A time-lapse rock burst grading early warning method and system

Abstract

This invention discloses a method and system for graded early warning of time-delayed rockbursts, belonging to the field of underground engineering disaster monitoring and early warning technology. The method includes acquiring microseismic monitoring signals and surrounding rock stress monitoring signals from various assessed locations of the tunnel main structure; calculating the microseismic energy index change rate, microseismic b-value decrease, Schmidt number, relative quiet period duration, and stress-intensity ratio time-dependent increment based on the microseismic monitoring signals and surrounding rock stress monitoring signals; comparing these five indicators with preset energy level grading thresholds to determine the rockburst energy level; extracting structural damage feature parameters from structural damage images and comparing them with preset structural damage grading thresholds to determine the structural damage level of each location; inputting the rockburst energy level and structural damage level into a coupled evaluation model, and outputting the overall early warning level of the time-delayed rockburst and the corresponding early warning control signal. This invention can comprehensively reflect the disaster-causing degree of time-delayed rockbursts and improve the proactive prevention and control capabilities of time-delayed rockburst disasters.

Description

Technical Field

[0001] This invention belongs to the field of underground engineering disaster monitoring and early warning technology, specifically relating to a time-delayed rockburst graded early warning method and system. Background Technology

[0002] In the field of underground engineering, rockburst is a common geological hazard in rock engineering projects such as deep-buried tunnels and mines. Currently, there is considerable research on evaluation methods for instantaneous rockbursts (rockbursts occurring shortly after excavation), and scholars both domestically and internationally have proposed various rockburst classification and evaluation systems based on rock mechanical properties, surrounding rock stress state, and microseismic monitoring parameters. For example, methods using single or multiple indicators such as the ratio of uniaxial compressive strength to maximum principal stress, elastic strain energy index, and brittleness index are employed to classify and predict the tendency and intensity of rockbursts. In terms of monitoring and early warning, microseismic monitoring technology is widely used for real-time tracking of rock mass fracturing activity, assessing surrounding rock stability by analyzing the spatial distribution, frequency, and energy release characteristics of microseismic events; digital image processing technology is also being gradually introduced into the identification and assessment of apparent defects in tunnel structures.

[0003] However, time-delayed rockbursts refer to the sudden and violent destructive phenomenon that occurs after underground engineering excavation, following a period of stress adjustment and crack propagation in the surrounding rock, with a lag time ranging from several hours to several months. These rockbursts are highly concealed, have short warning windows, and pose a significant threat to construction personnel and equipment. Existing evaluation methods for time-delayed rockbursts still have many shortcomings: First, existing rockburst classification and evaluation methods are mostly aimed at immediate rockbursts, failing to fully consider the core characteristics unique to time-delayed rockbursts, such as stress evolution over time, slow energy accumulation, and the time-varying fracture mechanism, lacking a dedicated classification and evaluation system for time-delayed rockbursts. Second, in terms of evaluation dimensions, existing methods either only focus on the mechanical parameters and energy indicators of the surrounding rock or only provide qualitative manual descriptions of the apparent damage phenomena, lacking technical means to comprehensively correlate and analyze microseismic monitoring data, stress monitoring data, and structural apparent damage images. Furthermore, existing methods lack sectional evaluation standards for the differentiated damage characteristics of different parts of the tunnel (face, crown, sidewalls, and invert), making it difficult to accurately reflect the different disaster-causing forms of time-delayed rockbursts at different locations within the tunnel. These deficiencies make it difficult to quickly and accurately determine and warn of the rockburst level and severity of time-delayed rockbursts, seriously threatening the safety of construction personnel and equipment. Summary of the Invention

[0004] The purpose of this invention is to address the problems in the prior art by providing a time-delayed rockburst classification and early warning method and system. By acquiring microseismic monitoring signals, stress monitoring signals, and structural damage image information from various parts of the tunnel body, five rockburst energy indicators are calculated and structural damage characteristic parameters are extracted to determine the energy level and structural damage level respectively. Then, the overall rockburst early warning level and corresponding early warning control signal are output through a coupled evaluation model.

[0005] To achieve the above objectives, the present invention provides the following technical solution: Firstly, a time-delayed rockburst classification and early warning method is provided, including: Obtain microseismic monitoring signals and surrounding rock stress monitoring signals from various assessed locations of the main tunnel structure; The microseismic energy index change rate, microseismic b-value decrease, Schmidt number, and relative quiet period duration are calculated based on the microseismic monitoring signals. The stress-intensity ratio aging increment is calculated based on the surrounding rock stress monitoring signals. The microseismic energy index change rate, microseismic b-value decrease, Schmidt number, stress-intensity ratio aging increment, and relative quiet period duration are compared with preset energy level classification thresholds. The rockburst energy level is determined based on the comparison results. Obtain structural damage image information of each assessed part of the main tunnel body, extract structural damage feature parameters from the structural damage image information, compare each structural damage feature parameter with the preset structural damage grading threshold, and determine the structural damage level of each assessed part based on the comparison results; The rockburst energy level and the structural damage level of each assessed location are input into a preset coupled evaluation model, and the coupled evaluation model outputs the overall early warning level of time-delayed rockburst. Output the corresponding early warning control signal based on the overall early warning level.

