A method and system for fine characterization of a blasting damage zone and calculation of surrounding rock load

Abstract

This invention provides a method and system for refined characterization of blasting damage zones and calculation of surrounding rock loads. The method includes: acquiring working parameters related to tunnel blasting excavation; constructing a numerical model based on these parameters; solving the numerical model to obtain the strain increment of the tunnel surrounding rock under blasting loads; inputting the strain increment into a strain rate-related dual-scalar tensile-compressive damage constitutive model to obtain tensile damage factors and compressive-shear damage factors; establishing damage evolution laws related to strain rate for the tensile strain tensor and compressive-shear strain tensor respectively in the dual-scalar tensile-compressive damage constitutive model, independently characterizing the tensile damage mechanism and the compressive-shear damage mechanism; evaluating the damage zoning of the tunnel surrounding rock based on the tensile damage factors and compressive-shear damage factors to obtain tensile damage zones, compressive-shear damage zones, and refined zoning; and determining the surrounding rock load based on the tensile damage zones and compressive-shear damage zones. This invention achieves refined characterization of blasting damage, thereby enabling accurate determination of the surrounding rock load.

Description

Technical Field

[0001] This invention relates to the field of tunnel surrounding rock support technology, specifically to a method and system for refined characterization of blasting damage zones and calculation of surrounding rock loads. Background Technology

[0002] As transportation, water conservancy, and energy infrastructure extend into deeper strata, deep-buried tunnel projects are becoming increasingly common. Drill-and-blast method, due to its economy and adaptability, remains the mainstream excavation method for such projects. However, in deep, high-stress environments, the coupling effect between the blasting dynamic load and the existing stress field is significantly enhanced, leading to a more complex damage mechanism in the surrounding rock and a sharp increase in the risk of disasters such as collapses and rock bursts. Therefore, accurately characterizing the spatial distribution of surrounding rock damage induced by blasting excavation and determining reasonable support loads accordingly is crucial to ensuring the safety and long-term stability of deep tunnel construction.

[0003] Existing technologies suffer from the following technical problems: 1. Most existing rock damage constitutive models employ a single scalar damage variable. These models focus on describing damage dominated by either compression-shear or tension mechanisms, making it difficult to simultaneously and precisely characterize the complex evolution process of the coexistence, competition, and spatial differentiation of tensile and compression-shear damage under high strain rates in the near-field of blasting. This inadequate model descriptive capability directly limits the accuracy of numerical simulation predictions. 2. Blasting loads are dynamic processes with extremely high strain rates. Existing models do not fully consider the significant influence of strain rate on the evolution rate when describing damage evolution, making it difficult to accurately simulate the damage gradient changes from the near-field (crushing zone) to the far-field (excavation influence zone) of blasting, and also failing to truly reflect the impact of dynamic disturbances on the stability of high-stress surrounding rock. Consequently, it becomes impossible to accurately determine the tunnel surrounding rock load based on the damage zone.

[0004] Therefore, there is an urgent need to provide a refined characterization method and system for blasting damage zone and surrounding rock load calculation, which describes the damage evolution law based on strain rate and simultaneously characterizes both tensile damage and compressive-shear damage mechanisms, so as to achieve a refined characterization of the tensile and compressive damage evolution of tunnel surrounding rock under blasting load, and thus accurately determine the surrounding rock load. Summary of the Invention

[0005] In view of this, it is necessary to provide a method and system for refined characterization of blast damage zone and calculation of surrounding rock load, in order to solve the technical problems of existing models that focus on describing damage dominated by either compression-shear or tension, making it difficult to simultaneously and refinedly characterize the complex evolution process of tensile and compression-shear damage coexisting under high strain rate in the near field of blasting, and failing to fully consider the significant influence of strain rate evolution rate, which makes it difficult to accurately simulate the damage gradient change from the near-field to the far-field of blasting, resulting in inaccurate damage zone division and inability to accurately determine the surrounding rock load.

[0006] To address the aforementioned technical problems, in a first aspect, the present invention provides a method for refined characterization of blasting damage zones and calculation of surrounding rock loads, comprising:

[0007] Obtain the working condition parameters related to tunnel blasting excavation, construct a numerical model based on the working condition parameters, and solve the numerical model to obtain the strain increment of the tunnel surrounding rock under blasting load. The strain increment is input into a strain rate-dependent dual-scalar tensile-compressive damage constitutive model to obtain the tensile damage factor and the compressive-shear damage factor. The dual-scalar tensile-compressive damage constitutive model defines tensile damage variables and compressive-shear damage variables respectively, and establishes the damage evolution law related to strain rate for tensile strain tensor and compressive-shear strain tensor respectively, so as to independently characterize the tensile damage mechanism and the compressive-shear damage mechanism. Based on the tensile damage factor and the compressive shear damage factor, the tunnel surrounding rock is assessed for damage zoning, and tensile damage zone, compressive shear damage zone, and refined zoning composed of the tensile damage zone and the compressive shear damage zone are obtained. The surrounding rock load is determined based on the tensile damage zone and the compressive shear damage zone.

