Analysis method for time-varying stability of surrounding rock of super-large buried depth tunnel and related equipment

Abstract

The invention relates to the technical field of tunnels and underground engineering, in particular to an analysis method and related equipment for the time-varying stability of surrounding rock of a super-large-depth tunnel, and the method comprises the steps: obtaining engineering geological survey data and engineering design data, constructing a tunnel numerical model, carrying out the crustal stress initialization to obtain an initialized model, and carrying out the initial crustal stress balance processing; clearing the balanced model displacement field to obtain a reference model; configuring an elastic-plastic-viscous constitutive model for the surrounding rock of the reference model, simulating a tunnel excavation construction process, and identifying a plastic yield unit in the model to obtain an excavation simulation result containing plastic unit information; based on the yield state of the plastic yield unit, carrying out real-time dynamic reduction on physical and mechanical parameters of the plastic unit, and judging the stability of the surrounding rock by combining a preset stability criterion to obtain a stability analysis result; and outputting a surrounding rock time-varying stability analysis report. According to the method, the precision of time-varying stability analysis of the surrounding rock of the super-large buried-depth tunnel is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnels and underground engineering, in particular to an analysis method for time-varying stability of surrounding rock of an ultra-deep tunnel and related equipment. BACKGROUND

[0002] With the deepening of infrastructure construction, the demand for tunnel engineering in the fields of transportation, water conservancy, energy, etc. continues to grow, and the number of ultra-deep tunnels passing through high-stress rock mass is increasing. The geological environment of such tunnels is extremely special. The surrounding rock not only needs to withstand extremely high initial ground stress, but also shows significant time effect. During the tunnel excavation disturbance and subsequent operation process, the surrounding rock will continue to creep deformation, accompanied by strength damage and deterioration. If the above characteristics cannot be effectively controlled, it is easy to cause excessive deformation of the supporting structure or even failure, which in turn leads to instability of the tunnel surrounding rock, seriously threatening the safety of construction personnel, the progress of engineering construction and the long-term operation reliability of the tunnel.

[0003] Currently, the analysis methods for tunnel surrounding rock stability in the industry are mostly based on the elastic-plastic theory, but such methods have obvious technical limitations. On the one hand, the process of dynamic deterioration of rock mechanical parameters with time after shear and tensile yield is not fully considered, which cannot accurately reflect the decay law of the mechanical properties of the surrounding rock. On the other hand, the coupling mechanism between creep deformation and damage evolution is ignored, making it difficult to completely depict the whole process of mechanical response of the surrounding rock from initial deformation to final instability.

[0004] In actual engineering applications, traditional analysis methods such as strength reduction method and convergence-constraint method are limited by the above theoretical defects, making it difficult to accurately predict the self-stability time of the surrounding rock of ultra-deep high-stress tunnels and to accurately determine the potential damage location and damage mode of the surrounding rock. This directly leads to the fact that existing methods cannot provide reliable theoretical basis for dynamic optimization design of supporting structures and early prevention and control of construction risks, which is seriously out of line with the current demand for "dynamic and refined support design" in ultra-deep tunnel engineering.

[0005] Therefore, developing an analysis method that can accurately simulate the whole process of creep damage of the surrounding rock and scientifically judge the stability of the tunnel during the whole construction and operation cycle has become a key requirement for ensuring the safe construction and long-term stable operation of ultra-deep high-stress tunnels, and is also a technical problem urgently to be solved in the current tunnel engineering field. SUMMARY

[0006] In order to overcome the defects of the prior art, the purpose of the present application is to provide an analysis method for time-varying stability of surrounding rock of an ultra-deep tunnel and related equipment, to solve the technical problem of how to improve the accuracy of the time-varying stability analysis of the surrounding rock of an ultra-deep tunnel.

[0007] The application is realized by the following technical scheme: The application provides an analysis method for time-varying stability of surrounding rock of an ultra-large buried deep tunnel, comprising the following steps: Obtaining engineering geological survey data and engineering design data, constructing a tunnel numerical model based on the engineering geological survey data and the engineering design data, and initializing the ground stress to obtain an initialized model; Performing initial ground stress balance processing on the initialized model, and clearing the displacement field of the balanced model to obtain a reference model; Configuring an elastic-plastic-viscous constitutive model for the surrounding rock of the reference model, simulating the tunnel excavation construction process, and identifying the plastic yield unit in the model to obtain an excavation simulation result containing plastic unit information; Based on the yield state of the plastic yield unit, the physical and mechanical parameters of the plastic unit are dynamically reduced in real time, and the stability of the surrounding rock is discriminated in combination with a preset stability criterion to obtain a stability analysis result; Based on the stability analysis result, a surrounding rock time-varying stability analysis report for support design is output, and the time-varying stability analysis of the surrounding rock of the ultra-large buried deep tunnel is realized.

