A rock mass disturbance stress direction identification method based on sound source characteristics

Abstract

The present application relates to the technical field of geotechnical engineering, and discloses a rock mass disturbance stress direction identification method based on sound source characteristics, comprising the following steps: environment preparation, signal acquisition, data processing, and disturbance stress direction identification; the method upgrades single-point measurement to regional multi-index measurement, measures the wave speed and sound source characteristic parameters of the target rock mass region through arranging a plurality of microseismic sensors, and reverses the anisotropy nature of the fine microscopic damage of the rock mass through the anisotropy phenomenon of the macroscopic wave speed change and the sound source characteristic parameter change, so as to identify the engineering disturbance stress direction; the method does not need to consider the rock stratum and geological environment of the target region, and can accurately judge the engineering disturbance stress direction only according to the measured wave speed and the sound source characteristic parameter change trend, has the characteristics of rigorous theory, simple operation, strong applicability, etc., can provide a basis for the stability judgment of the surrounding rock of structures such as tunnels and roadways, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering technology, specifically relating to a method for identifying the direction of rock mass disturbance stress based on sound source characteristics. Background Technology

[0002] The stress environment of underground engineering projects is complex, encompassing the self-weight stress of overlying strata, tectonic stress, and engineering disturbance stress. The tectonic stress of the rock mass constantly changes and adjusts with crustal tectonic movements, and its direction exhibits significant uncertainty. Furthermore, the intricate network of tunnels and chambers within the rock mass, the presence of internal faults and pore water pressure, and the varying properties of the rock itself all contribute to the complexity of the stress environment. Engineering disturbances cause the re-accumulation and migration of original rock stress, further exacerbating the problem. Disturbance stress significantly impacts the stability of the rock mass structure, and identifying the direction of disturbance stress is crucial for the safe and efficient operation of the project.

[0003] Commonly used stress direction measurement methods in engineering include borehole wall strain method, borehole diameter deformation method, and borehole bottom strain method. These methods require drilling in the field and identifying the stress direction of the rock mass based on the stress-strain relationship. They are costly, complex to operate, and are essentially single-point measurements. If the rock mass is disturbed by engineering activities and stress redistribution occurs, remeasurement and correction are necessary. However, in field rock masses, after a long period of geological processes, the rock mass has reached a state of equilibrium. The focus should be on monitoring the disturbance stress state within the target area, as single-point stress state measurements have significant limitations. Microseismic monitoring technology has been widely applied in mining and geotechnical engineering. Combining rock mass disturbance stress direction identification with microseismic monitoring can improve the accuracy of engineering stability assessment and the targeted nature of prevention and control. Therefore, finding a widely applicable and easy-to-operate method for identifying rock mass disturbance stress direction based on microseismic monitoring has significant engineering value. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a novel method for identifying the direction of disturbed stress, addressing the traditional limitations and complexity of existing methods for identifying the direction of rock mass stress. This method upgrades from single-point measurement to comprehensive measurement of multiple indicators across a region, using the changing characteristics of macroscopic sound source parameters to infer the anisotropic nature of microscopic damage in the rock mass, thereby identifying the direction of disturbed stress in the rock mass. It has the advantages of rigorous theory, simple operation, strong applicability, and high accuracy.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] The rock mass disturbance stress direction identification method based on sound source characteristics described in this invention includes the following steps:

[0007] S1. Environmental Preparation:

[0008] In the target rock mass area, a three-dimensional coordinate system is established. Following the designed microseismic sensor deployment scheme, several microseismic sensors are deployed at the engineering site. The minimum wave velocity v of the microseismic sensor signal propagating in the target rock mass area is measured. min ;

[0009] S2, Signal Acquisition:

[0010] Before the engineering disturbance, each microseismic sensor is controlled to transmit or receive signals, and the transmission time, reception time, and sound source characteristic parameters of the active seismic source signal are collected and recorded at least once as reference data; after the engineering disturbance, the transmission time, reception time, and sound source characteristic parameters of the active seismic source signal are continuously collected and recorded.

[0011] S3, Data Processing:

[0012] Based on the data collected by S2, calculate the real-time wave velocity changes and sound source characteristic parameter changes of each propagation path in the target rock mass area before and after the engineering disturbance;

[0013] S4. Identification of the direction of disturbance stress:

[0014] Based on the wave velocity changes along each propagation path and the evolution characteristics of the sound source's characteristic parameters, a disturbance stress identification objective function G(x,y,z) is constructed. The actual disturbance stress direction in the target rock mass region is obtained based on the objective function.