[0008] In one possible implementation, the working parameters include surrounding rock properties, ground stress magnitude, tunnel geometry, and blasting hole layout; then, the step of obtaining the working parameters related to tunnel blasting excavation, constructing a numerical model based on the working parameters, and solving the numerical model to obtain the strain increment of the tunnel surrounding rock under blasting load includes: Based on the properties of the surrounding rock, the magnitude of the in-situ stress, and the tunnel geometry, the numerical model is established using the finite difference method. The numerical model is meshed, material parameters are assigned, and dynamic boundary conditions are applied. The equivalent blasting load is determined based on the blasting hole network arrangement, and the equivalent blasting load is applied to the numerical model. The numerical model is then solved to obtain the strain increment.

[0009] In one possible implementation, inputting the strain increment into a strain rate-dependent dual-scalar tensile-compressive damage constitutive model to obtain tensile damage factor and compressive-shear damage factor includes: For each computational unit in the numerical model, the trial stress is calculated based on the current stress state and the strain increment; The yielding criterion is used to determine the yield of the tested stress. If the yield does not occur, the stress state is updated based on the elastic constitutive relation, and the damage variable remains unchanged. If you yield, then: The effective stress tensor corresponding to the previous stress state is decomposed into tensile stress components and compressive shear stress components. Based on the yield criterion, flow law, and strain rate-related hardening law, the plasticity multiplier is calculated. The total strain tensor obtained by solving the numerical model is decomposed into tensile strain components and compressive shear strain components; the decomposition process depends on the plasticity multiplier and the tensile stress components and compressive shear stress components. The tensile damage factor is determined based on the tensile strain components; The compression-shear damage factor is determined based on the compression-shear strain components.

[0010] In one possible implementation, the yield criterion is a truncated Mohr-Coulomb criterion, which is as follows:

[0011]

[0012]

[0013] In the formula, The yield criterion function; The tensile strength of rock materials; The maximum effective stress; The minimum effective stress; A coefficient related to the internal friction angle; It is the internal friction angle; This is a dynamic cohesive force function based on strain rate; For strain rate; The initial strain rate; The strain rate sensitivity coefficient; This represents the initial cohesion of the rock material.

[0014] In one possible implementation, the tensile stress component is:

[0015] The compressive-shear stress components are:

[0016] In the formula, For tensile stress components; For effective stress tensor The i-th eigenvalue; This is the normalized eigenvector of the i-th eigenvalue of the effective stress tensor. For the fourth-order projection tensor of the tensile stress components; These are the components of the compressive-shear stress. Let be the fourth-order projective tensor of the compressive and shear stress components. , It is a fourth-order unit tensor; For Macaulay operators; This is the double dot product operation for tensors.

[0017] In one possible implementation, the plastic multiplier is:

[0018]

[0019]

[0020]

[0021] In the formula, It is a plastic multiplier; For the fourth-order elastic stiffness tensor of the material; For strain increment; Let be the plastic potential function; The correlation coefficient is the expansion angle. It is the expansion angle; This represents the volumetric strain increment; This represents the increment of shear plastic strain.

[0022] In one possible implementation, the tensile damage factor is:

[0023]

[0024] The compression-shear damage factor is:

[0025]

[0026] In the formula, Tensile damage factor; It is the first material constant; This is the second material constant; For volumetric tensile strain; The critical tensile strain; For fracture toughness; Density of the rock; For longitudinal wave velocity; The maximum volumetric strain rate; The principal components of the tensile strain tensor; It is the compression-shear damage factor; It is the third material constant; It is the fourth material constant; This is the equivalent compression-shear strain; The critical compressive-shear strain; The duration of the blasting load; The principal components of the compression-shear strain tensor are given.

[0027] In one possible implementation, the step of assessing the damage zoning of the tunnel surrounding rock based on the tensile damage factor and the compressive-shear damage factor to obtain a tensile damage zone, a compressive-shear damage zone, and a refined zoning composed of the tensile damage zone and the compressive-shear damage zone includes: Obtain the tensile damage factor threshold and the compressive-shear damage factor threshold; The region with a tensile damage factor greater than or equal to the tensile damage factor threshold is determined as the tensile damage region; The region where the compression-shear damage factor is greater than or equal to the compression-shear damage factor threshold is determined as the compression-shear damage region; The tensile damage zone and the compressive shear damage zone together constitute the refined partitioning.

[0028] In one possible implementation, the method further includes: The surrounding rock load is determined based on the tensile damage zone and the compressive shear damage zone; The surrounding rock load is:

[0029] In the formula, For surrounding rock load; Density of the rock; It is the acceleration due to gravity; The loose rock mass is located in the compression-shear damage zone. Deformed rock mass in the tension damage zone; The load contribution function for the tensile damage zone; The load contribution function for the compression-shear damage zone; The depth of damage; For tunnel span; This represents the deformation stress influence coefficient in the tensile damage zone.