[0008] Preferably, the specific method of ground stress initialization comprises applying vertical equivalent ground stress to the model through the overburden command in the FLAC software, applying horizontal ground stress to the model through the ratio command, and assigning the ground stress field to the entire tunnel numerical model at one time; the upper, lower, left and right boundaries of the tunnel numerical model are not less than 5 times the maximum excavation span from the tunnel excavation contour, and the entire model unit is assigned with an elastic-plastic constitutive model and corresponding physical and mechanical parameters of the surrounding rock.

[0009] Preferably, the specific process of initial ground stress balance processing comprises running the initialized model until the initial ground stress reaches a balanced state, clearing the displacement field of the model at this time, and taking this state as the reference state for subsequent tunnel excavation construction simulation.

[0010] Preferably, the specific method of identifying the plastic yield unit in the model comprises traversing all rock units in the model at every calculation time step or every N calculation time step, and screening out units that meet the plastic yield limit state of the elastic-plastic-viscous constitutive model; the plastic yield limit state is defined by the FISH language function in the FLAC software, including: local shearnow = 1, indicating that the unit enters the shear yield plastic state; local tensionnow = 2, indicating that the unit enters the tensile yield plastic state.

[0011] Preferably, the parameter updating operation is automatically performed by a script program written in FISH language or C++ language embedded in FLAC software; when the yield state of the plastic yield element is a shearing yield plastic state, i.e., local shearnow = 1, the mechanical parameters are reduced according to the following formula:

[0012] In the formula, M c is a current parameter value, M i is an initial parameter value, E i is an initial elastic modulus value, E u is a final elastic modulus value, alpha is an attenuation parameter, e is a natural constant, and t is time, and the units of the variables are corresponding international units.

[0013] Further, when the yield state of the plastic yield element is a tensile yield plastic state, i.e., local tensionnow = 2, the dynamic reduction mode of the parameters is that the tensile strength ft of the element = 0, and the remaining mechanical parameters are reduced according to the following formula:

[0014] In the formula, M c is a current parameter value, M i is an initial parameter value, E i is an initial elastic modulus value, E u is a final elastic modulus value, alpha is an attenuation parameter, e is a natural constant, and t is time, and the units of the variables are corresponding international units.

[0015] Preferably, the preset stability criterion includes a displacement convergence rate criterion and a calculation convergence criterion; the displacement convergence rate criterion includes that when the displacement rate of a key point of the surrounding rock exceeds a critical value and accelerates, it is determined that the surrounding rock is unstable; and the calculation convergence criterion includes that when the numerical calculation cannot converge due to excessive distortion of the element, it is determined that the surrounding rock has been damaged.

[0016] Preferably, the time-varying stability analysis report of the surrounding rock includes a self-stabilization time of the surrounding rock after excavation of the super-large buried depth tunnel and a damage position of the surrounding rock.

[0017] In a second aspect, the present application further provides a time-varying stability analysis system of surrounding rock of a super-large buried depth tunnel, based on the time-varying stability analysis method of surrounding rock of a super-large buried depth tunnel, comprising: The model initialization module is configured to obtain engineering geological survey data and engineering design data, construct a tunnel numerical model based on the engineering geological survey data and the engineering design data, and initialize the ground stress to obtain an initialized model. The balance zeroing module is configured to perform initial ground stress balance processing on the initialized model, and zero the displacement field of the balanced model to obtain a reference model. The excavation identification module is configured to configure an elastoplastic-viscous constitutive model for the surrounding rock of the reference model, simulate a tunnel excavation construction process, and identify plastic yield units in the model to obtain an excavation simulation result containing plastic unit information. The reduction discrimination module is configured to dynamically reduce physical and mechanical parameters of the plastic units based on the yield state of the plastic yield units, discriminate the stability of the surrounding rock based on a preset stability criterion, and obtain a stability analysis result. The report output module is configured to output a surrounding rock time-varying stability analysis report for support design based on the stability analysis result, and realize time-varying stability analysis of the surrounding rock of the super-large buried depth tunnel.

