Method and system for comprehensively evaluating rockburst risk in deeply-buried hard rock tunnel construction process

Abstract

The invention discloses a comprehensive assessment method and system for rockburst risk in a deep-buried hard rock tunnel construction process, and the method comprises the steps: 1, preliminarily determining whether surrounding rock has basic conditions for rockburst occurrence, and 2, carrying out the sound wave test of potential dangerous parts of the surrounding rock if the conditions of the step 1 are satisfied, and carrying out the sound wave test of the potential dangerous parts of the surrounding rock. Estimating a geological strength index GSI and characteristic parameters of a damage area; 3, according to the distribution characteristics of the rock mass strength-stress ratio SSRrm in the excavation damage area range, the rock burst susceptibility of the surrounding rock is evaluated; and 4, on the basis of estimating the depth of the surrounding rock rockburst pit, further evaluating the intensity when the rockburst occurs. And step 5, coupling the susceptibility grade and the intensity grade, and comprehensively evaluating the risk of rock burst. The obtained rockburst susceptibility and intensity result can provide specific and targeted basis for rockburst prevention and control measures, is helpful for improving disaster prevention and reduction efficiency and reducing risks faced by personnel and equipment, and has remarkable economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of rockburst hazard assessment for deep-buried hard rock tunnels, and specifically relates to a comprehensive assessment method and system for rockburst hazard during the construction process of deep-buried hard rock tunnels. Background Technology

[0002] With the construction of numerous hydropower projects and transportation tunnels in western China, the region, characterized by its continuous mountain ranges and frequent geological activity, often requires traversing high mountains and steep ridges during the construction of deep-buried hard rock tunnels (hydropower tunnels, railway tunnels, and highway tunnels). Under the combined effects of plate compression and the self-weight stress of the overlying rock mass, rockburst disasters frequently occur during the construction of deep-buried hard rock tunnels. These disasters manifest as sudden fracturing, ejection, or even throwing of surrounding rock, seriously threatening the safety of construction personnel and machinery, and directly impacting the smooth progress of the project. Therefore, accurately assessing the rockburst risk during the construction of deep-buried hard rock tunnels is of great significance for the effective prevention and control of rockburst disasters.

[0003] In rockburst hazard assessment, two main methods are currently used: one is based on the energy index of rock materials (such as the elastic energy index W). ET Energy Impact Index A CF Elastic strain potential energy (PES) and residual elastic energy index (A) EF (e.g., judging rockburst tendency); secondly, judging rockburst tendency by strength-stress ratio (σ) ci / σ1) or stress intensity ratio (σ θ Parameters such as / σ1 are used to assess the potential rockburst level of the surrounding rock in the project.

[0004] However, existing energy indicators fail to comprehensively consider the quality of the surrounding rock and the effects of excavation disturbance, resulting in assessment results that cannot accurately reflect the true rockburst tendency of the surrounding rock; while the strength-stress ratio and stress-intensity ratio do not consider the weakening effect of excavation disturbance on the properties of the surrounding rock, and are only applicable to the exploration and design stage, and are difficult to apply directly to the construction stage.

[0005] Traditional criteria (such as Tao Zhenyu's criteria and Russenes' criteria) are mostly based on the original ground stress and rock strength. However, in actual construction, excavation and unloading will cause the surrounding rock to produce an "excavation damage zone (EDZ)". The physical and mechanical properties of the rock mass exhibit non-uniform deterioration in space, and static indicators are difficult to capture this dynamic weakening.

[0006] Existing technologies often only focus on "whether a rockburst occurs" or "the energy level of a rockburst," with a single evaluation dimension, lacking a comprehensive quantification of the probability of rockburst occurrence (spatial distribution) and the severity of damage (depth and energy).

[0007] Furthermore, while patents CN202211032650.5, CN202311869495.7, and CN202310712880.4 propose different methods for evaluating the tendency of surrounding rock to burst, and consider rock mass quality and excavation disturbance effects in their indicators, their evaluation results mainly reflect the intensity of a potential rock burst, but cannot determine whether a rock burst actually occurs. Another patent, CN202310714623.4, provides criteria for rock burst occurrence and a method for estimating the depth of a rock burst crater, but it cannot determine the level of rock bursts that may occur within the rock burst crater area.

[0008] Secondly, the parameters are difficult to obtain and are delayed. Laboratory core testing cannot reflect the real damage state of the surrounding rock in real time, resulting in poor timeliness of early warning.

[0009] Rockburst hazard should encompass both susceptibility and severity. Clearly, existing criteria and methods are insufficient for a comprehensive evaluation of rockburst hazard (i.e., susceptibility and severity). Therefore, it is necessary to establish a comprehensive assessment method and system for rockburst hazard during the construction of deeply buried hard rock tunnels. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention provides a comprehensive assessment method and system for rockburst hazard during the construction of deep-buried hard rock tunnels. The aim is to solve the problem that existing methods cannot comprehensively assess the susceptibility and severity of rockbursts, thereby achieving a comprehensive evaluation of rockburst hazards.

[0011] To achieve the above results, the technical solution adopted by the present invention is as follows: A comprehensive assessment method for rockburst hazard during the construction of deep-buried hard rock tunnels includes the following steps: Step 1: Obtain the basic physical and mechanical parameters and geostress parameters of the surrounding rock in the section to be tested, and preliminarily determine whether the surrounding rock has the basic conditions for rock burst occurrence; Step 2: When the basic conditions are met, conduct acoustic wave testing at potentially hazardous areas of the surrounding rock. Based on the spatial distribution of P-wave velocity, estimate the geological strength index (GSI) and characteristic parameters of the damaged area; wherein, the characteristic parameters of the damaged area include the excavation depth h of the damaged area. EDZ Depth h of the heavily damaged area HDZ Depth h of weak damage zone WDZ The disturbance factor D of the excavation profile surface s And the evolution function describing the evolution of the perturbation factor with depth within the damaged area; Step 3: Combining the parameters obtained in Step 2, construct the rock mass strength stress ratio (SSR) that takes into account excavation disturbance. rm Distribution model to quantitatively evaluate the susceptibility level of rockburst in surrounding rock; Step 4: Estimate the depth h of the rockburst crater based on rock strength, initial stress, and the evolution function of the damage zone. rb, and calculate the overall average remaining elastic energy REE within the rockburst pit rmp , and evaluate the severity level during rockburst occurrence; Step 5: Couple the susceptibility level and the severity level, and determine the final rockburst hazard level and failure depth of the surrounding rock through the comprehensive hazard evaluation matrix.