[0030] Secondly, the present invention also provides a system for refined characterization of blasting damage zones and calculation of surrounding rock loads, comprising: The numerical model construction and solution unit is used to obtain working condition parameters related to tunnel blasting excavation, construct a numerical model based on the working condition parameters, and solve the numerical model to obtain the strain increment of the tunnel surrounding rock under blasting load. The dual-scalar tensile-compressive damage constitutive model calculation unit is used to input the strain increment into the strain rate-related dual-scalar tensile-compressive damage constitutive model to obtain the tensile damage factor and the compressive-shear damage factor. The dual-scalar tensile-compressive damage constitutive model defines tensile damage variables and compressive-shear damage variables respectively, and establishes the damage evolution law related to the tensile strain tensor and compressive-shear strain tensor and strain rate based on the tensile and compressive-shear decomposition of stress tensor and strain tensor, respectively, so as to independently characterize the tensile damage mechanism and compressive-shear damage mechanism of the material. The damage zone fine assessment unit is used to assess the damage zoning of the tunnel surrounding rock based on the tensile damage factor and the compressive shear damage factor, and to obtain the tensile damage zone, the compressive shear damage zone, and the fine zoning composed of the tensile damage zone and the compressive shear damage zone. The surrounding rock load determination unit is used to determine the surrounding rock load based on the tensile damage zone and the compressive shear damage zone.

[0031] The beneficial effects of this invention are as follows: The method for refined characterization of blasting damage zone and calculation of surrounding rock load provided by this invention, by constructing a strain rate-dependent dual-scalar tensile-compressive damage constitutive model, innovatively introduces independent tensile damage variables and compressive-shear damage variables, overcoming the limitation of traditional single-scalar models that cannot distinguish the physical mechanism of damage. It can clearly and independently characterize and output the spatial distribution of damage dominated by tension and compressive-shear in the surrounding rock, thereby improving the refined characterization of the intrinsic physical mechanism of blasting damage.

[0032] Secondly, the dual-scalar tensile-compressive damage constitutive model in this invention is related to strain rate. Through strain rate, it can accurately reflect the dynamic strengthening behavior and damage accumulation law of rock under high strain rate blasting load, and thus more realistically reproduce the damage gradient from the near zone (high strain rate crushing) to the far zone (low strain rate vibration) of the blast hole, significantly improving the accuracy of predicting the damage range and severity.

[0033] Furthermore, by accurately determining the tensile damage zone and the compressive shear damage zone, the accuracy of the surrounding rock load determination can be achieved, providing a data basis for the support design and safety assessment of deep tunnel engineering under brittle high-stress rock mass conditions, and improving the accuracy of engineering assessment. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1This is a schematic flowchart of an embodiment of the method for refined characterization of blasting damage zone and calculation of surrounding rock load provided by the present invention. Figure 2 For the present invention Figure 1 A schematic diagram of an embodiment of step S101; Figure 3 For the present invention Figure 1 A schematic diagram of an embodiment of step S102; Figure 4 A schematic flowchart illustrating an embodiment of the process for determining the compressive-shear damage factor based on the compressive-shear strain components at yield, as provided by the present invention; Figure 5 For the present invention Figure 1 A schematic flowchart of an embodiment of step S103; Figure 6 Damage zoning diagram of deep-buried tunnel excavation using the drill-and-blast method provided by this invention; Figure 7 This is a damage comparison diagram of the model of this invention with other damage constitutive models; Figure 8 This is a comparison diagram of the surrounding rock load calculated by the present invention and the surrounding rock load obtained by other schemes. Figure 9 This is a schematic diagram of an embodiment of the system for refined characterization of blasting damage zone and calculation of surrounding rock load provided by the present invention. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] It should be understood that the illustrative drawings are not drawn to scale. The flowcharts used in this invention illustrate operations implemented according to some embodiments of the invention. It should be understood that the operations in the flowcharts may be implemented out of order, and steps without logical contextual relationships may be reversed or performed simultaneously. Furthermore, those skilled in the art, guided by the content of this invention, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor systems and / or microcontroller systems.

[0038] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0039] This invention provides a method and system for refined characterization of blasting damage zones and calculation of surrounding rock loads, which will be described below.

[0040] Tunnel surrounding rock refers to the rock mass behind and around the tunnel excavation face. In other words, it is the portion of the rock mass surrounding a man-made tunnel whose stress state and physical and mechanical properties have been significantly altered due to engineering activities.