[0018] In a third aspect, the present application further provides a mobile terminal comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for analyzing the time-varying stability of the surrounding rock of the super-large buried depth tunnel.

[0019] Compared with the prior art, the present application has the following beneficial technical effects: The present application provides a method for analyzing the time-varying stability of the surrounding rock of a super-large buried depth tunnel. The tunnel numerical model is constructed based on the engineering geological survey data and the engineering design data, and the ground stress is initialized. After initial ground stress balance and displacement field zeroing processing, a nonlinear elastoplastic-viscous constitutive model considering shear and tensile yield is configured for the surrounding rock. During the simulation of the tunnel excavation process, plastic yield units are accurately identified. Based on the unit yield state, the physical and mechanical parameters are dynamically reduced in real time. The comprehensive stability criterion is combined to complete the stability discrimination of the surrounding rock and output the analysis report. This process effectively solves the technical defects of the existing analysis method based on the elastoplastic theory, which does not fully consider the parameter time-varying degradation process and the coupling effect of creep and damage after rock shear and tensile yield. Through the combination of the elastoplastic-viscous constitutive model and the dynamic reduction of parameters, the decay law of rock mass strength and stiffness with plastic development can be accurately reflected, and the rock mass creep damage behavior can be more realistically simulated. At the same time, combined with the comprehensive stability criterion of the plastic zone state, displacement rate, and calculation convergence, compared with the traditional strength reduction method or the convergence-constraint method, the self-stabilization time and the damage area of the surrounding rock can be scientifically determined, and the accuracy of the stability analysis is greatly improved.

[0020] Further, the method has high automation degree, can be directly embedded in general numerical software such as FLAC for running, has strong engineering applicability, can provide key decision basis for support opportunity selection and support scheme design for high-risk tunnels such as super-large buried depth high-stress tunnels, effectively makes up for the deficiency that the existing method cannot provide reliable support for dynamic and refined support design, and guarantees the construction safety and long-term operation stability of high-risk tunnels. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A flow chart of the analysis method of the time-varying stability of the super-large buried depth tunnel surrounding rock in the embodiment of the present application is shown in the figure. Figure 2 A flow chart of the analysis method of the time-varying stability of the super-large buried depth tunnel surrounding rock in the embodiment of the present application is shown in the figure. Figure 3 A principle diagram of the analysis system of the time-varying stability of the super-large buried depth tunnel surrounding rock in the embodiment of the present application is shown in the figure. In the figure: 1, model initialization module; 2, balance zero module; 3, excavation identification module; 4, reduction discrimination module; 5, report output module. DETAILED DESCRIPTION

[0022] In order to enable personnel in the art to better understand the present application scheme, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0023] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0024] The purpose of the present application is to provide an analysis method of the time-varying stability of the super-large buried depth tunnel surrounding rock and related equipment, to solve the technical problem of how to improve the accuracy of the analysis of the time-varying stability of the super-large buried depth tunnel surrounding rock.

[0025] The application will be described in further detail below with reference to the drawings: Referring to Figure 1 and Figure 2 In one embodiment of the application, a time-varying stability analysis method of surrounding rock of an ultra-deep tunnel is provided, which can be realized through a FLAC numerical calculation platform and a FISH programming language embedded therein, and the specific implementation process is as follows: Step 1, obtain engineering geological survey data and engineering design data, construct a tunnel numerical model based on the engineering geological survey data and engineering design data, and perform initial stress initialization to obtain an initialized model; Specifically, the specific method of initial stress initialization includes applying vertical equivalent ground stress to the model through the overburden command in the FLAC software, applying horizontal ground stress to the model through the ratio command, and assigning the ground stress field to the entire tunnel numerical model at one time; the upper and lower and left and right boundaries of the tunnel numerical model are not less than 5 times the maximum excavation span from the tunnel excavation contour, and the model global unit is assigned with an elastoplastic constitutive model and corresponding surrounding rock physical and mechanical parameters.

[0026] In this embodiment, a tunnel numerical model is established, the model size is set, and material parameters are assigned using a Mohr-Coulomb elastoplastic constitutive model. The overburden command is used to apply vertical stress, and the ratio command is used to apply horizontal stress.

[0027] Step 2, perform initial ground stress balance processing on the initialized model, and clear the displacement field of the balanced model to obtain a reference model; Specifically, the specific process of initial ground stress balance processing includes running the initialized model until the initial ground stress reaches a balanced state, clearing the displacement field of the model at this time, and taking this state as a reference state for subsequent tunnel excavation construction simulation.