[0006] As a preferred option, the evaluation areas of the main tunnel structure include the tunnel face, the arch, the sidewalls, and the invert. The process of acquiring structural damage image information of various assessed locations of the main tunnel structure and extracting structural damage feature parameters from the structural damage image information includes the following steps: For the working face, the extracted structural failure feature parameters include any one or more combinations of cracking feature parameters, spalling feature parameters, ejection feature parameters, and collapse feature parameters; For the arch, the extracted structural failure characteristic parameters include any one or more combinations of cracking characteristic parameters, spalling characteristic parameters, block falling characteristic parameters, detachment characteristic parameters, fracture characteristic parameters, and collapse characteristic parameters. For the sidewall, the extracted structural failure characteristic parameters include any one or more combinations of the following: spalling characteristic parameters, peeling characteristic parameters, bulging characteristic parameters, and collapse characteristic parameters; For the invert arch, the extracted structural failure characteristic parameters include any one or more combinations of cracking characteristic parameters, crushing characteristic parameters, bottom bulging characteristic parameters, and fracture characteristic parameters.

[0007] As a preferred embodiment, in the step of comparing each structural failure characteristic parameter with a preset structural failure grading threshold, the structural failure grading threshold of the working face includes: The severe damage threshold is a structural failure characteristic parameter that characterizes full-section blasting, ejected boulders, and abrupt displacement of the tunnel face. Medium damage threshold is a structural damage characteristic parameter that characterizes the ejection of blocks, the formation of craters, and the overall backward displacement of the working face; The slight damage threshold is a structural damage characteristic parameter that characterizes the development of plate-like cracks, thin sheet ejection or spalling, and the formation of shallow grooves. The basic integrity threshold is a characteristic parameter that characterizes surface microcracks, flaking, and static falling of fragments.

[0008] As a preferred embodiment, in the step of comparing each structural failure characteristic parameter with a preset structural failure classification threshold, the structural failure classification threshold of the arch includes: Severe damage threshold is a structural damage characteristic parameter that characterizes the progressive collapse of the arch, the breakage of anchor bolts and cables, the twisting and fracture of the steel arch frame, the spillage of concrete, and the complete destruction of the support system. Medium failure threshold is a structural failure parameter that characterizes the following: arch block falling off with a single block diameter of 20cm to 60cm forming a collapse cavity; spray layer peeling off; anchor bolt end pulling out or breaking; anchor cable end lock cracking; and steel strip tearing. The minor damage threshold is a structural damage characteristic parameter that characterizes the structural damage features of falling blocks near the center of the arch with a single block diameter of less than 20 cm, accompanied by sheet-like collapse, loosening of anchor plates, and local cracking of the sprayed layer. The basic integrity threshold is a characteristic parameter representing debris fallout.

[0009] As a preferred embodiment, in the step of comparing each structural failure characteristic parameter with a preset structural failure classification threshold, the structural failure classification threshold of the sidewall includes: Severe damage threshold is a structural damage characteristic parameter that characterizes sidewall bursting, equipment damage, and complete failure of the support system. Medium failure threshold, a structural failure characteristic parameter that characterizes sidewall bulging, steel frame twisting and deformation, partial collapse and spray layer damage; The threshold for minor damage is a structural damage parameter that characterizes spalling, plate-like peeling with parallel cavity walls, and outward bulging of sidewalls. The basic integrity threshold is a characteristic parameter that characterizes localized sheet-like peeling and the absence of lateral bulging.

[0010] As a preferred embodiment, in the step of comparing each structural failure characteristic parameter with a preset structural failure classification threshold, the structural failure classification threshold of the invert arch includes: The severe damage threshold is a structural damage characteristic parameter that characterizes the following: invert arch uplift with an uplift amount greater than 15cm, complete structural fracture, bottom rock mass inflow into the tunnel, tearing at the connection between the invert arch and the sidewall, and tunnel section encroachment. Medium failure threshold is a structural failure characteristic parameter that characterizes the bottom bulge of the inverted arch with a bulge of 5cm to 15cm, concrete fracture misalignment, and the breakage or pull-out of the bottom plate anchor rod. The minor damage threshold is a structural failure parameter that characterizes the expansion of longitudinal cracks in the invert arch, the formation of longitudinal tension cracks, the bottom heave of 2cm to 5cm, and the local crushing of the infill concrete. The basic integrity threshold is a characteristic parameter that characterizes the appearance of longitudinal cracks in the centerline of the invert arch, the heave of less than 2 cm, and the increase of water seepage points on the surface of the bottom slab concrete.

[0011] As a preferred embodiment, the rate of change of the microseismic energy index is calculated according to the following formula: EIR =( E I - E I0 ) / E I0 In the formula, E I Energy index E I0 The initial energy index; The decrease in the microseismic b-value is determined according to the Gutenberg-Richter relation, and the calculation expression is as follows: Lg N=a- b M In the formula, N is the cumulative frequency of events with a magnitude of not less than M; a represents the overall level of seismic activity within a specific time period; b The value reflects the distribution characteristics of the fracture scale; The Schmidt number is the ratio of shear component to tensile component in the source rupture. The stress-strength ratio aging increment is the net increase in stress-strength ratio over time under the dual effects of stress transfer to deeper rock mass after excavation and rock strength degradation over time. The duration of the relative calm period is the duration during which microseismic activity decreases to below a preset threshold.

