Automatic pre-tightening method for anchor cable and anchor rod based on acoustic and seismic wave feedback

Abstract

The application relates to the technical field of roadway support, and particularly discloses an automatic pre-tightening method for anchor cables and anchor rods based on acoustic and seismic wave feedback, which comprises an anchoring piece, a sensor array, a control unit, a data acquisition unit and an automatic pre-tightening device, the anchoring piece is connected to surrounding rock, the sensor array is arranged in the anchoring piece body and / or the surrounding rock around the anchoring piece body, the control unit comprises a signal receiver, a processor and a signal generator, the data acquisition unit is electrically connected with the sensor array and the control unit respectively, the output end of the automatic pre-tightening device is arranged on the free section of the anchoring piece, the fixed end of the automatic pre-tightening device is connected to the surrounding rock or abuts against the surrounding rock, the automatic pre-tightening device is electrically connected with the control unit, and the automatic pre-tightening device comprises a micro motor and / or a hydraulic driving device. The application can actively identify crack expansion and automatically adjust the pre-tightening force, thereby reducing safety accidents.

Description

Technical Field

[0001] This invention relates to the field of tunnel support technology, and in particular to an automatic pre-tightening method for anchor cables and anchor bolts based on acoustic and seismic wave feedback. Background Technology

[0002] In environments where the rock strata or surrounding rock are not fractured and prone to displacement, active support methods such as anchor cables and bolts are crucial for stabilizing the surrounding rock. Traditional support methods, such as shotcrete and protective plates, primarily provide passive protection for the surface of the rock mass or surrounding rock, making it difficult to detect and control deep fissures or hidden deformations in a timely manner, resulting in limited support effectiveness. In contrast, active support technologies such as anchor cables and bolts can apply preload to the deep layers of the surrounding rock, thereby inhibiting further loosening or deformation of the surrounding rock and significantly improving the overall stability of roadways or tunnels.

[0003] However, existing anchor cable / anchor bolt pretensioning is typically applied all at once during the initial construction phase, and the prestress value is often based on design and construction experience rather than on a comprehensive analysis of dynamic changes in surrounding rock stress, high-frequency microseismic activity, and seismic waves. As the mining area advances, the rock mass structure evolves, and stress redistributes around the tunnel, the initially applied pretensioning may become insufficient or loose, failing to adapt to the complex stress changes in the surrounding rock throughout its service life. Furthermore, the surrounding rock often contains natural fissures, weak interlayers, or new microcracks that develop during excavation. When these fissures expand or abruptly become unstable under external loads, microseismic or acoustic emission events often occur. Without real-time monitoring and analysis of these micro-fracture signals, geological engineers cannot promptly predict potential instability risks.

[0004] Therefore, although the deployment of anchor cable and anchor bolt combined monitoring systems has begun in major geotechnical engineering projects such as mines and tunnels, the following limitations still exist:

[0005] 1. Limited monitoring methods: Most monitoring methods are limited to timed measurements of displacement and total stress, lacking real-time capture and analysis of microseismic waveforms and acoustic characteristics, and thus failing to quickly detect early signs of rock rupture.

[0006] 2. Pretension force cannot be dynamically adjusted: If the surrounding rock conditions change rapidly, traditional anchoring methods cannot be automated to retension or unload the force. Manual operation is both time-consuming and poses safety hazards.

[0007] 3. Lack of intelligent analysis and early warning: Although some projects have installed acoustic and seismic wave acquisition systems, data processing mostly relies on offline processes or manual observation, and a complete real-time early warning and active control closed loop has not been formed. Summary of the Invention

[0008] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose an automatic pre-tightening system for anchor cables and bolts based on acoustic and seismic wave feedback. This system can actively identify crack propagation and automatically adjust the pre-tightening force, reducing safety accidents.

