipe full-anchor test pieces; S61: prepare a seamless steel pipe with a length of 200-400 mm, an outer diameter of 50-55 mm, an inner diameter of 40-45 mm, and one end open and the other end closed; prepare an ordinary steel pipe with an outer diameter of 30 mm and a length of 300-550 mm, and apply vaseline on the outer wall of the ordinary steel pipe, then insert the ordinary steel pipe into the seamless steel pipe in the center, and expose the outer end of the ordinary steel pipe to the outside of the open end of the seamless steel pipe; S62: according to the lithology of the rock mass within the height L2 of the anchoring bonding section of the anchor rod (5) in the top plate (4), a mortar concrete is prepared by using a similar ratio to simulate the lithology of the rock mass within the height L2, and the mortar concrete is poured into the annular gap between the ordinary steel pipe and the seamless steel pipe, and cured for 28 days; S63: The ordinary steel pipe is pulled out, that is, a mortar ring with a thickness of 10 to 15 mm and a test hole with a diameter of 30 mm are formed in the inner cavity of the seamless steel pipe; S64: placing the resin anchoring agent and the left-hand threaded steel anchor rod with a length of 300 to 500 mm and a diameter of 22 mm in the test hole in turn to complete the production of the steel pipe full anchor test piece; Step seven: Use a low-frequency vibration simulation test system, and perform vibration excitation on the prepared steel pipe full-anchor specimen according to the vibration excitation data in the vibration signal database. Then use the electro-hydraulic servo mechanical test system to perform a pull-out test on the steel pipe full-anchor specimen. Combine the pull-out stress and displacement data during the pull-out experiment and the acoustic emission monitoring data obtained by the acoustic emission monitoring system to obtain the anchor force change, rod wall relative displacement and rupture information of the steel pipe full-anchor specimen. Compare and analyze the weakening law of the bonding strength caused by the amplitude and vibration frequency, and then clarify the loosening damage characteristics of the bonding interface between the inner and outer rings of the anchor. According to the experimental test results, the loosening damage law of the anchor interface is analyzed.

2. A method for measuring loosening damage of anchor bolt anchoring interface during cyclic tunneling disturbance according to claim 1, characterized in that: The shell (8-5) is connected to the head end of the supporting steel pipe (8-1) by welding.

3. The method for measuring the loosening damage of the anchor bolt anchoring interface during the cyclic excavation disturbance of the tunnel according to claim 1 is characterized in that: The distance between two adjacent vibration signal pick-ups (8-2) is 50 to 200 mm.

4. The method for measuring the loosening damage of the anchor bolt anchoring interface during the cyclic excavation disturbance of the tunnel according to claim 1 is characterized in that: In step three, the critical sensing distance value is 60-100m.

5. A method for determining loosening damage of anchor bolt anchoring interface during excavation disturbance according to claim 6, characterized in that: In step 2, the length of the support steel pipe (8-1) is 300 to 600 mm longer than the anchor rod (5) anchored in the top plate (4), and the diameter of the support steel pipe (8-1) is 30 to 60 mm; the length of the vibration signal sensor (8-2) is 30 to 60 mm, and the width is 20 to 40 mm.

6. A method for determining loosening damage of anchor bolt anchoring interface during excavation disturbance according to claim 7, characterized in that: In step 2, the length of the test borehole (6) is adapted to the length of the support steel pipe (8-1), and its hole diameter is 6 to 10 mm larger than the sum of the diameter of the support steel pipe (8-1) and the width of the vibration signal pickup (8-2).

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