[0028] In this embodiment, the solve or step command is executed to complete the initial ground stress balance. After balancing, the initialize velocity-x 0 y 0 z 0 (in three dimensions) and initialize displacement-x 0 y 0 z 0 (in three dimensions) commands are used to clear the velocities and displacements of all units.

[0029] Step 3, configure an elastoplastic viscous constitutive model for the surrounding rock of the reference model, simulate the tunnel excavation construction process, and identify the plastic yield units in the model to obtain an excavation simulation result containing plastic unit information; Specifically, the specific way of identifying the plastic yield unit in the model includes, at each calculation time step or every N calculation time steps, traversing all rock mass units in the model, and screening out units that meet the plastic yield limit state of the elastic-plastic-viscous constitutive model; the plastic yield limit state is defined by the FISH language function in the FLAC software, including: local shearnow = 1, indicating that the unit enters the shear yield plastic state; local tensionnow = 2, indicating that the unit enters the tensile yield plastic state.

[0030] In this embodiment, the surrounding rock mass elastic-plastic-viscous constitutive model is assigned by zone cmodel, and the rock mass physical and mechanical parameters are assigned by zone property, and the excavation unloading is simulated by model null. After each step of calculation, the FISH function is called to traverse all units, and the plastic state indicator variable (state) is read. A judgment statement is written: if the unit enters the shear plastic yield state, mark shearnow = 1; if it enters the tensile plastic yield state, mark tensionnow = 2.

[0031] Step 4, based on the yield state of the plastic yield unit, the physical and mechanical parameters of the plastic unit are dynamically reduced in real time, and the stability of the surrounding rock is judged based on the preset stability criterion to obtain the stability analysis result; Specifically, the parameter updating operation is automatically performed by a script program written in FISH language or C++ language embedded in the FLAC software; when the yield state of the plastic yield unit is the shear yield plastic state, i.e. local shearnow = 1, the mechanical parameters are reduced according to the following formula: (Formula 1) In the formula, M c is the current parameter value, M i is the initial parameter value, E i is the initial elastic modulus value, E u is the final elastic modulus value, α is the attenuation parameter, e is the natural constant, t is the time, and the units of the variables are the corresponding international units.

[0032] When the yield state of the plastic yield unit is the tensile yield plastic state, i.e. local tensionnow = 2, the parameter dynamic reduction method is: the unit tensile strength ft = 0, and the remaining mechanical parameters are reduced according to (Formula 1): Specifically, the preset stability criterion includes a displacement convergence rate criterion and a calculation convergence criterion; the displacement convergence rate criterion includes that when the displacement rate of a key point of the surrounding rock exceeds a critical value and accelerates, it is determined that the surrounding rock is unstable; the calculation convergence criterion includes that when the numerical calculation cannot converge due to excessive distortion of an element, it is determined that the surrounding rock has been damaged.

[0033] In the embodiment, the FISH function is programmed, for all elements marked as plastic state, according to the plastic yield state, the reduction formula is called to update the parameters in real time. For example, for the tensile yield element, the tensile strength ft is immediately set to 0; for other parameters, the exponential decay model (formula 1) is calculated and assigned.

[0034] Step 5, based on the stability analysis result, outputting a surrounding rock time-varying stability analysis report for support design, realizing the time-varying stability analysis of the surrounding rock of the super-large buried depth tunnel.

[0035] Specifically, the surrounding rock time-varying stability analysis report includes the self-stability time of the surrounding rock after the excavation of the super-large buried depth tunnel and the damage position of the surrounding rock.

[0036] In the embodiment, the displacement-time curve of the key point (the vault top, the haunch and the bottom) is monitored, and the rate is calculated. At the same time, the system calculation convergence is monitored. Once the displacement rate continuously increases and exceeds the threshold value or the calculation no longer converges, it is determined that the surrounding rock is unstable, and the time is recorded as the self-stability time. Finally, the plastic zone cloud picture, the displacement field and the damage element information are extracted to form an analysis report containing the self-stability time and the damage position.

