Active prevention and control method for inoculation process of fracture-type rock burst in deep-buried tunnel

Abstract

The present invention relates to the technical field of rock burst prevention and control of deep-buried tunnels, and provides an active prevention and control method for an inoculation process of a fracture-type rock burst in a deep-buried tunnel. The method comprises: before fracture exposure, determining whether a fracture is distributed in front of a tunnel face, a fracture attitude, a chainage at which the fracture intersects a tunnel crown, and a direction in which the tunnel traverses fracture; a tensile crack initiation stage: on the basis of a cumulative apparent volume sudden increase rate of adjacent microseismic events, determining a time of taking measures for reducing stress concentration of the tunnel surrounding rock, to inhibit generation of tensile crack; a crack propagation stage: on the basis of a K value growth rate, determining a time of drilling stress-relief holes in the fracture, to release the confined stress near the fracture; a crack accumulation-fracture slip stage: installing shear-resistant anchor rods in the fracture, to suppress crack penetration and fracture slip; and after the tunnel surrounding rock and the fracture are locked and before the fracture is exposed on the tunnel face, taking appropriate measures on the basis of a fracture-type rock burst risk level until the tunnel face safely advances through the fracture. The number of arches used is reduced while engineering safety is ensured, and economic costs are reduced.

Description

A proactive prevention and control method for the incubation process of fracture-type rockburst in deep-buried tunnels Technical Field

[0001] This invention relates to the field of rockburst prevention and control technology for deep-buried tunnels, and in particular to an active prevention and control method for the incubation process of fracture-type rockbursts in deep-buried tunnels. Background Technology

[0002] During the excavation of deep-buried tunnels, the tunnels often pass through fracture structures or large structural planes, resulting in fracture-type rockbursts. Fracture-type rockbursts have a large impact area and strong destructive force, and may even induce continuous and intense or extremely intense rockbursts, causing sudden accidents, equipment damage, and serious delays in the construction period. Therefore, implementing safe and economical prevention and control measures for fracture-type rockbursts is crucial to ensuring the safe construction of deep-buried tunnels.

[0003] Currently, the main methods for rockburst prevention and control include stress relief and anchor bolt support technologies. Examples include patents such as "Active Rockburst Prevention and Control System" (patent number CN202310498496.9), "An Instantaneous Active Rockburst Prevention and Control Method for Deep-Buried Tunnels" (patent number CN201810031286.8), "A Prevention and Control Structure for Rockburst Tunnels" (patent number CN202310498734.6), and "Rockburst Control and Design Method" (patent number CN202310494561.0). These inventions differentiate rockburst levels and employ stress relief and anchor bolt support techniques accordingly. Techniques such as anchor cable support have proven effective in preventing rockbursts, particularly those caused by high stress, such as strain-type rockbursts. However, for fracture-type rockbursts, if their development cannot be prevented before excavation, relying solely on strong support measures after excavation or only applying stress relief and conventional system support in high-stress areas is insufficient to effectively prevent their occurrence. Furthermore, after excavation, a fracture-type rockburst may have already occurred, making timely strong support impossible, leading to serious consequences such as unexpected accidents, equipment damage, and project delays.

[0004] Therefore, a method for actively controlling the incubation process of rockburst in tunnel fracture is needed. Summary of the Invention

[0005] In view of this, the present invention provides an active prevention and control method for the incubation process of fracture-type rockburst in deep-buried tunnels. Based on microseismic information, the fracture occurrence and location are identified in advance, and stress release and support measures are implemented in advance according to the fracture occurrence, location and incubation process. The surrounding rock stress and the sealing stress near the fracture are pre-released to reduce the degree of fracture of the surrounding rock and near the fracture, further lock the fracture, reduce the risk of fracture initiation, and achieve the purpose of controlling the incubation process of fracture-type rockburst.

