Rock burst evaluation method and system fusing brittleness and strength characteristics of surrounding rock

Abstract

The invention provides a rockburst assessment method and system fusing brittleness and strength characteristics of surrounding rock, and relates to the technical field of potential rockburst risk assessment, and the method comprises the steps: obtaining indoor uniaxial compression test data and true triaxial compression test data; calculating the indoor uniaxial compression test data and the true triaxial compression test data according to a preset surrounding rock brittleness index calculation formula to obtain the brittleness index of each surrounding rock under each preset confining pressure; on the basis of preset historical first information and the surrounding rock brittleness indexes under the multiple preset confining pressures, brittleness indexes corresponding to all surrounding rocks under the actual surrounding rock condition are obtained; the brittleness indexes corresponding to all the surrounding rocks under the actual surrounding rock condition are compared with a preset rockburst tendency threshold value, and a comparison result is obtained; and on the basis of the comparison result, the first information and a Hoeke-Brown surrounding rock strength criterion, determining a potential rockburst area which can trigger rockburst. According to the method, rockburst dynamic evaluation in the tunnel construction stage can be carried out, and the number of required rockburst evaluation parameters is small.

Description

Technical Field

[0001] This invention relates to the field of potential rockburst risk assessment technology, and more specifically, to a rockburst assessment method and system that integrates the brittleness and strength characteristics of the surrounding rock. Background Technology

[0002] Rockburst is a typical dynamic failure phenomenon caused by excavation and unloading of hard and brittle surrounding rock in deeply buried, high-stress environments. Its suddenness and intensity seriously threaten the safety of underground engineering projects. Current rockburst assessment criteria proposed in domestic and international research mainly rely on single static indicators, which cannot quantitatively assess the depth, range, and spatial distribution characteristics of rockburst damage, and do not fully consider the true triaxial stress state of the surrounding rock and its coupling effect with geological structures. Its implementation requires complex elastic-brittle-plastic constitutive models describing the mechanical behavior of hard rock. These models have a large parameter system, some parameters are difficult to obtain through conventional laboratory tests, and parameter values ​​depend on human experience, resulting in highly subjective and low-generalizability assessment results.

[0003] There is an urgent need for a rockburst assessment method and system that integrates the brittleness and strength characteristics of the surrounding rock to solve the above-mentioned technical problems. Summary of the Invention

[0004] The purpose of this invention is to provide a rockburst assessment method and system that integrates the brittleness and strength characteristics of surrounding rock, thereby improving the aforementioned problems. To achieve the above objective, the technical solution adopted by this invention is as follows: Firstly, this application provides a rockburst assessment method that integrates the brittleness and strength characteristics of surrounding rock, including: Sampling was conducted on the surrounding rock at the engineering excavation site, and indoor uniaxial compression tests and true triaxial compression tests were performed based on the collected samples to obtain first information, which included indoor uniaxial compression test data and true triaxial compression test data. The first information and at least two preset confining pressures are calculated according to the preset formula for calculating the brittleness index of the surrounding rock to obtain the brittleness index of each surrounding rock under each preset confining pressure. Based on the preset historical first information and the brittleness index of each surrounding rock under each preset confining pressure, the fitting process is performed. The relationship obtained by the fitting process, the indoor uniaxial compression test data and the true triaxial compression test data are matched and processed to obtain the brittleness index of all surrounding rocks under the actual surrounding rock conditions. The brittleness index of all surrounding rocks under the actual surrounding rock conditions is compared with the preset rockburst tendency threshold to obtain the comparison results; Based on the comparison results, the first information, and the Hoeke-Brown surrounding rock strength criterion, potential rockburst zones that could trigger rockbursts were identified.

[0005] Secondly, this application also provides a rockburst assessment system that integrates the brittleness and strength characteristics of surrounding rock, characterized in that it includes: The acquisition unit is used to sample the surrounding rock at the engineering excavation site and conduct indoor uniaxial compression tests and true triaxial compression tests based on the collected samples to obtain first information, which includes indoor uniaxial compression test data and true triaxial compression test data. The calculation unit is used to calculate the first information and at least two preset confining pressures according to the preset formula for calculating the brittleness index of the surrounding rock, so as to obtain the brittleness index of each surrounding rock under each preset confining pressure. The processing unit is used to perform fitting processing based on the preset historical first information and the brittleness index of each surrounding rock under each preset confining pressure. The relationship obtained by the fitting processing, the indoor uniaxial compression test data and the true triaxial compression test data are matched and processed to obtain the brittleness index of all surrounding rocks under the actual surrounding rock conditions. The comparison unit is used to compare the brittleness index of all surrounding rocks under the actual surrounding rock conditions with the preset rockburst tendency threshold to obtain the comparison result; The determination unit is used to determine potential rockburst zones that will trigger rockbursts based on the comparison results, the first information, and the Hoeke-Brown surrounding rock strength criterion.

