Surrounding rock instability trace dynamic searching method based on safety factor, computer device and storage medium

Abstract

The application discloses a kind of based on safety coefficient's surrounding rock instability trace dynamic searching method, computer equipment and storage medium, mainly including three-dimensional numerical model, simulates tunnel excavation and support construction process, calculates the safety factor of each unit body of surrounding rock after current excavation cycle is completed, traverses all surrounding rock units, extracts and processes safety factor data, identifies potential instability unit, carries out unit screening focus instability area, uses closed loop mechanism to carry out dynamic iteration and instability simulation, finally output result.Above scheme is used, the stable state of surrounding rock under different stress conditions can be accurately identified, with better versatility, through dynamic iteration simulation development process, overcome the defects that traditional method cannot consider instability dynamic characteristics, can provide dynamic, reliable basis for the optimization design of support scheme.

Description

Technical Field

[0001] This invention belongs to the field of numerical simulation-assisted intelligent construction and engineering safety decision-making technology. Specifically, it relates to a dynamic search method for the instability traces of surrounding rock based on a safety factor, computer equipment, and storage medium. It is particularly suitable for intelligent risk early warning and support design optimization in similar geotechnical engineering projects such as urban underground space development, traffic tunnels, and mine roadways. Background Technology

[0002] Surrounding rock stability is a core scientific issue in tunnel engineering, directly affecting the safety and long-term durability of the project. Conducting surrounding rock stability analysis not only helps accurately predict geological hazards such as collapses and rock bursts, but also provides a scientific basis for support structure design, thus significantly reducing construction risks. In my country, surrounding rock is typically classified into five levels (I to V) based on factors such as rock strength, rock mass integrity, and groundwater conditions, with level I exhibiting the best stability and level V the worst. Existing technologies often utilize numerical methods such as the finite element method, finite difference method, and discrete element method to construct geomechanical models, simulating the entire process of tunnel excavation and support construction. This allows for precise analysis of the surrounding rock's displacement field, stress field, and plastic zone distribution, thereby comprehensively assessing the stability of the surrounding rock.

[0003] The safety factor method based on strength theory is a common quantitative evaluation method. Existing technologies propose an element-based safety factor method. This method mainly utilizes FLAC 3D software and its embedded FISH language to calculate the safety factor of each element of the surrounding rock after tunnel excavation according to the Mohr-Coulomb criterion, and sets a uniform safety threshold (e.g., ...). F s The surrounding rock condition is evaluated using a value of >1 (meaning stability), but the entire process is a static and open-loop process.

[0004] At present, although numerical software such as FLAC 3D and PLAXIS 3D can be used to analyze the development of the plastic zone of the surrounding rock after excavation, using the range of the shear and tensile plastic zone as the stability criterion alone still lacks universality, especially in soft rock strata with high ground stress, misjudgment is easy to occur. The applicant has found through in-depth research and practice that the above-mentioned existing technologies have at least the following shortcomings, which hinder their direct and effective application in complex engineering: (1) They fail to intuitively show the location and range of the surrounding rock instability; the process of surrounding rock instability is dynamic, and the stability of the surrounding rock will change with the collapse and rockfall of the surrounding rock. In other words, the operation of the above method is to perform a safety factor calculation and threshold judgment only once, and the result is a static "safety factor cloud map". It cannot intuitively show where the surrounding rock is specifically unstable and in what form it begins to become unstable, and it cannot simulate the dynamic physical process of the instability area gradually expanding and falling off (such as rockfall and collapse). Engineers still need to indirectly infer the potential failure area from the abstract coefficient distribution map, which is highly subjective. That is, it is difficult to intuitively present the specific location and range of influence of the surrounding rock instability; (2) The above method only identifies units with a safety factor less than 1 as "unstable," but does not further consider that once these units become unstable and detach, they will cause stress redistribution in the surrounding rock mass, which may lead to the instability of new units. Its "calculation-judgment" is open-loop, and no feedback mechanism is established for the impact of "failure of unstable units" on subsequent stability. In strata with high ground stress, soft rock, etc., which are prone to progressive failure, this will lead to a serious underestimation of the scale and form of instability, that is, it fails to fully consider the dynamic characteristics of the surrounding rock instability process—as instability phenomena such as collapse and rockfall occur, the stability state of the surrounding rock will also change accordingly. Therefore, it is urgent to establish a more scientific and more universal method for evaluating the stability of surrounding rock. Summary of the Invention

[0005] In view of this, the present invention provides a method, computer equipment and storage medium for dynamic searching of surrounding rock instability traces based on a safety factor, in order to solve the problem that the current methods for judging the stability of surrounding rock in tunnel engineering are static and cannot dynamically simulate evolution.