[0009] The automatic pre-tightening system for anchor cables and bolts based on acoustic and seismic wave feedback according to this invention includes an anchor, a sensor array, a control unit, a data acquisition unit, and an automatic pre-tightening device. The anchor is connected to the surrounding rock. The sensor array is disposed in the anchor body and / or the surrounding rock. The sensor array includes multiple high-speed acoustic emission sensors, multiple micro-vibration pickups, multiple stress sensors, and multiple deformation monitors, used to capture high-frequency micro-vibration waveforms and acoustic characteristics generated when the surrounding rock undergoes micro-crack propagation and energy release. The control unit includes a signal receiver, a processor, and a signal generator. The control unit is disposed in the well. The data acquisition unit is electrically connected to the sensor array and the control unit respectively in the control center or ground monitoring center. The data acquisition unit includes a high-speed acquisition card and / or a downhole data acquisition module. The data acquisition unit is used to perform preliminary filtering and amplification of the electrical signals of the sensor array, and then transmit them to the control unit in real time or periodically. The output end of the automatic pre-tightening device is installed on the free section of the anchor. The fixed end of the automatic pre-tightening device is connected to or abuts against the surrounding rock, and the automatic pre-tightening device is electrically connected to the control unit. The automatic pre-tightening device includes a micro motor and / or a hydraulic drive device.

[0010] The automatic pre-tightening system for anchor cables and bolts based on acoustic and seismic wave feedback of the present invention has at least the following advantages:

[0011] 1. Active crack propagation identification: Early identification is achieved by capturing minute cracks or sudden load changes in the surrounding rock through acoustic and microseismic signals.

[0012] 2. Automatic adjustment of preload: No frequent manual intervention is required; adaptive anchoring is achieved based on changes in geological conditions.

[0013] 3. Reduce safety accidents: Effectively prevent accidents such as collapses and roof falls, and adapt to the safety production needs in complex geological environments.

[0014] In some embodiments, the anchor is constructed in an integrated manner during a single full-length grouting process, where the anchor section is grouted and the free section is not bonded to the grout, so as to preserve the free section of the anchor and the outer end of the free section of the anchor is covered with at least one layer of flexible isolation material.

[0015] In some embodiments, the outer edge of the anchoring section of the anchor is provided with a corrosion-resistant sheath and / or a flow guide hole.

[0016] In some embodiments, the anchor includes a screw-end anchor or a JM12 type anchor, or the free section of the anchor is connected to a mechanically reinforced tensile lock and a mining prestressed anchor lock.

[0017] In some embodiments, the automatic pre-tightening device further includes a force measuring device connected to the end of the anchor and electrically connected to the data acquisition unit or the control unit.

[0018] In some embodiments, the automatic pre-tightening system for anchor cables and bolts based on acoustic and seismic wave feedback further includes an auxiliary protection unit. The auxiliary protection unit is installed on the surrounding rock or in the tunnel. The auxiliary protection unit includes an auxiliary shotcrete device and / or an auxiliary support device. Both the auxiliary shotcrete device and the auxiliary support device are electrically connected to the control unit.

[0019] In some embodiments, the automatic pre-tightening system for anchor cables and bolts based on acoustic and seismic wave feedback further includes multiple early warning modules. The early warning modules are connected to the surrounding rock, the downhole control center, and the surface monitoring center. The early warning modules are electrically connected to the control unit. Each early warning module includes at least one audible and visual alarm.

[0020] The second aspect of the present invention provides an automatic pre-tightening method for anchor cables and bolts based on acoustic and seismic wave feedback, comprising:

[0021] Anchors are installed, and an automatic pre-tightening system as described in any of the above embodiments is provided. Anchor holes are drilled in the surrounding rock, and anchors with flexible isolation material are inserted into the anchor holes. After installing a grout stop plug, a tray, and an initial lock at the hole opening, the grouting pipeline is connected to complete the full-length grouting in one go. The set pressure method is used to effectively fill the cracks or broken surrounding rock. If screw end rod anchors or anchor components of JM12 type anchors are used, the next step is performed directly after the grout solidifies. If ordinary anchor rods or anchor cables are used, the next step is performed after the grout solidifies by connecting mechanical reinforcement anti-tensile locks or replacing the mining prestressed anchor locks on the free section of the anchor.