[0006] Therefore, the present invention provides the following technical solution:

[0007] A method for proactively preventing and controlling the incubation process of fracture-type rockburst in deep-buried tunnels includes:

[0008] By deploying a microseismic monitoring system behind the tunnel face, microseismic events during the excavation process are monitored in real time. Before the fault is exposed, the microseismic event information is used to determine whether there are faults in front of the tunnel face, as well as the orientation of the faults, the mileage of the faults intersecting with the tunnel arch, and the direction in which the tunnel crosses the faults.

[0009] The severity and incubation stage of fracture-type rockbursts can be determined by microseismic event information.

[0010] Based on the risk level of fracture-type rockburst, the incubation stage of fracture-type rockburst, and the direction of the tunnel crossing the fracture, the prevention and control measures for fracture-type rockburst are dynamically adjusted:

[0011] During the rupture initiation stage, the timing of measures to reduce stress concentration in the surrounding rock of the tunnel is determined based on the cumulative apparent volume increase rate of adjacent microseismic events, thereby suppressing the occurrence of tension rupture.

[0012] During the fracture propagation stage, the timing of stress relief holes is selected based on the growth rate of the K value to release the closed stress near the fracture.

[0013] During the fracture accumulation-fracture slip stage, depending on the distance between the tunnel face and the fracture, shear anchors or anchor cables are installed to lock the surrounding rock of the tunnel and the fracture, thereby preventing fracture penetration and fracture slip.

[0014] After the surrounding rock of the tunnel is locked with the fracture and before the fracture is exposed at the working face, corresponding measures are taken according to the risk level of fracture-type rockburst until the working face passes through the fracture.

[0015] Furthermore, the microseismic event information includes:

[0016] The number of microseismic events, the energy released by microseismic events, and the three-dimensional coordinates of rock fracturing events in space.

[0017] Furthermore, prior to the exposure of the fracture, the determination of whether fractures are distributed ahead of the tunnel face based on microseismic event information, as well as the fracture orientation, the mileage intersecting with the tunnel arch, and the direction in which the tunnel crosses the fracture, includes:

[0018] Based on the three-dimensional spatial coordinates of the rock fracture event and the microseismic release energy, a cloud map of the spatial distribution of the rock fracture event and the microseismic release energy in front of the tunnel face is drawn by interpolation.

[0019] When the rock fracture event space and the microseismic energy release distribution cloud map have linear or strip distribution characteristics, it is determined that there is a fracture in front of the tunnel face. Connecting the extreme points into a line indicates the fracture and obtains the spatial information of the fracture.

[0020] The orientation of the fracture, the mileage of the intersection with the tunnel arch, and the direction in which the tunnel crosses the fracture are determined based on the spatial information of the fracture.

[0021] The directions in which the tunnel crosses the fracture include tunneling from the upper plate to the lower plate and from the lower plate to the upper plate.

[0022] Furthermore, the fracture-type rockburst grade includes:

[0023] Rockbursts can be categorized into non-fractured rockbursts, slightly fractured rockbursts, moderately fractured rockbursts, severely fractured rockbursts, and extremely severely fractured rockbursts.

[0024] Furthermore, the determination of the incubation stage of fracture-type rockburst through microseismic event information includes:

[0025] If the number of cumulative microseismic events per day is less than 20, and all of them are tensile ruptures with release energies of less than 1000J, then it is judged to be in the rupture initiation stage.

[0026] When the cumulative number of microseismic events per day is 20 to 40, and includes more than 3 rupture events with a release energy higher than 1000J, it is judged to be in the rupture propagation stage.

[0027] When the cumulative number of microseismic events per day is greater than 40, and includes more than one shear rupture event with a release energy higher than 10,000 J, it is judged to be in the rupture accumulation-fracture slip stage.

[0028] Furthermore, during the rupture initiation stage, determining the timing of measures to reduce stress concentration in the tunnel surrounding rock based on the cumulative apparent volume surge rate of adjacent microseismic events, and suppressing the generation of tension rupture, includes:

[0029] If the rockburst is identified as a medium-sized fracture rockburst and the cumulative apparent volume surge rate of adjacent microseismic events is greater than 45%, reduce the tunneling rate.