[0006] The technical solution is as follows: A dynamic search method for surrounding rock instability traces based on a safety factor, the key of which includes the following steps: S1: Obtain tunnel and soil information, construct a three-dimensional numerical model including soil and initial tunnel support, and assign material constitutive, boundary conditions and load conditions. S2, simulate the excavation of the tunnel rock and soil and the construction of the initial support in the three-dimensional numerical model; S3, Calculate the safety factor of each unit of the surrounding rock after one excavation cycle. F s The safety factorF s Based on the Drucker-Prager yield criterion, it is used to characterize the stability state of the surrounding rock unit when, F s >1 indicates stability; F s =1 indicates critical equilibrium; F s <1 indicates instability; S4, iterate through all cells and obtain the cell number. i and the corresponding safety factor F s,i ,in i It is a natural number greater than or equal to 1; S6, Extract safety factor F s,i The element number corresponding to the element with value <1 i And number the extracted units. i Store in collection {M}; S7, traverse the units above the tunnel arching line to obtain the unit number. j And store it in the set {N}; S8, calculate the intersection of set {M} and set {N}: {M}∩{N}; S9, determine whether the set {M}∩{N} is an empty set; If it is not empty, delete all the unit cells corresponding to the numbers in the intersection in the simulation software, return to step S3 for iterative calculation, until {M}∩{N} is empty; If empty, proceed to step S11; S11, based on the current three-dimensional numerical model, outputs the final instability traces of the surrounding rock.

[0007] The core of the above scheme lies in the introduction of a closed-loop dynamic iterative mechanism of "calculation-identification-screening-rejection-recalculation". This method, for the first time, develops the traditional static safety factor evaluation index into a control parameter driving the entire process of dynamic evolution of surrounding rock instability. This is achieved by automatically identifying potential instability units (…). F s <1), and focus on key parts of the tunnel (above the arch line), physically remove these elements in the numerical model to simulate their failure and detachment, thereby triggering stress redistribution and the next stability calculation, and so on until the system is stable.

[0008] The entire simulation process intuitively and automatically reproduces the complete dynamic process of surrounding rock instability from its inception to its final formation. It fundamentally solves the major shortcomings of existing technologies, which can only provide static safety factor cloud maps but cannot simulate instability evolution or intuitively judge the instability morphology and extent. It provides a reliable quantitative analysis tool for dynamic design, risk warning and support optimization of tunnel engineering.

[0009] As a preferred option, step S5, which involves extracting the safety factor for each unit, is included between steps S4 and S6. F s,i , build A A ×2 matrix X, where A The matrix X represents the total number of units. The first column stores the unit number, and the second column stores the corresponding safety factor. The matrix is ​​then rearranged in ascending order based on the safety factor. This approach, by introducing the step of constructing and sorting the safety factor matrix into the iterative loop, significantly improves computational efficiency and reliability. Organizing massive unit data into an association matrix and sorting it by safety factor allows the program to handle large-scale complex engineering models with extremely low time complexity, facilitating the transition from theoretical methods to practical engineering applications. Furthermore, the sorted data facilitates the rapid identification of the "most dangerous" units, further enhancing the method's engineering decision support capabilities.

[0010] As a preferred option: in step S3 F s The calculation formula is: ; in, F s This represents the safety factor of the unit cell. , These are all material parameters. I 1 is the first invariant of stress. J 2 represents the second invariant of stress skewness. Using the above scheme, compared to the simple "plastic zone" judgment, this index can more precisely reflect the gradual process of the surrounding rock from stability to failure, with high quantitative accuracy. It provides a reliable and unified mathematical criterion for subsequent automatic identification and dynamic iteration, enhancing the scientific rigor and comprehensiveness of the entire methodology.