[0006] The beneficial effects of this invention are as follows: This invention can quantitatively assess the depth, extent, and spatial distribution characteristics of rockburst damage, taking into account the true triaxial stress state of the surrounding rock and its coupling effect with geological structures. It requires relatively few rockburst assessment parameters, most of which can be obtained through conventional laboratory tests, resulting in objective and universally applicable assessment results. For large-scale underground engineering projects, it provides data support for cavern selection, layout scheme comparison, and dynamic rockburst assessment during tunnel construction, guiding targeted support design.

[0007] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1This is a schematic diagram of the rockburst assessment method integrating the brittleness and strength characteristics of the surrounding rock as described in this embodiment of the invention; Figure 2 This is a schematic diagram of the rockburst assessment system that integrates the brittleness and strength characteristics of surrounding rock as described in this embodiment of the invention; Figure 3 This is a stress-strain curve obtained from a true triaxial compression test in the rockburst assessment method that integrates the brittleness and strength characteristics of the surrounding rock as described in this embodiment of the invention. Figure 4 This is a schematic diagram illustrating the calculation of the rock brittleness index based on the stress-strain curve in the rockburst assessment method that integrates the brittleness and strength characteristics of surrounding rock as described in this embodiment of the invention. Figure 5 This is a borehole camera image from the rockburst assessment method that integrates the brittleness and strength characteristics of the surrounding rock, as described in this embodiment of the invention. Figure 6 This is a three-dimensional numerical simulation diagram established by solving the secondary stress field in the rockburst assessment method that integrates the brittleness and strength characteristics of surrounding rock as described in this embodiment of the invention. Figure 7 This is a diagram showing the maximum principal stress distribution in the secondary stress field of the rockburst assessment method that integrates the brittleness and strength characteristics of the surrounding rock, as described in this embodiment of the invention. Figure 8 This is a comparison diagram of the results of identifying potential rockburst areas in intact rock mass and the actual rockburst occurrence in the rockburst assessment method that integrates the brittleness and strength characteristics of surrounding rock described in this embodiment of the invention. Figure 9 This is a comparison chart showing the results of identifying potential rockburst areas in geological structures and the actual rockburst occurrence in the rockburst assessment method that integrates the brittleness and strength characteristics of surrounding rock, as described in this embodiment of the invention.

[0010] In the figure: 1. Stress drop degree; 2. Post-peak strain increase; 3. Assessment of potential rockburst area; 4. Actual rockburst area on site; 5. Structural surface; 701. Acquisition unit; 702. Calculation unit; 703. Processing unit; 704. Comparison unit; 705. Determination unit. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the 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.

[0012] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0013] Example 1: This embodiment provides a rockburst assessment method that integrates the brittleness and strength characteristics of the surrounding rock.

[0014] See Figure 1 The figure shows that the method includes steps S1, S2, S3, S4 and S5.

[0015] Step S1: Sample the surrounding rock at the engineering excavation site, and conduct indoor uniaxial compression tests and true triaxial compression tests based on the collected samples to obtain first information, which includes indoor uniaxial compression test data and true triaxial compression test data. The purpose of collecting surrounding rock samples in this step is understandable: to ensure that the test results reflect the characteristics of the surrounding rock during actual excavation. Specifically, surrounding rock samples are collected from different areas of the tunnel at the excavation site, and then subjected to uniaxial compression tests and true triaxial compression tests. Different types of rock exhibit different properties under stress, including strength, brittleness, and deformation behavior under different conditions. Uniaxial compression tests measure the compressive strength of rock in a single direction, while true triaxial compression tests simulate the behavior of rock under more complex, multi-directional stresses, more accurately reflecting the mechanical performance of the surrounding rock in the actual underground environment. These data directly reflect the rock's response to stress changes during excavation. The uniaxial and true triaxial test data provide the inputs required for the calculation methods and system brittleness index method and system, which is a key indicator for assessing rockburst risk. These data provide the methodological and systematic quantitative basis for the entire rockburst risk assessment, allowing engineering design to rely on actual experimental results rather than estimations or overly simplistic models.