[0015]

[0016] In the formula: Δv′ ij Let ΔA′ be the normalized value of the wave speed. ij Δf′ is the normalized value of the amplitude. mij The normalized value of the main frequency, Δf′ cij θ is the normalized value of the frequency centroid. ij This represents the angle between each propagation path and the direction of the actual disturbance stress.

[0017] Furthermore, in step S1, the microseismic sensors are deployed according to the following scheme:

[0018] Each microseismic sensor has the function of transmitting and receiving active seismic source signals, that is, each microseismic sensor can be an active seismic source;

[0019] The microseismic sensors are installed in boreholes and are arranged non-coplanarly around the target rock mass area. The total number of microseismic sensors is no less than 5, and the number increases as the target area increases. The microseismic sensors are arranged in multiple angles and directions.

[0020] The distance between any two microseismic sensors is less than the farthest propagation distance of the active seismic source signal.

[0021] Furthermore, the microseismic sensor signal in the target rock mass region p ij The propagation speed along the propagation path is calculated according to formula (2);

[0022]

[0023] In the formula: p ij The propagation path is determined by the microseismic sensor S. i propagation to micro-vibration sensor S j The resulting propagation path, (x i ,y i ,z i ) is a micro-vibration sensor S i At the coordinates within the target rock mass area, t i For micro-vibration sensor S i The transmission time of the active source signal, (x j ,y j ,z j ) is a micro-vibration sensor S j At the coordinates within the target rock mass area, t j For micro-vibration sensor S j Signal reception time.

[0024] Furthermore, in step S1, the measured minimum wave velocity value v min At that time, each microseismic sensor is controlled to transmit an active source signal once in sequence, with a transmission interval of 0.1s-5s. Other microseismic sensors receive the signals in real time, and the transmission and reception times of each signal are recorded in real time. The wave velocity of each propagation path is calculated according to formula (2), and the minimum wave velocity value v is selected. min .

[0025] Furthermore, in step S2, the active seismic source signal after the engineering disturbance is transmitted or received according to the following scheme:

[0026] Each microseismic sensor sequentially transmits an active seismic source signal at the same time interval Δt, and the other microseismic sensors receive the corresponding signals, forming a loop. This loop is repeated multiple times for real-time monitoring until the end, and the time interval Δt satisfies the following:

[0027] Δt>Δt cr (3)

[0028] Δt cr =α(l max / v min (4)

[0029] Where: Δt cr The critical time interval is defined by α, which is an empirical coefficient ranging from 1.5 to 3, and the larger the target area, the larger the value of α.max The maximum distance between all microseismic sensors; v min This represents the minimum wave velocity value for the active seismic source signal to propagate in the target rock mass region.

[0030] Furthermore, the active source signal is a pulse signal or an acoustic signal.

[0031] Furthermore, the sound source characteristic parameters include amplitude A and dominant frequency f. m Frequency centroid f c .

[0032] Furthermore, the changes in wave velocity and sound source characteristic parameters are calculated according to formula (5):

[0033]

[0034] In the formula: v ij (t), A ij (t), f mij (t), f cij (t) represents the measured wave velocity and sound source characteristic parameter values ​​after the engineering disturbance, respectively; t is the active source signal reception time; v ij (0), A ij (0), f mij (0), f cij (0) represents the measured wave velocity and sound source characteristic parameter values ​​before the engineering disturbance.

[0035] Furthermore, step S4 also includes the following steps:

[0036] S4-1. Calculate the unit direction vector of each propagation path according to formula (6).

[0037]

[0038] S4-2, Assume the unit direction vector of the actual disturbance stress is... Then the directions of each propagation path With respect to the actual direction of disturbance stress The cosine of the included angle cosθ ij for:

[0039]

[0040] In the formula: x, y, z ∈ [-1, 1], x 2 +y 2 +z 2 =1;

[0041] S4-3, According to formula (8), the wave speed change value Δv ij and characteristic parameters ΔA of each sound source ij , Δfmij , Δf cij Normalize to the interval [-1, 1]:

[0042]

[0043] Where: Δv max and Δv max ΔA represents the maximum and minimum changes in wave velocity along all paths before and after the engineering disturbance. max ΔA min , Δf mmax , Δf mmin , Δf cmax , Δf cmin These represent the maximum and minimum values ​​of the changes in characteristic parameters of each sound source before and after the engineering disturbance;