[0012] The technical principle of this solution is as follows: Utilize the attenuation characteristics of acoustic wave P-wave velocity in damaged rock masses to inversely obtain the excavation disturbance factor D. By introducing the disturbance factor to modify the traditional Hoek-Brown criterion, construct a rock mass strength model that evolves with the excavation depth. On this basis, evaluate the susceptibility through "rock mass strength-stress ratio SSR" rm ", evaluate the severity through "remaining elastic energy REE" rmp ", and finally lock the hazard level through the dual-index matrix.

[0013] As a further improvement of the present invention, the basic conditions described in Step 1 include: the basic quality grade of the surrounding rock is Grade III or above, the uniaxial compressive strength of the rock σ ci ≥60 MPa, and the initial maximum principal stress of the surrounding rock σ1≥10 MPa.

[0014] As a further improvement of the present invention, the determination criterion for the potential dangerous parts of the surrounding rock in Step 2 is: When the initial maximum principal stress σ1 of the surrounding rock is greater than the minimum principal stress σ3, the test points are set at two surrounding rock parts in the direction of the minimum principal stress; When σ1 is equal to σ3, the test points are set at four surrounding rock parts in the directions of the maximum principal stress and the minimum principal stress.

[0015] As a further improvement of the present invention, the acquisition method of the characteristic parameters of the damaged area described in Step 2 includes: Obtain the P-wave velocity c at different depths h through acoustic wave testing p , determine the excavation damaged zone EDZ as the low-wave velocity zone near the excavation contour surface, and its deepest part is h EDZ ; the deep area outside the range of EDZ is the undamaged zone (UZ); Calculate the average wave velocity c of the undamaged zone UZ p0 , and calculate the geological strength index according to formula (1); (1) Calculate the disturbance factor D at each depth according to formula (2); (2) Let the area where D = 1 be the highly damaged zone HDZ, and the corresponding depth is h HDZ ; the range outside HDZ and satisfying 0 < D < 1 is the weakly damaged zone WDZ, and its depth hWDZ =h EDZ -h HDZ The disturbance factor on the excavation profile is defined as D. s .

[0016] As a further improvement of the present invention, the function describing the evolution of the perturbation factor within the damaged area in step 2 is based on h. HDZ Value classification construction: When h HDZ When =0m, formula (3) is used to solve for the trend of change of disturbance factor in the damaged area; (3) When h HDZ When the value is >0m, the piecewise function of formula (4) is used to solve for the trend of the change of the disturbance factor in the damaged area: (4) In the formula: h is the depth from the tunnel excavation outline.

[0017] As a further improvement of the present invention, the rockburst susceptibility evaluation standard in step 3 is as follows: Substituting the perturbation factor evolution function into formula (5), the rock mass strength stress ratio SSR is obtained. rm Curve showing variation with depth; (5) According to SSR rm Areas with a value <0.2 in the excavation damage zone h EDZ The proportions of each component are classified into different levels: If the ratio is 0, then it is "not likely to occur"; If the proportion is in the range of (0, 1 / 4], it is considered "more likely to occur"; If the ratio is within the range of (1 / 4, 1 / 2), it is considered "prone to occur". If the proportion is ≥1 / 2, it is considered "extremely likely to occur".

[0018] As a further improvement of the present invention, the rockburst crater depth h in step 4 rb The calculation formula is as follows: When h HDZ When =0m, the critical strength stress ratio =0.2、σ ci σ1, GSI, and h WDZ Substitute into formula (6) to calculate the depth h of the rockburst crater. rb (6) When h HDZ When >0m, σ ci σ1, GSI =0.2、h WDZ and h HDZ Substitute into formula (7) to calculate the depth h of the rockburst crater. rb ; (7) As a further improvement of the present invention, step 4 involves calculating the overall average residual elastic energy REE. rmp The methods include: The residual elastic energy (REE) within the depth range of the rockburst crater is calculated using formula (8). rm ; (8) The depth of the rockburst crater is h rb Divide the region into n sub-regions at 0.2m intervals; Calculate the residual elastic energy at the boundary points of each sub-region and take the average value to obtain the average residual elastic energy (REE) of each sub-region. rmi ; The average residual elastic energy (REE) within the rockburst crater area is obtained by averaging over all sub-regions. rmp .

[0019] As a further improvement of the present invention, the rockburst intensity level in step 4 is based on REE. rmp Determining the numerical range: REE rmp <50kJ / m 3 It is described as "no rockburst". 50kJ / m 3 ≤REE rmp <150kJ / m 3 It was classified as a "minor rockburst". 150kJ / m 3 ≤REE rmp ≤200kJ / m 3 It was classified as a "moderate rockburst". REE rmp >200kJ / m 3 It was described as a "strong rockburst".

[0020] Based on the above-mentioned comprehensive assessment method for rockburst hazard during the construction of deep-buried hard rock tunnels, this invention also proposes a comprehensive assessment system for rockburst hazard during the construction of deep-buried hard rock tunnels, comprising: Parameter input module: used to input surrounding rock strength, basic quality grade and initial stress parameters; Acoustic wave testing and processing module: used to acquire and process acoustic wave velocity data at different depths of surrounding rock, and automatically identify the extent of excavation damage zone and geological strength indicators; Evolution calculation module: used to construct functional models of the evolution of disturbance factor and rock mass strength-stress ratio with depth; Comprehensive evaluation module: Based on a preset evaluation matrix, it outputs the susceptibility, severity, and overall hazard level of rockbursts.