[0016] Step S2: Calculate the first information and at least two preset confining pressures according to the preset formula for calculating the brittleness index of the surrounding rock, and obtain the brittleness index of each surrounding rock under each preset confining pressure. Understandably, this step involves constructing stress-strain curves for the rock based on stress-strain data obtained from uniaxial compression tests and true triaxial compression tests. These curves reflect the deformation and failure characteristics of the rock under different stress states. In particular, these curves can identify the brittle behavior of the rock, i.e., how the stress decreases after peak stress and the strain changes. By accurately calculating the brittleness index of the surrounding rock under different confining pressures, the brittle characteristics of the rock are quantified, providing fundamental data for subsequent rockburst risk assessment. These brittleness indices effectively reflect the brittleness changes of the surrounding rock at different excavation stages or depths, helping to identify potential rockburst risk areas. In this step, step S2 includes steps S21 and S22.

[0017] Step S21: Construct stress-strain curves from the indoor uniaxial compression test data and true triaxial compression test data, and establish brittleness indices based on the stress-strain curves; Understandably, in this step of the uniaxial compression test, the rock sample is compressed vertically while the lateral stress remains constant. By gradually increasing the axial pressure and recording the rock's deformation, a stress-strain curve can be obtained. This curve shows the relationship between stress changes and corresponding strains in the rock during the loading process. Typically, the curve goes through an elastic stage, a yielding stage, and a stress decrease stage after peak strength. In a true triaxial compression test, the rock sample is subjected to pressure in three directions simultaneously, which better simulates the stress state of rock during actual underground excavation. This type of test allows for the acquisition of more complex stress-strain curves. Compared to uniaxial tests, triaxial tests provide more information about the strength and deformation characteristics of rock under multiaxial stress, especially its performance under different confining pressures.

[0018] Step S22: Based on the brittleness index and multiple preset confining pressures, calculate the brittleness index according to the preset formula for calculating the brittleness index of the surrounding rock, and obtain the brittleness index of each surrounding rock under each preset confining pressure.

[0019] Understandably, this step uses a specific formula to calculate the brittleness index based on the stress-strain curve described above. Typically, the brittleness index is determined by considering the stress drop, residual strain, and post-peak stress release rate of the stress-strain curve. A higher brittleness index indicates greater rock brittleness and a greater susceptibility to fracture or rockburst. The calculation formula is shown below: ; in, The brittleness index, For elastic modulus, The secant modulus after the peak; Peak intensity Residual strength; For peak strain, This represents residual strain.

[0020] Step S3: Based on the preset historical first information and the brittleness index of each surrounding rock under each preset confining pressure, the fitting process is performed. The relationship obtained by the fitting process, the indoor uniaxial compression test data and the true triaxial compression test data are matched and processed to obtain the brittleness index of all surrounding rocks under the actual surrounding rock conditions. It is understandable that this step utilizes historical experimental data and preset confining pressure conditions for fitting, thereby establishing a brittleness index formula applicable to actual engineering projects. This process, by comparing experimental data with historical information, ensures that the calculated brittleness index accurately reflects the brittle characteristics of the surrounding rock under different confining pressure conditions. In this step, step S3 includes steps S31, S32, and S33.

[0021] Step S31: Calculate the historical brittleness index of all surrounding rocks under all preset confining pressures based on the preset historical first information and the preset formula for calculating the brittleness index of surrounding rocks. It is understandable that the "first historical information" in this step refers to previous experimental data for similar geological conditions or rock types. This data comes from uniaxial compression tests and true triaxial compression tests under different confining pressures. Historical data is based on previous experimental or engineering experience conducted in similar geological environments and typically includes the mechanical properties, stress-strain curves, and brittle characteristics of the surrounding rock under different confining pressures. This data provides the standard and foundation for the calculation and fitting process. Using the first historical information and the preset brittleness index calculation formula, the historical brittleness index of various surrounding rocks under different confining pressures can be calculated. These historical brittleness indices reflect the brittleness characteristics of the surrounding rock under different stress states, providing a basis for subsequent evaluation and fitting work. Since confining pressure has a significant impact on rock brittleness, the brittleness performance of rocks will differ under different confining pressure conditions. By processing the historical test data, the brittleness index of the surrounding rock under each confining pressure condition can be obtained.

[0022] Step S32: Based on the historical brittleness index of all surrounding rocks under all preset confining pressures, establish fitting formulas for the relationship between the historical brittleness index and the lateral stress in all surrounding rocks and historical true triaxial compression tests.

