Tunnel micro-seismic monitoring construction method

Abstract

The invention discloses a tunnel micro-seismic monitoring construction method, which comprises the following steps: mounting micro-seismic sensors in the circumferential direction of a tunnel wall within a preset distance range behind a tunnel face, pre-burying a data acquisition line at a tunnel bottom plate, and connecting the mounted micro-seismic sensors to micro-seismic monitoring equipment through the data acquisition line, a rockburst real-time micro-seismic monitoring system and an early warning system are established, collected micro-seismic activity data are analyzed and processed in real time, and the fracture state and the rockburst danger level of the rock mass are judged according to the waveform, the frequency, the energy and other characteristic parameters of micro-seismic signals. According to the tunnel micro-seismic monitoring construction method, a Zhongcao micro-seismic monitoring system is adopted, the system can conduct timing, positioning and grading early warning on fracture of hard rock, micro-seismic sensor array arrangement is adopted, forward propelling is conducted close to a tunnel face, the seismic source space positioning precision is high, and uninterrupted continuous real-time monitoring of fracture of surrounding rock can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of tunnel microseismic monitoring, and in particular to a tunnel microseismic monitoring construction method. Background Art

[0002] Tunnel engineering is an indispensable part of highway construction. With the acceleration of highway construction, the construction of highway tunnels has also increased. In the process of tunnel excavation, tunnel collapse disasters are often caused by the falling of rock fragments and the collapse of large rocks. The prevention and control of tunnel geological disasters has become a frontier hotspot and key technical issue in the construction of the Western Land-Sea New Channel. At the least, it will delay the construction period and damage construction equipment, and at worst, it will cause casualties to construction personnel. Therefore, how to make timely and effective monitoring and early warning of tunnel collapse disasters is a "key technical problem that needs to be solved urgently:

[0003] 1: Traditional tunnel collapse monitoring and early warning are mostly implemented by checking whether the deformation amount, deformation rate and other indicators are exceeded. Usually, total stations and levels are used to measure the settlement of the tunnel vault, convergence meters are used to measure the convergence around the tunnel, and pressure meters are used to measure the surrounding rock pressure. The characteristic indicators of tunnel collapse measured by these methods mostly change after the surrounding rock mass has deformed. They are indirect means with a certain lag and cannot reflect the stability of the surrounding rock in a timely manner. It is even more difficult to discover the internal crack expansion trend and dynamic characteristics before the rock mass deforms and becomes unstable in advance;

[0004] 2: Traditional monitoring technology cannot achieve effective short-term early warning of sudden instability of tunnel rock mass. Therefore, in order to directly respond to subtle changes in the surrounding rock and monitor the actual stability of the surrounding rock in real time, it is necessary to propose a scientific and effective tunnel collapse monitoring and early warning technology to improve tunnel construction efficiency and ensure safe and orderly tunnel construction. Summary of the invention

[0005] The present application aims to solve one of the technical problems in the related art at least to some extent.

[0006] To this end, the first purpose of this application is to provide a tunnel microseismic monitoring construction method, which adopts the Zhongke microseismic monitoring system. The system can provide timing, positioning, and grading early warning for hard rock fractures. It adopts an array of microseismic sensors, closely follows the forward advancement of the heading face, has high spatial positioning accuracy of the earthquake source, and can achieve uninterrupted and continuous real-time monitoring of surrounding rock fractures.

[0007] The second purpose of this application is to propose a tunnel microseismic monitoring construction method, which adopts a method combining wavelet scattering transform and support vector machine model to identify rock fracture signals with high signal recognition accuracy. It adopts a method for locating the fracture source outside the array, which can quickly and efficiently locate rock fracture events outside the sensor array, and adopts automatic early warning of landslide events. It has a high degree of informatization and intelligence, and the early warning information is released in a timely and effective manner.

[0008] To achieve the above-mentioned purpose, the first embodiment of the present application proposes a tunnel microseismic monitoring construction method, the tunnel microseismic monitoring construction method, the method comprising the following steps:

[0009] Step 1: Install microseismic sensors along the tunnel wall within a predetermined distance behind the tunnel face;

[0010] Step 2: Pre-embed the data acquisition line at the tunnel floor, and connect the installed microseismic sensors to the microseismic monitoring equipment through the data acquisition line.

[0011] Step 3: Establish a real-time microseismic monitoring system and early warning system for rockbursts, and perform real-time analysis and processing of the collected microseismic activity data;

[0012] Step 4: Determine the fracture state of the rock mass and the risk level of rock burst based on the waveform, frequency, energy and other characteristic parameters of the microseismic signal;

[0013] Step 5: When the monitoring data is abnormal, the system automatically sends out an early warning signal to remind the construction personnel to take corresponding safety measures;

[0014] Step 6: According to the early warning of the rock burst hazard level, dynamically adjust the support measures for the next cycle of excavation, such as increasing the support strength, changing the excavation method, etc.;

[0015] Step 7: Regularly summarize and analyze monitoring data, evaluate monitoring results and provide feedback to the monitoring plan to optimize and adjust the monitoring plan.