[0021] Compared with the prior art, the present invention achieves at least the following beneficial effects: (1) The construction of the perturbation factor evolution function in this invention is different from the traditional method of treating the perturbation as a constant value. This invention proposes to construct a segmented or continuous exponential evolution function based on the existence of the depth of the high damage zone (HDZ), which accurately describes the transition state of the surrounding rock from "completely damaged" to "undamaged".

[0022] (2) The multi-index spatial coupling model in this invention is the first to logically correlate the spatial range of the excavation damage zone with the depth of the rockburst crater, realizing the synergistic prediction of damage depth and damage intensity. The method provided by this invention can not only assess the susceptibility to rockbursts, but also determine the intensity of rockbursts when they occur, realizing a comprehensive evaluation of rockburst hazards and breaking through the limitations of existing methods in systematic assessment.

[0023] (3) The method provided by this invention has strong engineering applicability. By adopting the mature method of acoustic testing, it achieves a seamless connection from geophysical data to mechanical evaluation. In addition, the equipment is portable and easy to operate, making the comprehensive evaluation process of rockburst hazard easy to implement and highly feasible.

[0024] (4) The method provided by the present invention provides results on the susceptibility and severity of rockbursts, which can provide specific and targeted basis for rockburst prevention and control measures, help improve the efficiency of disaster prevention and mitigation, reduce the risks faced by personnel and equipment, and have significant economic benefits. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a block diagram of the system of the present invention; Figure 3 This is a schematic diagram of the potential rockburst location in the surrounding rock in this invention; Figure 4 This is a schematic diagram illustrating the sub-region division within the depth range of the rockburst crater in this invention; Figure 5 This is a comprehensive evaluation matrix diagram of rockburst hazard in this invention; Figure 6 These are the acoustic wave test data at test points 1 and 2 of the surrounding rock in this embodiment of the invention; Figure 7 This is a graph showing the variation trend of the disturbance factor at test point 1 and test point 2 in the surrounding rock in this embodiment of the invention. Figure 8 The rock mass strength stress ratio (SSR) within the excavation damage zone at test point 1 in this embodiment of the invention is... rm Trend chart; Figure 9 The rock mass strength stress ratio (SSR) within the excavation damage zone at test point 2 in this embodiment of the invention is... rm Trend chart; Figure 10 This is a graph showing the trend of residual elastic energy variation within the depth range of the rockburst crater at test point 1 in the surrounding rock of this embodiment of the invention. Figure 11 This is a graph showing the trend of residual elastic energy variation within the depth range of rockburst craters at test point 2 in the surrounding rock of this invention. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and various embodiments. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent changes or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the protection scope of the present invention.

[0027] This invention, combining extensive engineering experience with rock mass strength and energy indicators, establishes a comprehensive assessment method for rockburst hazard during the construction of deep-buried hard rock tunnels. The implementation process of this invention is described below. Figure 1 .

[0028] This invention discloses a method for quantitatively evaluating the rockburst tendency of surrounding rock considering the excavation disturbance effect, comprising the following steps: Step 1: Preliminary determination of whether the surrounding rock meets the basic conditions for rockburst occurrence. The criteria for judgment include: the basic quality of the surrounding rock is Grade III or above, and the uniaxial compressive strength σ of the rock... ci ≥60MPa, and the initial maximum principal stress of the surrounding rock σ1≥10MPa.

[0029] Step 2: If the above basic conditions are met, conduct acoustic testing on potentially hazardous areas of the surrounding rock. Based on the test results, estimate the Geological Strength Index (GSI) and characteristic parameters of the damaged zone. The characteristic parameters of the damaged zone include the depth h of the excavated damaged zone (EDZ). EDZ Depth h of the high-intensity damage zone (HDZ) HDZ Depth h of the weak damage zone (WDZ) WDZ The disturbance factor D of the excavation profile surface s And a function describing the changing trend of the disturbance factor within the damaged area.

[0030] Step 3: Based on the estimation results of Step 2, and according to the rock mass strength stress ratio (SSR) within the excavation damage zone... rm Distribution characteristics are used to assess the susceptibility of rockbursts in the surrounding rock.

[0031] Step 4: Based on the results of Step 2 and Step 3, on the basis of estimating the depth of the rockburst pit in the surrounding rock, further evaluate the severity of the rockburst when it occurs.

[0032] Step 5: According to the results of Step 3 and Step 4, comprehensively evaluate the risk of rockburst.

[0033] The specific method of the above-mentioned Step 2 is as follows: (1) According to the magnitudes of the initial maximum principal stress σ1 and minimum principal stress σ3, the potential dangerous parts of the surrounding rock are divided into the following two cases: Case 1 is when σ1 > σ3, the rockburst dangerous parts are located at two surrounding rock parts in the direction of the minimum principal stress, and sonic wave tests need to be carried out at test points 1 and 2; Case 1 is when σ1 = σ3, the rockburst dangerous parts are located at four surrounding rock parts in the directions of the minimum principal stress and the maximum principal stress, and sonic wave tests need to be carried out at test points 1 to 4; Figure 3 (2) Drill sonic wave test holes with a depth of 9 m at the test points. According to the requirements of the "Rock Test Regulations for Water Conservancy and Hydropower Projects" (SLT264-2020), use sonic wave test equipment to measure the sonic wave P-wave velocity c every 0.2 m in the hole to obtain a scatter plot of a series of sonic wave P-wave velocities c corresponding to different depths; p p (3) The obvious low-wave-velocity area near the excavation contour line is regarded as the excavation damaged zone (EDZ), and the deep area outside the EDZ range is the undamaged zone (UZ). The depth h EDZ of the EDZ is equal to the maximum depth of the low-wave-velocity area of the excavation contour line; (4) Take the average value of the wave velocity data in the UZ range to obtain the average wave velocity c p0 of the undamaged rock mass. Substitute it into the following formula (1) to obtain the geological strength index GSI at each test point. Take the average value of the GSI of each test point to obtain the overall GSI of this excavation section: (1) (5) Substitute the sonic wave data in the EDZ range into formula (2) to obtain the disturbance factor D at different depths of the surrounding rock of the test point. The area where the disturbance factor D = 1 near the tunnel excavation contour is the highly damaged zone (HDZ), and its depth is the depth h HDZ of the HDZ; the range where 0 < D < 1 outside the HDZ is the weakly damaged zone (WDZ), and the depth of the WDZ can be calculated by h WDZ = h EDZ - h HDZ ; the disturbance factor defined on the excavation contour is D s , where D s ​​The sound wave velocity measured at the excavation profile can be determined using formula (2); if the wave velocity is not measured at the excavation profile, the fitting equation can be obtained by linear fitting based on the quantization result of the disturbance factor D in the WDZ range, and then h=0 is taken as the disturbance factor Ds at the excavation profile: (2) (6) When the obtained HDZ depth h HDZ When =0m (i.e., HDZ does not exist in the surrounding rock), h EDZ and D s Substituting into formula (3) to solve for the function describing the changing trend of the disturbance factor within the damaged area; when the obtained HDZ depth h HDZ When h > 0m (i.e., HDZ exists in the surrounding rock), h HDZ and h WDZ Substituting into formula (3) to solve for the function describing the changing trend of the disturbance factor within the damaged area: (3) (4) In the formula: h is the depth from the tunnel excavation outline.