[0044] S4-4, The cosine of the included angle cosθ obtained from S4-2 ij The wave velocity change value Δv obtained from S4-3 ij and the change values ​​ΔA of the characteristic parameters of each sound source ij , Δf mij , Δf cij Construct the disturbance stress identification objective function G(x,y,z) according to formula (1), substitute the measured wave velocity and sound source characteristic parameters of each propagation path to solve for the maximum value of the objective function G(x,y,z). The coordinate direction of the maximum value is the actual disturbance stress direction.

[0045] The basic principle of the method described in this invention is briefly described as follows: Since engineering disturbances can cause stress redistribution in the original rock and lead to anisotropy of the internal structure of the rock mass under stress release or stress concentration, when elastic waves propagate in the rock mass and encounter changes in the internal structure of the rock mass, the microscopic propagation path of the wave will change, which will then be macroscopically manifested as anisotropy of wave velocity and sound source characteristic parameters. That is, the anisotropy of crack morphology caused by external engineering disturbances is the essential reason, while the anisotropy of wave velocity and sound source characteristic parameters is the external phenomenon. Based on the long-term research of our research group, it has been found that under the influence of external disturbances, a large number of existing microcracks in the rock mass will close to a certain extent and generate a large number of new disturbance-induced microcracks. Among them, the long axis of closed microcracks is mostly perpendicular to the direction of disturbance stress, and the long axis of disturbance-induced microcracks is mostly parallel to the direction of disturbance stress. Figure 1 This demonstrates the mechanism by which changes in crack shape before and after disturbance lead to anisotropic changes in wave velocity and acoustic source characteristic parameters. Figure 1 (a) is a schematic diagram of the morphology of the primary microfractures in the rock mass before disturbance. Figure 1 (b) is a schematic diagram of the morphology of disturbance-induced microcracks. Figure 1(c) is a schematic diagram of the wave propagation path in the case of a single crack. It can be seen that the wave propagation path in the direction of the disturbance stress increases slightly, the wave propagation path in the direction perpendicular to the disturbance stress increases significantly, and the wave propagation path in other angular directions increases slightly. Since the macroscopic wave velocity and sound source characteristic parameters change basically unchanged or with little change when the wave propagates in the same or very similar propagation paths in the rock mass, the microscopic wave velocity and sound source characteristic parameters will decrease. When the microscopic wave propagation path becomes longer, the wave propagation attenuation increases and the propagation time becomes longer, so the obtained macroscopic wave velocity and sound source characteristic parameters will decrease. The greater the decrease in wave velocity and sound source characteristic parameters before and after engineering disturbance, the greater the increase in the microscopic propagation path of the wave, which means that the wave passes through more disturbance-induced microcracks. If the decrease in macroscopic wave velocity and sound source characteristic parameters is the largest, it means that the path is close to the direction perpendicular to the disturbance stress. Conversely, the greater the increase in macroscopic wave velocity and sound source characteristic parameters before and after engineering disturbance, the greater the path is close to the direction of the disturbance stress. Combining and superimposing this simplified model gives the true propagation of the wave. Since engineering disturbance is difficult to identify, this invention uses the changes in sound source characteristic parameters of the target rock mass area through actual measurement. By using the anisotropic phenomenon of sound source characteristic changes, the anisotropic nature of the microscopic damage of the rock mass can be deduced, thereby identifying the direction of disturbance stress in the engineering.

[0046] Beneficial effects

[0047] This invention addresses the difficulty in determining the direction of disturbance stress in engineering rock masses and the drawbacks of existing measurement methods, such as high cost and complex operation. It proposes upgrading single-point measurement to regional multi-index measurement, considering the macro-microscopic relationship between the anisotropy of sound source characteristic parameters and the anisotropy of stress-induced rock mass fracture structure changes. A method for identifying the direction of disturbance stress in rock masses based on sound source characteristics is proposed. This method does not require consideration of the rock strata and geological environment of the target rock mass area; it can accurately determine the direction of disturbance stress in engineering projects simply by analyzing the measured wave velocity changes and the trends of sound source characteristic parameters. It features rigorous theory, simple operation, and strong applicability, providing a basis for judging the stability of surrounding rock in tunnels, roadways, and other structures, and has broad application prospects. Attached Figure Description

[0048] Figure 1 This is a schematic diagram showing the changes in microcracks in the rock mass before and after the disturbance.