[0016] According to the tunnel microseismic monitoring construction method of the embodiment of the present application, the China Science and Technology microseismic monitoring system is used. The system can provide timing, positioning, and classification warnings for hard rock fractures. It adopts an array arrangement of microseismic sensors, closely follows the forward advancement of the heading face, has high spatial positioning accuracy of the earthquake source, and can achieve uninterrupted and continuous real-time monitoring of surrounding rock fractures.

[0017] In addition, the tunnel microseismic monitoring construction method proposed in the present application may also have the following additional technical features:

[0018] In one embodiment of the present application, the specific process of installing the microseismic sensor in step 1 is as follows:

[0019] Step 1.1: Clarify the purpose of tunnel microseismic monitoring, such as predicting geological disasters such as rock bursts and sudden water inrush, or evaluating the impact of tunnel excavation on the surrounding rock mass;

[0020] Step 1.2: Design a reasonable monitoring plan based on the geological conditions, construction methods and monitoring objectives of the tunnel, including sensor type, quantity, and layout location;

[0021] Step 1.3: According to the monitoring plan, multiple rings of microseismic sensors are installed along the tunnel wall within a predetermined distance behind the tunnel face to fully cover the possible monitoring area;

[0022] Step 1.4: Install the microseismic sensors at the predetermined positions according to the design requirements. The main installation method of the microseismic sensors is to stagger the sensors in space and keep up with the movement of the face.

[0023] In one embodiment of the present application, the specific process of real-time analysis and processing of the microseismic activity data collected in step 3 is as follows:

[0024] Step 3.1: First, filter out the background noise of the original microseismic signal, and use the combination of wavelet scattering transform and support vector machine model to intelligently identify the most realistic rock fracture signal;

[0025] Step 3.2: Then, each rock fracture microseismic event is located using the array external fracture source location method;

[0026] Step 3.3: Then obtain the time and spatial position of the rock fracture microseismic event, and then calculate the source parameters of the located rock fracture microseismic event, such as the radiation energy of the microseismic event, the microseismic apparent volume, the cumulative number of microseismic events, etc.

[0027] In one embodiment of the present application, the specific process of step 4 is to judge the fracture state of the rock mass and the rock burst hazard level according to the characteristic parameters such as the waveform, frequency, and energy of the microseismic signal:

[0028] The key to setting the early warning management level is to select the source parameters of rock fracture microseismic events that can represent the activity level of rock fracture according to the spatial distribution of microseismic activities in the tunnel under construction, the characteristics of the excavation disturbance area and the construction plan, set certain early warning thresholds, and propose corresponding risk levels.

[0029] In one embodiment of the present application, in step 5, when the monitoring data is abnormal, the system automatically sends out an early warning signal to remind the construction personnel to take corresponding safety measures;

[0030] Step 5.1: When the rock fracture microseismic event parameters uploaded to the cloud early warning APP reach a certain risk level, an early warning signal will be sent to the mobile phones of on-site staff to achieve real-time early warning of tunnel microseismic monitoring;

[0031] Step 5.2: When the landslide risk level is medium or above, the on-site staff should issue early warning information in a timely manner. Through mobile phone calls (note to turn on call recording), text messages or WeChat, the early warning information should be promptly conveyed to: the person in charge of construction, the person in charge of supervision, and the person designated by the owner.

[0032] In one embodiment of the present application, the step 6 is to dynamically adjust the support measures for the next cycle of excavation according to the early warning of the rock burst hazard level, such as increasing the support strength, changing the excavation method, etc.

[0033] 1: Minor rock burst hazard level, excavation method: use smooth blasting technology, strictly control the amount of drugs, reduce the impact of blasting on the surrounding rock, make the excavation section as regular as possible, adopt the "short footage, multiple cycles" excavation method, and control the footage of each cycle within 2.5m. Support measures: strengthen construction support work, spray steel fiber or plastic fiber concrete on the arch and side wall immediately after blasting, add anchor rods and steel mesh, and set up steel arch frames for support when necessary. Lining work is carried out closely following the excavation process to reduce the exposure time of the rock formation.

[0034] 2: Medium rock burst hazard level, excavation method: further shorten the advance, reduce the disturbance of single blasting to the surrounding rock, adopt the construction method of "dense drilling and weak blasting" in the rock burst area, reduce the blasting intensity, support measures: strengthen the support structure, increase the number and length of anchor rods, improve the support strength, add temporary steel supports in the area with severe rock burst, form a joint support system with the shotcrete mesh, strengthen the monitoring of the support structure, and ensure the support effect;

[0035] 3: Strong rock burst hazard level. Excavation method: Suspend excavation operations, reinforce the face, and continue excavation after the risk of rock burst is reduced. If excavation is necessary, adopt extremely small advance and extremely low intensity blasting methods, and strictly control the blasting range. Support measures: Immediately implement comprehensive reinforcement measures, including increasing the density, length and diameter of anchor rods, adding steel supports, etc., cut grooves in the rock wall to release stress, reduce the intensity of rock burst, strengthen monitoring and early warning, and ensure construction safety.