[0030] When a rockburst is identified as a severe fracture rockburst or an extremely severe fracture rockburst, and the cumulative apparent volume increase rate of adjacent microseismic events is greater than 45%, the tunneling rate should be reduced, and radial stress relief holes should be installed perpendicular to the surrounding rock surface.

[0031] The depth of the stress relief hole exceeds the depth of the microseismic event concentration zone.

[0032] Furthermore, during the fracture propagation stage, selecting the timing for arranging stress relief holes based on the K-value growth rate to release the closed stress near the fracture includes:

[0033] When the direction of tunnel crossing the fracture is that the tunnel is excavated from the upper plate to the lower plate of the fracture, and the K value growth rate is greater than 15%, stress relief holes are arranged in the upper plate of the fracture, and the depth of the stress relief holes exceeds the stress concentration zone.

[0034] When the direction of tunnel crossing the fracture is that the tunnel is excavated from the lower plate to the upper plate of the fracture, and the K value growth rate is greater than 17%, stress relief holes are arranged on the fracture surface, and the depth of the stress relief holes exceeds the fracture surface.

[0035] Furthermore, during the fracture accumulation-fracture slip stage, based on the distance between the tunnel face and the fracture, shear anchors or anchor cables are applied to lock the tunnel surrounding rock and the fracture, thereby inhibiting fracture penetration and fracture slip, including:

[0036] When the tunnel passes through the fracture in the direction of tunnel excavation from the upper plate to the lower plate of the fracture, shear anchors or anchor cables should be used to pass through the fracture surface 0.8 times the tunnel diameter in advance;

[0037] When the direction of tunnel crossing the fracture is that the tunnel is excavated from the lower plate to the upper plate of the fracture, shear anchors or anchor cables are used to pass through the fracture surface in advance with a tunnel diameter of 1.

[0038] The angle between the shear anchor or anchor cable and the fracture surface is greater than 45°.

[0039] Furthermore, after the tunnel surrounding rock and fracture locking are completed and before the fracture is exposed at the tunnel face, taking corresponding measures according to the fracture-type rockburst risk level until the tunnel face passes through the fracture includes:

[0040] The risk level of fracture-type rockburst has been reduced to medium or below. Arch support is not required. Microseismic activity is monitored until the working face safely passes through the fracture zone.

[0041] The risk level of fracture-type rockburst is strong or above, and arch support is used according to the direction of the tunnel face crossing the fracture.

[0042] Furthermore, the arch support according to the direction of the tunnel crossing the fracture includes:

[0043] When the direction of the tunnel face through the fracture is such that the tunnel face passes through the hanging wall of the fracture, the arch frame is installed when the tunnel face is 0.5 times the tunnel diameter away from the fracture, until the tunnel face passes through the fracture to a distance of 0.8 times the tunnel diameter.

[0044] When the tunnel face passes through the fracture in the direction that the tunnel face passes through the fracture underside, the arch frame is installed when the tunnel face is 0.8 times the tunnel diameter away from the fracture, until the tunnel face passes through the fracture 0.5 times the tunnel diameter.

[0045] Advantages and positive effects of the present invention:

[0046] (1) This invention identifies the fracture occurrence, location and the way it crosses the fracture in advance through microseismic monitoring, and carries out stress release in advance during the incubation of fracture-type rockburst to reduce the stress concentration, install shear anchors, reduce the tendency of rock mass fracture expansion, effectively curb the incubation of fracture-type rockburst and reduce the risk of rockburst.

[0047] (2) Take proactive prevention and control measures during the incubation of fracture-type rockbursts to reduce the demand and quantity of rigid support measures such as arch frames, thereby significantly reducing economic costs and construction risks.