[0049] Figure 2 This is a flowchart of the method described in this invention.

[0050] Figure 3 The sensor arrangement and simulated disturbance load diagram for the sample in Example 1 are shown.

[0051] Figure 4 The stress-time relationship diagram is shown for the biaxial loading of the specimen in Example 1.

[0052] Figure 5 This is a time-series diagram of the wave velocity difference of the sample in Example 1.

[0053] Figure 6 This is a graphical representation of the method for finding the maximum and minimum values ​​of a function in Example 1.

[0054] Figure 1 In the diagram, ↓ represents the direction of the disturbance stress. These are primary microcracks in the rock. For disturbance-induced microcracks, · represents the sensor monitoring point. The path before the disturbance is indicated by '-', and the path after the disturbance is indicated by '-'. A, B, C, D, and E are schematic diagrams of signal transmission or reception points.

[0055] Figure 1 (a) is a schematic diagram of the microcracks in the rock mass before disturbance. It can be seen from the figure that the microcracks in the rock mass before disturbance are of different shapes and disordered, without typical distribution characteristics.

[0056] Figure 1 (b) is a schematic diagram of microcracks in the rock mass after disturbance. It can be seen from the figure that under the influence of disturbance load, the original microcracks in the rock have closed or expanded to different degrees. A large number of microcracks with their long axis perpendicular to the disturbance stress have closed, while microcracks with their long axis parallel to the disturbance stress have expanded further. At the same time, induced microcracks with their long axis parallel to the disturbance stress have been generated.

[0057] Figure 1 (c) is the selection Figure 1 (b) is a schematic diagram of the propagation path of a single crack wave. It can be seen from the figure that the propagation path of the wave in the direction of the disturbance stress has increased slightly, the propagation path of the wave in the direction perpendicular to the disturbance stress has increased significantly, and the propagation path of the wave in other angular directions has increased slightly.

[0058] Figure 5 Direction-σ x Direction-σ y Direction-σ z The curves represent the difference curves of the average wave velocity before and after the sample is loaded, for the propagation paths parallel to the x-axis, y-axis, and z-axis, respectively. Direction-45° represents the wave velocity difference curve for the propagation path at a 45° angle to the z-axis, and Direction-14° represents the wave velocity difference curve for the propagation path at a 14° angle to the z-axis.

[0059] Figure 6 (a) is a three-dimensional analytical plot of G(x,y,z). Figure 6 (b) is Figure 6 (a) is the y-axis view. Figure 6 (c) is Figure 6 (a) x-axis view. Detailed Implementation

[0060] The present invention will be further described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0061] Since implementation and verification of field-based experiments are difficult, this invention is based on laboratory experiments. By testing rock samples, the reliability and accuracy of the method described in this invention are verified, thereby providing a reference for practical engineering applications.

[0062] Example 1;

[0063] See Figure 1-6 The rock mass disturbance stress direction identification method based on sound source characteristics described in this embodiment of the invention includes the following steps:

[0064] S1. Environmental Preparation:

[0065] This embodiment is based on an indoor triaxial rock test. The test loading equipment is the TRW-3000 true triaxial electro-hydraulic servo mutation experimental system. The sensor is a Vallen acoustic emission sensor, which has the function of both transmitting and receiving acoustic signals, that is, both can be active vibration sources. The model is VS45-H-Vallen Systeme.

[0066] A granite sample was selected as the target rock mass region. The sample size was 100mm × 100mm × 100mm. A coordinate system for the target rock mass region was established with the lower left corner of the front side of the sample as the origin O. Figure 3 As shown, a total of 22 microseismic sensors were arranged on the surface of the rock sample, with 5 on the front and rear sides of the sample and 4 on the left, right and top sides. The numbers and coordinates of the microseismic sensors are shown in Table 1.