[0036] In one embodiment of the present application, the specific process of step 1.4 is:

[0037] Step 1.4.1: Anchor bolt layout: When two inverts are made (the face advance is about 20m), the construction personnel on site shall be informed in advance during the excavation and drilling stage of the face. The holes required for anchor bolt layout shall be reserved in advance in the surrounding rock of the side wall of the face section. Three holes of high, medium and low shall be reserved on the left or right side of the section. The diameter of the drill hole is about 1.5 times the diameter of the installed sensor. Communicate with the construction personnel on site in advance during the initial support stage of the face. Three exposed long anchor bolts of high, medium and low shall be laid in the reserved holes on one side (left or right) of the face section. The buried depth is about 2 to 3m. If the microseismic signal received by the sensor installed on the long anchor bolt is verified by the later experiments to be not much different from the signal received by the short steel bar installed at a buried depth of about 0.5m, the short steel bar can be considered to be laid for sensor installation in the later stage to increase installation flexibility and improve work efficiency. The specific location and depth of the anchor bolt installation need to be reflected in the drawings and explained to the construction personnel to facilitate the subsequent mobile installation of the probe;

[0038] Step 1.4.2: Sensor arrangement: The spatial positions of the six sensors are staggered as much as possible and placed on different horizontal planes. The longitudinal (Y direction) spacing of the probes on the same side is 5 to 10 meters, and the transverse (X direction) spacing is 20 meters. Since there is an invert between the tunnel face and the tunnel opening, the probe closest to the tunnel face can be placed across the invert to the anchor with the lowest reserved height while ensuring the spacing of the sensor array. The two-core extension line is used. In order to ensure the safety of the probe, you can choose to retract the probe in advance before the invert blasting, or place the probe on the opposite side of the invert blasting, depending on the specific situation on site. In order to prevent the tunnel face and invert blasting from damaging the signal transmission cable across the invert, use a smooth cloth-covered explosion-proof hose to wrap the signal transmission cable;

[0039] Step 1.4.3: Probe movement: As the construction of the tunnel face and secondary lining progresses, move the probe that is currently farthest from the tunnel face to the front end (closest to the tunnel face).

[0040] In one embodiment of the present application, the specific process of step 3.3 is:

[0041] The sensor array formed by six microseismic sensors monitors rock fracture activities near the face during tunnel construction 24 hours a day. The signals are transmitted via a two-core cable to an eight-core cable laid parallel to the tunnel axis. The eight-core cable is connected to a signal fidelity box in a central server near the tunnel entrance, and then to a collector via a channel cable. The data is then transmitted wirelessly to the microseismic monitoring cloud platform.

[0042] In one embodiment of the present application, the step 2 is to pre-embed a data acquisition line at the tunnel floor, and connect the installed microseismic sensor to the microseismic monitoring device through the data acquisition line. The specific process is:

[0043] Step 2.1: On-site staff carry the required eight-core wire to the designated location and cut the corresponding length of the eight-core wire;

[0044] Step 2.2: On-site staff need to install the cables according to the following wiring mode. The positive pole is connected to the red wire of the eight-core wire, and the negative pole is connected to the white wire of the eight-core wire. It is necessary to avoid contaminating the connector and causing abnormal reception of signals.

[0045] Step 2.3: After installation, calibrate the oscilloscope instrument;

[0046] Step 2.4: After the equipment is connected, the data server needs to be set up to achieve effective transmission of microseismic data;

[0047] Step 2.5: After connecting and collecting, observe the indicator light on the signal acquisition instrument and perform subsequent operations according to the indicator light.

[0048] In one embodiment of the present application, the specific process of microseismic signal denoising in step 3.1 is as follows:

[0049] Step 3.1.1: Through the on-site inspection of the construction situation by on-site personnel, the construction procedures at different times are recorded, and the corresponding different microseismic source signal waveforms are obtained and analyzed;

[0050] Step 3.1.2: Analyze the time-frequency characteristics of the signal through continuous wavelet transform;

[0051] Step 3.1.3: Extract signals with typical features through discrete wavelet transform;

[0052] Step 3.1.4: Obtain characteristic parameters of typical signals through wavelet scattering transform and establish a sample database;

[0053] Step 3.1.5: Based on the support vector machine model, the model is trained by building a good sample database to establish a neural network model that can filter and analyze the original microseismic signals.

[0054] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0056] Figure 1 A schematic diagram of a microseismic monitoring process for a positive step tunnel according to a tunnel microseismic monitoring construction method according to an embodiment of the present application;

[0057] Figure 2 FIG. 1 is a process flow chart of microseismic monitoring of a step tunnel according to a tunnel microseismic monitoring construction method according to an embodiment of the present application;

[0058] Figure 3 A schematic diagram of anchor arrangement of a tunnel microseismic monitoring construction method according to an embodiment of the present application;

[0059] Figure 4 A schematic diagram of sensor arrangement for a tunnel microseismic monitoring construction method according to an embodiment of the present application;

[0060] Figure 5 This is a table of standards for determining the landslide risk level of a tunnel microseismic monitoring construction method according to an embodiment of the present application. DETAILED DESCRIPTION

[0061] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limitations on the present application. On the contrary, the embodiments of the present application include all changes, modifications and equivalents that fall within the spirit and connotation of the appended claims.