[0012] As a preferred embodiment, in the step of comparing the rate of change of the microseismic energy index, the decrease in the microseismic b-value, the Schmidt number, the stress-intensity ratio aging increment, and the duration of the relative calm period with preset energy level classification thresholds, and determining the rockburst energy level based on the comparison results, the energy level classification thresholds include: The Class A threshold corresponds to: microseismic energy index change rate EIR > 1.2, microseismic b-value decrease > 30%, and Schmidt number. S c <0.5 and showing a sharp decreasing trend, stress-strength ratio aging increment >0.3, and the duration of the relatively calm period T q >72h; The Class B threshold corresponds to: a microseismic energy index change rate (EIR) of 0.6–1.2, a microseismic b-value decrease of 15%–30%, and a Schmidt number. S c The stress-to-strength ratio was 0.5–1.0 and showed a decreasing trend; the aging increment was 0.15–0.3; and the duration of the relative calm period was [not specified]. T q The duration is 24–72 hours. The C-level threshold corresponds to: a microseismic energy index change rate (EIR) of 0.2–0.6, a microseismic b-value decrease of 5%–15%, and a Schmidt number. S c The stress-to-strength ratio aging increment is 0.05–0.15, and the duration of the relative quiescent period is 1.0–2.0. T q For 2 to 24 hours; The D-level threshold corresponds to: microseismic energy index change rate EIR < 0.2, microseismic b-value decrease < 5%, and Schmidt number. S c >2.0 and stable, stress-strength ratio aging increment <0.05, relative quiescent period duration T q <2h.

[0013] As a preferred embodiment, the coupled evaluation model combines the rockburst energy level with the structural damage level of each assessed location, and outputs the overall early warning level of time-delayed rockburst in the following manner: When the structural damage level and rockburst energy level of the assessed location are both Class D, the overall early warning level for time-delayed rockburst is Class I. When the structural damage level of the assessed location is D and the rockburst energy level is C, or the structural damage level of the assessed location is C and the rockburst energy level is D, or both the structural damage level and the rockburst energy level of the assessed location are C, the overall warning level for time-delayed rockburst is Level II. When the structural damage level of the assessed location is B and the rockburst energy level is D, or the structural damage level of the assessed location is D and the rockburst energy level is B, or the structural damage level of the assessed location is B and the rockburst energy level is C, or the structural damage level of the assessed location is C and the rockburst energy level is B, or both the structural damage level and the rockburst energy level of the assessed location are B, the overall warning level for time-delayed rockburst is Level III. When either the structural damage level or the rockburst energy level of the assessed location is Grade A, the overall early warning level for time-delayed rockbursts is Grade IV.

[0014] Secondly, a time-delayed rockburst classification early warning system is provided, comprising: Microseismic monitoring units are deployed at various assessment locations within the main tunnel structure to collect microseismic monitoring signals. Stress monitoring units are deployed at various assessment locations in the main tunnel structure to collect surrounding rock stress monitoring signals. The image acquisition unit is used to acquire structural damage image information of various assessed parts of the main tunnel structure. The storage unit stores preset energy level classification thresholds, structural damage classification thresholds, and coupled evaluation models. A processor, connected to the microseismic monitoring unit, stress monitoring unit, image acquisition unit, and storage unit, is configured to: calculate the microseismic energy index change rate, microseismic b-value decrease, Schmidt number, and relative quiet period duration based on the microseismic monitoring signals; calculate the stress-intensity ratio aging increment based on the surrounding rock stress monitoring signals; compare the microseismic energy index change rate, microseismic b-value decrease, Schmidt number, stress-intensity ratio aging increment, and relative quiet period duration with energy level classification thresholds, and determine the rockburst energy level based on the comparison results; extract structural damage feature parameters from structural damage image information, compare each structural damage feature parameter with the structural damage classification thresholds, and determine the structural damage level of each assessment location based on the comparison results; input the rockburst energy level and the structural damage level of each assessment location into a preset coupled evaluation model, and output the overall early warning level of time-delayed rockburst through the coupled evaluation model; An output unit, connected to the processor, is used to output a corresponding warning control signal according to the overall warning level.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: This invention integrates and analyzes three heterogeneous data sources: microseismic monitoring signals, surrounding rock stress monitoring signals, and structural damage image information. It achieves a complete processing flow from data acquisition and index calculation to level determination and early warning output, overcoming the limitations of existing technologies that rely on qualitative evaluation based on human experience, and significantly improving evaluation efficiency and objectivity. This invention uses five physical indicators—microseismic energy index change rate, microseismic b-value decrease, Schmidt number, relative quiet period duration, and stress-intensity ratio aging increment—as objective criteria for energy level determination. These five indicators characterize the evolution of time-delayed rockbursts from five independent dimensions: energy release efficiency, fracture scale evolution, fracture mechanism transformation, precursor quiet period identification, and stress-aging drive. This forms a scientifically complete multi-parameter comprehensive criterion system, significantly improving the accuracy and reliability of energy level determination compared to single-indicator evaluation methods. This invention employs a coupled evaluation model to achieve a two-dimensional comprehensive decision-making process, integrating rockburst energy levels with the structural damage levels of various assessed locations. This overcomes the limitation of single-dimensional evaluation, which cannot fully reflect the disaster-causing extent of time-delayed rockbursts. It achieves synergistic analysis of microscopic fracture evolution mechanisms and macroscopic structural damage levels, outputting an overall early warning level that directly indicates the direction of engineering intervention, effectively enhancing the proactive prevention and control capabilities for time-delayed rockburst disasters. Based on the overall early warning level, this invention outputs corresponding early warning control signals, with the evaluation results directly driving engineering decisions, providing quantifiable and actionable technical guarantees for the safety of underground engineering construction.