[0022] Sensors are installed by embedding high-speed acoustic emission sensors, micro-vibration pickups, stress sensors, and deformation monitors in the anchor body and / or the surrounding rock to form a sensor array for comprehensive information collection of the anchor and the surrounding rock.

[0023] Set up an automatic pre-tightening device, connect the output end of the automatic pre-tightening device to the free section of the anchor, connect the fixed end of the automatic pre-tightening device to the surrounding rock, and electrically connect the automatic pre-tightening device to the control unit.

[0024] Set up a data acquisition unit, and set up a high-speed acquisition card and / or downhole data acquisition module at a suitable location on the surrounding rock to form a data acquisition unit. Connect the data acquisition unit to the sensor array and control unit. After receiving and processing the signals from the sensor array, the data acquisition unit sends the processed data to the control unit.

[0025] The control unit receives data and comprehensively evaluates the stability of the surrounding rock, crack distribution, and effectiveness of the pretension force. When the microseismic activity or acoustic characteristics of the surrounding rock are detected to be abnormally increased, the control unit controls the automatic pretensioning device to automatically increase the pretension force of the anchor cable according to the algorithm to inhibit the continued expansion of cracks in the surrounding rock. When the anchor cable is under excessive stress or the deformation of the surrounding rock tends to stabilize, the control unit controls the automatic pretensioning device to actively reduce the pretension force according to the algorithm to avoid the anchor cable or surrounding rock from developing new cracks due to excessive constraint.

[0026] When abnormal data is detected, the control unit issues an alarm signal to warn staff and / or automatically executes emergency plans.

[0027] The automatic pre-tightening method for anchor cables and bolts based on acoustic and seismic wave feedback of the present invention has at least the following advantages:

[0028] 1. Active crack propagation identification: Early identification is achieved by capturing minute cracks or sudden load changes in the surrounding rock through acoustic and microseismic signals.

[0029] 2. Automatic adjustment of preload: No frequent manual intervention is required; adaptive anchoring is achieved based on changes in geological conditions.

[0030] 3. Reduce safety accidents: Effectively prevent accidents such as collapses and roof falls, and adapt to the safety production needs in complex geological environments.

[0031] In some embodiments, when setting up a sensor array, listening points are set in the anchored section, free section and anchor cable end according to the tunnel layout, rock strata structure and anchor cable distribution, so as to achieve all-round capture of micro-fracture signals of the surrounding rock. If the surrounding rock fractures are severely developed or the rock strata are clearly divided, multiple sets of sensors can be arranged at different depths or in different directions to form an observation network, which helps to accurately locate the micro-cracks and assess the crack development trend.

[0032] In some embodiments, the automatic pre-tightening method for anchor cables and anchor bolts based on acoustic and seismic wave feedback further includes periodically analyzing the sensor's working status and self-diagnostic information using a monitoring database. If sensor signal attenuation or abnormal noise levels are detected, the control unit issues a sensor abnormality signal to alert the staff. Attached Figure Description

[0033] Figure 1This is a schematic diagram of an automatic pre-tightening method for anchor cables and anchor bolts based on acoustic and seismic wave feedback according to an embodiment of the present invention. Detailed Implementation

[0034] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0035] The following describes, with reference to the accompanying drawings, an automatic pre-tightening system for anchor cables and bolts based on acoustic and seismic wave feedback according to an embodiment of the present invention.

