Numerical simulation method and device for tunnel construction considering evolution of mechanical properties of soft rock

Abstract

The present disclosure provides a method and device for numerical simulation of tunnel construction that considers the evolution of mechanical properties of soft rock, belonging to the field of data processing technology, the method comprising: constructing a numerical model based on numerical simulation software, the numerical model is used to characterize the interaction relationship between the tunnel and the surrounding rock; initializing the parameters of the numerical model based on the constitutive model of the tunnel support system, the parameters of the tunnel support system, the constitutive model of the surrounding rock and the mechanical parameters of the surrounding rock; performing multiple iterative calculations on the numerical model based on the soft rock mechanical parameter evolution model until convergence is reached to obtain the numerical simulation result of tunnel construction; the soft rock mechanical parameter evolution model is used to characterize the change process of the mechanical parameters of the surrounding rock under different stress and strain states. The method and device for numerical simulation of tunnel construction that considers the evolution of mechanical properties of soft rock provided by the present disclosure can improve the accuracy of numerical simulation of tunnel construction.

Description

Technical Field

[0001] The present disclosure belongs to the field of data processing technology, and more specifically, to a method and device for numerical simulation of tunnel construction taking into account the evolution of soft rock mechanical properties. Background Art

[0002] In recent years, with the increasing scale and number of high-in-situ stress soft rock tunnel construction, the large deformation problem of high-in-situ stress soft rock tunnels has become a major engineering problem that tunnel practitioners and scientific researchers need to solve urgently. After the excavation of high-in-situ stress soft rock tunnels, the stress state of the surrounding rock is adjusted, which causes the mechanical parameters of the surrounding rock around the tunnel to undergo complex evolution under the influence of the coupling of confining pressure and plastic strain, resulting in extremely complex evolution of the stress field and displacement field of the surrounding rock around the high-in-situ stress soft rock tunnel. Therefore, accurately calculating the evolution law of the surrounding rock stress field and displacement field after the excavation of high-in-situ stress soft rock tunnels (i.e., the mechanical response problem of high-in-situ stress soft rock tunnel construction) is the fundamental prerequisite for solving the engineering problem of large deformation of high-in-situ stress soft rock tunnels.

[0003] At present, numerical simulation methods are usually used to study the mechanical response of soft rock tunnel construction with high geostress. The calculation principle is mainly to use finite element method or finite difference method for analysis and calculation based on continuous medium model. However, the evolution of soft rock mechanical properties cannot be fully considered in the traditional numerical simulation calculation process of tunnel construction. The mechanical parameters of surrounding rock are usually set as constants before the calculation begins. As a result, the calculation results of surrounding rock stress field and displacement field around the tunnel are greatly different from the actual results, which cannot provide effective guidance for actual engineering.

[0004] Therefore, it is urgent to propose a new numerical simulation calculation method for high ground stress soft rock tunnel construction, so as to make up for the shortcomings and defects of traditional numerical simulation methods and make the numerical simulation calculation results more accurate, so as to provide effective guidance and suggestions for actual projects. Summary of the invention

[0005] The purpose of the present disclosure is to provide a method and device for numerical simulation of tunnel construction taking into account the evolution of mechanical properties of soft rock, so as to improve the accuracy of numerical simulation of tunnel construction.

[0006] A first aspect of the embodiments of the present disclosure provides a numerical simulation method for tunnel construction considering the evolution of soft rock mechanical properties, comprising:

[0007] Building a numerical model based on numerical simulation software, wherein the numerical model is used to characterize the interaction relationship between the tunnel and the surrounding rock;

[0008] Initializing the parameters of the numerical model based on the constitutive model of the tunnel support system, the parameters of the tunnel support system, the constitutive model of the surrounding rock, and the mechanical parameters of the surrounding rock;

[0009] The numerical model is iterated and calculated multiple times based on the soft rock mechanical parameter evolution model until convergence is reached to obtain the numerical simulation result of tunnel construction; the soft rock mechanical parameter evolution model is used to characterize the change process of surrounding rock mechanical parameters under different stress and strain states.

[0010] A second aspect of the embodiments of the present disclosure provides a numerical simulation device for tunnel construction taking into account the evolution of soft rock mechanical properties, comprising:

[0011] A model building module, used to build a numerical model based on numerical simulation software, wherein the numerical model is used to characterize the interaction relationship between the tunnel and the surrounding rock;

[0012] An initialization module, used to initialize the parameters of the numerical model based on the constitutive model of the tunnel support system, the parameters of the tunnel support system, the constitutive model of the surrounding rock and the mechanical parameters of the surrounding rock;

[0013] The data calculation module is used to perform multiple iterative calculations on the numerical model based on the soft rock mechanical parameter evolution model until convergence is reached to obtain the numerical simulation results of tunnel construction; the soft rock mechanical parameter evolution model is used to characterize the change process of the surrounding rock mechanical parameters under different stress and strain states.

[0014] According to a third aspect of an embodiment of the present disclosure, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of the above-mentioned method for numerical simulation of tunnel construction considering the evolution of mechanical properties of soft rock are implemented.

[0015] According to a fourth aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above-mentioned method for numerical simulation of tunnel construction considering the evolution of mechanical properties of soft rock are implemented.