[0016] Furthermore, the assessment of the main tunnel structure includes the tunnel face, arch, sidewalls, and invert. By comprehensively covering these four parts, this invention achieves the assessment of the structural damage level of the entire cross-section of the main tunnel structure. It fully considers the differentiated disaster-causing characteristics and damage forms exhibited by time-delayed rockbursts in different spatial locations, overcomes the shortcomings of existing technologies that evaluate the tunnel structure as a whole, and provides a technical basis for the refined prevention and control of tunnel zones.

[0017] Furthermore, this invention extracts corresponding structural damage feature parameters from structural damage images for different assessment locations, ensuring a precise match between the extracted image features and the actual damage manifestations of each location. This guarantees the completeness and relevance of the extracted structural damage feature parameters and improves the accuracy of structural damage level determination for each location. Simultaneously, it sets separate structural damage grading thresholds for the four locations: the tunnel face, the arch, the sidewalls, and the invert, forming four grading thresholds covering severe damage, moderate damage, minor damage, and essentially intact levels, with each grading threshold using structural damage feature parameters as the basis for judgment. Through this location-specific and grade-specific threshold system, this invention transforms the original damage assessment relying on subjective descriptions into an objective quantitative judgment based on image feature parameter extraction and automatic threshold comparison. This significantly improves the consistency and repeatability of structural damage level assessment and provides clear technical standards for independent automated grading determination of each location.

[0018] Furthermore, this invention proposes calculation methods for five energy indicators: the rate of change of the microseismic energy index, the decrease in the microseismic b-value, the Schmidt number, the stress-intensity ratio aging increment, and the duration of the relative calm period. This ensures the objectivity and standardization of rockburst energy level determination. Simultaneously, specific numerical ranges are established for the energy level classification thresholds, realizing a shift from qualitative to quantitative judgment of energy levels. This overcomes the deficiency of existing technologies in energy level determination due to the lack of clear numerical basis, significantly improving the objectivity, accuracy, and operability of rockburst energy level assessment, and providing a clear judgment logic for graded early warning.

[0019] Furthermore, the coupled evaluation model of this invention combines the rockburst energy level with the structural damage level of each assessed location to output the overall early warning level of time-delayed rockbursts. This achieves a standardized expression of the complex mapping relationship between the structural damage level of different locations and the overall energy level. Simultaneously, it can output different control signals according to different overall early warning levels, including instructions to allow normal operations, execute borehole depressurization and enhanced monitoring, execute advanced depressurization and enhanced support and real-time monitoring, execute complete tunnel closure and long-term monitoring and re-supporting, etc. This invention transforms the abstract graded evaluation results into clear disposal instructions that can be directly understood and executed by engineers, forming a complete closed loop from disaster assessment to engineering response. This effectively shortens the time delay from early warning issuance to measure implementation and significantly improves the emergency response efficiency of time-delayed rockburst disasters. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 Flowchart of the time-delay rockburst classification and early warning method according to an embodiment of the present invention; Figure 2 A schematic diagram of the structure of the time-delay rockburst graded early warning system according to an embodiment of the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, those skilled in the art can obtain other embodiments without creative effort.

[0023] Time-delayed rockbursts refer to a sudden and violent destructive phenomenon that occurs after excavation in underground engineering projects, following a period of time during which stress adjustment and crack propagation in the surrounding rock occur. This delay can range from several hours to several months. These rockbursts are highly concealed, have a short warning window, and pose a significant threat to construction personnel and equipment. Please refer to... Figure 1 To intuitively reflect the disaster-causing form and damage degree of time-delayed rockbursts occurring in tunnels, and to specify corresponding treatment measures in a targeted manner, this invention proposes a graded early warning method for time-delayed rockbursts, including: S1. Obtain microseismic monitoring signals and surrounding rock stress monitoring signals from various assessed locations of the main tunnel structure; S2. Calculate the microseismic energy index change rate, microseismic b-value decrease, Schmidt number, and relative quiet period duration based on the microseismic monitoring signal; calculate the stress-intensity ratio aging increment based on the surrounding rock stress monitoring signal; compare the microseismic energy index change rate, microseismic b-value decrease, Schmidt number, stress-intensity ratio aging increment, and relative quiet period duration with preset energy level classification thresholds, and determine the rockburst energy level based on the comparison results; S3. Obtain structural damage image information of each assessed part of the main tunnel body, extract structural damage feature parameters from the structural damage image information, compare each structural damage feature parameter with the preset structural damage grading threshold, and determine the structural damage level of each assessed part according to the comparison results. S4. Input the rockburst energy level and the structural damage level of each assessed location into a preset coupled evaluation model. The coupled evaluation model outputs the overall early warning level of time-delayed rockburst. S5. Output the corresponding early warning control signal according to the overall early warning level.

[0024] In one possible implementation, the evaluation areas of the main tunnel structure in step S1 include the tunnel face, the arch, the sidewalls, and the invert.

[0025] Furthermore, step S3, which involves acquiring structural damage image information of various assessed locations of the tunnel body and extracting structural damage feature parameters from the structural damage image information, specifically includes: For the working face, the extracted structural failure feature parameters include any one or more combinations of cracking feature parameters, spalling feature parameters, ejection feature parameters, and collapse feature parameters; For the arch, the extracted structural failure characteristic parameters include any one or more combinations of cracking characteristic parameters, spalling characteristic parameters, block falling characteristic parameters, detachment characteristic parameters, fracture characteristic parameters, and collapse characteristic parameters. For the sidewall, the extracted structural failure characteristic parameters include any one or more combinations of the following: spalling characteristic parameters, peeling characteristic parameters, bulging characteristic parameters, and collapse characteristic parameters; For the invert arch, the extracted structural failure characteristic parameters include any one or more combinations of cracking characteristic parameters, crushing characteristic parameters, bottom bulging characteristic parameters, and fracture characteristic parameters.