[0067] Table 1. Microseismic Sensor Numbers and Coordinates

[0068]

[0069]

[0070] Biaxial loading was applied to the specimen to simulate engineering disturbances, and the initial stress state of the specimen was σ. z =σ x =σ y =0, loading technical parameters are: σx =0~10MPa, σ z =0 ~ failure load, loading rate is 0.001mm / s;

[0071] In this embodiment, before conducting the triaxial test, the minimum wave velocity v of the active source signal propagating in the target rock mass region is measured using a microseismic sensor. min The microseismic sensor signal is in the target rock mass region p ij The propagation speed along the propagation path is calculated according to formula (2), and the wave speed and wave speed statistics table 2 for each propagation path are obtained. The minimum wave speed value v is selected from the table. min =3382m / s;

[0072]

[0073] In the formula: p ij The propagation path is determined by the microseismic sensor S. i propagation to micro-vibration sensor S j The resulting propagation path, (x i ,y i ,z i ) is a micro-vibration sensor S i At the coordinates within the target rock mass area, t i For micro-vibration sensor S i The transmission time of the active source signal, (x j ,y j ,z j ) is a micro-vibration sensor S j At the coordinates within the target rock mass area, t j For micro-vibration sensor S j Signal reception time.

[0074] Table 2 Wave Speed ​​Statistics

[0075] Number of transmission paths (number of paths) Maximum wave speed (m / s) Minimum wave speed (m / s) Median wave speed (m / s) 231 5988 3382 3993

[0076] S2, Signal Acquisition

[0077] The signal acquisition scheme is as follows: Before loading the sample, each microseismic sensor is controlled to transmit or receive signals, and the transmission time, reception time, and sound source characteristic parameters of the active source signal are acquired and recorded at least once; after loading begins, the transmission time, reception time, and sound source characteristic parameters of the active source signal are continuously acquired and recorded.

[0078] The critical time interval Δt is calculated according to formula (4). cr ;

[0079] Δt cr =α(l max / v min (4)

[0080] Let α = 1.5, l max =0.117m, the critical time interval Δt is calculated. cr =1.5×(0.117÷3382)=0.00005s;

[0081] Since the time interval Δt of the active seismic source signal transmission must meet the requirements of formula (3);

[0082] Δt>Δt cr (3)

[0083] Therefore, the time interval Δt = 0.0001s is taken;

[0084] 1) Before loading the sample, control the No. 1 microseismic sensor to emit a signal once, and the other microseismic sensors to receive the signal. The emission time and reception time of the active source signal are collected and recorded in real time. Then, according to the microseismic sensor numbering order, control each microseismic sensor to emit a signal once in sequence at a time interval Δt = 0.0001s, and the other microseismic sensors to receive the signal, forming a emission cycle.

[0085] 2) After loading begins, collect and record the active source signal transmission time and reception time in real time in the same manner as described above, and repeat the collection and recording process multiple times.

[0086] S3, Data Processing:

[0087] Based on the data collected in step S2, the real-time wave velocity variation and sound source characteristic parameter variation values ​​for each propagation path of the sample are calculated, resulting in a wave velocity-time series diagram for each propagation path. Some of the wave velocity-time series diagrams for the propagation paths are shown below. Figure 5 ;

[0088] The changes in wave velocity and sound source characteristic parameters are calculated according to formula (5):

[0089]

[0090] In the formula: v ij (t), A ij (t), f mij (t), f cij (t) represents the measured wave velocity and sound source characteristic parameter values ​​after the engineering disturbance, respectively; t is the active source signal reception time; v ij (0), A ij (0), f mij (0), f cij (0) represents the measured wave velocity and sound source characteristic parameter values ​​after engineering disturbance;

[0091] S4: Disturbance stress direction identification:

[0092] Based on the wave velocity changes along each propagation path and the evolution characteristics of the sound source's characteristic parameters, a disturbance stress identification objective function G(x,y,z) is constructed. The true disturbance stress direction of the target rock mass region is obtained based on the objective function.

[0093] Furthermore, step S4 also includes the following steps:

[0094] S4-1. Calculate the unit direction vector of each propagation path according to formula (6). The unit direction vectors of some propagation paths are shown in Table 3:

[0095]

[0096] Table 3 shows the unit direction vector of some propagation paths.

[0097]

[0098] S4-2, Assume the unit direction vector of the actual disturbance stress is... Then the directions of each propagation path With respect to the actual direction of disturbance stress The cosine of the included angle cosθ ij for:

[0099]

[0100] In the formula: x, y, z ∈ [-1, 1], x 2 +y 2 +z 2 =1;

[0101] Since the angle between the two vectors ranges from (0, π), and the object of this study is the dual force, the actual range of its angle with the propagation direction is... Therefore, the cosine value of the included angle is squared subsequently.