[0016] The tunnel construction numerical simulation method and device provided by the embodiments of the present disclosure taking into account the evolution of soft rock mechanical properties have the following beneficial effects:

[0017] The disclosed embodiment performs multiple iterative calculations on the numerical model. The soft rock mechanical parameter evolution model can characterize the change process of the mechanical parameters of the surrounding rock under different stress-strain states. When performing numerical simulation of soft rock tunnel construction, the evolution process of the mechanical characteristics of the soft rock can be fully considered. According to the stress state and strain state of the surrounding rock itself, the mechanical parameters are automatically identified, calculated and updated. Compared with the existing method of setting the mechanical parameters of the surrounding rock as constants, the numerical simulation calculation results are more accurate, which can provide effective guidance and suggestions for actual engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A schematic diagram of a flow chart of a numerical simulation method for tunnel construction taking into account the evolution of soft rock mechanical properties provided by an embodiment of the present disclosure;

[0020] Figure 2 A schematic diagram of an iterative calculation process provided by an embodiment of the present disclosure;

[0021] Figure 3 A comparison diagram of stress-strain curves of rock samples provided in an embodiment of the present disclosure;

[0022] Figure 4 A comparison diagram of the stress field distribution of surrounding rocks around a tunnel provided in an embodiment of the present disclosure;

[0023] Figure 5 A comparison diagram of tunnel circumferential displacement and plastic zone radius provided in an embodiment of the present disclosure;

[0024] Figure 6 A comparison diagram of tunnel perimeter failure modes provided by an embodiment of the present disclosure; wherein: Figure 6 (a) is a schematic diagram of the tunnel perimeter failure mode obtained by the numerical simulation method of this embodiment, Figure 6 (b) Schematic diagram of tunnel perimeter failure mode obtained from indoor scale model test;

[0025] Figure 7 A structural block diagram of a numerical simulation device for tunnel construction considering the evolution of soft rock mechanical properties provided by an embodiment of the present disclosure;

[0026] Figure 8 A schematic block diagram of an electronic device provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] In the following description, specific details such as specific system structures and technologies are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present disclosure. However, it should be clear to those skilled in the art that the present disclosure may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obstructing the description of the present disclosure with unnecessary details.

[0028] In order to make the purpose, technical solutions and advantages of the present disclosure more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0029] Please refer to Figure 1 , Figure 1 A schematic flow chart of a numerical simulation method for tunnel construction considering the evolution of soft rock mechanical properties provided by an embodiment of the present disclosure, the method comprising:

[0030] S101: A numerical model is constructed based on numerical simulation software. The numerical model is used to characterize the interaction between the tunnel and the surrounding rock.

[0031] In this embodiment, tunnel excavation will cause stress redistribution of the surrounding rock. At the same time, the surrounding rock will have an effect on the tunnel structure. This interaction relationship includes deformation of the surrounding rock, stress transfer, force on the tunnel structure and other aspects.

[0032] Numerical simulation software can be used to construct a numerical model of the interaction between the tunnel and the surrounding rock, and based on the numerical model, various stages of the tunnel construction process can be simulated to predict possible problems during the construction process. For example, the influence of construction processes such as tunnel excavation sequence, support methods and timing, and grouting reinforcement on the surrounding rock and tunnel structure can be simulated to provide a scientific basis for construction.

[0033] At the same time, numerical models can also be used to study the interaction mechanism between tunnels and surrounding rocks and explore new design theories and construction technologies. For example, the performance of new support materials and structures can be studied, and intelligent tunnel monitoring and early warning systems can be developed.

[0034] In the field of geotechnical engineering, commonly used numerical simulation software includes FLAC 3D (Fast Lagrangian Analysis of Continua in 3 Dimensions, finite element difference numerical simulation), Midas GTS (Midas Geotechnical and Tunnel Simulation, Midas geotechnical and tunnel simulation analysis software), etc.

[0035] S102: Initializing the parameters of the numerical model based on the constitutive model of the tunnel support system, the parameters of the tunnel support system, the constitutive model of the surrounding rock, and the mechanical parameters of the surrounding rock.

[0036] In this embodiment, the constitutive model of the tunnel support system is used to characterize the stress-strain relationship of the tunnel support structure material under stress. For example, for a concrete support system, the constitutive model can adopt a linear elastic model or a nonlinear model considering concrete cracking, and for a steel support system, the constitutive model can adopt an ideal elastic-plastic model.

[0037] The parameters of the tunnel support system may include the elastic modulus, Poisson's ratio, yield strength, etc. of the support system. By inputting these parameters into the numerical model, the mechanical response of the support system under different stress conditions can be simulated.

[0038] The constitutive model of surrounding rock is used to characterize the deformation characteristics of surrounding rock under different stress states. Common surrounding rock constitutive models include elastic model, Mohr-Coulomb model, Drucker-Prager model, etc. Different constitutive models are suitable for different types of surrounding rock and engineering conditions. Technical personnel in this field can select the appropriate constitutive model according to actual needs.

[0039] The mechanical parameters of surrounding rock include elastic modulus, Poisson's ratio, friction angle, cohesion, etc. The soft rock mechanical parameter evolution model takes into account the process of changes in the mechanical parameters of surrounding rock as the stress-strain state changes during tunnel excavation and construction. For example, as the surrounding rock deforms, its elastic modulus, cohesion, internal friction angle and other parameters may weaken or strengthen.

[0040] Before simulating each stage of the tunnel construction process based on the numerical model, it is necessary to construct the constitutive model of the tunnel support system based on the actual engineering parameters of the tunnel support system, construct the constitutive model of the surrounding rock based on the actual engineering parameters of the surrounding rock, calculate the mechanical parameters of the surrounding rock based on the actual engineering parameters of the surrounding rock and the soft rock mechanical parameter evolution model, and input the constitutive model of the tunnel support system, the engineering parameters of the tunnel support system, the constitutive model of the surrounding rock and the actual mechanical parameters of the surrounding rock into the numerical model to initialize the numerical model.

[0041] S103: Perform multiple iterative calculations on the numerical model based on the soft rock mechanical parameter evolution model until convergence is achieved to obtain the numerical simulation results of tunnel construction; the soft rock mechanical parameter evolution model is used to characterize the change process of the mechanical parameters of the surrounding rock under different stress-strain states.