[0036] The automatic pre-tightening system for anchor cables and bolts based on acoustic and seismic wave feedback according to this invention includes an anchor, a sensor array, a control unit, a data acquisition unit, and an automatic pre-tightening device, wherein:

[0037] Anchors are connected to the surrounding rock. Depending on the specific needs and geological conditions of the tunnel support, anchors can be specific anchor cables or anchor rods. When installing anchors, referring to the "method and process for realizing full-length prestressed grouting anchors," a layer of flexible isolation material (such as rubber or polyester) can be wrapped around the outer end of the free section of the anchor cable. This allows for integrated construction of "grouting of the anchor section + no adhesion between the free section and the grout" during a single full-length grouting operation. This preserves the free section of the anchor cable for subsequent application or adjustment of preload. Corrosion-resistant sheaths or guide holes can also be installed along the outer edge of the anchor section to enhance the grouting effect and improve the initial bonding strength with the surrounding rock.

[0038] The sensor array is installed in the anchor body and / or its surrounding rock. The array includes multiple high-speed acoustic emission sensors, multiple micro-vibration pickups, multiple stress sensors, and multiple deformation monitors. These sensors are positioned at key locations such as the anchored section, free section, and anchor cable ends, based on the roadway layout, rock strata structure, and anchor cable distribution, to achieve comprehensive capture of micro-fracture signals in the surrounding rock. In areas with severe rock fissures or distinct strata zoning, multiple sensor sets can be deployed at different depths or orientations to form an "observation network," helping to accurately locate micro-cracks and assess crack development trends. These sensors form a comprehensive, multi-layered monitoring network to capture the high-frequency micro-vibration waveforms and acoustic characteristics generated when micro-fractures propagate and energy is released in the surrounding rock, serving as a crucial basis for assessing rock stability. Furthermore, these sensors possess a certain level of downhole protection, such as moisture-proof, dust-proof, and impact-resistant characteristics, ensuring long-term stable operation in humid, high-temperature, and high-dust environments.

[0039] The control unit includes a signal receiver, a processor, and a signal generator. The control unit is located in the downhole control center or the surface monitoring center. The signal receiver is responsible for receiving electrical signals from the data acquisition unit. The processor performs preliminary processing and advanced analysis on these signals. The signal generator sends control commands to the automatic pretensioning device or other lower-level units or devices based on the analysis results of the processor, so as to realize real-time control and early warning of the pretensioning force.

[0040] The data acquisition unit is electrically connected to both the sensor array and the control unit. The data acquisition unit is used to perform preliminary filtering and amplification of the electrical signals from the sensor array, and then transmit them to the control unit in real time or periodically. The data acquisition unit includes a high-speed acquisition card and / or a downhole data acquisition module. The high-speed acquisition card can quickly capture high-frequency micro-vibration signals and ensure that they are not distorted. The downhole data acquisition module has the ability to work stably in harsh environments. Depending on the actual situation, one of them can be used alone or in combination to ensure that the data acquisition unit can accurately and quickly transmit signals to the control unit.

[0041] The output end of the automatic pre-tightening device is installed on the free section of the anchor, the fixed end of the automatic pre-tightening device is connected to or abuts against the surrounding rock, and the automatic pre-tightening device is electrically connected to the control unit. The automatic pre-tightening device includes a micro motor and / or a hydraulic drive device. When the automatic pre-tightening device receives a control signal from the control unit, the automatic pre-tightening device is activated to increase or decrease the prestress of the anchor to adapt to the surrounding rock.

[0042] The control unit, data acquisition unit, and automatic pretensioning device transmit data over long distances using industrial Ethernet, fiber optic, or low-power wireless transmission technologies to ensure high bandwidth and data integrity.

[0043] The automatic pre-tightening system for anchor cables and bolts based on acoustic and seismic wave feedback of the present invention has at least the following advantages:

[0044] 1. Active crack propagation identification: Early identification is achieved by capturing minute cracks or sudden load changes in the surrounding rock through acoustic and microseismic signals.

[0045] 2. Automatic adjustment of preload: No frequent manual intervention is required; adaptive anchoring is achieved based on changes in geological conditions.

[0046] 3. Reduce safety accidents: Effectively prevent accidents such as collapses and roof falls, and adapt to the safety production needs in complex geological environments.