[0041] Figure 1 This is a schematic flowchart of an embodiment of the method for refined characterization of blasting damage zone and calculation of surrounding rock load provided by the present invention, as shown below. Figure 1 As shown, the methods for refined characterization of blast damage zones and calculation of surrounding rock loads include: S101. Obtain the working condition parameters related to tunnel blasting excavation, construct a numerical model based on the working condition parameters, and solve the numerical model to obtain the strain increment of the tunnel surrounding rock under blasting load.

[0042] In a specific embodiment of the present invention, the working parameters include the properties of the surrounding rock, the magnitude of the ground stress, the tunnel geometry, and the arrangement of the blasting hole network.

[0043] Among them, the surrounding rock properties refer to the set of physical, mechanical, and dynamic characteristic parameters of the rock mass within the influence range of tunnel excavation. Surrounding rock properties include, but are not limited to, density, elastic modulus, internal friction angle, fracture toughness, and P-wave velocity. The surrounding rock properties determine the basic mechanical response of the rock mass in the numerical model.

[0044] The magnitude of in-situ stress refers to the magnitude and direction of the three-dimensional stress state naturally existing in the rock mass of the engineering area before tunnel excavation, in its original rock state. It constitutes the initial stress state of the surrounding rock.

[0045] Tunnel geometry refers to the shape and controlling dimensions of the tunnel's cross-section and longitudinal section. It forms the basis for constructing the geometric entity of the numerical model.

[0046] The blasting hole layout refers to the spatial arrangement design parameters of all blast holes (including slotting holes, auxiliary holes, peripheral holes, etc.) on the excavation surface in order to achieve one-time blasting and shaping of the tunnel cross section.

[0047] S102. Input the strain increment into the strain rate-dependent dual-scalar tensile-compressive damage constitutive model to obtain the tensile damage factor and the compressive-shear damage factor. The dual-scalar tensile-compressive damage constitutive model defines tensile damage variables and compressive-shear damage variables respectively, and establishes the damage evolution law related to strain rate for tensile strain tensor and compressive-shear strain tensor respectively, so as to independently characterize the tensile damage mechanism and the compressive-shear damage mechanism.

[0048] Specifically, by defining tensile damage variables and compressive-shear damage variables separately and establishing their evolution relationship with strain rate, the dynamic evolution and spatial distribution of these two types of damage throughout the blasting process can be independently and accurately described and predicted, providing a model basis for the subsequent refined characterization of the damage zone.

[0049] S103. Based on the tensile damage factor and the compressive shear damage factor, the tunnel surrounding rock is assessed by damage zoning to obtain the tensile damage zone, the compressive shear damage zone, and the refined zoning composed of the tensile damage zone and the compressive shear damage zone. S104. Determine the surrounding rock load based on the tensile damage zone and the compressive shear damage zone.

[0050] It should be understood that the refined characterization of the blast damage zone and the calculation method of the surrounding rock load in the embodiments of the present invention can be implemented in any device based on the refined characterization of the blast damage zone and the calculation method of the surrounding rock load, such as electronic devices such as blast damage zone equipment. Specifically, the refined characterization of the blast damage zone and the calculation method of the surrounding rock load are stored in the aforementioned device as a pre-programmed program. When the device is started, the program is invoked, and the refined characterization of the blast damage zone and the calculation method of the surrounding rock load are implemented.

[0051] Compared with existing technologies, the refined characterization of blast damage zones and the calculation method of surrounding rock load provided in this invention, by constructing a strain rate-dependent dual-scalar tensile-compressive damage constitutive model, innovatively introduces independent tensile damage variables and compressive-shear damage variables. This overcomes the limitation of traditional single-scalar models in being unable to distinguish the physical mechanisms of damage, and can clearly and independently characterize and output the spatial distribution of damage dominated by tension and compressive-shear in the surrounding rock, thereby improving the refined characterization of the intrinsic physical mechanisms of blast damage.

[0052] Secondly, the dual-scalar tensile-compressive damage constitutive model in this embodiment of the invention is related to strain rate. Through strain rate, the dynamic strengthening behavior and damage accumulation law of rock under high strain rate blasting load can be accurately reflected. In this way, the damage gradient from the near zone (high strain rate crushing) to the far zone (low strain rate vibration) of the blast hole can be reproduced more realistically, which significantly improves the accuracy of predicting the damage range and severity.

[0053] Furthermore, by accurately determining the tensile damage zone and the compressive shear damage zone, the accuracy of the surrounding rock load determination can be achieved, providing a data basis for the support design and safety assessment of deep tunnel engineering under brittle high-stress rock mass conditions, and improving the accuracy of engineering assessment.

[0054] In some embodiments of the present invention, such as Figure 2 As shown, step S101 includes: S201. Based on the properties of the surrounding rock, the magnitude of the in-situ stress, and the geometric dimensions of the tunnel, a numerical model is established using the finite difference method.

[0055] The finite difference method refers to discretizing a continuous tunnel surrounding rock region into a series of regularly arranged grid elements (such as cubes). Each element (or node) is assigned material parameters obtained from the surrounding rock properties, and the mechanical behavior is described by solving within these parameters.