[0048] (3) Continuously monitor the risk of fracture rockburst during tunnel excavation through microseismic monitoring, and provide operation parameters and timing for arch support measures to reduce economic costs while ensuring project safety. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 is a flowchart of the implementation of the fracture-type rockburst prevention and control design method in an embodiment of the present invention;

[0051] Figure 2 is a distribution diagram of rock fracture events during the tunnel fracture-type rockburst incubation process in an embodiment of the present invention;

[0052] Figure 3 is a cloud map showing the distribution of microseismic energy release during a rock fracture event in an embodiment of the present invention.

[0053] Figure 4 is a schematic diagram of active prevention and control of fracture-type rockburst during the tension fracture initiation stage in an embodiment of the present invention;

[0054] Figure 5 is a schematic diagram of active prevention and control of fracture-type rockburst during the fracture propagation stage in this embodiment; where a represents tunneling from the hanging wall to the footwall, and b represents tunneling from the footwall to the hanging wall;

[0055] Figure 6 is a schematic diagram of active prevention and control of fracture-type rockburst during the fracture accumulation-fracture slip stage in this embodiment; where a represents tunneling from the hanging wall to the footwall, and b represents tunneling from the footwall to the hanging wall. Detailed Implementation

[0056] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0057] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0058] This invention provides an active prevention and control method for the incubation process of fracture-type rockburst in deep-buried tunnels, as shown in Figure 1, which mainly includes the following steps.

[0059] S1. A microseismic monitoring system is installed behind the tunnel face to capture continuous microseismic information during the tunnel excavation process, identify rock fracture events, accurately locate the rock fracture events, and calculate the microseismic release energy.

[0060] In this embodiment, the location of the rock fracture event includes the three-dimensional coordinates of the event in space;

[0061] S2. Based on the spatial location of rock fracture events in S1, use interpolation to draw and analyze in real time the spatial distribution cloud map of rock fracture events and microseismic energy release in front of the tunnel face. At the same time, combine the rock debris information to determine whether there are fractures in front of the tunnel face.

[0062] In this embodiment, if the spatial distribution of rock fracture events and the distribution cloud map of microseismic release energy have linear or strip-like distribution characteristics, it indicates that there are fractures in front of the tunnel face and a potential risk of fracture-type rockburst.

[0063] When the angle between the fracture and the tunnel excavation direction is less than 30°, it is difficult to determine whether there is a fracture in front of the tunnel face based on the spatial distribution of rock fracture events and the microseismic energy release cloud map. At this time, the fracture can be exposed earlier, and it is possible to observe whether the rock debris contains rock blocks with fractures, thus determining the risk of fracture-type rockburst.

[0064] S3. Based on the spatial distribution of rock fracture events, the cloud map of microseismic energy release, and tunnel excavation information in S2, determine the fracture orientation, mileage, and the direction in which the tunnel crosses the fracture.

[0065] Based on the linear or strip-shaped distribution characteristics of the spatial and microseismic energy release cloud map of rock fracture events shown in S2, the extreme points of the cloud map connected to form a line represent the fracture, thus determining the fracture orientation, the mileage intersecting with the tunnel arch, and the direction in which the tunnel crosses the fracture.

[0066] In this embodiment, the tunnel crossing the fracture includes tunneling from the hanging wall to the footwall and from the footwall to the footwall. Because the risk and development process of fracture-type rockbursts differ significantly under different fracture crossing directions, it is essential to distinguish the direction of the tunnel crossing the fracture.

[0067] S4. Determine the potential risk level of fracture-type rockburst by microseismic activity during the incubation process of fracture-type rockburst;

[0068] The risk levels of fracture-type rockbursts include no rockburst, minor rockburst, moderate rockburst, severe rockburst, and extremely severe rockburst. This invention is mainly for fracture-type rockburst operations with moderate and higher risk levels.

[0069] S5. Based on the distance between the tunnel face and the fault and the changes in the stages of the fault-type rockburst incubation process, and considering the direction of the tunnel crossing the fault and the rockburst risk level, dynamically adjust the prevention and control measures taken for proactive prevention and control of fault-type rockburst.