[0062] The tunnel microseismic monitoring construction method according to an embodiment of the present application is described below with reference to the accompanying drawings.

[0063] like Figure 1 and Figure 2 As shown, the tunnel microseismic monitoring construction method of the embodiment of the present application may include the following steps:

[0064] Step 1: Install microseismic sensors along the tunnel wall within a predetermined distance behind the tunnel face;

[0065] Step 2: Pre-embed the data acquisition line at the tunnel floor, and connect the installed microseismic sensors to the microseismic monitoring equipment through the data acquisition line.

[0066] Step 3: Establish a real-time microseismic monitoring system and early warning system for rockbursts, and perform real-time analysis and processing of the collected microseismic activity data;

[0067] Step 4: Determine the fracture state of the rock mass and the risk level of rock burst based on the waveform, frequency, energy and other characteristic parameters of the microseismic signal;

[0068] Step 5: When the monitoring data is abnormal, the system automatically sends out an early warning signal to remind the construction personnel to take corresponding safety measures;

[0069] Step 6: According to the early warning of the rock burst hazard level, dynamically adjust the support measures for the next cycle of excavation, such as increasing the support strength, changing the excavation method, etc.;

[0070] Step 7: Regularly summarize and analyze monitoring data, evaluate monitoring results and provide feedback to the monitoring plan to optimize and adjust the monitoring plan;

[0071] 1. Perform on-site inspection of microseismic sensors and lines once a day, test the status of sensors and lines by knocking on the surrounding rocks on site, and deal with any problems in a timely manner.

[0072] 2. When on-site staff discover that the system's real-time monitoring signal is abnormal, they must promptly eliminate the fault and try to ensure normal 24-hour system monitoring.

[0073] 3. On-site staff must prepare a daily monitoring report on time every day and report the day’s work content to the relevant person in charge in a timely manner.

[0074] Specifically, the China Science and Technology microseismic monitoring system is used, which can provide timing, positioning, and classification warnings for hard rock fractures. The microseismic sensor array is arranged and advances forward closely following the face of the hand. The spatial positioning accuracy of the earthquake source is high, and uninterrupted and continuous real-time monitoring of surrounding rock fractures can be achieved. The rock fracture signal is identified by combining wavelet scattering transform and support vector machine model, and the signal recognition accuracy is high. The method of locating the fracture source outside the array is adopted, which can quickly and efficiently locate rock fracture events outside the sensor array. Automatic warning of landslide events is adopted, with a high degree of informatization and intelligence, and the warning information is released in a timely and effective manner.

[0075] Furthermore, the tunnel microseismic monitoring construction method further includes:

[0076] In the embodiments of this application.

[0077] In one embodiment of the present application, the specific process of installing the microseismic sensor in step 1 is as follows:

[0078] Step 1.1: Clarify the purpose of tunnel microseismic monitoring, such as predicting geological disasters such as rock bursts and sudden water inrush, or evaluating the impact of tunnel excavation on the surrounding rock mass;

[0079] Step 1.2: Design a reasonable monitoring plan based on the geological conditions, construction methods and monitoring objectives of the tunnel, including sensor type, quantity, and layout location;

[0080] Step 1.3: According to the monitoring plan, multiple rings of microseismic sensors are installed along the tunnel wall within a predetermined distance behind the tunnel face to fully cover the possible monitoring area;

[0081] Step 1.4: Install the microseismic sensors at the predetermined positions according to the design requirements. The main installation method of the microseismic sensors is to stagger the sensors in space and keep up with the movement of the face.

[0082] In another embodiment of the present application,

[0083] In this embodiment, the specific process of real-time analysis and processing of the microseismic activity data collected in step 3 is as follows:

[0084] Step 3.1: First, filter out the background noise of the original microseismic signal, and use the combination of wavelet scattering transform and support vector machine model to intelligently identify the most realistic rock fracture signal;

[0085] Step 3.2: Then, each rock fracture microseismic event is located using the array external fracture source location method;

[0086] Step 3.3: Then obtain the time and spatial position of the rock fracture microseismic event, and then calculate the source parameters of the located rock fracture microseismic event, such as the radiation energy of the microseismic event, the microseismic apparent volume, the cumulative number of microseismic events, etc.

[0087] In this embodiment, step 4 determines the fracture state of the rock mass and the rock burst hazard level according to the characteristic parameters of the microseismic signal such as waveform, frequency, and energy. The specific process is as follows:

[0088] The key to setting the early warning management level is to select the source parameters of rock fracture microseismic events that can represent the activity level of rock fracture according to the spatial distribution of microseismic activities in the tunnel under construction, the characteristics of the excavation disturbance area and the construction plan, set certain early warning thresholds, and propose corresponding risk levels.