[0056] S202. Mesh the numerical model, assign material parameters, and apply dynamic boundary conditions.

[0057] The dynamic boundary condition is a non-reflective viscous boundary.

[0058] S203. Determine the equivalent blasting load based on the layout of the blasting hole network, apply the equivalent blasting load to the numerical model, solve the numerical model, and obtain the strain increment.

[0059] It should be noted that since the numerical model is symmetric, only half of the numerical model can be simulated and solved to improve its computational efficiency.

[0060] When the computational unit does not yield, the material does not undergo new plastic deformation, and the damage state does not evolve. To avoid performing complex elastoplastic damage calculations on the unyielded computational unit, which results in low computational efficiency, in some embodiments of the present invention, such as... Figure 3 As shown, step S102 includes: S301. For each computational unit in the numerical model, calculate the trial stress based on the current stress state and strain increment.

[0061] Here, the computational unit refers to each grid cell after the grid is divided.

[0062] Specifically, the current stress state includes the stress tensor, total strain tensor, plastic strain tensor, damage variable, and energy release rate. Among them, the damage variable is a set of dual scalar variables, representing the tensile damage factor and the compressive-shear damage factor, respectively.

[0063] S302. Determine the yield strength of the test stress based on the yield criterion; S303. If the yield is not achieved, the stress state is updated based on the elastic constitutive relation, and the damage variable remains unchanged. S304. If yielding occurs, determine the damage variables, which include tensile damage factor and compressive-shear damage factor.

[0064] Specifically, such as Figure 4 As shown, the process for determining the tensile damage factor and the compressive-shear damage factor is as follows: S401. Decompose the effective stress tensor corresponding to the previous stress state into tensile stress components and compressive shear stress components. S402. Calculate the plasticity multiplier based on the yield criterion, flow law, and strain rate-related hardening law.

[0065] S403. Decompose the total strain tensor obtained by solving the numerical model into tensile strain components and compressive shear strain components; the decomposition process depends on the plasticity multiplier and tensile stress components and compressive shear stress components. S404. Determine the tensile damage factor based on the tensile strain component, and determine the compressive-shear damage factor based on the compressive-shear strain component.

[0066] In this embodiment of the invention, it is considered that when the load is not yielded, there is no need to perform the calculation process of elastic-plastic damage iteration. By setting the judgment logic based on the yield criterion, when the load is not yielded, the complex elastic-plastic damage iteration calculation can be skipped and the stress can be updated directly according to the elastic constitutive relationship. Under the premise of ensuring the correct physical response, the computational efficiency of the entire numerical simulation process is significantly improved.

[0067] It should be noted that the calculation process of each calculation unit is an iterative process based on time steps. When the number of iterations reaches the maximum number of iterations or the difference between two iteration results is less than the preset difference, the iteration is determined to end. At this time, the tensile damage factor and compressive shear damage factor obtained are the tensile damage factor and compressive shear damage factor of the calculation unit.

[0068] The above embodiments only illustrate the tensile / compressive decomposition of stress / strain. The following explains why this decomposition is possible.

[0069] First, in order to simultaneously describe the damage caused by two different physical mechanisms, tension and compression-shear, a decomposable Helmholtz free energy function is defined within a thermodynamic framework, which is expressed as the sum of the elastic and plastic components related to tensile damage and compression-shear damage, respectively.

[0070] Specifically, Helmholtz free energy The process is represented as follows: (1) In the formula, It is the elastic free energy function; It is the plastic free energy function; For elastic strain; For strain rate tensor, For damage variables, superscript This indicates that the quantity includes tensile and compressive shear components, where Represents the stretching component. This represents the compression-shear component.

[0071] Combining the Clausius-Duhelm inequality and the small strain assumption, the relationship between stress and Helmholtz free energy can be expressed as: (2) In the formula, For stress tensor; It is the first derivative of the plastic strain tensor; This is the first derivative of the plastic strain tensor; Tensile injury; This is the first derivative of tensile damage; This is due to compression-shear damage; The first derivative of the compression-shear damage; The first derivative of the total strain tensor; Let be the second derivative of the total strain tensor.

[0072] The embodiments of the present invention ensure that the energy dissipation of the material is always non-negative during plastic deformation, damage evolution and dynamic processes through the above formula (2), which conforms to the second law of thermodynamics.

[0073] Secondly, the thermodynamic generalized forces driving the respective damage evolution—namely, the energy release rates of tensile and compressive-shear damage—are defined, specifically: Assuming that both damage and plastic unloading processes are elastic, equation (2) remains valid for any value of elastic strain increment under the following conditions. and (3) In the formula, It is the elastic free energy; It is a fourth-order isotropic stiffness tensor. It is a fourth-order flexibility tensor. Therefore, the energy release rate of tensile damage and the energy release rate of compressive-shear damage can be expressed as a function of the corresponding damage variables. Conjugate thermodynamic forces (4) In the formula, The energy release rate during tensile damage; The energy release rate of compression-shear damage; It is the plastic free energy.