[0047] In some embodiments, the anchor includes a screw-end anchor or a JM12 type anchor, or the free section of the anchor is connected to a mechanically reinforced tensile lock and a mining prestressed anchor bolt lock, which can ensure that the anchor can be tensioned repeatedly.

[0048] In some embodiments, the automatic pretensioning device further includes a force measuring device connected to the end of the anchor and electrically connected to a data acquisition unit or control unit. The force measuring device is used to monitor the tension force in real time and send the data to the data acquisition unit or control unit, ensuring that the control unit can accurately adjust the pretension force according to the real-time monitored tension data.

[0049] In some embodiments, the automatic pre-tightening system for anchor cables and bolts based on acoustic and seismic wave feedback also includes an auxiliary protection unit. The auxiliary protection unit is installed on the surrounding rock or in the roadway. The auxiliary protection unit includes an auxiliary shotcrete device and / or an auxiliary support device. Both the auxiliary shotcrete device and the auxiliary support device are electrically connected to the control unit to form a multi-layered integrated support system, thereby improving the overall stability of the surrounding rock.

[0050] It should be noted that when using the auxiliary shotcrete device, if it is determined that the stability of the surrounding rock has decreased or there is a potential risk, the control unit sends an activation command to the auxiliary shotcrete device. The valve of the auxiliary shotcrete device opens and the drive mechanism is activated to reinforce the dangerous face with shotcrete. When using the auxiliary support device, if no activation command is received from the control unit, the auxiliary support device retracts to reduce the space occupied. When an activation command is received from the control unit, the drive mechanism of the auxiliary support device drives the support device to unfold to support the dangerous face.

[0051] In some embodiments, the automatic pre-tightening system for anchor cables and bolts based on acoustic and seismic wave feedback also includes multiple early warning modules. The early warning modules are connected to multiple locations such as the surrounding rock, the downhole control center, and the surface monitoring center. The early warning modules are electrically connected to the control unit and include at least one audible and visual alarm. When the monitoring system detects abnormal data or reaches the preset early warning conditions, the early warning module will immediately activate the audible and visual alarm signal to remind on-site personnel and managers to pay attention and take corresponding countermeasures.

[0052] The second aspect of the present invention provides an automatic pre-tightening method for anchor cables and bolts based on acoustic and seismic wave feedback, comprising:

[0053] S1. Anchors are installed, and an automatic pre-tightening system as described in any of the above embodiments is provided. Anchor holes are drilled in the surrounding rock, and anchors with flexible isolation material are inserted into the anchor holes to prevent the grout from adhering to the free section of the anchor during grouting. After installing a grout stop plug, a tray, and an initial locking device at the hole opening, the grouting pipeline is connected to complete the full-length grouting in one go. The set pressure method is used to effectively fill the fissures or broken surrounding rock. After the grout initially sets, the anchor section and the surrounding rock form a good bond, while the free section remains isolated until prestress is applied. This method simplifies the cumbersome process of traditional staged grouting or local anchoring followed by grouting, and greatly improves construction efficiency.

[0054] If using bolted end anchors or JM12 type anchors, which are suitable for repeated tensioning, proceed directly to the next step after the grout has solidified. If using ordinary anchor rods or anchor cables, after the grout has solidified, connect mechanical reinforcement anti-tensile locks to the free section of the anchor or replace them with mining prestressed anchor bolt locks before proceeding to the next step.

[0055] S2. Install sensors by embedding high-speed acoustic emission sensors, micro-vibration pickups, stress sensors, and deformation monitors into the anchor body and / or its surrounding rock to form a sensor array. These sensors can collect information about the anchor and surrounding rock from all angles, including micro-vibration waveforms, acoustic characteristics, stress state, and deformation.

[0056] S3. Set up an automatic pre-tightening device, connect the output end of the automatic pre-tightening device to the free section of the anchor, connect the fixed end of the automatic pre-tightening device to the surrounding rock, and electrically connect the automatic pre-tightening device to the control unit.