[0042] In this embodiment, the numerical simulation software will divide the tunnel and surrounding rock into several units according to the numerical method adopted (such as finite element method, finite difference method, etc.), and solve the physical quantities such as stress, strain and displacement of each unit. The initialization data of the numerical model is usually approximate estimated data. Therefore, the result of the first calculation will have a certain deviation from the actual situation. Through multiple iterative calculations, the numerical simulation software will continuously adjust the parameters and conditions of the numerical model based on the soft rock mechanical parameter evolution model to gradually approach the actual engineering situation.

[0043] The convergence condition of the numerical model can be judged by setting a convergence standard, such as the maximum unbalanced force ratio is less than a certain set value (1×10 -5 ), or the number of iterations reaches a certain number.

[0044] It can be concluded from the above that this embodiment performs multiple iterative calculations on the numerical model based on the soft rock mechanical parameter evolution model. The soft rock mechanical parameter evolution model can characterize the change process of the mechanical parameters of the surrounding rock under different stress-strain states. When performing numerical simulation of soft rock tunnel construction, the evolution process of the mechanical characteristics of the soft rock can be fully considered. According to the stress state and strain state of the surrounding rock itself, the mechanical parameters are automatically identified, calculated and updated. Compared with the existing method of setting the mechanical parameters of the surrounding rock as constants, the numerical simulation calculation results are more accurate, which can provide effective guidance and suggestions for actual engineering.

[0045] In one embodiment of the present disclosure, the soft rock mechanical parameter evolution model includes:

[0046]

[0047] in, represents the plastic deviatoric strain, represents the strength stress ratio ( ), represents the confining pressure, Indicates the uniaxial compressive strength of the rock sample; represents the plastic deviatoric strain ratio, represents the critical plastic deviatoric strain; represents the dimensionless value of the elastic modulus, Indicates the real-time value of the elastic modulus, represents the elastic modulus of soft rock in the elastic stage under uniaxial conditions, represents the dimensionless value of Poisson's ratio, represents the real-time value of Poisson's ratio, represents the Poisson's ratio of soft rock in elastic stage under uniaxial condition, represents the dimensionless value of the friction angle, Indicates the real-time value of the friction angle, represents the friction angle of soft rock in elastic stage under uniaxial condition, is the dimensionless value of cohesion, Represents cohesion, represents the cohesion of soft rock in the elastic stage under uniaxial conditions, Represents exponential operation with constant e as base; is a proportional parameter, which is obtained by fitting the triaxial compression test data of soft rock under cyclic loading and unloading conditions under different confining pressures.

[0048] In this embodiment, the soft rock mechanical parameter evolution model used can fully characterize the change process of mechanical parameters of soft rock in different deformation stages (elastic stage, softening stage, residual stage) with confining pressure and plastic deviatoric strain. Among them, the surrounding rock mechanical parameters include elastic modulus, Poisson's ratio, friction angle and cohesion. In addition, the above-mentioned soft rock mechanical parameter evolution model fully considers the coupling effect of confining pressure and plastic strain, and can accurately characterize the evolution process of soft rock mechanical parameters under the coupling effect of confining pressure and plastic strain, making the numerical simulation calculation results more accurate.

[0049] The construction process of the soft rock mechanical parameter evolution model is as follows:

[0050] (1) The stress-strain relationship curve of the surrounding rock under different confining pressures can be obtained through the triaxial compression test of soft rock with cyclic loading and unloading.

[0051] (2) Based on the mechanical stress-strain relationship data of soft rock under different confining pressures, the mechanical parameters, plastic deviatoric strain and critical plastic deviatoric strain of soft rock under different confining pressures are obtained.

[0052] (3) Based on the mechanical parameters and plastic deviatoric strain of soft rock under different confining pressures, a mapping relationship between the mechanical parameters of soft rock and confining pressure and plastic deviatoric strain is established to obtain a first data set; if the plastic deviatoric strain is greater than the critical plastic deviatoric strain, the plastic deviatoric strain is determined as the critical plastic deviatoric strain.

[0053] Among them, the mapping relationship between the mechanical parameters of soft rock and the confining pressure and plastic deviatoric strain can be constructed in the form of a table. Each entry in the table records a set of confining pressure, plastic deviatoric strain and corresponding mechanical parameter values. Multiple sets of data corresponding to multiple sets of confining pressures constitute the first data set.

[0054] The full stress-strain curve of soft rock can be divided into three stages: elastic deformation stage, softening deformation stage, and residual deformation stage, and the control factors of the evolution of mechanical parameters of soft rock are different in different deformation stages. In the elastic deformation stage, the deformation of the material is reversible, only elastic strain occurs, no plastic deformation occurs, the plastic deviator strain is 0, and the evolution of mechanical parameters of soft rock is controlled by the confining pressure factor; in the soft rock deformation stage, the material begins to deform plastically, but has not been completely destroyed, and the plastic deviator strain is in a state of increasing from zero but not reaching the critical plastic deviator strain, that is, it is between zero and the critical plastic deviator strain. The mechanical parameters are not only affected by the confining pressure, but also change with the change of the plastic strain degree, that is, the evolution of mechanical parameters of soft rock is affected by the coupling of confining pressure and plastic strain; in the residual deformation stage, the soft rock has undergone complete plastic deformation and reached the limit state it can bear. At this time, the plastic deviator strain is greater than the critical plastic deviator strain, and the plastic strain degree no longer changes. The evolution of mechanical parameters of soft rock is controlled by the confining pressure factor.

[0055] Therefore, in order to uniformly fit all the mechanical parameters of the soft rock in the elastic deformation, softening deformation and residual deformation stages, when the plastic deviator strain is greater than the critical plastic deviator strain, it indicates that the soft rock is in the residual deformation stage and the degree of plastic strain no longer changes. The plastic deviator strain can be determined as the critical plastic deviator strain. In this way, the soft rock mechanical parameter evolution model obtained by fitting is only related to the confining pressure in the residual deformation stage.

[0056] (4) Data fitting is performed based on the first data set to obtain the soft rock mechanical parameter evolution model.