[0023] Understandably, in historical experiments, historical brittleness indices for each surrounding rock were obtained through test data on surrounding rocks under different confining pressures. The calculation of each brittleness index considers the rock's mechanical behavior, stress-strain characteristics, and different mechanical parameters. Therefore, the rock brittleness index under different confining pressures can be seen as an expression of the relationship between rock type (e.g., different lithologies), confining pressure, and stress state. In a true triaxial compression test, the lateral stress ( and The brittleness index (BCI) is an important control parameter reflecting the strength and brittleness characteristics of rocks under multiaxial stress. Historical test data can reveal the changes in brittleness of surrounding rocks under different lateral stresses. Therefore, the relationship between the BCI and lateral stress is a key aspect requiring fitting and analysis. Through regression analysis or least squares fitting, a mathematical formula or relation can be established to quantify the relationship between the BCI and surrounding rock type, confining pressure, and lateral stress in historical true triaxial compression tests. These relations will help determine how the brittle characteristics of the surrounding rock change under different lateral stresses and confining pressures. The relations are shown below: ; in, The brittleness index, Lithology and The lateral stress in a true triaxial test, Lithology Lateral stress in true triaxial experiments and The relationship between them.

[0024] Step S33: Substitute the indoor uniaxial compression test data and true triaxial compression test data into the relationship fitting formula to obtain the brittleness index corresponding to all surrounding rocks under actual surrounding rock conditions.

[0025] Understandably, in practical applications, this step involves substituting the confining pressure and lateral stress data collected from uniaxial compression tests and true triaxial compression tests, along with lithological characteristics (such as rock type, density, and elastic modulus), into the established fitting formula for calculation. In this way, the brittleness index of the surrounding rock at each specific location and under different confining pressure conditions can be obtained. This allows for the accurate calculation of the brittleness index under different confining pressures and stresses. This process transforms the calculation of the brittleness index from a theoretical estimate into a precise assessment based on real data, thus providing a more reliable basis for rockburst risk prediction.

[0026] Step S4: Compare the brittleness index of all surrounding rocks under the actual surrounding rock conditions with the preset rockburst tendency threshold to obtain the comparison results; Understandably, this step involves comparing the brittleness index of all surrounding rocks under actual conditions with a preset rockburst tendency threshold to determine which surrounding rocks may pose a rockburst risk. This step is crucial in rockburst assessment because by comparing with the threshold, potential rockburst areas can be accurately identified, providing a basis for subsequent support design and safety precautions. In this step, step S4 includes steps S41 and S42.

[0027] Step S41: Use the rockburst tendency threshold as a preset condition for judgment. The rockburst tendency threshold is determined based on the first information to determine the lithological characteristics of all surrounding rocks and is obtained by analyzing the stress-strain curve and the lithological characteristics of all surrounding rocks. It is understandable that the rockburst tendency threshold can be determined in the following ways depending on the different construction stages: For underground projects that have only carried out geological borehole exploration and have not yet carried out preliminary tunnel excavation, the rockburst tendency threshold can be determined by the brittle and ductile characteristics of the stress-strain curve obtained by test; For underground projects that have carried out preliminary tunnel excavation, the rockburst tendency threshold can be determined based on the brittle and ductile characteristics of the stress-strain curve obtained by test, combined with the rock fracture depth obtained by on-site geological reconnaissance, sonic logging, and borehole photography.

[0028] Brittle rocks typically exhibit a rapid decrease in stress after reaching peak stress, meaning they quickly lose strength after peak stress, showing no significant plastic deformation. Ductile rocks, on the other hand, typically show a slow decrease in stress-strain curve after peak stress and exhibit a more significant plastic zone. Rocks can continue to deform after peak stress and possess strong deformation capacity. Then, through expert experience and historical data statistical analysis, a rockburst tendency threshold is scientifically determined. Expert experience, based on long-term accumulated engineering practice data, helps establish the relationship between the brittleness index and rockburst risk. Historical data statistical analysis, through reviewing and statistically analyzing actual rockburst events, establishes a model of the relationship between rock brittleness, confining pressure, and rockburst occurrence, thereby deriving a more accurate rockburst tendency threshold. The combination of these two methods helps engineers make dynamic adjustments based on actual conditions, ensuring the scientific rigor and accuracy of rockburst risk assessment. Step S42: Compare the rockburst tendency threshold with the brittleness index corresponding to all surrounding rocks under the actual surrounding rock conditions to obtain a comparison result showing whether the brittleness index corresponding to all surrounding rocks under the actual surrounding rock conditions is greater than or equal to the rockburst tendency threshold.

[0029] Step S42: Compare the rockburst tendency threshold with the brittleness index of all surrounding rocks under the actual surrounding rock conditions to obtain a comparison result of whether the brittleness index of all surrounding rocks under the actual surrounding rock conditions is greater than or equal to the rockburst tendency threshold.

[0030] Understandably, this step compares the stress-strain curve analysis results with the rockburst tendency threshold to determine whether the surrounding rock is in a high-risk area for rockburst. If the brittleness index of the surrounding rock is greater than the set rockburst tendency threshold, it indicates that the area may have a rockburst tendency, and corresponding protective measures should be taken, such as reinforcement and support, reducing the excavation rate, and adjusting the construction plan.