[0089] In this embodiment, step 5, as Figure 5 As shown in the figure, when the monitoring data is abnormal, the system automatically sends out an early warning signal to remind the construction personnel to take corresponding safety measures;

[0090] Step 5.1: When the rock fracture microseismic event parameters uploaded to the cloud early warning APP reach a certain risk level, an early warning signal will be sent to the mobile phones of on-site staff to achieve real-time early warning of tunnel microseismic monitoring;

[0091] Among them, on-site staff must open their mobile APP 24 hours a day and pay attention to whether there are any APP alarm messages;

[0092] (1) If the APP alarm is triggered, on-site staff should immediately review the situation, including:

[0093] 1) Review whether the APP alarm information comes from rock fracture;

[0094] 2) Review the time and location of rock failure;

[0095] 3) Review whether there is any human interference on site;

[0096] 4) Review the landslide risk level

[0097] Step 5.2: When the landslide risk level is medium risk or above, the on-site staff should issue early warning information in a timely manner. Through mobile phone calls (note to turn on call recording), text messages or WeChat, the early warning information should be promptly conveyed to: the construction manager, the supervision manager, and the owner's designated person in charge.

[0098] Specifically: 1. On-site workers must pay attention to the vehicles coming and going when entering and exiting the cave, and try to walk on both sides of the cave entrance.

[0099] 2. When blasting operations are being carried out on site, on-site staff are prohibited from entering the tunnel to debug microseismic monitoring equipment.

[0100] 3. Workers installing sensors in tunnels must undergo safety briefings and safety education, and wear necessary safety protection equipment such as safety helmets and reflective clothing. Construction is not allowed without wearing safety protection equipment.

[0101] 4. Before entering the cave, you must register and be inspected by the cave entrance staff

[0102] In this embodiment, step 6 is a specific process of dynamically adjusting the next cycle of excavation support measures, such as increasing support strength, changing excavation methods, etc., according to the early warning of the rock burst hazard level:

[0103] 1: Minor rock burst hazard level, excavation method: use smooth blasting technology, strictly control the amount of drugs, reduce the impact of blasting on the surrounding rock, make the excavation section as regular as possible, adopt the "short footage, multiple cycles" excavation method, and control the footage of each cycle within 2.5m. Support measures: strengthen construction support work, spray steel fiber or plastic fiber concrete on the arch and side wall immediately after blasting, add anchor rods and steel mesh, and set up steel arch frames for support when necessary. Lining work is carried out closely following the excavation process to reduce the exposure time of the rock formation.

[0104] 2: Medium rock burst hazard level, excavation method: further shorten the advance, reduce the disturbance of single blasting to the surrounding rock, adopt the construction method of "dense drilling and weak blasting" in the rock burst area, reduce the blasting intensity, support measures: strengthen the support structure, increase the number and length of anchor rods, improve the support strength, add temporary steel supports in the area with severe rock burst, form a joint support system with the shotcrete mesh, strengthen the monitoring of the support structure, and ensure the support effect;

[0105] 3: Strong rock burst hazard level. Excavation method: Suspend excavation operations, reinforce the face, and continue excavation after the risk of rock burst is reduced. If excavation is necessary, adopt extremely small advance and extremely low intensity blasting methods, and strictly control the blasting range. Support measures: Immediately implement comprehensive reinforcement measures, including increasing the density, length and diameter of anchor rods, adding steel supports, etc., cut grooves in the rock wall to release stress, reduce the intensity of rock burst, strengthen monitoring and early warning, and ensure construction safety.

[0106] In this embodiment, the specific process of step 1.4 is:

[0107] Step 1.4.1: Figure 3 As shown, anchor bolt arrangement: when two inverts are made (the face advance is about 20m), the face excavation and drilling stage is explained in advance to the on-site construction personnel, and the holes required for anchor bolt arrangement are reserved in advance in the surrounding rock of the side wall of the face section. Three high, medium and low holes are reserved on the left or right side of the section, and the drilling diameter is about 1.5 times the diameter of the sensor installation. In the initial support stage of the face, communicate with the on-site construction personnel in advance, and lay three exposed long anchor bolts of high, medium and low in the reserved holes on one side (left or right) of the face section, with a buried depth of about 2 to 3m. The anchor bolt arrangement diagram is shown in Figure 3 As shown. If the microseismic signal received by the sensor installed on the long anchor rod is verified by later experiments to be not much different from the signal received by the sensor installed on the short steel bar with a buried depth of about 0.5m, it can be considered to lay out the short steel bar for sensor installation in the later stage to increase installation flexibility and improve work efficiency. The specific location and depth of the anchor rod installation need to be reflected in the drawings and handed over to the construction personnel for the subsequent mobile installation of the probe.

[0108] The anchor rods should be selected with the help of the primary support arch as much as possible and should be inserted deeper into the rock;

[0109] 2. When selecting the anchor position, check the integrity of the surrounding rock at the anchor in advance. Select a relatively complete bedrock as the anchor position.