[0057] Please refer to Figure 2 In one embodiment of the present disclosure, any iterative calculation process includes:

[0058] Extract the stress state, strain state and coordinate information of the i-th unit in the numerical model;

[0059] Calculate the corresponding radial stress based on the stress state and coordinate information of the i-th unit;

[0060] The corresponding plastic deviatoric strain information is calculated based on the strain state of the i-th unit, and the corresponding critical plastic deviatoric strain information is obtained based on the radial stress, plastic deviatoric strain information and soft rock mechanical parameter evolution model of the i-th unit;

[0061] Based on the radial stress, plastic deviatoric strain information, critical plastic deviatoric strain information and soft rock mechanical parameter evolution model of the i-th unit, the corresponding first mechanical parameter value is obtained;

[0062] If the name of the i-th unit shows that the i-th unit is a surrounding rock unit, the surrounding rock state is determined based on the relative size of the plastic deviatoric strain information and the critical plastic deviatoric strain information of the i-th unit; the surrounding rock state is used to characterize whether the surrounding rock is in the elastic stage, the plastic stage or the residual stage;

[0063] If the surrounding rock state of the i-th unit shows that the surrounding rock is in the elastic stage or the plastic stage, the i-th unit is updated based on the first mechanical parameter value;

[0064] If the state of the surrounding rock of the i-th unit shows that the surrounding rock is in the residual stage, delete the i-th unit.

[0065] In this embodiment, based on FLAC 3D The numerical simulation software establishes the numerical model of the interaction between the tunnel and the surrounding rock. 3D In the numerical simulation software, based on the FISH language, the "traversal loop calculation judgment update" program is called and run to implement multiple iterative calculations. The program includes the following steps:

[0066] (S1) Extracting current unit information: extracting the mechanical information of the ith unit in the numerical model, including stress state, strain state, and coordinate information.

[0067] Among them, the stress state includes principal stress, shear stress, stress tensor, etc.; the strain state includes principal strain, shear strain, strain tensor, etc.

[0068] In FLAC 3D In numerical simulation software, you can use built-in commands or functions to extract the mechanical information of the ith unit. For example, you can use the command "zone stress id=i" to obtain the stress state of the ith unit, you can use "zone strain id=i" to obtain the strain information of the ith unit, and you can use "zone grid point id=i" to obtain the coordinate information of the location of the ith unit.

[0069] (S2) Calculating key stress and strain information of units: Calculate the key stress information (radial and tangential stress) of the ith unit; at the same time, calculate the key strain information (plastic deviatoric strain, critical plastic deviatoric strain) of the ith unit in combination with the soft rock mechanical parameter evolution model.

[0070] In this example, the corresponding radial stress can be calculated based on the stress state and coordinate information of the i-th unit. The specific process may include:

[0071] Establish a local coordinate system based on the coordinate information of the i-th unit;

[0072] The stress tensor is decomposed based on the local coordinate system to obtain the corresponding radial stress and tangential stress.

[0073] The direction of the local coordinate system can be determined by querying the coordinate information of the ith unit and the relative position of the surrounding units. Radial stress is usually the stress component pointing to the center of the unit, while tangential stress is the stress component perpendicular to the radial direction.

[0074] In this example, the corresponding plastic deviatoric strain information can be calculated based on the strain state of the i-th unit. The specific process may include:

[0075] Decompose the strain tensor of the i-th unit to obtain the plastic strain;

[0076] The increment of plastic strain is determined based on the yield criterion and the flow law, and the plastic deviatoric strain information is obtained by gradually accumulating the increment of plastic strain.

[0077] The strain tensor can be decomposed into an elastic strain tensor and a plastic strain tensor. The plastic strain can be calculated using the incremental theory or the full theory to obtain the plastic deviatoric strain. For example, the plastic strain increment can be determined using a method based on the yield criterion and the flow law, and then the plastic deviatoric strain can be obtained by gradually accumulating it.

[0078] Specifically, based on the yield criterion or the current plastic strain of the unit, it is determined whether the soft rock material has entered the plastic state, and the yield function is determined to provide a basis for calculating the plastic factor increment. Based on the flow law, the direction of the plastic strain increment and the form of the consistency condition equation can be determined to ensure the accurate description and calculation direction of the soft rock plastic deformation in the calculation of the plastic strain increment and the subsequent plastic strain accumulation process.

[0079] In the embodiment, based on the characteristics of soft rock, the yield criterion can be the Mohr-Coulomb criterion, and the flow law can be the non-associative flow law. First, the stress tensor and the yield function are calculated according to the current stress state, and the plastic factor increment is determined by combining the consistency condition with the flow law. Then, the plastic strain increment is calculated according to the flow law, and the plastic strain increment is gradually accumulated to obtain the plastic strain tensor, and finally the plastic deviatoric strain is calculated.

[0080] In this embodiment, the corresponding critical plastic deviator strain information can be obtained based on the radial stress of the i-th unit and the soft rock mechanical parameter evolution model. The specific process includes:

[0081] The radial stress and plastic deviatoric strain information of the i-th unit is input into the soft rock mechanical parameter evolution model to obtain the corresponding critical plastic deviatoric strain information.

[0082] Among them, the soft rock mechanical parameter evolution model includes the corresponding relationship between critical plastic deviatoric strain and confining pressure, as shown below:

[0083]

[0084] in, represents the strength stress ratio ( ), represents the confining pressure, Indicates the uniaxial compressive strength of the rock sample; represents the critical plastic deviatoric strain.

[0085] Based on the unit stress tensor information and the rotation axis formula of elastic mechanics, the radial stress and tangential stress corresponding to the unit in the polar coordinate system (with the center of the tunnel as the origin) can be calculated; and the radial stress is used as the third principal stress (i.e., regarded as the confining pressure) and the tangential stress is used as the first principal stress. Therefore, in this embodiment, the radial stress is used as the confining pressure and input into the soft rock mechanics parameter evolution model to obtain the corresponding critical plastic deviator strain information.