[0011] Preferably, the method further includes step S10, where, after determining that the intersection is not empty in step S9, and before deleting the corresponding unit, the initial instability trace of the surrounding rock after the current excavation cycle is output and viewed. By adding the step of outputting the initial instability trace, the above scheme provides the capability for process visualization and comparative analysis. Users can not only obtain the final instability morphology but also observe the unstable area initially identified by the system before the iteration begins (i.e., the initial trace). This helps engineers understand the origin and evolution mechanism of instability, and by comparing the differences between the initial and final traces, they can more intuitively assess the extent of the instability range expansion, thereby gaining a deeper understanding of the failure mode and potential risks of the surrounding rock, and providing crucial information for subsequent targeted control measures.

[0012] Preferably, step S1 includes: S1.1, Solid elements are used to model the soil and rock mass and the initial support of the tunnel; S1.2, the soil and rock mass and the initial support of the tunnel are divided into grids, and the grid size of the initial support of the tunnel and the soil and rock mass in the vicinity is smaller than the grid size of the soil and rock mass in other areas; S1.3, the grid is divided into grid groups, namely surrounding rock, primary lining and excavation, which respectively represent the surrounding rock, primary support and excavation rock mass; S1.4, assigns a material constitutive model to the three-dimensional numerical model, in which the Drucker-Prager yield criterion is adopted for the soil and rock mass, and the linear elastic homogeneous constitutive model is adopted for the initial support of the tunnel, and assigns corresponding physical and mechanical parameters to both. S1.5 assigns boundary conditions and load conditions to the three-dimensional numerical model. The bottom surface of the model is constrained for horizontal and vertical displacement, the surrounding area is constrained for horizontal displacement, and the top surface is set as a free boundary. The load conditions include a vertically downward gravity load and a vertically downward uniformly distributed load simulating the self-weight of the overlying rock mass of the tunnel.

[0013] Preferably, step S2 includes: S2.1, the excavation simulation of soil and rock masses is achieved by assigning constitutive properties to empty units of the unit body; S2.2, the construction simulation of the initial support of the tunnel is realized by transforming the constitutive model of the unit body.

[0014] By adopting the above scheme, the standardized implementation method of the excavation and support construction process in the numerical model is further clarified. Moreover, the above method can accurately simulate the spatiotemporal effects of tunnel construction, ensuring that the stress state after each excavation cycle is consistent with the actual situation. Thus, the safety factor calculated based on this state and the subsequent dynamic identification results can truly reflect the stability of the surrounding rock under specific construction steps.

[0015] Preferably, in step S7, the traversal of the units above the tunnel arching line is achieved by determining whether the vertical coordinates of the centroids of each unit are greater than the elevation of the tunnel arching line. By comparing the vertical coordinates of the unit centroids with the elevation of the arching line, this method achieves automatic and precise spatial filtering of critical unstable areas, ensuring the objectivity of the results.

[0016] This application also provides a computer device, the key feature of which is that the electronic device includes: Memory, which stores executable instructions; A processor that executes the executable instructions in the memory to implement the above-described dynamic search method for surrounding rock instability traces based on a safety factor.

[0017] Another aspect of this application provides a computer-readable storage medium, the key feature of which is that the computer-readable storage medium stores a computer program, which, when executed by a processor, implements the above-described dynamic search method for surrounding rock instability traces based on a safety factor.

[0018] Compared with the prior art, the beneficial effects of the present invention are: (1) A safety factor calculation system based on the Drucker-Prager yield criterion is introduced. Through the precise derivation of material parameters, the first invariant of stress, and the second invariant of stress deviation, the ratio of the surrounding rock’s resistance to failure to the actual load is quantified. This breaks through the limitation of the existing technology that only uses the range of the plastic zone as the criterion. It can accurately identify the stability state of the surrounding rock under different stress conditions. In particular, it can effectively avoid misjudgment problems in soft rock strata with high ground stress and has better versatility.

[0019] (2) A closed-loop process of "dynamic iteration - automatic identification - physical elimination - feedback loop" was proposed. It is not only a follow-up processing of the safety factor calculation results, but also uses the safety factor as the core criterion to drive the evolution of a dynamic system. Through iteration, the gradual development process of instability is realistically simulated, overcoming the shortcomings of traditional methods that cannot take into account the dynamic characteristics of instability. The iterative mechanism effectively simulates the evolution process of surrounding rock instability, providing a dynamic and reliable basis for the optimization design of support schemes.