[0037] In summary, the analysis method of the time-varying stability of the surrounding rock of the super-large buried depth tunnel provided in the embodiment includes model construction, high ground stress equivalent initialization, initial ground stress balance and displacement zero, tunnel excavation and creep damage simulation, parameter dynamic reduction, stability discrimination and output. The elastic-plastic-viscous constitutive model is introduced, the plastic element is automatically identified by traversing the model, and the physical and mechanical parameters of the plastic element are reduced in real time based on the shear and tensile yield criterion, so as to accurately reflect the creep damage process of the surrounding rock. The displacement convergence rate and the calculation convergence are used as the stability criterion, the self-stability time and the damage position of the surrounding rock after the tunnel excavation are comprehensively judged, and the time-varying stability analysis report for the support design is formed. The invention can more truly simulate the time-dependent deformation and damage mechanism of the surrounding rock under high ground stress environment, and provide effective technical support for the safe construction and long-term stability evaluation of the super-large buried depth tunnel.

[0038] The embodiment introduces a nonlinear elastic-plastic-viscous constitutive model considering shear and tensile yield, and realizes real-time dynamic reduction of physical mechanics parameters, accurately reflects the attenuation process of rock mass strength and stiffness with plastic development, and can more truly simulate the creep damage behavior of rock mass; a comprehensive stability criterion combining the state of plastic zone, displacement rate and calculation convergence is proposed to scientifically determine the self-stability time and failure area of surrounding rock; it has high automation degree, can be directly embedded in general numerical software (such as FLAC) for operation, has strong engineering applicability, and can provide key decision basis for support timing and scheme design of high-risk tunnels.

[0039] Embodiment 2 According to Figure 3 As shown in the figure, the embodiment also provides a time-varying stability analysis system of surrounding rock of a super-large buried depth tunnel, based on the time-varying stability analysis method of surrounding rock of a super-large buried depth tunnel, comprising: A model initialization module 1 is configured to obtain engineering geological survey data and engineering design data, construct a tunnel numerical model based on the engineering geological survey data and engineering design data, and perform initial stress initialization to obtain an initialized model; A balance clearing module 2 is configured to perform initial stress balance processing on the initialized model, and clear the displacement field of the balanced model to obtain a reference model; An excavation identification module 3 is configured to configure an elastic-plastic-viscous constitutive model for the surrounding rock of the reference model, simulate the tunnel excavation construction process, and identify the plastic yield unit in the model to obtain an excavation simulation result containing plastic unit information; A reduction discrimination module 4 is configured to perform real-time dynamic reduction of the physical mechanics parameters of the plastic unit based on the yield state of the plastic yield unit, discriminate the stability of the surrounding rock in combination with a preset stability criterion, and obtain a stability analysis result; A report output module 5 is configured to output a time-varying stability analysis report of surrounding rock for support design based on the stability analysis result, and realize time-varying stability analysis of surrounding rock of a super-large buried depth tunnel.

[0040] Embodiment 3 The embodiment also provides a mobile terminal, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the time-varying stability analysis method of surrounding rock of a super-large buried depth tunnel when executing the computer program.

[0041] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it. Although the present application has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application.

Claims

1. A method for analyzing the time-varying stability of surrounding rock in ultra-deep tunnels, characterized in that, include: Acquire engineering geological survey data and engineering design data, construct a tunnel numerical model based on the engineering geological survey data and engineering design data, and initialize the ground stress to obtain the initialized model; The initial model is subjected to initial stress equilibrium treatment, and the displacement field of the equilibrium model is cleared to zero to obtain the reference model; An elastoplastic-viscosity constitutive model is configured for the surrounding rock of the benchmark model to simulate the tunnel excavation process. At the same time, plastic yielding elements in the model are identified to obtain excavation simulation results containing information about plastic elements. Based on the yield state of the plastic yielding unit, the physical and mechanical parameters of the plastic unit are dynamically reduced in real time, and the stability of the surrounding rock is judged by combining the preset stability criteria to obtain the stability analysis results. Based on the stability analysis results, a time-varying stability analysis report of the surrounding rock for support design is output, realizing the time-varying stability analysis of the surrounding rock of ultra-deep tunnels.

2. The method for analyzing the time-varying stability of surrounding rock in ultra-deep tunnels according to claim 1, characterized in that, The specific method for initializing the geostress includes applying vertical equivalent geostress to the model using the overburden command in FLAC software, applying horizontal geostress to the model using the ratio command, and assigning the geostress field to the entire tunnel numerical model at once; the upper, lower, left, and right boundaries of the tunnel numerical model are not less than 5 times the maximum excavation span from the tunnel excavation outline, and the model's global elements are assigned an elastoplastic constitutive model and corresponding surrounding rock physical and mechanical parameters.