[0086] (S3) Calculation of unit mechanical parameters: Combined with the soft rock mechanical parameter evolution model, the unit mechanical parameters are calculated according to the key stress and strain information in S2.

[0087] In an embodiment, based on the radial stress, plastic deviatoric strain information, and critical plastic deviatoric strain information of the i-th unit, the above information can be input into the soft rock mechanical parameter evolution model to obtain the corresponding first mechanical parameter value (that is, the current mechanical parameter value of the i-th unit).

[0088] (S4) Determine the meaning of unit representation: Determine the meaning of unit representation based on the unit name.

[0089] In an embodiment, when establishing a numerical model, each unit may be given a corresponding name to distinguish different units, for example, the units numbered 1 to 8 may be given the name "surrounding rock", and the units numbered 9 to 10 may be given the name "tunnel". Based on the name of the i-th unit, the numerical simulation software may determine whether the i-th unit is a surrounding rock unit or a tunnel unit. If the i-th unit is a surrounding rock unit, step (S5) is executed, otherwise the current cycle is exited.

[0090] (S5) Determine the plastic state of the surrounding rock unit: Combine the key strain information in S2 to determine the plastic state of the i-th surrounding rock unit. If the plastic deviatoric strain of the surrounding rock unit is 0, it is determined that the surrounding rock is currently in an elastic state; if the plastic deviatoric strain of the surrounding rock unit is greater than 0 but less than the critical plastic deviatoric strain, it is determined that the surrounding rock is currently in a softening state; if the plastic deviatoric strain of the surrounding rock unit is greater than or equal to the critical plastic deviatoric strain, it is determined that the surrounding rock is currently in a residual state.

[0091] In this embodiment, the state of the surrounding rock may be determined based on the relative magnitudes of the plastic deviatoric strain information and the critical plastic deviatoric strain information of the ith unit.

[0092] Plastic deviator strain is a physical quantity that describes the plastic deformation of surrounding rock. It is used to characterize the change in shape of surrounding rock during stress without considering the change in volume. Critical plastic deviator strain is used to characterize the maximum plastic deformation that surrounding rock can withstand under specific conditions. If this value is exceeded, the mechanical behavior of surrounding rock will change significantly and may enter a residual state or be completely destroyed.

[0093] If the plastic deviatoric strain information of the ith unit is equal to zero, it means that the unit has not undergone plastic deformation, and there is a linear relationship between stress and strain. After unloading, the surrounding rock can completely recover to its original shape and size, and no permanent deformation occurs. At this time, the surrounding rock is in an elastic state. For example, in the early stage of tunnel excavation, the surrounding rock may be in an elastic state. At this time, if the surrounding rock is unloaded, the surrounding rock can completely recover to its original state.

[0094] If the plastic deviatoric strain information of the ith unit is between zero and the critical plastic deviatoric strain information, it indicates that the unit has undergone a certain degree of plastic deformation, but has not yet reached the level of complete destruction. At this time, the surrounding rock is in a softening state, and its strength gradually decreases with the increase of deformation. For example, during tunnel excavation, as the surrounding rock deforms, some areas may enter a softening state.

[0095] If the plastic deviatoric strain information of the i-th unit is greater than or equal to the critical plastic deviatoric strain information, it means that the unit has undergone severe plastic deformation and has reached the level of complete destruction. At this time, the surrounding rock is in a residual state, and its strength has been reduced to a relatively stable low value. For example, in some areas around the tunnel, if the surrounding rock is subjected to large stress, it may enter a residual state.

[0096] (S6) Updating mechanical parameters of surrounding rock units: For surrounding rock units in an elastic state or a softened state, the mechanical parameters of the surrounding rock units are updated to the mechanical parameters of the surrounding rock units calculated in S3.

[0097] In this embodiment, for the surrounding rock unit in an elastic state or a softened state, the mechanical parameters of the surrounding rock unit can be updated based on the mechanical parameters of the surrounding rock unit calculated in S3 for the next iterative calculation.

[0098] (S7) Delete surrounding rock units: Delete surrounding rock units that have reached a residual state.

[0099] In this embodiment, by deleting the surrounding rock units that have reached the residual state, the evolution process of the destruction and instability of the surrounding rock around the tunnel can be simulated, and a more reasonable evaluation of the stability of the tunnel chamber can be made, which overcomes the defect that the traditional numerical simulation method of tunnel construction based on the continuous medium model cannot simulate the evolution process of the destruction and instability of the surrounding rock around the tunnel.

[0100] In order to verify the calculation effect of the method in this embodiment, the tunnel construction numerical simulation method in this embodiment is verified at two scales (rock sample scale and engineering scale). The verification and comparison results are as follows: Figure 3-Figure 6 As shown in the figure, the comparison results show that, at the rock sample scale, the rock stress-strain curve obtained by the numerical simulation method for tunnel construction in this embodiment is highly consistent with the stress-strain curve of the test; at the engineering scale, the stress field distribution around the tunnel, the radius around the tunnel and the radius of the plastic zone obtained by the numerical simulation method for tunnel construction in this embodiment are highly consistent with the results obtained by the theoretical method, and the failure mode around the tunnel is also highly consistent with the results of the indoor scaled model test, indicating that the calculation accuracy of the numerical simulation method for tunnel construction in this embodiment is high, and it can accurately reflect the mechanical response process and characteristics of high-stress soft rock tunnel construction.