[0020] (3) It deeply integrates automated data processing (matrix construction and sorting, set operation), spatial logic judgment (spatial filtering based on arch line), and dynamic model update, integrating these discrete steps into a fully automatic and intelligent analysis process, which not only greatly improves efficiency, but also ensures the objectivity and repeatability of the identification process. Attached Figure Description

[0021] Figure 1 This is a schematic flowchart of the method of the present invention; Figure 2 This is a schematic diagram of tunnel support excavation. Figure 3 This is a schematic diagram illustrating the initial instability traces of the surrounding rock during an iterative cycle. Figure 4 In order to be in Figure 3 Based on the above, a conceptual diagram of the final instability traces of the surrounding rock obtained by iterative cycling is shown. Figure 5 This is a diagram of the finite difference model of the three-dimensional numerical model in this embodiment; Figure 6 Based on Figure 5 The model shown is a diagram of the initial instability traces of the surrounding rock during the iterative cycle. Figure 7 This is the final instability trace diagram of the surrounding rock obtained from the iterative cycle. Detailed Implementation

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

[0023] refer to Figures 1 to 7 The dynamic search method for surrounding rock instability traces based on the safety factor, as shown, mainly includes the following steps: Step S1: Obtain tunnel and soil information, construct a three-dimensional numerical model including soil and initial tunnel support, and assign material constitutive, boundary conditions and load conditions.

[0024] Step S2: Simulate the excavation of the tunnel rock and soil mass and the construction of initial support in the three-dimensional numerical model.

[0025] Step S3: Calculate the safety factor of each unit of the surrounding rock after one excavation cycle. F s The safety factor F s Based on the Drucker-Prager yield criterion, it is used to characterize the stability state of the surrounding rock unit when, F s >1 indicates that the unit is in a stable state; F s =1 indicates critical equilibrium, meaning the element is in a critical yielding state; F s <1 indicates that the element has undergone shear failure, and is therefore considered unstable.

[0026] Step S4: Traverse all cells and obtain the cell number.i and the corresponding safety factor F s,i ,in i It is a natural number greater than or equal to 1.

[0027] Step S6, extract the safety factor F s,i The element number corresponding to the element with value <1 i And number the extracted units. i Store in collection {M}.

[0028] Step S7: Traverse the units above the tunnel arching line and obtain the unit number. j And store it in the set {N}.

[0029] Step S8: Calculate the intersection of set {M} and set {N}, {M}∩{N}.

[0030] Step S9: Determine whether the set {M}∩{N} is empty. This step is primarily implemented using Python's collaborative computation feature.

[0031] If it is not empty, delete all the units corresponding to the numbers in the intersection in the simulation software, return to step S3 for iterative calculation, until {M}∩{N} is empty.

[0032] If empty, proceed to step S11.

[0033] Step S11: Based on the current three-dimensional numerical model, output the final instability traces of the surrounding rock.

[0034] In practice, step S5 is included between step S4 and step S6: that is, extracting the safety factor of each unit. F s,i , build A A ×2 matrix X, where A The total number of units is represented by the first column, which stores the unit number, and the second column stores the corresponding safety factor. The matrix X is then rearranged in ascending order based on the safety factor. Before step S11, there is step S10, which is to output and view the initial instability traces of the surrounding rock after the current excavation cycle is completed, after determining that the intersection is not empty in step S9 and before deleting the corresponding unit.

[0035] In step S3 F s The calculation formula is: ; in, F s This represents the safety factor of the unit cell. , These are all material parameters.I 1 is the first invariant of stress. J 2 is the second invariant of stress deviator.

[0036] Step S1 specifically includes the following sub-steps: Step S1.1: Model the soil and rock mass 1 and the initial support of the tunnel 2 using solid elements.

[0037] Step S1.2: Grid division is performed on the soil and rock mass and the initial support of the tunnel, and the grid size of the initial support of the tunnel and the soil and rock mass in the vicinity is smaller than the grid size of the soil and rock mass in other areas.

[0038] Step S1.3: The grid is divided into three groups: surrounding rock, primary lining, and excavation, which are used to characterize the surrounding rock, primary support, and excavated rock mass, respectively.

[0039] Step S1.4: Assign a material constitutive model to the three-dimensional numerical model. The constitutive model includes the Drucker-Prager yield criterion and the linear elastic homogeneous constitutive model. The soil-rock mass 1 adopts the Drucker-Prager yield criterion, and the initial support of the tunnel adopts the linear elastic homogeneous constitutive model. Assign corresponding physical and mechanical parameters to both.