[0057] S4. Set up a data acquisition unit. Set up a high-speed acquisition card and / or downhole data acquisition module at a suitable location on the surrounding rock to form a data acquisition unit. Connect the data acquisition unit to the sensor array and control unit. After receiving and processing the signals from the sensor array, the data acquisition unit sends the processed data to the control unit.

[0058] S5. The control unit receives data and comprehensively evaluates the stability of the surrounding rock, crack distribution, and effectiveness of the pre-tightening force. When the microseismic activity or acoustic characteristics of the surrounding rock are abnormally increased, the control unit controls the automatic pre-tightening device to automatically increase the pre-tightening force of the anchor cable according to the algorithm to suppress the continued expansion of cracks in the surrounding rock. When the anchor cable is under excessive stress or the deformation of the surrounding rock tends to stabilize, the control unit controls the automatic pre-tightening device to actively reduce the pre-tightening force according to the algorithm to avoid new cracks in the anchor cable or surrounding rock due to excessive constraint.

[0059] It should be noted that the data acquisition unit integrates data from multiple sources, such as acoustic-seismic wave modules, stress sensors, and deformation monitors, into the control unit. The control unit uses big data algorithms or deep learning models to comprehensively determine the stability of the surrounding rock, crack distribution, and effectiveness of prestressing force. It processes the spectral characteristics, energy release rate, and spatial location of the rupture signal and, combined with the anchor cable prestress value, determines the safety margin or risk level of the surrounding rock.

[0060] The control unit can also link historical data with geological parameters and construction information to provide big data support for the design of similar tunnel projects or support schemes in the future.

[0061] S6. When abnormal data is detected (e.g., when acoustic events and pretension force data show significant abnormalities), the control unit issues an alarm signal to warn staff and / or automatically executes emergency plans. For example, the main control algorithm can autonomously control the automatic pretensioning device to complete stress adjustment in the shortest possible time based on preset thresholds or model prediction results, thereby preventing the potential for accidents from escalating further.

[0062] The automatic pre-tightening method for anchor cables and bolts based on acoustic and seismic wave feedback of the present invention has at least the following advantages:

[0063] 1. Active crack propagation identification: Early identification is achieved by capturing minute cracks or sudden load changes in the surrounding rock through acoustic and microseismic signals.

[0064] 2. Automatic adjustment of preload: No frequent manual intervention is required; adaptive anchoring is achieved based on changes in geological conditions.

[0065] 3. Reduce safety accidents: Effectively prevent accidents such as collapses and roof falls, and adapt to the safety production needs in complex geological environments.

[0066] In some embodiments, when setting up a sensor array, listening points are set at key locations such as the anchoring section, free section, and anchor cable ends, according to the tunnel layout, rock strata structure, and anchor cable distribution, in order to achieve all-round capture of micro-fracture signals in the surrounding rock. If the surrounding rock fractures are severely developed or the rock strata are clearly divided, multiple sets of sensors can be arranged at different depths or in different directions to form an observation network, which helps to accurately locate the micro-cracks and assess the crack development trend.

[0067] In some embodiments, the automatic pre-tightening method for anchor cables and anchor bolts based on acoustic and seismic wave feedback further includes establishing a dedicated monitoring database to store the working status of sensors, self-diagnostic information, and collected data. The monitoring database periodically analyzes the working status and self-diagnostic information of the sensors, which can promptly detect problems with the sensors. If sensor signal attenuation or abnormal noise level is detected, the control unit sends a sensor abnormality signal to alert the staff.