[0101] In summary, this embodiment proposes a numerical simulation calculation method for tunnel construction that takes into account the evolution of soft rock mechanical properties, which makes up for the deficiency of the traditional numerical simulation calculation method for tunnel construction that cannot fully consider the evolution process of soft rock mechanical properties. The numerical simulation method for tunnel construction in this embodiment can realize the automatic identification, calculation and update of mechanical parameters of the surrounding rock unit according to its own stress state and strain state in the numerical calculation, so that the numerical simulation calculation results are more accurate and can provide effective guidance and suggestions for actual projects. At the same time, the numerical simulation method for tunnel construction in this embodiment can simulate the evolution process of the destruction and instability of the surrounding rock around the tunnel by deleting the surrounding rock units that have reached the residual state, and make a more reasonable evaluation of the stability of the tunnel cavern, which overcomes the defect that the traditional numerical simulation method for tunnel construction based on the continuous medium model cannot simulate the evolution process of the destruction and instability of the surrounding rock around the tunnel.

[0102] Corresponding to the numerical simulation method of tunnel construction considering the evolution of soft rock mechanical properties in the above embodiment, Figure 7 A block diagram of a numerical simulation device for tunnel construction considering the evolution of soft rock mechanical properties provided by an embodiment of the present disclosure. For ease of explanation, only the parts related to the embodiment of the present disclosure are shown. Figure 7 The tunnel construction numerical simulation device 20 considering the evolution of soft rock mechanical properties includes: a model building module 21, an initialization module 22 and a data calculation module 23.

[0103] The model building module 21 is used to build a numerical model based on numerical simulation software, and the numerical model is used to characterize the interaction relationship between the tunnel and the surrounding rock;

[0104] An initialization module 22, for initializing the parameters of the numerical model based on the constitutive model of the tunnel support system, the parameters of the tunnel support system, the constitutive model of the surrounding rock and the mechanical parameters of the surrounding rock;

[0105] The data calculation module 23 is used to perform multiple iterative calculations on the numerical model based on the soft rock mechanical parameter evolution model until convergence is reached to obtain the numerical simulation results of tunnel construction; the soft rock mechanical parameter evolution model is used to characterize the change process of the mechanical parameters of the surrounding rock under different stress and strain states.

[0106] In one embodiment of the present disclosure, the soft rock mechanical parameter evolution model includes:

[0107]

[0108] in, represents the plastic deviatoric strain, represents the strength stress ratio ( ), represents the confining pressure, Indicates the uniaxial compressive strength of the rock sample; represents the plastic deviatoric strain ratio, represents the critical plastic deviatoric strain; represents the dimensionless value of the elastic modulus, Indicates the real-time value of the elastic modulus, represents the elastic modulus of soft rock in the elastic stage under uniaxial conditions, represents the dimensionless value of Poisson's ratio, represents the real-time value of Poisson's ratio, represents the Poisson's ratio of soft rock in elastic stage under uniaxial condition, represents the dimensionless value of the friction angle, Indicates the real-time value of the friction angle, represents the friction angle of soft rock in elastic stage under uniaxial condition, is the dimensionless value of cohesion, Represents cohesion, represents the cohesion of soft rock in the elastic stage under uniaxial conditions, Represents exponential operation with constant e as base; is a proportional parameter, which is obtained by fitting the triaxial compression test data of soft rock under cyclic loading and unloading conditions under different confining pressures.

[0109] In one embodiment of the present disclosure, the data calculation module 23 is specifically used to:

[0110] Extract the stress state, strain state and coordinate information of the i-th unit in the numerical model;

[0111] Calculate the corresponding radial stress based on the stress state and coordinate information of the i-th unit;

[0112] The corresponding plastic deviatoric strain information is calculated based on the strain state of the i-th unit, and the corresponding critical plastic deviatoric strain information is obtained based on the radial stress of the i-th unit and the soft rock mechanical parameter evolution model;

[0113] Based on the radial stress, plastic deviatoric strain information, critical plastic deviatoric strain information and soft rock mechanical parameter evolution model of the i-th unit, the corresponding first mechanical parameter value is obtained;

[0114] If the name of the i-th unit shows that the i-th unit is a surrounding rock unit, the surrounding rock state is determined based on the relative size of the plastic deviatoric strain information and the critical plastic deviatoric strain information of the i-th unit; the surrounding rock state is used to characterize whether the surrounding rock is in the elastic stage, the plastic stage or the residual stage;

[0115] If the surrounding rock state of the i-th unit shows that the surrounding rock is in the elastic stage or the plastic stage, the i-th unit is updated based on the first mechanical parameter value;

[0116] If the state of the surrounding rock of the i-th unit shows that the surrounding rock is in the residual stage, delete the i-th unit.

[0117] In one embodiment of the present disclosure, the stress state of the i-th unit includes a stress tensor, and the data calculation module 23 is further used to:

[0118] Establish a local coordinate system based on the coordinate information of the i-th unit;

[0119] The stress tensor is decomposed based on the local coordinate system to obtain the corresponding radial stress and tangential stress.

[0120] In one embodiment of the present disclosure, the strain state of the i-th unit includes a strain tensor, and the data calculation module 23 is further used to:

[0121] Decompose the strain tensor of the i-th unit to obtain the plastic strain;

[0122] The increment of plastic strain is determined based on the yield criterion and the flow law, and the plastic deviatoric strain information is obtained by gradually accumulating the increment of plastic strain.

[0123] In one embodiment of the present disclosure, the data calculation module 23 is further configured to:

[0124] The radial stress and plastic deviatoric strain information of the i-th unit is input into the soft rock mechanical parameter evolution model to obtain the corresponding critical plastic deviatoric strain information.

[0125] In one embodiment of the present disclosure, the data calculation module 23 is further configured to:

[0126] The radial stress, plastic deviator strain information and critical plastic deviator strain information of the i-th unit are input into the soft rock mechanical parameter evolution model to obtain the corresponding first mechanical parameter value.

[0127] In one embodiment of the present disclosure, the data calculation module 23 is further configured to:

[0128] If the plastic deviatoric strain information of the ith element is equal to zero, the state of the surrounding rock is determined to be an elastic state;

[0129] If the plastic deviatoric strain information of the i-th unit is between zero and the critical plastic deviatoric strain information, the state of the surrounding rock is determined to be a softening state;

[0130] If the plastic deviatoric strain information of the i-th unit is greater than or equal to the critical plastic deviatoric strain information, the state of the surrounding rock is determined to be a residual state.