[0031] During actual excavation, the stress state of the surrounding rock may change as construction progresses. Therefore, periodic stress-strain tests are conducted to dynamically adjust the brittleness index and rockburst tendency threshold, ensuring real-time assessment of rockburst risk.

[0032] Step S5: Based on the comparison results, the first information, and the Hoeke-Brown surrounding rock strength criterion, determine the potential rockburst areas that will trigger rockbursts.

[0033] Understandably, this step identifies potential rockburst zones by comparing the rock's brittleness index and rockburst tendency threshold, combined with first-information data and the Hoek-Brown surrounding rock strength criterion. This process combines brittleness and strength analysis to scientifically and quantitatively predict which surrounding rock areas are likely to experience rockbursts, providing guidance for subsequent support design and safety precautions. In this step, step S5 includes steps S51, S52, S53, and S54.

[0034] Step S51: Based on the first information and the Hoeke-Brown surrounding rock strength criterion, determine the maximum principal stress of all surrounding rocks at failure. It is understandable that in this step, based on the Hoeke-Brown rock strength formula considering the surrounding rock grade, blasting disturbance, and confining pressure, and based on the preset secondary stress field distribution, the maximum principal stress at which the surrounding rock fails at any location can be determined. ; in, and These represent the maximum and minimum principal stresses at rock mass failure. , and It is the rock mass material constant, given by the following formula: ; ; ; in, It is the material constant of the intact rock. It is a coefficient that depends on the degree of disturbance to the rock mass caused by explosive damage and stress relaxation. This is the geological intensity index.

[0035] Step S52: Analyze the comparison results. If the comparison results show that the brittleness index of all surrounding rocks under the actual surrounding rock conditions is greater than or equal to the rockburst tendency threshold, then the surrounding rock is determined to be a potential rockburst surrounding rock. It is understandable that if the comparison result shows that the brittleness index is greater than or equal to the rockburst tendency threshold, it indicates that the surrounding rock belongs to a potential rockburst area, that is, the brittleness index of the surrounding rock in this area is high and the possibility of rockburst is relatively high.

[0036] Step S53: If the comparison result is that the brittleness index of all surrounding rocks under the actual surrounding rock conditions is less than the rockburst tendency threshold, then the maximum principal stress of the secondary stress field distribution of the pre-set excavated cavern is compared with the maximum principal stress of all surrounding rocks at the time of failure. If the maximum principal stress of the secondary stress field distribution of the pre-set excavated cavern is greater than or equal to the maximum principal stress of the surrounding rock at the time of failure, then the surrounding rock is judged to be a potential rockburst surrounding rock. It is understood that if the comparison result shows that the brittleness index of all surrounding rocks under the actual surrounding rock conditions is less than the rockburst tendency threshold, the susceptibility of the surrounding rock to rockburst is determined by comparing the maximum principal stress of the secondary stress field distribution with the maximum principal stress of the surrounding rock at failure. If the maximum principal stress of the secondary stress field is greater than or equal to the maximum principal stress of the surrounding rock at failure, the area should be identified as potential rockburst surrounding rock, and necessary safety measures should be taken.

[0037] Step S54: Treat all potential rockburst surrounding rocks as potential rockburst zones that will trigger rockbursts.

[0038] Understandably, all potential rockburst-prone surrounding rock identified in this step is designated as potential rockburst zones, thus providing a basis for subsequent risk assessment and safety management. This step further confirms rockburst risk areas, providing clear guidance for developing effective protective measures, support designs, and construction plans.

[0039] In a specific implementation, the specific operation scheme is shown in the following example: like Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 and Figure 9 As shown, this specific implementation method uses a horseshoe-shaped tunnel in southwestern my country as an example for detailed explanation. The tunnel is buried at a depth of approximately 400-600 meters, with the surrounding rock mainly consisting of diorite. The tunnel dimensions are 7.5m wide × 7.5m high. The specific implementation steps are as follows: First, this invention involves sampling the surrounding rock of the horseshoe-shaped tunnel after excavation to prepare rock samples for testing. Based on these samples, indoor uniaxial compression tests and true triaxial compression tests are conducted. Using the secondary stress field after tunnel excavation, confining pressure values ​​are taken at depths of 0m, 0.2m, 0.5m, 1m, 2m, 3m, and 5m from the tunnel wall, and indoor true triaxial compression test schemes under different confining pressures are designed (see Table 1). Through indoor true triaxial compression tests, stress-strain curves under different stress states are obtained (e.g., ...). Figure 3 As shown in Table 1). A brittleness index calculation formula based on the stress-strain curve was selected to calculate the brittleness index of the rock under different confining pressures (see Table 1). Figure 4 As shown, the degree of rock brittleness takes into account the type of post-peak in the stress-strain curve, the magnitude of the stress drop, and the stress release rate.