[0026] In one possible implementation, during step S3, when comparing each structural failure characteristic parameter with a preset structural failure grading threshold, the structural failure grading thresholds for the working face are shown in Table 1, including: The severe damage threshold is a structural failure characteristic parameter that characterizes full-section blasting, ejected boulders, and abrupt displacement of the tunnel face. Medium damage threshold is a structural damage characteristic parameter that characterizes the ejection of blocks, the formation of craters, and the overall backward displacement of the working face; The slight damage threshold is a structural damage characteristic parameter that characterizes the development of plate-like cracks, thin sheet ejection or spalling, and the formation of shallow grooves. The basic integrity threshold is a characteristic parameter that characterizes surface microcracks, flaking, and static falling of fragments.

[0027] Table 1

[0028] The structural failure grading thresholds for the vault are shown in Table 2, including: Severe damage threshold is a structural damage characteristic parameter that characterizes the progressive collapse of the arch, the breakage of anchor bolts and cables, the twisting and fracture of the steel arch frame, the spillage of concrete, and the complete destruction of the support system. Medium failure threshold is a structural failure parameter that characterizes the following: arch block falling off with a single block diameter of 20cm to 60cm forming a collapse cavity; spray layer peeling off; anchor bolt end pulling out or breaking; anchor cable end lock cracking; and steel strip tearing. The minor damage threshold is a structural damage characteristic parameter that characterizes the structural damage features of falling blocks near the center of the arch with a single block diameter of less than 20 cm, accompanied by sheet-like collapse, loosening of anchor plates, and local cracking of the sprayed layer. The basic integrity threshold is a characteristic parameter representing debris fallout.

[0029] Table 2

[0030] The structural damage grading thresholds for the sidewalls are shown in Table 3, including: Severe damage threshold is a structural damage characteristic parameter that characterizes sidewall bursting, equipment damage, and complete failure of the support system. Medium failure threshold, a structural failure characteristic parameter that characterizes sidewall bulging, steel frame twisting and deformation, partial collapse and spray layer damage; The threshold for minor damage is a structural damage parameter that characterizes spalling, plate-like peeling with parallel cavity walls, and outward bulging of sidewalls. The basic integrity threshold is a characteristic parameter that characterizes localized sheet-like peeling and the absence of lateral bulging.

[0031] Table 3

[0032] The structural failure grading thresholds for inverted arches are shown in Table 4, including: The severe damage threshold is a structural damage characteristic parameter that characterizes the following: invert arch uplift with an uplift amount greater than 15cm, complete structural fracture, bottom rock mass inflow into the tunnel, tearing at the connection between the invert arch and the sidewall, and tunnel section encroachment. Medium failure threshold is a structural failure characteristic parameter that characterizes the bottom bulge of the inverted arch with a bulge of 5cm to 15cm, concrete fracture misalignment, and the breakage or pull-out of the bottom plate anchor rod. The minor damage threshold is a structural failure parameter that characterizes the expansion of longitudinal cracks in the invert arch, the formation of longitudinal tension cracks, the bottom heave of 2cm to 5cm, and the local crushing of the infill concrete. The basic integrity threshold is a characteristic parameter that characterizes the appearance of longitudinal cracks in the centerline of the invert arch, the heave of less than 2 cm, and the increase of water seepage points on the surface of the bottom slab concrete.

[0033] Table 4

[0034] In one possible implementation, the rate of change of the microseismic energy index in step S2 is calculated according to the following formula: EIR =( E I - E I0 ) / E I0 In the formula, E I Energy index EI0 The initial energy index; The rate of change of the microseismic energy index, i.e., the relative speed at which the microseismic energy index changes over time, can reflect the degree to which rock mass stress approximates its strength. If... EIR A sustained positive value and an increasing value indicate that the rock mass is rapidly approaching its peak strength, which is an important precursor to time-delayed rockbursts.

[0035] The reduction in the microseismic b-value mentioned in step S2 is determined according to the Gutenberg-Richter relation, and the calculation expression is as follows: Lg N=a- b M In the formula, N is the cumulative frequency of events with a magnitude of not less than M; a represents the overall level of seismic activity within a specific time period; b The b-value reflects the distribution characteristics of the fracture scale; a high b-value (e.g., >1.2) indicates that small fracture events account for the vast majority, the stress distribution within the rock mass is relatively uniform, and microcrack initiation and propagation are dominant. A continuous decrease in the b-value indicates that the proportion of large-scale fracture events is increasing, and microcracks are coalescing and nucleating, which is a precursor to rock mass instability and large-scale rockbursts.

[0036] The Schmitt number mentioned in step S2 S c An index describing the source mechanism type of microseismic events is defined as the ratio of shear components to dilatational (tensional) components in the source rupture. S c A high value (e.g., >2.0) indicates that the rock mass is mainly in the stage of micro-fracture opening and expansion, and the damage is mostly surface spalling or spalling. S c The value continues to decline and approaches below 1.0, indicating that the proportion of shear fracture is increasing, and the rock mass is transforming from volume expansion to shear slip, which foreshadows a more violent energy release, i.e., a precursor to the main fracture of the time-delayed rockburst. S c A sharp drop in magnitude often indicates that a major earthquake is imminent.