[0131] See also Figure 8 , Figure 8 A schematic block diagram of an electronic device provided by an embodiment of the present disclosure. Figure 8The electronic device 300 in the embodiment shown may include: one or more processors 301, one or more input devices 302, one or more output devices 303 and one or more memories 304. The processors 301, input devices 302, output devices 303 and memories 304 communicate with each other via a communication bus 305. The memory 304 is used to store computer programs, which include program instructions. The processor 301 is used to execute the program instructions stored in the memory 304. The processor 301 is configured to call the program instructions to execute the functions of each module / unit in the above-mentioned device embodiments, such as Figure 7 The functions of modules 21 to 23 are shown.

[0132] It should be understood that in the embodiment of the present disclosure, the processor 301 may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0133] The input device 302 may include a touch panel, a fingerprint collection sensor (for collecting the user's fingerprint information and fingerprint direction information), a microphone, etc., and the output device 303 may include a display (LCD, etc.), a speaker, etc.

[0134] The memory 304 may include a read-only memory and a random access memory, and provide instructions and data to the processor 301. A portion of the memory 304 may also include a non-volatile random access memory. For example, the memory 304 may also store information about the device type.

[0135] In a specific implementation, the processor 301, input device 302, and output device 303 described in the embodiments of the present disclosure can execute the implementation methods described in the first and second embodiments of the numerical simulation method for tunnel construction considering the evolution of soft rock mechanical properties provided by the embodiments of the present disclosure, and can also execute the implementation methods of the electronic device described in the embodiments of the present disclosure, which will not be repeated here.

[0136] In another embodiment of the present disclosure, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, wherein the computer program includes program instructions, and when the program instructions are executed by the processor, all or part of the processes in the above-mentioned embodiment method are implemented, and the computer program can also be completed by instructing the relevant hardware through the computer program. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed by the processor, the steps of each of the above-mentioned method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0137] The computer-readable storage medium may be an internal storage unit of the electronic device of any of the aforementioned embodiments, such as a hard disk or memory of the electronic device. The computer-readable storage medium may also be an external storage device of the electronic device, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (SecureDigital, SD) card, a flash card (Flash Card), etc. equipped on the electronic device. Furthermore, the computer-readable storage medium may also include both an internal storage unit of the electronic device and an external storage device. The computer-readable storage medium is used to store computer programs and other programs and data required by the electronic device. The computer-readable storage medium may also be used to temporarily store data that has been output or is to be output.

[0138] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this disclosure.

[0139] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the electronic devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0140] In the several embodiments provided in the present application, it should be understood that the disclosed electronic devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces or units, or it can be an electrical, mechanical or other form of connection.

[0141] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of the present disclosure.

[0142] In addition, each functional unit in each embodiment of the present disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0143] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present disclosure, and these modifications or replacements should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A numerical simulation method for tunnel construction considering the evolution of soft rock mechanical properties, characterized in that: include: Building a numerical model based on numerical simulation software, wherein the numerical model is used to characterize the interaction relationship between the tunnel and the surrounding rock; Initializing the parameters of the numerical model based on the constitutive model of the tunnel support system, the parameters of the tunnel support system, the constitutive model of the surrounding rock, and the mechanical parameters of the surrounding rock; The numerical model is iterated and calculated multiple times based on the soft rock mechanical parameter evolution model until convergence is reached to obtain the numerical simulation result of tunnel construction; The soft rock mechanical parameter evolution model is used to characterize the change process of surrounding rock mechanical parameters under different stress and strain states; The soft rock mechanical parameter evolution model includes: in, represents the plastic deviatoric strain, represents the strength stress ratio ( ), represents the confining pressure, Indicates the uniaxial compressive strength of the rock sample; represents the plastic deviatoric strain ratio, represents the critical plastic deviatoric strain; represents the dimensionless value of the elastic modulus, Indicates the real-time value of the elastic modulus, represents the elastic modulus of soft rock in the elastic stage under uniaxial conditions, represents the dimensionless value of Poisson's ratio, represents the real-time value of Poisson's ratio, represents the Poisson's ratio of soft rock in elastic stage under uniaxial condition, represents the dimensionless value of the friction angle, Indicates the real-time value of the friction angle, represents the friction angle of soft rock in elastic stage under uniaxial condition, is the dimensionless value of cohesion, Represents cohesion, represents the cohesion of soft rock in the elastic stage under uniaxial conditions, Represents exponential operation with constant e as base; is a proportional parameter, which is obtained by fitting the triaxial compression test data of soft rock under cyclic loading and unloading conditions under different confining pressures.

2. The method for numerical simulation of tunnel construction considering the evolution of soft rock mechanical properties according to claim 1, characterized in that: Any iterative calculation process includes: Extract the stress state, strain state and coordinate information of the i-th unit in the numerical model; Calculating the corresponding radial stress based on the stress state and coordinate information of the i-th unit; Calculating corresponding plastic deviatoric strain information based on the strain state of the i-th unit, and obtaining corresponding critical plastic deviatoric strain information based on the radial stress of the i-th unit and a soft rock mechanical parameter evolution model; Obtaining a corresponding first mechanical parameter value based on the radial stress, plastic deviatoric strain information, critical plastic deviatoric strain information and a soft rock mechanical parameter evolution model of the i-th unit; If the name of the i-th unit shows that the i-th unit is a surrounding rock unit, the surrounding rock state is determined based on the relative size of the plastic deviatoric strain information and the critical plastic deviatoric strain information of the i-th unit; the surrounding rock state is used to characterize whether the surrounding rock is in an elastic stage, a plastic stage or a residual stage; If the surrounding rock state of the i-th unit shows that the surrounding rock is in an elastic stage or a plastic stage, updating the i-th unit based on the first mechanical parameter value; If the surrounding rock state of the i-th unit shows that the surrounding rock is in a residual stage, the i-th unit is deleted.