[0040] Step S1.5: Assign boundary conditions and load conditions to the three-dimensional numerical model. Constrain the horizontal and vertical displacements on the bottom surface of the model, constrain the horizontal displacements around the perimeter, and set the top surface as a free boundary. The load conditions include a vertically downward gravity load and a vertically downward uniformly distributed load simulating the self-weight of the overlying rock mass of the tunnel. The uniformly distributed load is used to simulate the self-weight of the overlying rock mass of the tunnel.

[0041] Step S2 includes the following sub-steps: Step S2.1: The excavation simulation of soil and rock mass 1 is achieved by assigning constitutive properties to empty elements of the unit body; Step S2.2: The construction simulation of the initial support 2 of the tunnel is realized by transforming the constitutive model of the unit body.

[0042] In step S7, traversing the units above the tunnel arch line is achieved by determining whether the vertical coordinates of the centroid of each unit are greater than the elevation of the tunnel arch line. That is, the centroid coordinates (x, y, z) of each surrounding rock unit in the three-dimensional numerical model are read; the elevation of the arch line Z_springline in the tunnel design parameters is obtained; and a comparison is made. If z > Z_springline, then the unit is located above the arch line, and its number is stored in the set {N}.

[0043] Furthermore, since the prediction process in this application primarily utilizes computer calculations, this application also provides a computer device comprising a memory and a processor. The memory stores executable instructions, and the processor is capable of executing the executable instructions in the memory to implement the aforementioned dynamic search method for surrounding rock instability traces based on a safety factor. Specifically, this method mainly implements the calculation process of the aforementioned model and outputs the results. Through the collaborative implementation of hardware and software, the aforementioned method is transformed into an executable computer program with efficient data processing capabilities, meeting the needs of engineering applications and enhancing the convenience and practicality of the technology application.

[0044] In another aspect, this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned dynamic search method for surrounding rock instability traces based on a safety factor, thereby achieving standardized storage and dissemination of the method application and facilitating deployment and application on different computer devices.

[0045] refer to Figures 1 to 7 Taking actual production data from a tunnel construction site as an example, this paper further describes the dynamic search method, computer equipment, and storage medium for surrounding rock instability traces based on the safety factor.

[0046] Step S1.1, construct the three-dimensional numerical model of the tunnel as follows: Figure 5 As shown, the parameters are as follows: the length of the soil and rock model 1 is 36 m, the width is 100 m, and the height is 80 m; the thickness of the initial support 2 for the tunnel is 260 mm; the burial depth of the tunnel model is 34 m; and the tunnel diameter is 10.4 m.

[0047] Step S1.2, Mesh Generation: Both the soil / rock mass 1 and the initial support 2 are discretized using 8-node hexahedral solid elements. To improve computational accuracy and efficiency, the mesh size is refined in the tunnel excavation-affected area (initial support 2 and the surrounding soil / rock mass within a certain range); the mesh size gradually increases in areas far from the tunnel.

[0048] Step S1.3, grid grouping: The grid is grouped for easier operation, mainly into: surrounding rock, primary lining, and excavation.

[0049] Step S1.4: Assign constitutive models and parameters to the materials: Soil and rock mass 1 adopts an elastoplastic constitutive model conforming to the Drucker-Prager yield criterion; the initial tunnel support 2 adopts a linear elastic constitutive model. The physical and mechanical parameters of the materials are determined based on field investigation and testing. In this embodiment, the physical and mechanical parameters include the density, elastic modulus, Poisson's ratio, cohesion, and internal friction angle of soil and rock mass 1, and the density, elastic modulus, and Poisson's ratio of the initial tunnel support 2. The physical and mechanical parameters of soil and rock mass 1 and the initial tunnel support 2 are obtained from field exploration. In this embodiment, the density of soil and rock mass 1 is 2200 kg / m³. 3 The elastic modulus is 1.8 GPa, Poisson's ratio is 0.35, cohesion is 0.2 MPa, and internal friction angle is 24.5°. The density of the initial support for the tunnel is 2350 kg / m³. 3 Its elastic modulus is 25.6 GPa and its Poisson's ratio is 0.23.

[0050] Step S1.5, apply boundary and load conditions: constrain all displacements (x, y, z directions) on the bottom surface of the model, constrain normal horizontal displacements on the four sides, and leave the top surface as a free surface. Apply gravitational acceleration to the entire model to simulate its own weight, and apply a uniformly distributed load to the top surface of the model to represent the weight of the overlying soil and rock.