[0110] Step 1.4.2: Sensor placement: Figure 4 As shown, the spatial positions of the six sensors are staggered as much as possible and placed on different horizontal planes. The longitudinal (Y direction) spacing of the probes on the same side is 5 to 10 meters, and the transverse (X direction) spacing is 20 meters. Since there is an invert between the tunnel face and the tunnel opening, the probe closest to the tunnel face can be placed across the invert to the anchor with the lowest reserved height while ensuring the spacing of the sensor array. The two-core extension line is used. In order to ensure the safety of the probe, the probe can be retracted in advance before the invert blasting, or the probe can be placed on the opposite side of the invert blasting, depending on the specific situation on site. In order to prevent the tunnel face and invert blasting from damaging the signal transmission cable across the invert, the signal transmission cable is wrapped with a smooth cloth-covered explosion-proof hose;

[0111] Before installing the sensor, check whether the anchor rod is firm. If not, refill the area with anchoring agent or cement mortar.

[0112] Step 1.4.3: Probe movement: As the construction of the tunnel face and secondary lining progresses, move the probe that is currently farthest from the tunnel face to the front end (closest to the tunnel face).

[0113] The positions of the probe anchor rods should be staggered left and right, up and down to form a detection array.

[0114] In this embodiment, the specific process of step 3.3 is:

[0115] The sensor array formed by six microseismic sensors monitors rock fracture activities near the face during tunnel construction 24 hours a day. The signals are transmitted via a two-core cable to an eight-core cable laid parallel to the tunnel axis. The eight-core cable is connected to a signal fidelity box in a central server near the tunnel entrance, and then to a collector via a channel cable. The data is then transmitted wirelessly to the microseismic monitoring cloud platform.

[0116] In this embodiment, in step 2, a data acquisition line is pre-buried at the tunnel floor, and the installed microseismic sensor is connected to the microseismic monitoring device through the data acquisition line. The specific process is as follows:

[0117] Step 2.1: On-site staff carry the required eight-core wire to the designated location and cut the corresponding length of the eight-core wire;

[0118] Step 2.2: On-site staff need to install the cables according to the following wiring mode. The positive pole is connected to the red wire of the eight-core wire, and the negative pole is connected to the white wire of the eight-core wire. It is necessary to avoid contaminating the connector and causing abnormal reception of signals.

[0119] 1. On-site signal transmission cables should be arranged reasonably to avoid interfering with the normal operations of construction personnel.

[0120] 2. When wiring, avoid the connectors being contaminated by dust and sand on site to ensure the accuracy of the transmitted signal.

[0121] 3. An emergency power supply should be available on site to prevent the microseismic monitoring equipment from stopping working due to power outages on site.

[0122] Step 2.3: After installation, calibrate the oscilloscope instrument;

[0123] Step 2.4: After the equipment is connected, the data server needs to be set up to achieve effective transmission of microseismic data;

[0124] Step 2.5: After connecting and collecting, observe the indicator light on the signal acquisition instrument and perform subsequent operations according to the indicator light.

[0125] In this embodiment, the specific process of microseismic signal denoising in step 3.1 is as follows:

[0126] Step 3.1.1: Through the on-site inspection of the construction situation by on-site personnel, the construction procedures at different times are recorded, and the corresponding different microseismic source signal waveforms are obtained and analyzed;

[0127] Step 3.1.2: Analyze the time-frequency characteristics of the signal through continuous wavelet transform;

[0128] Step 3.1.3: Extract signals with typical features through discrete wavelet transform;

[0129] Step 3.1.4: Obtain characteristic parameters of typical signals through wavelet scattering transform and establish a sample database;

[0130] Step 3.1.5: Based on the support vector machine model, the model is trained by building a good sample database to establish a neural network model that can filter and analyze the original microseismic signals.

[0131] It should be noted that the control method of the present application can be automatically controlled by a controller, and the control method of the controller can be implemented by simple programming by technicians in this field, which is common knowledge in this field, and the present application is mainly used to protect mechanical structures, so the present application will no longer explain the control method and circuit connection in detail.

[0132] In summary, the tunnel microseismic monitoring construction method of the embodiment of the present application and the positive step tunnel microseismic monitoring construction method solve the problem that the traditional tunnel collapse monitoring means cannot timely reflect the real stability of the surrounding rock and it is difficult to detect the internal crack expansion trend and dynamic characteristics before the rock mass deforms and becomes unstable in advance; the proposed sensor arrangement scheme is combined with the on-site construction process, which not only realizes 24-hour uninterrupted monitoring, but also greatly improves the efficiency of sensor arrangement; reduces the complexity and uncertainty brought by manual identification of microseismic signals, and realizes the intelligentization and automation of the collapse disaster monitoring and early warning process; determines a set of collapse risk level determination standards suitable for microseismic monitoring of this project, Providing a scientific basis for the targeted prevention and control of tunnel collapse, the microseismic monitoring of the positive step tunnel can realize the effective short-term forecast of sudden collapse of large-volume rock mass in the tunnel, avoid damage to construction equipment or casualties of construction personnel, and thus cause unnecessary economic losses. At the same time, this method adopts intelligent real-time automatic monitoring. Compared with traditional tunnel collapse monitoring, it saves labor costs and improves monitoring efficiency. The microseismic monitoring of the positive step tunnel can scientifically and effectively implement all-weather real-time monitoring of rock microseismic activities in the risk area of ​​the tunnel, and can provide real-time early warning for tunnel collapses of different risk levels, effectively ensuring construction safety and providing valuable experience for tunnel collapse monitoring with similar excavation methods.