[0037] The stress-strength ratio increment mentioned in step S2 is the net increase in stress-strength ratio over time under the dual effects of stress transfer to the deeper rock mass after excavation and the deterioration of rock strength over time. The continuously increasing increment is the core driving force of time-delayed rockburst: stress gradually concentrates on the rock wall, or the rock strength decreases under the influence of humidity and chemical effects, both of which cause the stress-strength ratio at the same location to increase over time.

[0038] The duration of the relative calm period described in step S2 T q The duration of microseismic activity reduced to below a preset threshold, followed by a sudden increase in activity after a long period of calm, is a typical precursor to time-delayed rockbursts.

[0039] In one possible implementation, step S2 compares the microseismic energy index change rate, microseismic b-value decrease, Schmidt number, stress-intensity ratio aging increment, and relative calm period duration with preset energy level classification thresholds, respectively. Based on the comparison results, the rockburst energy level is determined. The rockburst energy level is divided into four levels, A, B, C, and D, from highest to lowest, as shown in Table 5. The energy level classification thresholds include: The Class A threshold corresponds to: microseismic energy index change rate EIR > 1.2, microseismic b-value decrease > 30%, and Schmidt number. S c <0.5 and showing a sharp decreasing trend, stress-strength ratio aging increment >0.3, and the duration of the relatively calm period T q >72h; The Class B threshold corresponds to: a microseismic energy index change rate (EIR) of 0.6–1.2, a microseismic b-value decrease of 15%–30%, and a Schmidt number. S c The stress-to-strength ratio was 0.5–1.0 and showed a decreasing trend; the aging increment was 0.15–0.3; and the duration of the relative calm period was [not specified]. T q The duration is 24–72 hours. The C-level threshold corresponds to: a microseismic energy index change rate (EIR) of 0.2–0.6, a microseismic b-value decrease of 5%–15%, and a Schmidt number. S c The stress-to-strength ratio aging increment is 0.05–0.15, and the duration of the relative quiescent period is 1.0–2.0. T q For 2 to 24 hours; The D-level threshold corresponds to: microseismic energy index change rate EIR < 0.2, microseismic b-value decrease < 5%, and Schmidt number. S c >2.0 and stable, stress-strength ratio aging increment <0.05, relative quiescent period duration T q <2h.

[0040] Table 5

[0041] In one possible implementation, as shown in Table 6, the coupled evaluation model described in step S4 combines the rockburst energy level with the structural damage level of each evaluated location to output the overall early warning level of time-delayed rockburst in the following manner: When the structural damage level and rockburst energy level of the assessed location are both Class D, the overall early warning level for time-delayed rockburst is Class I. When the structural damage level of the assessed location is D and the rockburst energy level is C, or the structural damage level of the assessed location is C and the rockburst energy level is D, or both the structural damage level and the rockburst energy level of the assessed location are C, the overall warning level for time-delayed rockburst is Level II. When the structural damage level of the assessed location is B and the rockburst energy level is D, or the structural damage level of the assessed location is D and the rockburst energy level is B, or the structural damage level of the assessed location is B and the rockburst energy level is C, or the structural damage level of the assessed location is C and the rockburst energy level is B, or both the structural damage level and the rockburst energy level of the assessed location are B, the overall warning level for time-delayed rockburst is Level III. When either the structural damage level or the rockburst energy level of the assessed location is Grade A, the overall early warning level for time-delayed rockbursts is Grade IV.

[0042] Table 6

[0043] Based on the survey data of time-delayed rockburst tunnels and current specifications, and considering the characteristics of tunnel damage, the degree of disaster caused by rockbursts is divided into four levels from mild to severe: I, II, III, and IV. The corresponding treatment measures are shown in Table 7.

[0044] Table 7

[0045] This invention establishes a comprehensive evaluation standard and system for the degree of time-delayed rockburst damage covering the main body of railway tunnels, enabling rapid evaluation and accurate classification of time-delayed rockbursts in railway tunnels, and providing a scientific basis for the prevention and control of time-delayed rockbursts.

[0046] Please see Figure 2 Another embodiment of the present invention also proposes a time-delay rockburst classification early warning system, comprising: Microseismic monitoring units are deployed at various assessment locations within the main tunnel structure to collect microseismic monitoring signals. Stress monitoring units are deployed at various assessment locations in the main tunnel structure to collect surrounding rock stress monitoring signals. The image acquisition unit is used to acquire structural damage image information of various assessed parts of the main tunnel structure. The storage unit stores preset energy level classification thresholds, structural damage classification thresholds, and coupled evaluation models. A processor, connected to the microseismic monitoring unit, stress monitoring unit, image acquisition unit, and storage unit, is configured to: calculate the microseismic energy index change rate, microseismic b-value decrease, Schmidt number, and relative quiet period duration based on the microseismic monitoring signals; calculate the stress-intensity ratio aging increment based on the surrounding rock stress monitoring signals; compare the microseismic energy index change rate, microseismic b-value decrease, Schmidt number, stress-intensity ratio aging increment, and relative quiet period duration with energy level classification thresholds, and determine the rockburst energy level based on the comparison results; extract structural damage feature parameters from structural damage image information, compare each structural damage feature parameter with the structural damage classification thresholds, and determine the structural damage level of each assessment location based on the comparison results; input the rockburst energy level and the structural damage level of each assessment location into a preset coupled evaluation model, and output the overall early warning level of time-delayed rockburst through the coupled evaluation model; An output unit, connected to the processor, is used to output a corresponding warning control signal according to the overall warning level.