[0034] The specific method for step 3 is as follows: (1) Take formula (3) from step 2 (when h HDZ When =0m) or formula (4) (when h =0m) or formula (4) HDZ When the depth is >0m, substitute the values ​​into formula (5) to calculate the rock mass strength stress ratio (SSR) at different depths within the excavation damage zone of the test point. rm Trend chart: (5) (2) Based on engineering practice experience in multiple tunnels, the critical strength stress ratio corresponding to rock burst occurrence is =0.2. Based on statistical analysis of numerous rockburst cases, the susceptibility of rockbursts can be categorized as unlikely to occur, relatively likely to occur, likely to occur, and extremely likely to occur. The assessment criteria for susceptibility are: ① Unlikely to occur: When the SSR within the excavated damaged area... rm When both are above 0.2, rockburst is unlikely to occur; ② It is relatively easy to occur: when 1 / 4 h of the excavation damage zone is above 0.2. EDZ SSR in depth range rm When the rock burst is below 0.2, it is more likely to occur during subsequent excavation if there is no disturbance or only slight disturbance; ③ It is more likely to occur: when 1 / 4 h of the excavation damage zone is affected. EDZ ~1 / 2h EDZ SSR in depth range rm When the rock burst is below 0.2, it is likely to occur during subsequent excavation if there is no disturbance or only slight disturbance; ④ It is extremely likely to occur: when there is not less than 1 / 2 h in the excavation damage zone. EDZSSR in depth range rm When the value is below 0.2, rockbursts are very likely to occur during subsequent excavation processes if there is no disturbance or only slight disturbance.

[0035] The specific method for step 4 is as follows: (1) Based on the results in steps 2 and 3, calculate the depth of the rockburst crater in the surrounding rock: when h HDZ When =0m, σ ci σ1, GSI =0.2 and h WDZ Substitute into formula (6) to calculate the depth h of the rockburst crater. rb When h HDZ When >0m, σ ci σ1, GSI =0.2、h WDZ and h HDZ Substitute into formula (7) to calculate the depth h of the rockburst crater. rb ; (6) (7) (2) Based on the results in step 2, combine GSI and formula (3) (when h HDZ When =0m) or formula (4) (when h =0m) or formula (4) HDZ When the depth is >0m, substitute into formula (8) to calculate the residual elastic energy (REE) within the depth range of the rockburst crater. rm ; (8) Starting from the tunnel excavation outline at a rockburst crater depth h rb The area is divided into n sub-regions at 0.2m intervals, such as... Figure 4 As shown, within the depth of the rockburst crater, n sub-regions are divided with a length of 0.2m each. The last sub-region, which may be less than 0.2m, is counted as a separate sub-region. For example, if the rockburst crater depth is 4m, then 20 sub-regions would be created with each sub-region being 0.2m long. If the rockburst crater depth is 4.1m, then 20 sub-regions of 0.2m length and 1 sub-region of 0.1m depth would be created, for a total of 21 sub-regions.

[0036] The average residual elastic energy (REE) of each sub-region is calculated by dividing the result by (residual elastic energy at the upper boundary of the sub-region + residual elastic energy at the lower boundary of the sub-region) by 2. rmi Finally, the overall average residual elastic energy (REE) for the rockburst crater depth range is calculated as (the sum of the average residual elastic energies of all sub-regions) / n. rmp .

[0037] (4) Based on the calculated total average residual elastic energy (REE) within the depth range of the rockburst crater. rmp According to REE rmp The size of the surrounding rock is used to assess the severity level of the rock mass. Specifically: REE rmp <50kJ / m 3 It is described as "no rockburst". 50kJ / m 3 ≤REE rmp <150kJ / m 3 It was classified as a "minor rockburst". 150kJ / m 3 ≤REE rmp ≤200kJ / m 3 It was classified as a "moderate rockburst". REE rmp >200kJ / m 3 It was described as a "strong rockburst".

[0038] The specific method for step 5 is as follows: (1) Organize the assessment results of rockburst susceptibility and severity in steps 3 and 4; (2) Based on Figure 5 To comprehensively evaluate the risk of rockburst and give the depth at which rockburst occurs.

[0039] Based on the aforementioned comprehensive assessment method for rockburst hazard during the construction of deep-buried hard rock tunnels, this invention also proposes a comprehensive assessment system for rockburst hazard during the construction of deep-buried hard rock tunnels, as detailed in [link to details]. Figure 2 ,include: Parameter input module: used to input surrounding rock strength, basic quality grade and initial stress parameters; (1) Specific Functions: This module serves as the human-computer interaction interface of the system and is responsible for inputting the static geological parameters of the segment to be evaluated. These include the initial maximum principal stress σ1, the initial minimum principal stress σ3, and the uniaxial compressive strength σ of the surrounding rock. ci The module also includes a basic rock quality grade (BQ or RMR index). Additionally, it has a parameter verification function; if the input value deviates significantly from the physical logic, the system will prompt for re-entry. (2) Hardware implementation: It consists of a portable industrial ruggedized tablet (IP67 protection), a keyboard / touchscreen, and a memory. It is connected to the system's main control core via an industrial control bus.