[0070] Compared to tunneling from the hanging wall to the footwall of a fault, rockburst prevention measures are implemented earlier when tunneling from the footwall to the footwall. This is because fracture-type rockbursts begin to develop earlier and pose a higher risk when tunneling from the footwall to the footwall.

[0071] Active prevention and control of fracture-type rockbursts can be divided into three stages, and the criteria for judgment include:

[0072] The rupture initiation stage is the initial stage of fracture-type rockburst incubation, mainly characterized by tensile rupture with energy below 1000J, and the cumulative number of microseismic events per day is less than 20.

[0073] The rupture propagation stage is the intermediate stage of the fracturing rockburst incubation process. Microseismic events increase rapidly, including a certain number of rupture events with energy higher than 1000J. The cumulative number of microseismic events per day is between 20 and 40.

[0074] The rupture accumulation-fracture slip stage is the final stage of the fracture-type rockburst incubation process, during which microseismic events increase sharply, including a certain number of shear rupture events with energy higher than 10,000 J, with the cumulative number of microseismic events exceeding 40 per day.

[0075] The first stage, S5.1, is the tension fracture initiation stage. This stage primarily involves measures to reduce stress concentration in the tunnel surrounding rock and suppress tension fracture. Tension fracture is a trigger for fracture propagation near the fracture site; suppressing tension fracture reduces the likelihood of fracture propagation. The specific timing of the operation is determined using the cumulative apparent volume surge rate (CAVG) of adjacent microseismic events.

[0076] Where: AV c AV represents the apparent microseismic volume of the current microseismic event. pFor the apparent microseismic volume of the previous microseismic event, AV a This represents the cumulative apparent volume of microseismic events up to the present.

[0077] The cumulative apparent volume surge rate of adjacent microseismic events during the fracture-type rockburst incubation process is calculated in real time. When this rate exceeds 45%, measures are taken. A surge in cumulative apparent volume indicates that the fracture is beginning to be affected by excavation disturbance.

[0078] For moderately fractured rockbursts, measures to reduce the tunneling rate are adopted. For severe and extremely severe fractured rockbursts, in addition to reducing the tunneling rate, radial stress relief holes need to be drilled perpendicular to the surrounding rock surface. The depth of the holes should exceed the depth of the microseismic event concentration zone to reduce the surrounding rock stress and inhibit the initiation of tensile fractures. At this stage, the difference in surrounding rock stress in different tunneling directions is not significant, and there is no need to distinguish between tunneling directions.

[0079] S5.2 The second stage is the fracture propagation stage. This stage mainly involves measures to release the closure stress near the fracture, reduce superimposed stress, and inhibit fracture propagation near the fracture. The specific timing of these measures is determined by the K-value growth rate.

[0080] Where: K a Let K be the value of K at the current moment. b This represents the K value at the previous adjacent time point. The K value is the ratio of cumulative apparent stress to cumulative dynamic stress drop. A rapid increase in the K value indicates that the fracture is further affected and has a tendency to shift.

[0081] The K-value growth rate is calculated in real time. When the tunnel is excavated from the hanging wall to the footwall of the fracture, if ΔK exceeds 15%, pre-stress relief holes are installed on the hanging wall, with the hole depth exceeding the stress concentration zone. When the tunnel is excavated from the footwall to the footwall of the fracture, if ΔK exceeds 17%, pre-stress relief holes are installed on the fracture surface, with the hole depth exceeding the fracture surface. For severe and extremely severe rockburst fractures, the number of stress relief holes is appropriately increased.

[0082] The third stage, S5.3, is the fracture accumulation-fracture slip stage. This stage primarily involves measures to anchor the surrounding rock and fracture, preventing fracture penetration and slippage. When the tunnel is excavated from the hanging wall to the footwall of the fracture, shear anchors / cables are used to cross the fracture surface 0.8 times the tunnel diameter in advance. When the tunnel is excavated from the footwall to the footwall of the fracture, shear anchors / cables are used to cross the fracture surface 1 time the tunnel diameter in advance.