[0040] Table 1 Stress Value Scheme for True Triaxial Compression Test

[0041] Next, based on extensive true triaxial tests conducted by predecessors on different rocks and under varying confining pressures, the brittleness index was calculated under different conditions (preset confining pressures) using the same brittleness index formula from the previous step. A relationship between the brittleness index and lithology was then established. , The fitting formula between them.

[0042] Then, in lithology, , Based on the fitting formula between the two, and according to the brittleness index obtained from the test calculation of the actual surrounding rock of this project, the brittleness index relationship applicable to the specific surrounding rock conditions of this project can be determined.

[0043] Furthermore, based on the stress-strain curves obtained from the experiments, the ductility characteristics were determined. For experiments 1 to 3 (Table 1), the stress-strain curves exhibited an elastic-brittle type, while for experiments 4 to 7 (Table 1), the stress-strain curves exhibited an elastic-plastic-brittle type. Combined with the maximum rock fracture depth obtained from on-site geological reconnaissance and borehole photography, the borehole photography data is as follows... Figure 5 As shown. Based on a combination of indoor tests and on-site assessments, the rockburst tendency threshold was determined to be 10.

[0044] Furthermore, this rockburst assessment evaluated both tunnel areas without structural planes and tunnel areas with structural planes. Therefore, numerical simulation methods were used to calculate the secondary stress field distribution in the tunnel. If geological structural features are not considered, the secondary stress field distribution after tunnel excavation can be directly obtained using Kirsch's theoretical formulas. A three-dimensional numerical model considering the distribution of structural planes was established based on advanced geological exploration, such as... Figure 6 As shown. During the calculation, the model was given an elastic constitutive model with an elastic modulus of 42.7 GPa, a Poisson's ratio of 0.25, and a rock density of 2.64 g / cm³. The front, rear, left, right, and bottom boundaries of the model were fixed in their normal directions, while the top boundary was a free boundary condition. The secondary stress field distribution after tunnel excavation is shown below. Figure 7 As shown, it can be seen that the location of a potential rockburst can be determined to some extent by the distribution of the maximum principal stress, but it is difficult to determine the depth and range of the potential rockburst.

[0045] Finally, based on the Hoeke-Brown surrounding rock strength criterion, potential rockburst zones that may trigger rockbursts were identified.

[0046] First, an HB surrounding rock strength formula was established, taking into account the surrounding rock grade, blasting disturbance, and confining pressure. The geological strength index of the surrounding rock in the tunnel section where rockburst was evaluated in this project was 70. The smooth blasting effect on site was good. The disturbance coefficient of blasting damage and stress relaxation was 0. The material constant of intact rock was 12. The uniaxial compressive strength of rock was 108 MPa.

[0047] Next, based on the secondary stress field results obtained through numerical calculations, the range of conditions necessary for rockburst occurrence is determined by calculating whether the brittleness index B is greater than or equal to 10 and whether the maximum principal stress is greater than or equal to the maximum principal stress of the surrounding rock at failure. This includes the identification results of potential rockburst zones in tunnel sections without structural surfaces, and a comparison with actual rockburst occurrence conditions on site. Figure 8 The results of identifying potential rockburst zones in tunnel sections containing structural surfaces, and a comparison with actual rockburst occurrences on site, are shown in the figure. Figure 9 As shown.

[0048] Example 2: like Figure 2 As shown, this embodiment provides a rockburst assessment system that integrates the brittleness and strength characteristics of surrounding rock. See [link to documentation]. Figure 2 The system shown includes an acquisition unit 701, a calculation unit 702, a processing unit 703, a comparison unit 704, and a determination unit 705.

[0049] The acquisition unit 701 is used to sample the surrounding rock at the engineering excavation site and conduct indoor uniaxial compression tests and true triaxial compression tests based on the collected samples to obtain first information, which includes indoor uniaxial compression test data and true triaxial compression test data. The calculation unit 702 is used to calculate the first information and at least two preset confining pressures according to the preset formula for calculating the brittleness index of the surrounding rock, so as to obtain the brittleness index of each surrounding rock under each preset confining pressure. The processing unit 703 is used to perform fitting processing based on the preset historical first information and the brittleness index of each surrounding rock under each preset confining pressure. The relationship obtained by the fitting processing, the indoor uniaxial compression test data and the true triaxial compression test data are matched and processed to obtain the brittleness index of all surrounding rocks under the actual surrounding rock conditions. The comparison unit 704 is used to compare the brittleness index of all surrounding rocks under the actual surrounding rock conditions with the preset rockburst tendency threshold to obtain the comparison result. The determination unit 705 is used to determine potential rockburst areas that will trigger rockbursts based on the comparison results, the first information, and the Hoeke-Brown surrounding rock strength criterion.