[0047] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A time-delay rockburst classification and early warning method, characterized in that, include: Obtain microseismic monitoring signals and surrounding rock stress monitoring signals from various assessed locations of the main tunnel structure; The microseismic energy index change rate, microseismic b-value decrease, Schmidt number, and relative quiet period duration are calculated based on the microseismic monitoring signals. The stress-intensity ratio aging increment is calculated based on the surrounding rock stress monitoring signals. The microseismic energy index change rate, microseismic b-value decrease, Schmidt number, stress-intensity ratio aging increment, and relative quiet period duration are compared with preset energy level classification thresholds. The rockburst energy level is determined based on the comparison results. Obtain structural damage image information of each assessed part of the main tunnel body, extract structural damage feature parameters from the structural damage image information, compare each structural damage feature parameter with the preset structural damage grading threshold, and determine the structural damage level of each assessed part based on the comparison results; The rockburst energy level and the structural damage level of each assessed location are input into a preset coupled evaluation model, and the coupled evaluation model outputs the overall early warning level of time-delayed rockburst. Output the corresponding early warning control signal based on the overall early warning level.

2. The energy consumption configuration and fault ride-through control method for a full DC collection and transmission system according to claim 1, characterized in that, The evaluation areas of the main tunnel structure include the tunnel face, the arch, the sidewalls, and the invert. The process of acquiring structural damage image information of various assessed locations of the main tunnel structure and extracting structural damage feature parameters from the structural damage image information includes the following steps: For the working face, the extracted structural failure feature parameters include any one or more combinations of cracking feature parameters, spalling feature parameters, ejection feature parameters, and collapse feature parameters; For the arch, the extracted structural failure characteristic parameters include any one or more combinations of cracking characteristic parameters, spalling characteristic parameters, block falling characteristic parameters, detachment characteristic parameters, fracture characteristic parameters, and collapse characteristic parameters. For the sidewall, the extracted structural failure characteristic parameters include any one or more combinations of the following: spalling characteristic parameters, peeling characteristic parameters, bulging characteristic parameters, and collapse characteristic parameters; For the invert arch, the extracted structural failure characteristic parameters include any one or more combinations of cracking characteristic parameters, crushing characteristic parameters, bottom bulging characteristic parameters, and fracture characteristic parameters.

3. The energy consumption configuration and fault ride-through control method for a full DC collection and transmission system according to claim 2, characterized in that, In the step of comparing each structural failure characteristic parameter with a preset structural failure grading threshold, the structural failure grading threshold of the working face includes: The severe damage threshold is a structural failure characteristic parameter that characterizes full-section blasting, ejected boulders, and abrupt displacement of the tunnel face. Medium damage threshold is a structural damage characteristic parameter that characterizes the ejection of blocks, the formation of craters, and the overall backward displacement of the working face; The slight damage threshold is a structural damage characteristic parameter that characterizes the development of plate-like cracks, thin sheet ejection or spalling, and the formation of shallow grooves. The basic integrity threshold is a characteristic parameter that characterizes surface microcracks, flaking, and static falling of fragments.

4. The energy consumption configuration and fault ride-through control method for a full DC collection and transmission system according to claim 2, characterized in that, In the step of comparing each structural failure characteristic parameter with a preset structural failure classification threshold, the structural failure classification threshold of the arch includes: Severe damage threshold is a structural damage characteristic parameter that characterizes the progressive collapse of the arch, the breakage of anchor bolts and cables, the twisting and fracture of the steel arch frame, the spillage of concrete, and the complete destruction of the support system. Medium failure threshold is a structural failure parameter that characterizes the following: arch block falling off with a single block diameter of 20cm to 60cm forming a collapse cavity; spray layer peeling off; anchor bolt end pulling out or breaking; anchor cable end lock cracking; and steel strip tearing. The minor damage threshold is a structural damage characteristic parameter that characterizes the structural damage features of falling blocks near the center of the arch with a single block diameter of less than 20 cm, accompanied by sheet-like collapse, loosening of anchor plates, and local cracking of the sprayed layer. The basic integrity threshold is a characteristic parameter representing debris fallout.

5. The energy consumption configuration and fault ride-through control method for a full DC collection and transmission system according to claim 2, characterized in that, In the step of comparing each structural failure characteristic parameter with a preset structural failure classification threshold, the structural failure classification threshold of the sidewall includes: Severe damage threshold is a structural damage characteristic parameter that characterizes sidewall bursting, equipment damage, and complete failure of the support system. Medium failure threshold, a structural failure characteristic parameter that characterizes sidewall bulging, steel frame twisting deformation, partial collapse and spray layer damage; The threshold for minor damage is a structural damage parameter that characterizes spalling, plate-like peeling with parallel cavity walls, and outward bulging of sidewalls. The basic integrity threshold is a characteristic parameter that characterizes localized sheet-like peeling and the absence of lateral bulging.

6. The energy consumption configuration and fault ride-through control method for a full DC collection and transmission system according to claim 2, characterized in that, In the step of comparing each structural failure characteristic parameter with a preset structural failure classification threshold, the structural failure classification threshold for the invert arch includes: The severe damage threshold is a structural damage characteristic parameter that characterizes the following: invert arch uplift with an uplift amount greater than 15cm, complete structural fracture, bottom rock mass inflow into the tunnel, tearing at the connection between the invert arch and the sidewall, and tunnel section encroachment. Medium failure threshold is a structural failure characteristic parameter that characterizes the bottom bulge of the inverted arch with a bulge of 5cm to 15cm, concrete fracture misalignment, and the breakage or pull-out of the bottom plate anchor rod. The minor damage threshold is a structural failure parameter that characterizes the expansion of longitudinal cracks in the invert arch, the formation of longitudinal tension cracks, the bottom heave of 2cm to 5cm, and the local crushing of the infill concrete. The basic integrity threshold is a characteristic parameter that characterizes the appearance of longitudinal cracks in the centerline of the invert arch, the heave of less than 2 cm, and the increase of water seepage points on the surface of the bottom slab concrete.