[0083] The shear anchor bolts / cables intersect the fracture surface at the largest possible angle. Preferably, the angle is greater than 45°. For severe and extremely severe rockbursts, the number of anchor bolts / cables should be appropriately increased.

[0084] S6. When the working face is about to expose a fracture, closely monitor microseismic activity during construction.

[0085] S6.1 If, through the aforementioned proactive prevention and control measures, microseismic monitoring shows that the risk of fracture-type rockburst has decreased to moderate or below, other support measures may not be taken for the time being. Instead, attention should be paid to microseismic activity until the working face safely passes through the fracture zone.

[0086] S6.2 If microseismic monitoring indicates a continued risk of strong or higher-level fracture-type rockburst, arch support is required. When the tunnel face passes through the hanging wall of the fracture, arch support installation should begin when the tunnel face is 0.5 times the tunnel diameter away from the fracture, and continue until the tunnel face passes through the fracture to a distance of 0.8 times the tunnel diameter. When the tunnel face passes through the footwall of the fracture, arch support installation should begin when the tunnel face is 0.8 times the tunnel diameter away from the fracture, and continue until the tunnel face passes through the fracture to a distance of 0.5 times the tunnel diameter.

[0087] The method of the present invention will be further illustrated by specific application examples:

[0088] This example describes a deep-buried TBM granite tunnel with a diameter of 7 meters. The tunnel's lithology is primarily Hercynian granite interbedded with biotite granite, characterized by hardness, integrity, and stability. On June 25, 2021, during tunnel face excavation to a certain mileage, a significant striped distribution of microseismic events and microseismic energy release was observed ahead of the tunnel face, as shown in Figures 2 and 3. Figures 2 and 3 represent the following: 1. Rock fracturing events; 2. Tunnel; 3. Fault; 4. Striped distribution area of ​​rock fracturing events. This indicates the presence of a fault ahead of the tunnel face, posing a potential risk of severe fault-induced rockburst, and the tunnel face passes through the hanging wall of the fault.

[0089] In this embodiment, the risk level of fracture-type rockburst is predicted using a deep convolutional neural network model based on the collected microseismic event information.

[0090] During the tension fracture initiation stage: At 16:32 on June 25, 2021, microseismic monitoring showed that CAVG > 45%. Energy reduction measures were adopted on site to reduce the TBM tunneling rate, which was reduced from 3.47m / 4h to 1.45m / 4h. At the same time, stress relief holes were constructed in the surrounding rock. Based on the spatial distribution characteristics of microseismic events, radial stress relief holes were arranged at the 10 o'clock and 11:30 azimuths, with a hole depth of 3.5m. At this time, the tunnel face was about 1.8D away from the fracture, as shown in Figure 4.

[0091] During the fracture propagation stage: As the TBM continued to advance, at 14:56 on June 26, microseismic monitoring showed that ΔK = 16.68% > 15%, at which point the tunnel face was approximately 1.2D away from the fracture. As shown in Figure 5a, stress relief holes were drilled into the hanging wall of the fracture, with a depth of approximately 8m.

[0092] During the fracture accumulation-fracture slip stage: at 12:00 on June 27, shear anchors were used to penetrate the fracture surface at a large angle. At this time, the working face was about 0.7D away from the fracture, as shown in Figure 6a.

[0093] At 4:00 AM on June 28, the excavation face revealed a fracture. During the excavation, micro-vibration activity was weak, and no arch support was installed. The excavation team then safely passed through the fracture area.