[0050] It should be noted that the specific methods by which each module performs operations in the system described in the above embodiments have been described in detail in the embodiments related to the method, and will not be elaborated here.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0052] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rockburst assessment method integrating the brittleness and strength characteristics of surrounding rock, characterized in that, include: Sampling was conducted on the surrounding rock at the engineering excavation site, and indoor uniaxial compression tests and true triaxial compression tests were performed based on the collected samples to obtain first information, which included indoor uniaxial compression test data and true triaxial compression test data. The first information and at least two preset confining pressures are calculated according to the preset formula for calculating the brittleness index of the surrounding rock to obtain the brittleness index of each surrounding rock under each preset confining pressure. Based on the preset historical first information and the brittleness index of each surrounding rock under each preset confining pressure, the fitting process is performed. The relationship obtained by the fitting process, the indoor uniaxial compression test data and the true triaxial compression test data are matched and processed to obtain the brittleness index of all surrounding rocks under the actual surrounding rock conditions. The brittleness index of all surrounding rocks under the actual surrounding rock conditions is compared with the preset rockburst tendency threshold to obtain the comparison results; Based on the comparison results, the first information, and the Hoeke-Brown surrounding rock strength criterion, potential rockburst zones that could trigger rockbursts were identified.

2. The rockburst assessment method integrating the brittleness and strength characteristics of surrounding rock according to claim 1, characterized in that, The first information and at least two preset confining pressures are calculated according to a preset formula for calculating the brittleness index of the surrounding rock, including: The indoor uniaxial compression test data and true triaxial compression test data are used to construct stress-strain curves, and brittleness indicators are established based on the stress-strain curves. Based on the brittleness index and multiple preset confining pressures, the brittleness index is calculated according to the preset formula for calculating the brittleness index of the surrounding rock, so as to obtain the brittleness index of each surrounding rock under each preset confining pressure.

3. The rockburst assessment method integrating the brittleness and strength characteristics of surrounding rock according to claim 1, characterized in that, Based on preset historical first information and the brittleness index of each surrounding rock under each preset confining pressure, a fitting process is performed. The fitted relationship, indoor uniaxial compression test data, and true triaxial compression test data are then matched and processed, including: Based on the preset historical first information and the preset formula for calculating the brittleness index of surrounding rock, the historical brittleness index of all surrounding rocks under all preset confining pressures is calculated. Based on the historical brittleness index of all surrounding rocks under all preset confining pressures, fitting formulas were established to establish the relationship between the historical brittleness index and the lateral stress in all surrounding rocks and historical true triaxial compression tests. Substituting the indoor uniaxial compression test data and true triaxial compression test data into the aforementioned relationship fitting formula, the brittleness index corresponding to all surrounding rocks under actual surrounding rock conditions is obtained.

4. The rockburst assessment method integrating the brittleness and strength characteristics of surrounding rock according to claim 2, characterized in that, The brittleness index of all surrounding rocks under the actual surrounding rock conditions is compared with a preset rockburst tendency threshold, including: The rockburst tendency threshold is used as a preset condition for judgment. The rockburst tendency threshold is determined based on the first information to determine the lithological characteristics of all surrounding rocks and is obtained by analyzing the stress-strain curve and the lithological characteristics of all surrounding rocks. The rockburst tendency threshold is compared with the brittleness index of all surrounding rocks under the actual surrounding rock conditions to obtain the comparison result of whether the brittleness index of all surrounding rocks under the actual surrounding rock conditions is greater than or equal to the rockburst tendency threshold.

5. The rockburst assessment method integrating the brittleness and strength characteristics of surrounding rock according to claim 1, characterized in that, Based on the comparison results, the first information, and the Hoeke-Brown surrounding rock strength criterion, potential rockburst zones that could trigger rockbursts were identified, including: Based on the first information and the Hoeke-Brown surrounding rock strength criterion, the maximum principal stress of all surrounding rocks at failure is determined; If the comparison results are analyzed and the brittleness index of all surrounding rocks under the actual surrounding rock conditions is greater than or equal to the rockburst tendency threshold, then the surrounding rock is determined to be a potential rockburst surrounding rock. If the comparison result is that the brittleness index of all surrounding rocks under the actual surrounding rock conditions is less than the rockburst tendency threshold, then the maximum principal stress of the secondary stress field distribution of the pre-set excavated cavern is compared with the maximum principal stress of all surrounding rocks at the time of failure. If the maximum principal stress of the secondary stress field distribution of the pre-set excavated cavern is greater than or equal to the maximum principal stress of the surrounding rock at the time of failure, then the surrounding rock is judged to be a potential rockburst surrounding rock. All surrounding rocks with potential rockbursts are considered potential rockburst zones that could trigger rockbursts.