7. The energy consumption configuration and fault ride-through control method for a full DC collection and transmission system according to claim 1, characterized in that, The rate of change of the microseismic energy index is calculated according to the following formula: EIR =( E I - E I0 ) / E I0 In the formula, E I Energy index E I0 The initial energy index; The decrease in the microseismic b-value is determined according to the Gutenberg-Richter relation, and the calculation expression is as follows: Lg N=a- b M In the formula, N is the cumulative frequency of events with a magnitude of not less than M; a represents the overall level of seismic activity within a specific time period; b The value reflects the distribution characteristics of the fracture scale; The Schmidt number is the ratio of shear component to tensile component in the source rupture. The stress-strength ratio aging increment is the net increase in stress-strength ratio over time under the dual effects of stress transfer to deeper rock mass after excavation and rock strength degradation over time. The duration of the relative calm period is the duration during which microseismic activity decreases to below a preset threshold.

8. The energy consumption configuration and fault ride-through control method for a full DC collection and transmission system according to claim 7, characterized in that, In the step of comparing the rate of change of the microseismic energy index, the decrease in the microseismic b-value, the Schmidt number, the stress-intensity ratio aging increment, and the duration of the relative quiet period with preset energy level classification thresholds, and determining the rockburst energy level based on the comparison results, the energy level classification thresholds include: The Class A threshold corresponds to: microseismic energy index change rate EIR > 1.2, microseismic b-value decrease > 30%, and Schmidt number. S c <0.5 and showing a sharp decreasing trend, stress-strength ratio aging increment >0.3, and the duration of the relatively calm period T q >72h; The Class B threshold corresponds to: a microseismic energy index change rate (EIR) of 0.6–1.2, a microseismic b-value decrease of 15%–30%, and a Schmidt number. S c The stress-to-strength ratio was 0.5–1.0 and showed a decreasing trend; the aging increment was 0.15–0.3; and the duration of the relative calm period was [not specified]. T q The duration is 24–72 hours. The C-level threshold corresponds to: a microseismic energy index change rate (EIR) of 0.2–0.6, a microseismic b-value decrease of 5%–15%, and a Schmidt number. S c The stress-to-strength ratio aging increment is 0.05–0.15, and the duration of the relative quiescent period is 1.0–2.

0. T q For 2 to 24 hours; The D-level threshold corresponds to: microseismic energy index change rate EIR < 0.2, microseismic b-value decrease < 5%, and Schmidt number. S c >2.0 and stable, stress-strength ratio aging increment <0.05, relative quiescent period duration T q <2h.

9. The energy consumption configuration and fault ride-through control method for a full DC collection and transmission system according to claim 1, characterized in that, The coupled evaluation model combines the rockburst energy level with the structural damage level of each assessed location, and outputs the overall early warning level of time-delayed rockburst in the following manner: When the structural damage level and rockburst energy level of the assessed location are both Class D, the overall early warning level for time-delayed rockburst is Class I. When the structural damage level of the assessed location is D and the rockburst energy level is C, or the structural damage level of the assessed location is C and the rockburst energy level is D, or both the structural damage level and the rockburst energy level of the assessed location are C, the overall warning level for time-delayed rockburst is Level II. When the structural damage level of the assessed location is B and the rockburst energy level is D, or the structural damage level of the assessed location is D and the rockburst energy level is B, or the structural damage level of the assessed location is B and the rockburst energy level is C, or the structural damage level of the assessed location is C and the rockburst energy level is B, or both the structural damage level and the rockburst energy level of the assessed location are B, the overall warning level for time-delayed rockburst is Level III. When either the structural damage level or the rockburst energy level of the assessed location is Grade A, the overall early warning level for time-delayed rockbursts is Grade IV.

10. A time-delay rockburst classification early warning system, characterized in that, include: Microseismic monitoring units are deployed at various assessment locations within the main tunnel structure to collect microseismic monitoring signals. Stress monitoring units are deployed at various assessment locations in the main tunnel structure to collect surrounding rock stress monitoring signals. The image acquisition unit is used to acquire structural damage image information of various assessed parts of the main tunnel structure. The storage unit stores preset energy level classification thresholds, structural damage classification thresholds, and coupled evaluation models. The processor is connected to the microseismic monitoring unit, stress monitoring unit, image acquisition unit, and storage unit, respectively. The processor is configured to: calculate the microseismic energy index change rate, microseismic b-value decrease, Schmidt number, and relative quiet period duration based on the microseismic monitoring signal; calculate the stress-intensity ratio aging increment based on the surrounding rock stress monitoring signal; compare the microseismic energy index change rate, microseismic b-value decrease, Schmidt number, stress-intensity ratio aging increment, and relative quiet period duration with energy level classification thresholds, and determine the rockburst energy level based on the comparison results. Structural damage feature parameters are extracted from the structural damage image information. Each structural damage feature parameter is compared with the structural damage grading threshold. Based on the comparison results, the structural damage level of each assessment location is determined. The rockburst energy level and the structural damage level of each assessed location are input into a preset coupled evaluation model, and the overall early warning level of time-delayed rockburst is output through the coupled evaluation model. An output unit, connected to the processor, is used to output a corresponding warning control signal according to the overall warning level.

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