[0102] S4-3, According to formula (8), the wave speed change value Δv ij and characteristic parameters ΔA of each sound source ij , Δf mij , Δf cij Normalized to the interval [-1,1], the normalized values ​​of wave velocity and sound source characteristic parameters of some propagation paths are shown in Table 4;

[0103]

[0104] Where: Δv′ ij Let ΔA′ be the normalized value of the wave speed. ij Δf′ is the normalized value of the amplitude. mij The normalized value of the main frequency, Δf′ cijLet Δv be the normalized value of the frequency centroid. max and Δv max ΔA represents the maximum and minimum changes in wave velocity along all paths before and after the engineering disturbance. max ΔA min , Δf mmax , Δf mmin , Δf cmax , Δf cmin These represent the maximum and minimum values ​​of the characteristic parameters of each sound source before and after the engineering disturbance;

[0105] Table 4 Normalized values ​​of some propagation path sound source characteristic parameters

[0106]

[0107] D15_20 -0.00223 0.096176 -0.3207 -0.32541

[0108] D15_6 -0.00223 0.096176 -0.3207 -0.32541

[0109] D15_10 -0.00223 0.096176 -0.3207 -0.32541

[0110] D15_18 -0.52298 0.059096 -0.70247 -0.48988

[0111] D15_12 -0.00223 0.096176 -0.3207 -0.32541

[0112] S4-4, The cosine of the included angle cosθ obtained from S4-2 ij The wave velocity change value Δv obtained from S4-3 ij and characteristic parameters ΔA of each sound source ij , Δf mij , Δf cij The objective function G(x,y,z) for fine identification of disturbance stress is constructed according to formula (1):

[0113]

[0114] The physical meaning of formula (1) is the sum of the projected components of the sound source characteristic parameters in the direction of the actual disturbance stress after a single engineering disturbance. The larger the value, the closer it is to the direction of the actual disturbance stress. G(x,y,z) is a quadratic function of x,y,z and x,y,z∈[-1,1],x 2 +y 2 +z2 =1, therefore its maximum value must exist, and the coordinate direction of this maximum value is the actual direction of the disturbance stress. The specific solution process is as follows:

[0115] Substituting the wave velocity and sound source characteristic parameters of each propagation path obtained from the indoor triaxial rock test into the objective function G(x,y,z), we can obtain:

[0116] G(x,y,z)=-106.95x 2 -0.74xy-1.26xz-123y 2 +2.68yz-80.24z 2

[0117] (x,y,z∈[-1,1],x 2 +y 2 +z 2 =1)

[0118] To find the maximum or minimum value of the above expression, we need to... Substituting the values ​​will transform it into:

[0119]

[0120] H can be obtained by using the graphical method. max (x=0,y=0)=-80.24(e.g.) Figure 6 Therefore, the unit direction vector of the disturbance stress is... or That is, σ z The direction is consistent with the direction of the external simulated load.

[0121] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for identifying the direction of rock mass disturbance stress based on sound source characteristics, characterized in that, Includes the following steps: S1. Environmental Preparation: In the target rock mass area, a three-dimensional coordinate system was established. Following the designed microseismic sensor deployment scheme, several microseismic sensors were deployed at the engineering site. The minimum wave velocity value of the microseismic sensor signals propagating in the target rock mass area was measured. ; S2, Signal Acquisition: Before the engineering disturbance, each microseismic sensor is controlled to transmit or receive signals, and the transmission time, reception time, and sound source characteristic parameters of the active seismic source signal are collected and recorded at least once as reference data; after the engineering disturbance, the transmission time, reception time, and sound source characteristic parameters of the active seismic source signal are continuously collected and recorded. S3, Data Processing: Based on the data collected by S2, calculate the real-time wave velocity changes and sound source characteristic parameter changes of each propagation path in the target rock mass area before and after the engineering disturbance; S4. Identification of the direction of disturbance stress: Based on the wave velocity variations along each propagation path and the evolution characteristics of the sound source's characteristic parameters, a disturbance stress identification objective function is constructed. The true direction of disturbance stress in the target rock mass region is obtained based on the objective function; （1） In the formula: This is the normalized value of the wave speed. This is the normalized value of the amplitude. The normalized value of the main frequency, This is the normalized value of the frequency centroid. The angle between each propagation path and the actual direction of the disturbance stress; S4 further includes the following steps: S4-1. Calculate the unit direction vector of each propagation path according to formula (6). : （6）； S4-2, Assume the unit direction vector of the actual disturbance stress is... Then each propagation path direction With respect to the actual direction of disturbance stress cosine of the included angle for: （7）； In the formula: ; For micro-vibration sensors The coordinates within the target rock mass area For micro-vibration sensors At the coordinate location within the target rock mass area, the propagation path is from the active source signal to the microseismic sensor. propagation to micro-vibration sensor form.