[0133] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0134] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0135] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and deform the above embodiments within the scope of the present application.

Claims

1. A tunnel microseismic monitoring construction method, characterized in that: The method comprises the following steps: Step 1: Install microseismic sensors along the tunnel wall within a predetermined distance behind the tunnel face; Step 2: Pre-embed the data acquisition line at the tunnel floor, and connect the installed microseismic sensors to the microseismic monitoring equipment through the data acquisition line. Step 3: Establish a real-time microseismic monitoring system and early warning system for rockbursts, and perform real-time analysis and processing of the collected microseismic activity data; Step 4: Determine the fracture state of the rock mass and the risk level of rock burst based on the waveform, frequency, energy and other characteristic parameters of the microseismic signal; Step 5: When the monitoring data is abnormal, the system automatically sends out an early warning signal to remind the construction personnel to take corresponding safety measures; Step 6: According to the early warning of the rock burst hazard level, dynamically adjust the support measures for the next cycle of excavation, such as increasing the support strength, changing the excavation method, etc.; Step 7: Regularly summarize and analyze monitoring data, evaluate monitoring results and provide feedback to the monitoring plan to optimize and adjust the monitoring plan.

2. The tunnel microseismic monitoring construction method according to claim 1 is characterized in that: The specific process of installing the microseismic sensor in step 1 is as follows: Step 1.1: Clarify the purpose of tunnel microseismic monitoring, such as predicting geological disasters such as rock bursts and sudden water inrush, or evaluating the impact of tunnel excavation on the surrounding rock mass; Step 1.2: Design a reasonable monitoring plan based on the geological conditions, construction methods and monitoring objectives of the tunnel, including sensor type, quantity, and layout location; Step 1.3: According to the monitoring plan, multiple rings of microseismic sensors are installed along the tunnel wall within a predetermined distance behind the tunnel face to fully cover the possible monitoring area; Step 1.4: Install the microseismic sensors at the predetermined positions according to the design requirements. The main installation method of the microseismic sensors is to stagger the sensors in space and keep up with the movement of the face.

3. The tunnel microseismic monitoring construction method according to claim 1 is characterized in that: The specific process of real-time analysis and processing of the microseismic activity data collected in step 3 is as follows: Step 3.1: First, filter out the background noise of the original microseismic signal, and use the combination of wavelet scattering transform and support vector machine model to intelligently identify the most realistic rock fracture signal; Step 3.2: Then, each rock fracture microseismic event is located using the array external fracture source location method; Step 3.3: Then obtain the time and spatial position of the rock fracture microseismic event, and then calculate the source parameters of the located rock fracture microseismic event, such as the radiation energy of the microseismic event, the microseismic apparent volume, the cumulative number of microseismic events, etc.

4. The tunnel microseismic monitoring construction method according to claim 1 is characterized in that: The specific process of step 4 is to judge the fracture state of the rock mass and the rock burst hazard level according to the characteristic parameters of the microseismic signal such as waveform, frequency, energy, etc.: The key to setting the early warning management level is to select the source parameters of rock fracture microseismic events that can represent the activity level of rock fracture according to the spatial distribution of microseismic activities in the tunnel under construction, the characteristics of the excavation disturbance area and the construction plan, set certain early warning thresholds, and propose corresponding risk levels.

5. The tunnel microseismic monitoring construction method according to claim 1 is characterized in that: In step 5, when the monitoring data is abnormal, the system automatically sends out an early warning signal to remind the construction personnel to take corresponding safety measures; Step 5.1: When the rock fracture microseismic event parameters uploaded to the cloud early warning APP reach a certain risk level, an early warning signal will be sent to the mobile phones of on-site staff to achieve real-time early warning of tunnel microseismic monitoring; Step 5.2: When the landslide risk level is medium or above, the on-site staff should issue early warning information in a timely manner. Through mobile phone calls (note to turn on call recording), text messages or WeChat, the early warning information should be promptly conveyed to: the person in charge of construction, the person in charge of supervision, and the person designated by the owner.

6. The tunnel microseismic monitoring construction method according to claim 1 is characterized in that: The specific process of step 6 is to dynamically adjust the support measures for the next excavation cycle according to the early warning of the rock burst danger level, such as increasing the support strength, changing the excavation method, etc.: 1: Minor rock burst hazard level, excavation method: use smooth blasting technology, strictly control the amount of drugs, reduce the impact of blasting on the surrounding rock, make the excavation section as regular as possible, adopt the "short footage, multiple cycles" excavation method, and control the footage of each cycle within 2.5m. Support measures: strengthen construction support work, spray steel fiber or plastic fiber concrete on the arch and side wall immediately after blasting, add anchor rods and steel mesh, and set up steel arch frames for support when necessary. Lining work is carried out closely following the excavation process to reduce the exposure time of the rock formation. 2: Medium rock burst hazard level, excavation method: further shorten the footage, reduce the disturbance of single blasting to the surrounding rock, adopt the construction method of "dense drilling and weak blasting" in the rock burst area to reduce the blasting intensity, support measures: strengthen the support structure, increase the number and length of anchor rods, improve the support strength, add temporary steel supports in the area with severe rock burst, form a joint support system with the shotcrete mesh, strengthen the monitoring of the support structure, and ensure the support effect; 3: Strong rock burst hazard level. Excavation method: Suspend excavation operations, reinforce the face, and continue excavation after the risk of rock burst is reduced. If excavation is necessary, adopt extremely small advance and extremely low intensity blasting methods, and strictly control the blasting range. Support measures: Immediately implement comprehensive reinforcement measures, including increasing the density, length and diameter of anchor rods, adding steel supports, etc., cut grooves in the rock wall to release stress, reduce the intensity of rock burst, strengthen monitoring and early warning, and ensure construction safety.