3. The method for numerical simulation of tunnel construction considering the evolution of soft rock mechanical properties according to claim 2, characterized in that: The stress state of the i-th unit includes a stress tensor, and the calculating of the corresponding radial stress based on the stress state and coordinate information of the i-th unit includes: Establishing a local coordinate system based on the coordinate information of the i-th unit; The stress tensor is decomposed based on the local coordinate system to obtain corresponding radial stress and tangential stress.

4. The method for numerical simulation of tunnel construction considering the evolution of soft rock mechanical properties according to claim 2, characterized in that: The strain state of the i-th unit includes a strain tensor, and the corresponding plastic deviatoric strain information is calculated based on the strain state of the i-th unit, including: Decomposing the strain tensor of the i-th unit to obtain the plastic strain; The increment of plastic strain is determined based on the yield criterion and the flow law, and the increment of plastic strain is gradually accumulated to obtain plastic deviatoric strain information.

5. The method for numerical simulation of tunnel construction considering the evolution of soft rock mechanical properties according to claim 2, characterized in that: The corresponding critical plastic deviator strain information is obtained based on the radial stress and soft rock mechanical parameter evolution model of the i-th unit, including: The radial stress and plastic deviatoric strain information of the i-th unit is input into the soft rock mechanical parameter evolution model to obtain the corresponding critical plastic deviatoric strain information.

6. The method for numerical simulation of tunnel construction considering the evolution of soft rock mechanical properties according to claim 2, characterized in that: The step of obtaining a corresponding first mechanical parameter value based on the radial stress, plastic deviator strain information, critical plastic deviator strain information and a soft rock mechanical parameter evolution model of the i-th unit includes: The radial stress, plastic deviatoric strain information and critical plastic deviatoric strain information of the i-th unit are input into the soft rock mechanical parameter evolution model to obtain the corresponding first mechanical parameter value.

7. The method for numerical simulation of tunnel construction considering the evolution of soft rock mechanical properties according to claim 2, characterized in that: The determining of the surrounding rock state based on the relative magnitude of the plastic deviatoric strain information and the critical plastic deviatoric strain information of the i-th unit includes: If the plastic deviatoric strain information of the i-th unit is equal to zero, the state of the surrounding rock is determined to be an elastic state; If the plastic deviatoric strain information of the i-th unit is between zero and critical plastic deviatoric strain information, the state of the surrounding rock is determined to be a softening state; If the plastic deviatoric strain information of the i-th unit is greater than or equal to the critical plastic deviatoric strain information, the surrounding rock state is determined to be a residual state.

8. A numerical simulation device for tunnel construction considering the evolution of soft rock mechanical properties, characterized in that: include: A model building module, used to build a numerical model based on numerical simulation software, wherein the numerical model is used to characterize the interaction relationship between the tunnel and the surrounding rock; An initialization module, used to initialize the parameters of the numerical model based on the constitutive model of the tunnel support system, the parameters of the tunnel support system, the constitutive model of the surrounding rock and the mechanical parameters of the surrounding rock; A data calculation module is used to perform multiple iterative calculations on the numerical model based on the soft rock mechanical parameter evolution model until convergence is reached to obtain a numerical simulation result of tunnel construction; The soft rock mechanical parameter evolution model is used to characterize the change process of surrounding rock mechanical parameters under different stress and strain states; The soft rock mechanical parameter evolution model includes: in, represents the plastic deviatoric strain, represents the strength stress ratio ( ), represents the confining pressure, Indicates the uniaxial compressive strength of the rock sample; represents the plastic deviatoric strain ratio, represents the critical plastic deviatoric strain; represents the dimensionless value of the elastic modulus, Indicates the real-time value of the elastic modulus, represents the elastic modulus of soft rock in the elastic stage under uniaxial conditions, represents the dimensionless value of Poisson's ratio, represents the real-time value of Poisson's ratio, represents the Poisson's ratio of soft rock in elastic stage under uniaxial condition, represents the dimensionless value of the friction angle, Indicates the real-time value of the friction angle, represents the friction angle of soft rock in elastic stage under uniaxial condition, is the dimensionless value of cohesion, Represents cohesion, represents the cohesion of soft rock in the elastic stage under uniaxial conditions, Represents exponential operation with constant e as base; is a proportional parameter, which is obtained by fitting the triaxial compression test data of soft rock under cyclic loading and unloading conditions under different confining pressures.

9. The tunnel construction numerical simulation device considering the evolution of soft rock mechanical properties according to claim 8, characterized in that: The data calculation module is specifically used for: Extract the stress state, strain state and coordinate information of the i-th unit in the numerical model; Calculating the corresponding radial stress based on the stress state and coordinate information of the i-th unit; Calculating corresponding plastic deviatoric strain information based on the strain state of the i-th unit, and obtaining corresponding critical plastic deviatoric strain information based on the radial stress of the i-th unit and a soft rock mechanical parameter evolution model; Obtaining a corresponding first mechanical parameter value based on the radial stress, plastic deviatoric strain information, critical plastic deviatoric strain information and a soft rock mechanical parameter evolution model of the i-th unit; If the name of the i-th unit shows that the i-th unit is a surrounding rock unit, the surrounding rock state is determined based on the relative size of the plastic deviatoric strain information and the critical plastic deviatoric strain information of the i-th unit; the surrounding rock state is used to characterize whether the surrounding rock is in an elastic stage, a plastic stage or a residual stage; If the surrounding rock state of the i-th unit shows that the surrounding rock is in an elastic stage or a plastic stage, updating the i-th unit based on the first mechanical parameter value; If the surrounding rock state of the i-th unit shows that the surrounding rock is in a residual stage, the i-th unit is deleted.

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