2. The method for identifying the direction of rock mass disturbance stress based on sound source characteristics according to claim 1, characterized in that, The microseismic sensors are arranged non-coplanarly around the target rock mass area, with a total of no less than 5 microseismic sensors deployed.

3. The method for identifying the direction of rock mass disturbance stress based on sound source characteristics according to claim 2, characterized in that, The distance between any two microseismic sensors is less than the farthest propagation distance of the active seismic source signal.

4. The method for identifying the direction of rock mass disturbance stress based on sound source characteristics according to claim 3, characterized in that, Microseismic sensor signals in the target rock mass area The propagation speed along the propagation path is calculated according to formula (2); （2） In the formula: The propagation path is determined by the microseismic sensor. propagation to micro-vibration sensor The resulting transmission path, For micro-vibration sensors The coordinates within the target rock mass area For micro-vibration sensors The transmission time of the active source signal. For micro-vibration sensors The coordinates within the target rock mass area For micro-vibration sensors Signal reception time.

5. The method for identifying the direction of rock mass disturbance stress based on sound source characteristics according to claim 4, characterized in that, In step S1, the measured minimum wave velocity value At that time, each microseismic sensor is controlled to transmit an active source signal once in sequence, with a transmission interval of 0.1s-5s. Other microseismic sensors receive the signals in real time, and the transmission and reception times of each signal are recorded in real time. The wave velocity of each propagation path is calculated according to formula (2), and the minimum wave velocity value is selected. .

6. The method for identifying the direction of rock mass disturbance stress based on sound source characteristics according to claim 5, characterized in that, In step S2, the active seismic source signal after the engineering disturbance is transmitted or received according to the following scheme: Each microseismic sensor operates at the same time interval. An active seismic source signal is emitted sequentially, and other microseismic sensors receive the corresponding signals, forming a loop. This loop is repeated multiple times in real time until the end, with time intervals between each iteration. satisfy: （3） （4） In the formula: The critical time interval, This is an empirical coefficient, ranging from 1.5 to 3, and the larger the target area, the better. The larger the value, the better; This represents the maximum distance between all microseismic sensors; This represents the minimum wave velocity value for the active seismic source signal to propagate in the target rock mass region.

7. The method for identifying the direction of rock mass disturbance stress based on sound source characteristics according to any one of claims 1-6, characterized in that, Active seismic source signals are either pulse signals or acoustic signals.

8. The method for identifying the direction of rock mass disturbance stress based on sound source characteristics according to claim 7, characterized in that, Sound source characteristic parameters include amplitude , main frequency Frequency centroid .

9. The method for identifying the direction of rock mass disturbance stress based on sound source characteristics according to claim 8, characterized in that, The changes in wave velocity and sound source characteristic parameters are calculated according to formula (5): （5） In the formula: , , , These are the measured wave velocity and sound source characteristic parameter values ​​after the engineering disturbance, respectively. This refers to the active source signal reception time. , , , These are the measured wave velocity and sound source characteristic parameter values ​​before the engineering disturbance, respectively.

10. The method for identifying the direction of rock mass disturbance stress based on sound source characteristics according to claim 9, characterized in that, Step S4 also includes the following steps: S4-3, According to formula (8), the wave speed change value and characteristic parameters of each sound source , , Normalize to the interval [-1, 1]: （8） in: and These represent the maximum and minimum changes in wave velocity along all paths before and after the engineering disturbance, respectively. , , , , , These represent the maximum and minimum values ​​of the changes in characteristic parameters of each sound source before and after the engineering disturbance; S4-4, Cosine of the included angle obtained from S4-2 Wave velocity variation values ​​obtained from S4-3 and the variation values ​​of characteristic parameters of each sound source , , The objective function for identifying disturbance stress is constructed according to formula (1). Substitute the measured wave velocities and sound source characteristic parameters for each propagation path into the objective function to solve. The maximum value, and the coordinate direction of the maximum value is the actual direction of the disturbance stress. .

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