3. The method for analyzing the time-varying stability of surrounding rock in ultra-deep tunnels according to claim 1, characterized in that, The specific process of the initial ground stress equilibrium treatment includes running the initialization model until the initial ground stress reaches equilibrium, clearing the displacement field of the model to zero at this time, and using this state as the reference state for subsequent tunnel excavation construction simulation.

4. The method for analyzing the time-varying stability of surrounding rock in ultra-deep tunnels according to claim 1, characterized in that, The specific method for identifying plastic yielding elements in the model includes traversing all rock mass elements in the model at each calculation step or every N calculation steps, and selecting elements that satisfy the plastic yield limit state of the elastic-plastic-viscosity constitutive model. The plastic yield limit state is defined using the FISH language function in FLAC software, including: local shearnow = 1, which indicates that the element has entered the shear yield plastic state; The value of local tensionnow = 2 indicates that the element has entered the tensile yield plastic state.

5. The method for analyzing the time-varying stability of surrounding rock in ultra-deep tunnels according to claim 1, characterized in that, The parameter update operation is automatically performed by a script program written in FISH or C++ language embedded in the FLAC software; when the yield state of the plastic yield element is the shear yield plastic state, i.e., local shearnow = 1, the mechanical parameters are reduced according to the following formula: In the formula, M c The current parameter value. M i These are the initial parameter values. E i The initial elastic modulus value, E u The final elastic modulus value is given by α, the decay parameter is given by e, the natural constant is given by t, and the units of each variable are in the corresponding International System of Units (SI).

6. The method for analyzing the time-varying stability of surrounding rock in ultra-deep tunnels according to claim 4 or 5, characterized in that, When the yield state of the plastic yield element is the tensile yield plastic state, i.e., local tensionnow = 2, the dynamic reduction of parameters is as follows: the tensile strength of the element ft = 0, and the other mechanical parameters are reduced according to the following formula: In the formula, M c The current parameter value. M i These are the initial parameter values. E i The initial elastic modulus value, E u The final elastic modulus value is given by α, the decay parameter is given by e, the natural constant is given by t, and the units of each variable are in the corresponding International System of Units (SI).

7. The method for analyzing the time-varying stability of surrounding rock in ultra-deep tunnels according to claim 1, characterized in that, The preset stability criteria include a displacement convergence rate criterion and a computational convergence criterion; the displacement convergence rate criterion includes determining that when the displacement rate of key points in the surrounding rock exceeds a critical value and accelerates, it is a precursor to the instability of the surrounding rock; the computational convergence criterion includes determining that the surrounding rock has been damaged when the numerical calculation fails to converge due to excessive distortion of the elements.

8. The method for analyzing the time-varying stability of surrounding rock in ultra-deep tunnels according to claim 1, characterized in that, The surrounding rock time-varying stability analysis report includes the self-stabilization time of the surrounding rock after the excavation of the ultra-deep tunnel and the location of the surrounding rock failure.

9. A system for analyzing the time-varying stability of surrounding rock in ultra-deep tunnels, characterized in that, A method for analyzing the time-varying stability of surrounding rock in ultra-deep tunnels according to any one of claims 1-8 includes: The model initialization module is used to acquire engineering geological survey data and engineering design data, construct a tunnel numerical model based on the engineering geological survey data and engineering design data, and perform in-situ stress initialization to obtain the initial model; The equilibrium clearing module is used to perform initial stress equilibrium processing on the initialized model and clear the displacement field of the balanced model to zero, so as to obtain the reference model. The excavation identification module is used to configure an elastic-plastic-viscosity constitutive model for the surrounding rock of the benchmark model, simulate the tunnel excavation construction process, and identify the plastic yielding elements in the model to obtain excavation simulation results containing plastic element information. The reduction and discrimination module is used to dynamically reduce the physical and mechanical parameters of the plastic yielding unit in real time based on the yielding state of the plastic yielding unit, and to judge the stability of the surrounding rock in combination with the preset stability criteria to obtain the stability analysis results. The report output module is used to output a time-varying stability analysis report of the surrounding rock for support design based on the stability analysis results, thereby realizing the time-varying stability analysis of the surrounding rock of ultra-deep tunnels.

10. A mobile terminal, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method for analyzing the time-varying stability of the surrounding rock of ultra-deep tunnels as described in any one of claims 1-8.

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