[0051] S2.1, Tunnel excavation simulation, realizes the excavation simulation of soil and rock mass by giving the unit body an empty constitutive model, and realizes the step-by-step excavation of soil and rock mass by setting the constitutive model of the unit in the excavation group to an "empty model".

[0052] S2.2, Support Construction Simulation, which is to simulate the construction of the initial support of the tunnel by transforming the constitutive model of the unit body. Specifically, after each excavation step, the constitutive model of the corresponding unit in the primary lining group is activated from the "empty model" to the "linear elastic model" and the support material parameters are assigned to simulate the timely construction of the initial support.

[0053] Step S3: Calculate the safety factor of each unit of the surrounding rock after the current excavation cycle is completed. F s The calculation formula is as follows:

[0054] in, F s This represents the safety factor of the unit cell. , These are all material parameters. I 1 is the first invariant of stress. J 2 is the second invariant of stress deviator; Furthermore, it is necessary to calculate the material parameters. Material parameters The expression is:

[0055] Among them, The internal friction angle of rock and soil mass 1 can be obtained from field experiments or estimated based on experience.

[0056] Calculate material parameters The material parameters The expression is:

[0057] in, The cohesion of the soil-rock mass 1, The internal friction angle of the soil-rock mass 1; Calculate the first invariant of stress I 1. First invariant of stress I The expression for 1 is:

[0058] in, , , These are the maximum principal stress, intermediate principal stress, and minimum principal stress of the soil and rock mass 1, respectively.

[0059] Calculate the second invariant of stress deviator J 2, the second invariant of the stress deviator J The expression for 2 is:

[0060] in, , , These are the maximum principal stress, intermediate principal stress, and minimum principal stress of the rock and soil mass, respectively.

[0061] In steps S4 and S5, numerical software is used to process and obtain the numbers of all surrounding rock units (surrounding rock groups) and their corresponding safety factor values. The safety factor is used as the sorting basis, and the matrix X is rearranged from smallest to largest. The constructed matrix is ​​then used for precise positioning.

[0062] Step S6: Extract all security factors from the sorted matrix X. F s The elements with values ​​less than 1 are numbered, and these numbers are stored in a set denoted as {M}. The set {M} contains all elements considered unstable under the current stress state.

[0063] Steps S7 to S11, involving dynamic iteration and instability simulation, are the core of the closed-loop feedback mechanism in this application. Figure 3 and Figure 4 As shown (label 3 in the figure represents the unstable zone of the surrounding rock; the unstable zone of the surrounding rock will change with different iteration cycles), specifically, when the intersection {M}∩{N} is not empty, perform the following operations: 1) Visualize the initial shape: In the numerical software, highlight the cells within the intersection with a special color (such as red) or export them separately to obtain the following: Figure 6 The diagram shows the initial instability pattern distribution of the surrounding rock. 2) Simulation element failure removal: In the numerical model, the mechanical constitutive models of all elements with corresponding numbers in the intersection are set to "empty models," which is equivalent to "removing" these unstable rock masses from the model, simulating their collapse and detachment process. 3) Stress redistribution calculation: Perform a numerical calculation step. Due to the "removal" of some rock masses, the original mechanical equilibrium is broken, and the stress in the surrounding rock will be redistributed.

[0064] 4) Feedback loop: After stress redistribution is completed, automatically return to step S3 and recalculate the safety factor of all remaining elements based on the new model state (some unstable elements have been removed). Then repeat steps S4 to S9.

[0065] like Figure 7 As shown, when the iteration cycle terminates, all the deleted elements in the numerical model collectively outline the final form of surrounding rock instability. This figure clearly illustrates the stable boundary form that the surrounding rock may reach after dynamic instability evolution.

[0066] This invention introduces a safety factor calculation system based on the Drucker-Prager yield criterion. Through the precise derivation of material parameters, the first invariant of stress, and the second invariant of stress deviance, it quantifies the ratio of the surrounding rock's resistance to failure to the actual load it bears. This breaks through the limitation of existing technologies that only use the range of the plastic zone as a criterion, and can accurately identify the stability state of the surrounding rock under different stress conditions. In particular, it can effectively avoid misjudgment problems in soft rock formations with high ground stress, and has better versatility.