[0094] The method of this invention can identify the fracture occurrence and location in advance, and design targeted step-by-step stress release and support measures in advance based on the fracture occurrence and location. The timing of the implementation of prevention and control measures can be determined according to its incubation process, thereby curbing its fracture propagation and fracture slip, and realizing active and precise prevention and control of fracture-type rockburst.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for proactively preventing and controlling the incubation process of fracture-type rockburst in deep-buried tunnels, characterized in that, include: A microseismic monitoring system deployed behind the tunnel face is used to monitor microseismic events in real time during the excavation process. Before the fault is exposed, microseismic event information is used to determine whether there are faults in front of the tunnel face, as well as the orientation of the faults, the mileage of the intersection with the tunnel arch, and the direction in which the tunnel crosses the faults. The severity and incubation stage of fracture-type rockbursts can be determined by microseismic event information. Based on the risk level of fracture-type rockburst, the incubation stage of fracture-type rockburst, and the direction of the tunnel crossing the fracture, the prevention and control measures for fracture-type rockburst are dynamically adjusted: During the rupture initiation stage, the timing of measures to reduce stress concentration in the surrounding rock of the tunnel is determined based on the cumulative apparent volume increase rate of adjacent microseismic events, thereby suppressing the occurrence of tension rupture. During the fracture propagation stage, the timing of stress relief holes is selected based on the growth rate of the K value to release the closed stress near the fracture. During the fracture accumulation-fracture slip stage, depending on the distance between the tunnel face and the fracture, shear anchors or anchor cables are installed to lock the surrounding rock of the tunnel and the fracture, thereby preventing fracture penetration and fracture slip. After the surrounding rock of the tunnel is locked with the fracture and before the fracture is exposed at the working face, corresponding measures are taken according to the risk level of fracture-type rockburst until the working face passes through the fracture.

2. The active prevention and control method for the incubation process of fracture-type rockburst in deep-buried tunnels according to claim 1, characterized in that, The microseismic event information includes: The number of microseismic events, the energy released by microseismic events, and the three-dimensional coordinates of rock fracturing events in space.

3. The active prevention and control method for the fracturing rockburst incubation process of deep-buried tunnels according to claim 1, characterized in that, Before the fracture is exposed, information from microseismic events is used to determine whether fractures are distributed ahead of the tunnel face, the orientation of the fractures, the mileage at which they intersect with the tunnel arch, and the direction in which the tunnel crosses the fractures, including: Based on the three-dimensional spatial coordinates of the rock fracture event and the microseismic release energy, a cloud map of the spatial distribution of the rock fracture event and the microseismic release energy in front of the tunnel face is drawn by interpolation. When the rock fracture event space and the microseismic energy release distribution cloud map have linear or strip distribution characteristics, it is determined that there is a fracture in front of the tunnel face. Connecting the extreme points into a line indicates the fracture and obtains the spatial information of the fracture. The orientation of the fracture, the mileage of the intersection with the tunnel arch, and the direction in which the tunnel crosses the fracture are determined based on the spatial information of the fracture. The directions in which the tunnel crosses the fracture include tunneling from the upper plate to the lower plate and from the lower plate to the upper plate.

4. The active prevention and control method for the incubation process of fracture-type rockburst in deep-buried tunnels according to claim 1, characterized in that, The fracture-type rockburst grades include: Rockbursts can be categorized into non-fractured rockbursts, slightly fractured rockbursts, moderately fractured rockbursts, severely fractured rockbursts, and extremely severely fractured rockbursts.

5. The active prevention and control method for the incubation process of fracture-type rockburst in deep-buried tunnels according to claim 1, characterized in that, The determination of the gestation stage of fracture-type rockburst through microseismic event information includes: If the number of cumulative microseismic events per day is less than 20, and all of them are tensile ruptures with release energies of less than 1000J, then it is judged to be in the rupture initiation stage. When the cumulative number of microseismic events per day is 20 to 40, and includes more than 3 rupture events with a release energy higher than 1000J, it is judged to be in the rupture propagation stage. When the cumulative number of microseismic events per day is greater than 40, and includes more than one shear rupture event with a release energy higher than 10,000 J, it is judged to be in the rupture accumulation-fracture slip stage.