[0068] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0069] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0070] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0071] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0072] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0073] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. An automatic pre-tightening method for anchor cables and anchor bolts based on acoustic and seismic wave feedback, characterized in that, include: The method is based on an automatic pre-tightening system for anchor cables and bolts using acoustic and seismic wave feedback. This automatic pre-tightening system includes: The system comprises an anchor, a sensor array, a control unit, a data acquisition unit, and an automatic pre-tightening device. The anchor is connected to the surrounding rock. The sensor array is disposed in the body of the anchor and / or the surrounding rock. The sensor array includes multiple high-speed acoustic emission sensors, multiple micro-vibration pickups, multiple stress sensors, and multiple deformation monitors, used to capture high-frequency micro-vibration waveforms and acoustic characteristics generated when the surrounding rock undergoes micro-crack expansion and energy release. The control unit includes a signal receiver, a processor, and a signal generator. The control unit is located in a downhole control center or a surface monitoring center. The data acquisition unit is electrically connected to both the sensor array and the control unit. The data acquisition unit includes a high-speed acquisition card and / or a downhole data acquisition module. The data acquisition unit is used to perform preliminary filtering and amplification of the electrical signals from the sensor array, and then transmit them to the control unit in real time or periodically. The output end of the automatic pre-tightening device is installed on the free section of the anchor. The fixed end of the automatic pre-tightening device is connected to or abuts against the surrounding rock, and the automatic pre-tightening device is electrically connected to the control unit. The automatic pre-tightening device includes a micro motor and / or a hydraulic drive device. Set up anchors, drill anchor holes in the surrounding rock, insert anchors with flexible isolation material into the anchor holes, install grout stop plugs, trays and initial locks at the hole openings, and connect the grouting pipeline to complete the full-length grouting in one go. Use the set pressure method to effectively fill the cracks or broken surrounding rock. If using screw end rod anchors or JM12 type anchor components, proceed directly to the next step after the grout has solidified. If using ordinary anchor rods or anchor cables, after the grout has solidified, connect mechanical reinforcement anti-tensile locks or replace the mining prestressed anchor rod locks on the free section of the anchors before proceeding to the next step. Sensors are installed by embedding high-speed acoustic emission sensors, micro-vibration pickups, stress sensors, and deformation monitors in the body of the anchor and / or the surrounding rock to form a sensor array for comprehensive information collection of the anchor and the surrounding rock. Set up an automatic pre-tightening device, connect the output end of the automatic pre-tightening device to the free section of the anchor, connect the fixed end of the automatic pre-tightening device to the surrounding rock, and electrically connect the automatic pre-tightening device to the control unit. Set up a data acquisition unit, and set up a high-speed acquisition card and / or downhole data acquisition module at a suitable location on the surrounding rock to form a data acquisition unit. Connect the data acquisition unit to the sensor array and control unit. After receiving and processing the signals from the sensor array, the data acquisition unit sends the processed data to the control unit. The control unit receives data and comprehensively evaluates the stability of the surrounding rock, crack distribution, and effectiveness of the pretension force. When the microseismic activity or acoustic characteristics of the surrounding rock are detected to be abnormally increased, the control unit controls the automatic pretensioning device to automatically increase the pretension force of the anchor cable according to the algorithm to inhibit the continued expansion of cracks in the surrounding rock. When the anchor cable is under excessive stress or the deformation of the surrounding rock tends to stabilize, the control unit controls the automatic pretensioning device to actively reduce the pretension force according to the algorithm to avoid the anchor cable or surrounding rock from developing new cracks due to excessive constraint. When abnormal data is detected, the control unit issues an alarm signal to warn staff and / or automatically executes emergency plans.

2. The automatic pre-tightening method for anchor cables and bolts based on acoustic and seismic wave feedback according to claim 1, characterized in that, When setting up the sensor array, listening points are set in the anchored section, free section and anchor cable end according to the tunnel layout, rock strata structure and anchor cable distribution, so as to achieve all-round capture of micro-fracture signals in the surrounding rock. If the surrounding rock fractures are severely developed or the rock strata are clearly divided, multiple sets of sensors can be arranged at different depths or in different directions to form an observation network, which helps to accurately locate the micro-cracks and assess the crack development trend.

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