6. A rockburst assessment system integrating the brittleness and strength characteristics of surrounding rock, characterized in that, include: The acquisition unit is used to sample the surrounding rock at the engineering excavation site and conduct indoor uniaxial compression tests and true triaxial compression tests based on the collected samples to obtain first information, which includes indoor uniaxial compression test data and true triaxial compression test data. The calculation unit is used to calculate the first information and at least two preset confining pressures according to the preset formula for calculating the brittleness index of the surrounding rock, so as to obtain the brittleness index of each surrounding rock under each preset confining pressure. The processing unit is used to perform fitting processing based on the preset historical first information and the brittleness index of each surrounding rock under each preset confining pressure. The relationship obtained by the fitting processing, the indoor uniaxial compression test data and the true triaxial compression test data are matched and processed to obtain the brittleness index of all surrounding rocks under the actual surrounding rock conditions. The comparison unit is used to compare the brittleness index of all surrounding rocks under the actual surrounding rock conditions with the preset rockburst tendency threshold to obtain the comparison result; The determination unit is used to determine potential rockburst zones that will trigger rockbursts based on the comparison results, the first information, and the Hoeke-Brown surrounding rock strength criterion.

7. The rockburst assessment system integrating the brittleness and strength characteristics of surrounding rock according to claim 6, characterized in that, The computing unit includes: The first calculation subunit is used to construct stress-strain curves from the indoor uniaxial compression test data and true triaxial compression test data, and to establish brittleness indexes based on the stress-strain curves. The second calculation subunit is used to calculate the brittleness index based on the brittleness index and multiple preset confining pressures according to the preset formula for calculating the brittleness index of the surrounding rock, so as to obtain the brittleness index of each surrounding rock under each preset confining pressure.

8. The rockburst assessment system integrating the brittleness and strength characteristics of surrounding rock according to claim 6, characterized in that, The processing unit includes: The first processing subunit is used to calculate the historical brittleness index of all surrounding rocks under all preset confining pressures based on preset historical first information and preset surrounding rock brittleness index calculation formula. The second processing subunit is used to establish fitting formulas for the relationship between the historical brittleness index and the lateral stress in all surrounding rocks and historical true triaxial compression tests, based on the historical brittleness index of all surrounding rocks under all preset confining pressures. The third processing subunit is used to substitute the indoor uniaxial compression test data and the true triaxial compression test data into the relationship fitting formula to obtain the brittleness index corresponding to all surrounding rocks under actual surrounding rock conditions.

9. The rockburst assessment system integrating the brittleness and strength characteristics of surrounding rock according to claim 7, characterized in that, The comparison unit includes: The first comparison subunit is used to use the rockburst tendency threshold as a preset condition as a judgment condition, wherein the rockburst tendency threshold is determined based on the first information to determine the lithological characteristics of all surrounding rocks, and is obtained by analyzing the stress-strain curve and the lithological characteristics of all surrounding rocks. The second comparison subunit is used to compare the rockburst tendency threshold with the brittleness index of all surrounding rocks under the actual surrounding rock conditions, and to obtain a comparison result of whether the brittleness index of all surrounding rocks under the actual surrounding rock conditions is greater than or equal to the rockburst tendency threshold.

10. The rockburst assessment system integrating the brittleness and strength characteristics of surrounding rock according to claim 6, characterized in that, The determining unit includes: The first determining sub-unit is used to determine the maximum principal stress of all surrounding rocks at failure based on the first information and the Hoeke-Brown surrounding rock strength criterion. The second determining subunit is used to analyze the comparison results. If the comparison results show that the brittleness index of all surrounding rocks under the actual surrounding rock conditions is greater than or equal to the rockburst tendency threshold, then the surrounding rock is determined to be a potential rockburst surrounding rock. The third determining subunit is used to compare the maximum principal stress of the secondary stress field distribution of the pre-set excavated cavern with the maximum principal stress of all surrounding rocks at the time of failure if the comparison result is that the brittleness index of all surrounding rocks under the actual surrounding rock conditions is less than the rockburst tendency threshold. If the maximum principal stress of the secondary stress field distribution of the pre-set excavated cavern is greater than or equal to the maximum principal stress of the surrounding rock at the time of failure, then the surrounding rock is determined to be a potential rockburst surrounding rock. The fourth sub-unit is used to identify all potential rockburst surrounding rocks as potential rockburst zones that could trigger rockbursts.

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