6. The active prevention and control method for the incubation process of fracture-type rockburst in deep-buried tunnels according to claim 1, characterized in that, During the rupture initiation stage, the timing for implementing measures to reduce stress concentration in the tunnel surrounding rock is determined based on the cumulative apparent volume surge rate of adjacent microseismic events, thereby suppressing the generation of tension rupture. This includes: If the rockburst is identified as a medium-sized fracture rockburst and the cumulative apparent volume surge rate of adjacent microseismic events is greater than 45%, reduce the tunneling rate. When a rockburst is identified as a severe fracture rockburst or an extremely severe fracture rockburst, and the cumulative apparent volume increase rate of adjacent microseismic events is greater than 45%, the tunneling rate should be reduced, and radial stress relief holes should be installed perpendicular to the surrounding rock surface. The depth of the stress relief hole exceeds the depth of the microseismic event concentration zone.

7. The active prevention and control method for the incubation process of fracture-type rockburst in deep-buried tunnels according to claim 1, characterized in that, During the fracture propagation stage, the timing for arranging stress relief holes is selected based on the K-value growth rate to release the closed stress near the fracture, including: When the direction of tunnel crossing the fracture is that the tunnel is excavated from the upper plate to the lower plate of the fracture, and the K value growth rate is greater than 15%, stress relief holes are arranged in the upper plate of the fracture, and the depth of the stress relief holes exceeds the stress concentration zone. When the direction of tunnel crossing the fracture is that the tunnel is excavated from the lower plate to the upper plate of the fracture, and the K value growth rate is greater than 17%, stress relief holes are arranged on the fracture surface, and the depth of the stress relief holes exceeds the fracture surface.

8. The active prevention and control method for the incubation process of fracture-type rockburst in deep-buried tunnels according to claim 1, characterized in that, During the fracture accumulation-fracture slip stage, based on the distance between the tunnel face and the fracture, shear anchors or cables are installed to secure the tunnel surrounding rock to the fracture, thereby preventing fracture penetration and slippage. This includes: When the tunnel passes through the fracture in the direction of tunnel excavation from the upper plate to the lower plate of the fracture, shear anchors or anchor cables should be used to pass through the fracture surface 0.8 times the tunnel diameter in advance; When the direction of tunnel crossing the fracture is that the tunnel is excavated from the lower plate to the upper plate of the fracture, shear anchors or anchor cables are used to pass through the fracture surface in advance with a tunnel diameter of 1. The angle between the shear anchor or anchor cable and the fracture surface is greater than 45°.

9. The active prevention and control method for the incubation process of fracture-type rockburst in deep-buried tunnels according to claim 1, characterized in that, After the tunnel surrounding rock and fracture locking are completed and before the fracture is exposed at the tunnel face, corresponding measures are taken according to the fracture-type rockburst risk level until the tunnel face passes through the fracture, including: The risk level of fracture-type rockburst has been reduced to medium or below. Arch support is not required. Microseismic activity is monitored until the working face safely passes through the fracture zone. The risk level of fracture-type rockburst is strong or above, and arch support is used according to the direction of the tunnel face crossing the fracture.

10. The active prevention and control method for the incubation process of fracture-type rockburst in deep-buried tunnels according to claim 9, characterized in that, The arch support method based on the direction of the tunnel crossing the fracture includes: When the direction of the tunnel face through the fracture is such that the tunnel face passes through the hanging wall of the fracture, the arch frame is installed when the tunnel face is 0.5 times the tunnel diameter away from the fracture, until the tunnel face passes through the fracture to a distance of 0.8 times the tunnel diameter. When the tunnel face passes through the fracture in the direction that the tunnel face passes through the fracture underside, the arch frame is installed when the tunnel face is 0.8 times the tunnel diameter away from the fracture, until the tunnel face passes through the fracture 0.5 times the tunnel diameter.

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