[0040] Acoustic wave testing and processing module: used to acquire and process acoustic wave velocity data at different depths of the surrounding rock, and automatically identify the extent of excavation damage zone and geological strength indicators.

[0041] (1) Specific functions: This is the core of the system’s “sensory” function; Transmission and reception: Control the ultrasonic transducer to transmit and receive acoustic signals in the borehole; First arrival wave extraction: Automatically identifies the P-wave origin point in the received signal and calculates the sound velocity c at different depths h. p； Partition identification: Automatic comparison of C p Wave velocity c in the undamaged region p0 It identifies the boundary depths of the High Damage Zone (HDZ) and the Excavation Damage Zone (EDZ) and calculates the Geological Strength Index (GSI) in real time. (2) Hardware implementation: Sensor hardware: A pair of high-frequency radial ultrasonic transducers (waterproof design); Signal acquisition hardware includes a multi-channel data acquisition unit, a low-noise signal amplifier (adjustable gain range 0-80dB), and an A / D conversion card (sampling frequency not less than 10MHz). Propulsion hardware: Automatic stepping deep hole sensor thruster, used to ensure the accuracy of sampling step length (e.g., 0.2m); The data acquisition unit is connected via BNC cable or digital transmission fiber optic cable. The data acquisition unit then transmits the digitized sound velocity curve to the "evolutionary computing module" via USB or wireless bridge.

[0042] Evolution calculation module: used to construct functional models of the evolution of disturbance factor and rock mass strength-stress ratio with depth; (1) Specific function: the "logical center" of the system; Function fitting: Convert the acoustic wave data into a perturbation factor D, and then fit it according to h. HDZ The value of is automatically matched and fitted to the evolution function of D(h) (piecewise or continuous function); Strength calculation: The entered σ ci Substituting σ1 and the real-time generated D(h) and GSI into the built-in strength-stress ratio calculation engine, SSR is generated. rm Spatial distribution model; Crater depth prediction: The embedded rockburst crater depth prediction algorithm is used to derive the theoretical failure depth h. rb； (2) Hardware implementation: Industrial-grade embedded computer (CPU uses a high-performance processor, such as an Intel Core i7 or an ARM chip with equivalent computing power), equipped with a large-capacity random access memory (RAM) to support fast matrix operations.

[0043] Comprehensive evaluation module: Based on a preset evaluation matrix, it outputs the susceptibility, severity, and overall hazard level of rockburst. (1) Specific functions: The system's "decision center": Automatic grading: SSR rmDistribution characteristics (susceptibility) and average residual elastic energy (SSR) within the rockburst crater area rmp Spatial coupling is performed based on the intensity of the event. Matrix comparison: Automatically retrieves the built-in "Rockburst Hazard Comprehensive Evaluation Matrix" and outputs the final hazard level; Visual output: Generates a rockburst risk heat map and directly marks dangerous areas and recommended support depths on the screen; Hardware implementation: High-definition industrial LCD display (for result presentation), graphics processing unit (GPU, for rendering heat maps), and alarm indicator (audio-visual alarm). In addition, the system includes a self-learning correction unit. This unit receives observational data (actual damage depth, actual magnitude, etc.) from the actual rockburst event on-site via a data communication interface, and uses a neural network algorithm to reverse-correct the function coefficients in the evolution calculation module, thereby achieving dynamic optimization of the evaluation model. Connections and data flow between the above modules The system operates following a logical chain of "data input → physical quantity conversion → mathematical model mapping → conclusion output": (1) Physical layer connection: The acoustic sensor penetrates into the surrounding rock through the borehole, and the physical signal is converted into a digital signal by the amplifier and A / D card and enters the system; (2) Data flow direction: Flow A: Data such as σ1 from the parameter input module flows to the "evolution calculation module" as the calculation base; Flow direction B: The "wave velocity-depth" array generated by the acoustic wave testing module flows to the "evolution calculation module" to determine the D(h) function; Flow to C: SSR generated by the evolutionary computation module rm Sequence and predicted pit depth h rb The funds flow to the "Comprehensive Evaluation Module"; (3) Final output: The comprehensive evaluation module combines all data streams to complete the final risk classification and sends control commands to the alarm hardware and display terminal.

[0044] The specific implementation process of this invention is as follows: Figure 1 As shown. To facilitate technical personnel's reference and application, the following will specifically explain the comprehensive evaluation method for rockburst risk, using a construction example from a section of a deep-buried water diversion tunnel in western my country. This tunnel has a maximum burial depth of over 2000 meters and exhibits typical characteristics of deep burial and high ground stress.

[0045] Example 1: like Figure 1 As shown, the present invention discloses a method and system for quantitatively evaluating the rockburst tendency of surrounding rock considering the excavation disturbance effect, comprising the following steps: Step 1: Make a preliminary determination of whether the surrounding rock has the basic conditions for rock burst occurrence.

[0046] The criteria for judgment include: the basic quality of the surrounding rock is Grade III or above (i.e., Grade I, Grade II, or Grade III), and the uniaxial compressive strength σ of the rock. ci ≥60MPa, and the initial maximum principal stress of the surrounding rock σ1≥10MPa; Specifically, according to the engineering geological survey data, the basic quality of the surrounding rock in this excavation section is Grade II, and the uniaxial compressive strength of the rock is σ. ci The initial maximum principal stress σ1 of the surrounding rock is 80 MPa, and the initial maximum principal stress σ1 of the surrounding rock is 65 MPa. Based on the basic conditions, "the basic quality of the surrounding rock is Grade III or above, and the uniaxial compressive strength of the rock σ..." ci "≥60MPa, and the initial maximum principal stress of the surrounding rock σ1≥10MPa" can be used to determine that the surrounding rock of this excavation section has the basic conditions for rock burst occurrence.