[0067] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention. Those skilled in the art, under the guidance of the present invention, can make various similar representations without departing from the spirit and claims of the present invention, and such modifications all fall within the protection scope of the present invention.

Claims

1. A dynamic search method for surrounding rock instability traces based on a safety factor, characterized in that, Includes the following steps: S1, acquire tunnel and soil information, construct a three-dimensional numerical model including soil and initial tunnel support, and assign material constitutive, boundary conditions and load conditions. S2, simulate the excavation of the tunnel rock and soil and the construction of the initial support in the three-dimensional numerical model; S3, Calculate the safety factor of each unit of the surrounding rock after one excavation cycle. F s The safety factor F s Based on the Drucker-Prager yield criterion, it is used to characterize the stability state of the surrounding rock unit when, F s >1 indicates stability; F s =1 indicates critical equilibrium; F s <1 indicates instability; S4: Traverse all cells and obtain the cell number. i and the corresponding safety factor F s,i ,in i It is a natural number greater than or equal to 1; S6, Extract safety factor F s,i The element number corresponding to the element with value <1 i And number the extracted units. i Store in collection {M}; S7, traverse the units above the tunnel arching line to obtain the unit number. j And store it in the set {N}; S8, calculate the intersection of set {M} and set {N}: {M}∩{N}; S9, determine whether the set {M}∩{N} is an empty set; If it is not empty, delete all the unit cells corresponding to the numbers in the intersection in the simulation software, return to step S3 for iterative calculation, until {M}∩{N} is empty; If empty, proceed to step S11; S11, based on the current three-dimensional numerical model, outputs the final instability traces of the surrounding rock.

2. The method according to claim 1, characterized in that, Step S5, which involves extracting the safety factor for each unit, is included between steps S4 and S6. F s,i , build A A ×2 matrix X, where A The total number of units is represented by the first column, which stores the unit number, and the second column stores the corresponding safety coefficient. The matrix X is then rearranged in ascending order based on the safety coefficient.

3. The method according to claim 1 or 2, characterized in that: In step S3 F s The calculation formula is: ； in, F s This represents the safety factor of the unit cell. , These are all material parameters. I 1 is the first invariant of stress. J 2 is the second invariant of stress deviator.

4. The method according to claim 1 or 2, characterized in that: The method further includes step S10, which, after determining that the intersection is not empty in step S9, outputs and views the initial instability traces of the surrounding rock after the current excavation cycle is completed before deleting the corresponding unit.

5. The method according to claim 1, characterized in that, Step S1 includes: S1.1, Solid elements are used to model the soil and rock mass and the initial support of the tunnel; S1.2, the soil and rock mass and the initial support of the tunnel are divided into grids, and the grid size of the initial support of the tunnel and the soil and rock mass in the vicinity is smaller than the grid size of the soil and rock mass in other areas; S1.3, the grid is divided into grid groups, namely surrounding rock, primary lining and excavation, which respectively represent the surrounding rock, primary support and excavation rock mass; S1.4, assigns a material constitutive model to the three-dimensional numerical model, in which the Drucker-Prager yield criterion is adopted for the soil and rock mass, and the linear elastic homogeneous constitutive model is adopted for the initial support of the tunnel, and assigns corresponding physical and mechanical parameters to both. S1.5 assigns boundary conditions and load conditions to the three-dimensional numerical model. The bottom surface of the model is constrained for horizontal and vertical displacement, the surrounding area is constrained for horizontal displacement, and the top surface is set as a free boundary. The load conditions include a vertically downward gravity load and a vertically downward uniformly distributed load simulating the self-weight of the overlying rock mass of the tunnel.

6. The method according to claim 1, characterized in that, Step S2 includes: S2.1, the excavation simulation of soil and rock masses is achieved by assigning constitutive properties to empty units of the unit body; S2.2, the construction simulation of the initial support of the tunnel is realized by transforming the constitutive model of the unit body.

7. The method according to claim 1, characterized in that: In step S7, the traversal of the unit cells above the tunnel arching line is achieved by determining whether the vertical coordinates of the centroid of each unit cell are greater than the elevation of the tunnel arching line.

8. A computer device, characterized in that, include: Memory, which stores executable instructions; A processor that executes the executable instructions in the memory to implement the dynamic search method for surrounding rock instability traces based on a safety factor as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the dynamic search method for surrounding rock instability traces based on a safety factor as described in any one of claims 1 to 7.

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