[0074] As can be seen from the above analysis, the tensile-compressive decomposition of stress tensor and strain tensor is an inherent requirement and a necessary mathematical result under the thermodynamic consistency theory framework, thus ensuring the clarity of the physical mechanism and the self-consistency of the entire model.

[0075] In some embodiments of the present invention, the yield criterion adopts a truncated Mohr-Coulomb criterion, wherein the truncated Mohr-Coulomb criterion is as follows: (5)

[0076] In the formula, The yield criterion function; The tensile strength of rock materials; The maximum effective stress obtained from the trial stress; The minimum effective stress obtained from the trial stress; A coefficient related to the internal friction angle; It is the internal friction angle; This is a dynamic cohesive force function based on strain rate.

[0077] In some embodiments of the present invention, the relationship between the effective stress tensor and the tensile stress component and the compressive shear stress component can be expressed as follows: (6) In the formula, For effective stress tensor; For tensile stress components; This represents the compressive-shear stress component.

[0078] Specifically, the tensile stress components are: (7) The compressive and shear stress components are: (8) In the formula, For effective stress tensor The i-th eigenvalue; This is the normalized eigenvector of the i-th eigenvalue of the effective stress tensor. For the fourth-order projection tensor of the tensile stress components; Let be the fourth-order projective tensor of the compressive and shear stress components. , It is a fourth-order unit tensor; For Macaulay operators, ; This is the double dot product operation for tensors.

[0079] Based on the above decomposition of the stress tensor, the strain tensor is decomposed, and simultaneously, because the total strain increment tensor... ,in For the elastic strain increment tensor, Since the tensor is the plastic strain increment tensor, the tensile strain tensor components and the compressive-shear strain tensor components can be expressed as: (9) Among them, the fourth-order projection tensor and , It is the first A normalized eigenvector.

[0080] In a specific embodiment of the present invention, the flow rule is as follows: (10) (11) In the formula, Plastic strain rate; It is a plastic multiplier; Let be the plastic potential function. .in, The correlation coefficient is the expansion angle. It is the expansion angle; This represents the volumetric strain increment; This represents the increment of shear plastic strain.

[0081] The hardening rules are: (12) In the formula, For strain rate; The initial strain rate; The strain rate sensitivity coefficient; This represents the initial cohesion of the rock material.

[0082] From the above formulas (5)-(12), the plastic multiplier can be obtained, and its expression is: (13) In the formula, It is a plastic multiplier; For the fourth-order elastic stiffness tensor of the material; This is the strain increment.

[0083] Specifically, the process for determining the tensile damage factor and the compressive-shear damage factor is as follows: First, the damage function is calculated based on the nonnormal dissipation law used in plasticity theory. and damage potential Damage variables It is expressed as follows: (14) in, It is the damage increment multiplier. .

[0084] Under tension conditions, an effective elastic modulus can be introduced by applying an average scheme to the damaged rock mass, and the tension damage factor is: (15)

[0085] Considering the extremely high strain rate impact generated by the blast load in the near-field region around the blast hole, the compressive-shear damage factor is: (16)

[0086] In the formula, Tensile damage factor; It is the first material constant; This is the second material constant; For volumetric tensile strain; The critical tensile strain; For fracture toughness; Density of the rock; For longitudinal wave velocity; The maximum volumetric strain rate; The principal components of the tensile strain tensor; It is the compression-shear damage factor; It is the third material constant; It is the fourth material constant; This is the equivalent compression-shear strain; The critical compressive-shear strain; The duration of the blasting load; The principal components of the compression-shear strain tensor are given.

[0087] In some embodiments of the present invention, such as Figure 5 As shown, step S103 includes: S501. Obtain the threshold values ​​for tensile damage factor and compressive shear damage factor.

[0088] In a specific embodiment of the present invention, both the tensile damage factor threshold and the compressive shear damage factor threshold are 1.0.

[0089] S502. The region where the tensile damage factor is greater than or equal to the tensile damage factor threshold is identified as the tensile damage region. S503. Regions with a compression-shear damage factor greater than or equal to the compression-shear damage factor threshold are identified as compression-shear damage zones. Among them, the tensile damage zone and the compressive shear damage zone are divided into finely divided zones.

[0090] It should be understood that: the tensile damage factors of all computational units form a tensile damage factor distribution map, and the compressive-shear damage factors of all computational units form a compressive-shear damage factor distribution map. Therefore, the tensile damage zone and the compressive-shear damage zone can be determined in the corresponding map based on the tensile damage factor threshold and the compressive-shear damage factor threshold.