[0047] Step 2: Damage zone parameter identification and evolution function construction based on acoustic wave testing If the above basic conditions are met, acoustic testing is conducted on potentially hazardous areas of the surrounding rock. Based on the test results, the Geological Strength Index (GSI) and characteristic parameters of the damaged zone are estimated. The characteristic parameters of the damaged zone include the depth h of the excavation damaged zone (EDZ). EDZ Depth h of the high-intensity damage zone (HDZ) HDZ Depth h of the weak damage zone (WDZ) WDZ The disturbance factor D of the excavation profile surface s And a function describing the changing trend of the disturbance factor within the damaged area.

[0048] Determine the test location: Specifically, firstly, since the maximum principal stress σ1 in this excavation section is in the vertical direction, the minimum principal stress σ3 is in the horizontal direction, and σ1 > σ3. Therefore, it can be determined that the potentially dangerous parts of the surrounding rock are the two points where the minimum principal stress intersects with the surrounding rock, which is equivalent to... Figure 3 In "Scenario 1," the rockburst hazard is concentrated on the side walls. Therefore, two test points, 1 and 2, were symmetrically set up on both side walls to conduct acoustic wave tests. On-site sound wave measurement: Secondly, 9m deep acoustic test holes were drilled at test points 1 and 2. In accordance with the requirements of the "Code for Rock Testing in Water Conservancy and Hydropower Engineering" (SLT264-2020), a high-precision ultrasonic depth sounder was used to measure the P-wave velocity c within the holes at 0.2m intervals. p Thus, the P-wave velocities c corresponding to different depths were obtained. p Scatter plot, such as Figure 6 As shown.

[0049] Identify partition feature points: Damage zone determination: Subsequently, the obvious low wave velocity zone near the excavation contour surface is regarded as the excavation damaged zone (EDZ), and the deep area outside the EDZ is the undamaged zone (UZ). As shown in Figure 6 Figure 2, the EDZ and UZ ranges at two test points are shown. The depth h EDZ of the EDZ is equal to the maximum depth of the low wave velocity zone of the excavation contour line. The EDZ depths at test points 1 and 2 are 1.8 m and 3.6 m respectively; Background wave velocity determination: Then, the average wave velocity c of the undamaged rock mass at test points 1 and 2 is obtained by taking the average value of the wave velocity data in the UZ range. p0 They are 6.24 km / s and 6.09 km / s respectively.

[0050] GSI index conversion: Substituting into formula (1), the geological strength indexes GSI of test points 1 and 2 can be obtained as 74.6 and 72.9 respectively, and the average value is GSI = 73.8; Calculating the disturbance factor and constructing the evolution function: Substituting the acoustic wave data in the EDZ range into formula (2), the disturbance factors D at different depths of the surrounding rock at test points 1 and 2 can be obtained. As shown in Figure 7 Figure 3, according to "the area with the disturbance factor D = 1 near the tunnel excavation contour is the high damage zone (HDZ), and its depth is the HDZ depth h HDZ ; the range with 0 < D < 1 outside the HDZ is the weak damage zone (WDZ), and the WDZ depth can be calculated by h WDZ = h EDZ - h HDZ ; the disturbance factor on the excavation contour is defined as D s "; The h HDZ = 1.2 m, h WDZ = 0.6 m, D s = 1.0 at test point 1 can be determined respectively, and the h HDZ = 2.6 m, h WDZ = 1.0 m, D s = 1.0 at test point 2; finally, since h HDZ > 0 m at test points 1 and 2, substituting the h HDZ and h WDZ of both into formula (4), the functions describing the change trend of the disturbance factor in the damage zone at test points 1 and 2 are shown as formulas (9) and (10) respectively: (9) (10) Step 3: Combining the estimation results of Step 2, based on the rock mass strength stress ratio SSR within the excavation damaged zone rmDistribution characteristics are used to assess the susceptibility of rockbursts in the surrounding rock.

[0051] Specifically, by substituting formulas (9) and (10) from step 2 into formula (5), the rock mass strength stress ratio (SSR) at different depths within the excavation damage zone at test points 1 and 2 can be calculated. rm Trend charts, respectively, are as follows: Figure 8 and 9 As shown.

[0052] According to the assessment criteria for rockburst susceptibility, "① Not likely to occur: When SSR in the excavated damage zone is..." rm When both are above 0.2, rockburst is unlikely to occur; ② It is relatively easy to occur: when 1 / 4 h of the excavation damage zone is above 0.2. EDZ SSR in depth range rm When the rock burst is below 0.2, it is more likely to occur during subsequent excavation if there is no disturbance or only slight disturbance; ③ It is more likely to occur: when 1 / 4 h of the excavation damage zone is affected. EDZ ~1 / 2h EDZ SSR in depth range rm When the rock burst is below 0.2, it is likely to occur during subsequent excavation if there is no disturbance or only slight disturbance; ④ It is extremely likely to occur: when there is not less than 1 / 2 h in the excavation damage zone. EDZ SSR in depth range rm When the value is below 0.2, rockbursts are highly likely to occur during subsequent excavation processes if there is no disturbance or only slight disturbance.

[0053] From test point 1 corresponding to Figure 8 It can be seen that within the 1.8m excavation damage zone, more than half of the area has SSR. rm All values ​​are below 0.2, therefore the rockburst susceptibility at this location is extremely high. (This is based on the data from test point 2.) Figure 9 It can be seen that within the 3.6m excavation damage zone, more than 3 / 4 of the area has SSR. rm All values ​​are below 0.2, therefore the rockburst susceptibility here is extremely high.

[0054] Step 4: Based on the results of Step 2 and Step 3, further assess the intensity of the rock burst based on the estimated depth of the surrounding rock crater.