7. The tunnel microseismic monitoring construction method according to claim 1 is characterized by: The specific process of step 1.4 is as follows: Step 1.4.1: Anchor bolt layout: When two inverts are made (the face advance is about 20m), the construction personnel on site shall be informed in advance during the excavation and drilling stage of the face. The holes required for anchor bolt layout shall be reserved in advance in the surrounding rock of the side wall of the face section. Three holes of high, medium and low shall be reserved on the left or right side of the section. The diameter of the drill hole is about 1.5 times the diameter of the installed sensor. Communicate with the construction personnel on site in advance during the initial support stage of the face. Three exposed long anchor bolts of high, medium and low shall be laid in the reserved holes on one side (left or right) of the face section. The buried depth is about 2 to 3m. If the microseismic signal received by the sensor installed on the long anchor bolt is verified by the later experiments to be not much different from the signal received by the short steel bar installed at a buried depth of about 0.5m, the short steel bar can be considered to be laid for sensor installation in the later stage to increase installation flexibility and improve work efficiency. The specific location and depth of the anchor bolt installation need to be reflected in the drawings and explained to the construction personnel to facilitate the subsequent mobile installation of the probe; Step 1.4.2: Sensor arrangement: The spatial positions of the six sensors are staggered as much as possible and placed on different horizontal planes. The longitudinal (Y direction) spacing of the probes on the same side is 5 to 10 meters, and the transverse (X direction) spacing is 20 meters. Since there is an invert between the tunnel face and the tunnel opening, the probe closest to the tunnel face can be placed across the invert to the anchor with the lowest reserved height while ensuring the spacing of the sensor array. The two-core extension line is used. In order to ensure the safety of the probe, you can choose to retract the probe in advance before the invert blasting, or place the probe on the opposite side of the invert blasting, depending on the specific situation on site. In order to prevent the tunnel face and invert blasting from damaging the signal transmission cable across the invert, use a smooth cloth-covered explosion-proof hose to wrap the signal transmission cable; Step 1.4.3: Probe movement: As the construction of the tunnel face and secondary lining progresses, move the probe that is currently farthest from the tunnel face to the front end (closest to the tunnel face).

8. The tunnel microseismic monitoring construction method according to claim 1 is characterized by: The specific process of step 3.3 is as follows: The sensor array formed by six microseismic sensors monitors rock fracture activities near the face during tunnel construction 24 hours a day. The signals are transmitted via a two-core cable to an eight-core cable laid parallel to the tunnel axis. The eight-core cable is connected to a signal fidelity box in a central server near the tunnel entrance, and then to a collector via a channel cable. The data is then transmitted wirelessly to the microseismic monitoring cloud platform.

9. The tunnel microseismic monitoring construction method according to claim 1, characterized in that: The step 2 is to pre-embed a data acquisition line at the tunnel floor, and connect the installed microseismic sensor to the microseismic monitoring device through the data acquisition line. The specific process is: Step 2.1: On-site staff carry the required eight-core wire to the designated location and cut the corresponding length of the eight-core wire; Step 2.2: On-site staff need to install the cables according to the following wiring mode. The positive pole is connected to the red wire of the eight-core wire, and the negative pole is connected to the white wire of the eight-core wire. It is necessary to avoid contaminating the connector and causing abnormal reception of signals. Step 2.3: After installation, calibrate the oscilloscope instrument; Step 2.4: After the equipment is connected, the data server needs to be set up to achieve effective transmission of microseismic data; Step 2.5: After connecting and collecting, observe the indicator light on the signal acquisition instrument and perform subsequent operations according to the indicator light.

10. The tunnel microseismic monitoring construction method according to claim 1, characterized in that: The specific process of microseismic signal denoising in step 3.1 is as follows: Step 3.1.1: Through the on-site inspection of the construction situation by on-site personnel, the construction procedures at different times are recorded, and the corresponding different microseismic source signal waveforms are obtained and analyzed; Step 3.1.2: Analyze the time-frequency characteristics of the signal through continuous wavelet transform; Step 3.1.3: Extract signals with typical features through discrete wavelet transform; Step 3.1.4: Obtain characteristic parameters of typical signals through wavelet scattering transform and establish a sample database; Step 3.1.5: Based on the support vector machine model, the model is trained by building a good sample database to establish a neural network model that can filter and analyze the original microseismic signals.

Images