[0091] It should be noted that in practical engineering applications, tensile damage zone, compressive-shear damage zone, or combined damage zone can be selected for research based on research needs. In other words, this embodiment of the invention, by separately determining the tensile damage zone and the compressive-shear damage zone under the premise that the original technology could only determine the combined damage zone, provides researchers with the option to select individual tensile damage zones and compressive-shear damage zones, thus achieving refined characterization of the damage zone.

[0092] To verify the effectiveness of the embodiments of the present invention, such as Figure 6 As shown, the dual-scalar tensile-compressive damage constitutive model of this invention is related to strain rate. Through strain rate, it can accurately reflect the dynamic strengthening behavior and damage accumulation law of rock under high strain rate blasting load. In this way, it can more realistically reproduce the damage gradient from the near zone (high strain rate crushing) to the far zone (low strain rate vibration) of the blast hole, significantly improving the accuracy of predicting the damage range and severity, and realizing fine zoning.

[0093] To further verify the effectiveness of the embodiments of the present invention, such as Figure 7 As shown, the strain rate-related dual-scalar tensile-compressive damage constitutive model in the embodiment of the present invention is compared with the existing TCK model, KUS model and Yang model. The comparison results show that the model in the embodiment of the present invention can divide tensile damage and compressive-shear damage into independent regions, and the division results are more accurate.

[0094] In some embodiments of the present invention, the surrounding rock load is: (17) In the formula, For surrounding rock load; Density of the rock; It is the acceleration due to gravity; The loose rock mass is located in the compression-shear damage zone. Deformed rock mass in the tension damage zone; The load contribution function for the tensile damage zone; The load contribution function for the compression-shear damage zone; The depth of damage; For tunnel span; This represents the deformation stress influence coefficient in the tensile damage zone.

[0095] The embodiments of the present invention determine the surrounding rock load by using tensile damage zone and compressive shear damage zone based on refined characterization, and can carry out reasonable support design based on accurate surrounding rock load to achieve the optimal balance between safety and economy.

[0096] To verify the effectiveness of the strain rate-dependent dual-scalar tensile-compressive damage constitutive model for surrounding rock loads proposed in this invention, the model in this invention is compared with the engineering design results, acoustic test results, and KUS model simulation results. The comparison results are as follows: Figure 8 As shown, Figure 8 The gray area represents the engineering design results, the black dashed line represents the acoustic wave test results, the red box-shaped line represents the KUS model simulation results, and the blue box-shaped line represents the model simulation results of this invention. Figure 8 It can be seen that, compared with the engineering specification design results and KUS model simulation results, the embodiments of the present invention require only a smaller surrounding rock load, thus reducing support costs. Compared with the acoustic wave test results, the surrounding rock load obtained by the embodiments of the present invention changes dynamically under different ground stresses, making it more suitable for actual scenarios.

[0097] In summary, the refined characterization of blasting damage zones and the method for calculating surrounding rock loads proposed in this invention effectively distinguish between tensile and compressive-shear failure mechanisms in blasting damage using stress decomposition and strain decomposition. This overcomes the limitations of existing damage models, which often emphasize only a single failure mechanism, thus enabling a more accurate reproduction of the complex damage evolution process of tunnel surrounding rock and achieving accurate zoning and assessment of blasting damage. Furthermore, by introducing a strain rate-dependent dual-scalar tensile-compressive damage constitutive model, this invention can accurately calculate the surrounding rock loads caused by blasting. This method uses the compressive-shear damage zone as the primary basis for calculating surrounding rock loads, providing a rapid and reliable calculation method for support design and safety assessment in deep tunnel engineering under brittle, high-stress rock mass conditions.

[0098] On the other hand, embodiments of the present invention also provide a system for refined characterization of blasting damage zones and calculation of surrounding rock loads, such as... Figure 9 As shown, the refined characterization of blast damage zone and the system for calculating surrounding rock load 900 includes: The numerical model building and solving unit 901 is used to obtain working condition parameters related to tunnel blasting excavation, build a numerical model based on the working condition parameters, and solve the numerical model to obtain the strain increment of the tunnel surrounding rock under blasting load. The dual-scalar tensile-compressive damage constitutive model calculation unit 902 is used to input the strain increment into the strain rate-related dual-scalar tensile-compressive damage constitutive model to obtain the tensile damage factor and the compressive-shear damage factor. The dual-scalar tensile-compressive damage constitutive model defines tensile damage variables and compressive-shear damage variables respectively, and establishes the damage evolution law related to the tensile strain tensor and compressive-shear strain tensor and strain rate based on the tensile and compressive-shear decomposition of stress tensor and strain tensor, respectively, so as to independently characterize the tensile damage mechanism and compressive-shear damage mechanism of the material. The damage zone fine assessment unit 903 is used to assess the damage zoning of the tunnel surrounding rock based on the tensile damage factor and the compressive shear damage factor, and to obtain the tensile damage zone, the compressive shear damage zone, and the fine zoning composed of the tensile damage zone and the compressive shear damage zone. The surrounding rock load determination unit 904 is used to determine the surrounding rock load based on the tensile damage zone and the compressive shear damage zone.