[0055] Specifically, the depth of the rockburst crater in the surrounding rock is calculated based on the results from steps 2 and 3. At test point 1, due to h HDZ >0m, therefore σ ci =80MPa, σ1=65MPa, GSI=73.8, =0.2、h WDZ =1.2m and h HDZ Substituting 0.6m into formula (7), calculate the depth h of the rockburst crater. rb =1.44m; At test point 2, due to h HDZ >0m, therefore σ ci =80MPa, σ1=65MPa, GSI=73.8, =0.2、h WDZ =2.6m and h HDZ Substituting 1.0m into formula (7), calculate the depth h of the rockburst crater. rb =3.01m.

[0056] Subsequently, based on the results in step 2, for test point 1, GSI=73.8 and formula (9) are substituted into formula (8) to calculate the residual elastic energy REE within the depth range of the rockburst crater. rm ,like Figure 10 As shown.

[0057] Then according to Figure 4 The tunnel excavation profile was divided into 8 sub-regions at 0.2m intervals. The average residual elastic energy (REE) of each sub-region was calculated as (residual elastic energy at the upper boundary of the sub-region + residual elastic energy at the lower boundary of the sub-region) / 2. rmi The overall average residual elastic energy (REE) for the rockburst crater depth range is finally calculated as (the sum of the average residual elastic energies of all sub-regions) / n. rmp =120.7kJ / m 3 .

[0058] For test point 2, substitute GSI=73.8 and formula (10) into formula (8) to calculate the residual elastic energy REE within the depth range of the rockburst crater. rm ,like Figure 11 As shown, then follow as follows Figure 4 The tunnel excavation profile was divided into 16 sub-regions at 0.2m intervals. The average residual elastic energy (REE) of each sub-region was calculated as (residual elastic energy at the upper boundary of the sub-region + residual elastic energy at the lower boundary of the sub-region) / 2. rmi Finally, the overall average residual elastic energy (REE) for the rockburst crater depth range is calculated as (the sum of the average residual elastic energies of all sub-regions) / n. rmp =115.7kJ / m 3 .

[0059] Based on the REE at the two test points rmp Based on the following rockburst classification, the REE values ​​at the two test points can be seen. rmp Both are within the range of minor rockbursts, so a minor rockburst will occur at test point 1 and test point 2.

[0060] REE rmp <50kJ / m 3It is described as "no rockburst". 50kJ / m 3 ≤REE rmp <150kJ / m 3 It was classified as a "minor rockburst". 150kJ / m 3 ≤REE rmp ≤200kJ / m 3 It was classified as a "moderate rockburst". REE rmp >200kJ / m 3 It was described as a "strong rockburst".

[0061] Step 5: Based on the results of Steps 3 and 4, comprehensively assess the risk of rockburst.

[0062] Specifically, analyzing the assessment results of rockburst susceptibility and severity in steps 3 and 4, it was found that the surrounding rock at test point 1 was highly susceptible to rockbursts, with a severity level of minor rockbursts and a damage depth of 1.44m; the surrounding rock at test point 2 was also highly susceptible to rockbursts, with a severity level of minor rockbursts and a damage depth of 3.01m. Therefore, it can be determined that minor rockbursts are highly likely to occur at test point 1 within a depth of 1.44m from the tunnel excavation outline; and minor rockbursts are highly likely to occur at test point 2 within a depth of 3.01m from the tunnel excavation outline.

[0063] Finally, the evaluation results of the above dimensions are coupled to the comprehensive risk assessment map. Figure 5 In order to comprehensively evaluate the risk of rockburst.

[0064] Thus, the rockburst risk assessment of a certain excavation section in the embodiment was completed. The assessment results are as follows: test point 1 is highly likely to experience minor rockburst within a depth of 1.44m from the tunnel excavation outline; test point 2 is highly likely to experience minor rockburst within a depth of 3.01m from the tunnel excavation outline. This provides an accurate reference for on-site rockburst prevention and control work.

[0065] The method and system provided by this invention can not only assess rockburst susceptibility but also determine the intensity of rockbursts during occurrence, achieving a comprehensive evaluation of rockburst hazards. This overcomes the limitations of existing methods in systematic assessment and demonstrates strong innovation. The obtained results regarding rockburst susceptibility and intensity provide specific and targeted basis for rockburst prevention measures, helping to improve disaster prevention and mitigation efficiency, reduce risks to personnel and equipment, and yield significant economic benefits.

[0066] Compared with existing technologies, this invention utilizes acoustic wave testing, a low-cost, non-contact method, to successfully establish a complete closed loop from "qualitative judgment" to "quantitative analysis" and then to "comprehensive early warning," significantly improving the efficiency of disaster prevention and mitigation during the construction process.

[0067] It should be noted that the above examples are only used to illustrate the method of the present invention in detail, and are not intended to limit its scope of application. Those skilled in the art can make modifications and substitutions to the method of the present invention, but this does not mean that it departs from the scope defined by the claims of the present invention.

Claims

1. A comprehensive assessment method for rockburst hazard during the construction of deep-buried hard rock tunnels, characterized in that, Includes the following steps: Step 1: Obtain the basic physical and mechanical parameters and geostress parameters of the surrounding rock in the section to be tested, and preliminarily determine whether the surrounding rock has the basic conditions for rock burst occurrence; Step 2: When the basic conditions are met, conduct acoustic wave testing at potentially hazardous areas of the surrounding rock. Based on the spatial distribution of P-wave velocity, estimate the geological strength index (GSI) and characteristic parameters of the damaged area; wherein, the characteristic parameters of the damaged area include the excavation depth h of the damaged area. EDZ Depth h of the heavily damaged area HDZ Depth h of weak damage zone WDZ The disturbance factor D of the excavation profile surface s And the evolution function describing the evolution of the perturbation factor with depth within the damaged area; Step 3: Combining the parameters obtained in Step 2, construct the rock mass strength stress ratio (SSR) that takes into account excavation disturbance. rm Distribution model to quantitatively evaluate the susceptibility level of rockburst in surrounding rock; Step 4: Estimate the rockburst crater depth h based on rock strength, initial stress, and damage zone evolution function. rb And calculate the overall average residual elastic energy (REE) within the rockburst crater area. rmp To evaluate the intensity level of a rock eruption; Step 5: Couple the susceptibility level and severity level, and determine the final rockburst hazard level and damage depth of the surrounding rock through the comprehensive hazard evaluation matrix.

2. The comprehensive assessment method for rockburst hazard during the construction of a deep-buried hard rock tunnel according to claim 1, characterized in that, The basic conditions mentioned in step 1 include: the basic quality grade of the surrounding rock is Grade III or above, and the uniaxial compressive strength of the rock is σ. ci ≥60MPa, and the initial maximum principal stress of the surrounding rock σ1≥10MPa.

3. The comprehensive assessment method for rockburst hazard during the construction of deep-buried hard rock tunnels according to claim 1, characterized in that, The criteria for determining potentially hazardous areas in the surrounding rock in step 2 are as follows: When the initial maximum principal stress σ1 of the surrounding rock is greater than the minimum principal stress σ3, the test points are set at two locations in the surrounding rock along the direction of the minimum principal stress. When σ1 equals σ3, the test points are set at four locations in the surrounding rock along the directions of the maximum principal stress and the minimum principal stress.

4. The comprehensive assessment method for rockburst hazard during the construction of a deep-buried hard rock tunnel according to claim 1, characterized in that, The methods for obtaining the characteristic parameters of the damaged area in step 2 include: The P-wave velocity c at different depths h was obtained through acoustic wave testing. p The low wave velocity zone near the excavation outline is defined as the excavation damage zone (EDZ), and its deepest point is h. EDZ The deep area outside the EDZ range is the undamaged zone (UZ). Calculate the average wave velocity c in the undamaged region UZ p0 The geological strength index is calculated according to formula (1); （1） Calculate the disturbance factor D at each depth according to formula (2); （2） Let the region where D = 1 be the high-damage zone HDZ, with a corresponding depth of h. HDZ The area outside the HDZ that satisfies 0 < D < 1 is the weakly damaged zone WDZ, with a depth h. WDZ =h EDZ -h HDZ The disturbance factor on the excavation profile is defined as D. s .

5. The comprehensive assessment method for rockburst hazard during the construction of a deep-buried hard rock tunnel according to claim 4, characterized in that, The function describing the evolution of the perturbation factor within the damaged area in step 2 is based on h. HDZ Value classification construction: When h HDZ When m = 0, formula (3) is used to solve for the trend of the change of the disturbance factor in the damaged area; （3） When h HDZ When m > 0, the piecewise function of formula (4) is used to solve for the trend of the perturbation factor change within the damage zone: （4） In the formula: h is the depth from the tunnel excavation outline.

6. The comprehensive assessment method for rockburst hazard during the construction of a deep-buried hard rock tunnel according to claim 1, characterized in that, The rockburst susceptibility evaluation criteria mentioned in step 3 are as follows: Substituting the perturbation factor evolution function into formula (5), the rock mass strength stress ratio SSR is obtained. rm Curve showing variation with depth; （5） According to SSR rm Areas with a value < 0.2 in the excavation damage zone h EDZ The proportions of each component are classified into different levels: If the ratio is 0, then it is "not likely to occur"; If the proportion is in the range of (0, 1 / 4], it is considered "more likely to occur"; If the ratio is within the range of (1 / 4, 1 / 2), it is considered "prone to occur"; If the proportion is ≥ 1 / 2, then it is "extremely likely to occur".

7. The comprehensive assessment method for rockburst hazard during the construction of a deep-buried hard rock tunnel according to claim 1, characterized in that, The rockburst crater depth h mentioned in step 4 rb The calculation formula is as follows: When h HDZ When =0m, the critical strength stress ratio =0.2、σ ci σ1, GSI, and h WDZ Substitute into formula (6) to calculate the depth h of the rockburst crater. rb （6） When h HDZ When >0m, σ ci σ1, GSI =0.2、h WDZ and h HDZ Substitute into formula (7) to calculate the depth h of the rockburst crater. rb： （7）。 8. The comprehensive assessment method for rockburst hazard during the construction of a deep-buried hard rock tunnel according to claim 1, characterized in that, Step 4 calculates the overall average residual elastic energy (REE). rmp The methods include: The residual elastic energy (REE) within the depth range of the rockburst crater is calculated using formula (8). rm ; （8） The depth of the rockburst crater is h rb Divide the region into n sub-regions at intervals of 0.2 m; Calculate the residual elastic energy at the boundary points of each sub-region and take the average value to obtain the average residual elastic energy (REE) of each sub-region. rmi ; The average residual elastic energy (REE) within the rockburst crater area is obtained by averaging over all sub-regions. rmp .

9. The comprehensive assessment method for rockburst hazard during the construction of a deep-buried hard rock tunnel according to claim 8, characterized in that, The rockburst intensity level described in step 4 is based on REE. rmp Determining the numerical range: REE rmp < 50 kJ / m 3 It is "rockburst-free"; 50 kJ / m 3 ≤ REE rmp < 150 kJ / m 3 It was classified as a "minor rockburst". 150 kJ / m 3 ≤ REE rmp ≤200 kJ / m 3 It was classified as a "moderate rockburst". REE rmp >200 kJ / m 3 It is described as a "strong rockburst".

10. A comprehensive assessment system for rockburst hazard during the construction of deep-buried hard rock tunnels using the method described in any one of claims 1-9, characterized in that, include: Parameter input module: used to input surrounding rock strength, basic quality grade and initial stress parameters; Acoustic wave testing and processing module: used to acquire and process acoustic wave velocity data at different depths of surrounding rock, and automatically identify the extent of excavation damage zone and geological strength indicators; Evolution calculation module: used to construct functional models of the evolution of disturbance factor and rock mass strength-stress ratio with depth; Comprehensive evaluation module: Based on a preset evaluation matrix, it outputs the susceptibility, severity, and overall hazard level of rockbursts.

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