[0099] The blast damage zone fine characterization and surrounding rock load calculation system 800 provided in the above embodiments can realize the technical solutions described in the above embodiments of the blast damage zone fine characterization and surrounding rock load calculation method. The specific implementation principles of each module or unit can be found in the corresponding content in the above embodiments of the blast damage zone fine characterization and surrounding rock load calculation method, which will not be repeated here.

[0100] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware (such as a processor, controller, etc.), and the computer program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0101] The above provides a detailed description of the method and system for refined characterization of blasting damage zones and calculation of surrounding rock loads provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for fine characterization of a blasting damage zone and calculation of surrounding rock load, characterized in that, include: Obtain the working condition parameters related to tunnel blasting excavation, construct a numerical model based on the working condition parameters, and solve the numerical model to obtain the strain increment of the tunnel surrounding rock under blasting load. The strain increment is input into a strain rate-dependent dual-scalar tensile-compressive damage constitutive model to obtain the tensile damage factor and the compressive-shear damage factor. The dual-scalar tensile-compressive damage constitutive model defines tensile damage variables and compressive-shear damage variables respectively, and establishes the damage evolution law related to strain rate for tensile strain tensor and compressive-shear strain tensor respectively, so as to independently characterize the tensile damage mechanism and the compressive-shear damage mechanism. Based on the tensile damage factor and the compressive shear damage factor, the tunnel surrounding rock is assessed for damage zoning, and tensile damage zone, compressive shear damage zone, and refined zoning composed of the tensile damage zone and the compressive shear damage zone are obtained. The surrounding rock load is determined based on the tensile damage zone and the compressive shear damage zone.

2. The method according to claim 1, wherein, The working parameters include surrounding rock properties, ground stress magnitude, tunnel geometry, and blasting hole layout; therefore, the process of obtaining working parameters related to tunnel blasting excavation, constructing a numerical model based on these parameters, and solving the numerical model to obtain the strain increment of the tunnel surrounding rock under blasting load includes: Based on the properties of the surrounding rock, the magnitude of the in-situ stress, and the tunnel geometry, the numerical model is established using the finite difference method. The numerical model is meshed, material parameters are assigned, and dynamic boundary conditions are applied. The equivalent blasting load is determined based on the blasting hole network arrangement, and the equivalent blasting load is applied to the numerical model. The numerical model is then solved to obtain the strain increment.

3. The method of claim 1, wherein the method is characterized by, The step of inputting the strain increment into a strain rate-dependent dual-scalar tensile-compressive damage constitutive model to obtain the tensile damage factor and the compressive-shear damage factor includes: For each computational unit in the numerical model, the trial stress is calculated based on the current stress state and the strain increment; The yielding criterion is used to determine the yield of the tested stress. If the yield does not occur, the stress state is updated based on the elastic constitutive relation, and the damage variables remain unchanged. If you yield, then: The effective stress tensor corresponding to the previous stress state is decomposed into tensile stress components and compressive shear stress components. Based on the yield criterion, flow law, and strain rate-related hardening law, the plasticity multiplier is calculated. The total strain tensor obtained by solving the numerical model is decomposed into tensile strain components and compressive shear strain components; the decomposition process depends on the plasticity multiplier and the tensile stress components and compressive shear stress components. The tensile damage factor is determined based on the tensile strain components; The compression-shear damage factor is determined based on the compression-shear strain components.

4. The method for refined characterization of blasting damage zone and calculation of surrounding rock load according to claim 3, characterized in that, The yield criterion adopts the truncated Mohr-Coulomb criterion, which is as follows: In the formula, The yield criterion function; The tensile strength of rock materials; The maximum effective stress obtained from the trial stress; The minimum effective stress obtained from the trial stress; A coefficient related to the internal friction angle; It is the internal friction angle; This is a dynamic cohesive force function based on strain rate; For strain rate; The initial strain rate; The strain rate sensitivity coefficient; This represents the initial cohesion of the rock material.

5. The method for refined characterization of blasting damage zone and calculation of surrounding rock load according to claim 4, characterized in that, The tensile stress component is: The compressive-shear stress components are: In the formula, For tensile stress components; For effective stress tensor The i-th eigenvalue; This is the normalized eigenvector of the i-th eigenvalue of the effective stress tensor. For the fourth-order projection tensor of the tensile stress components; These are the components of the compressive-shear stress. Let be the fourth-order projective tensor of the compressive and shear stress components. , It is a fourth-order unit tensor; For Macaulay operators; This is the double dot product operation for tensors.

6. The method for refined characterization of blasting damage zone and calculation of surrounding rock load according to claim 5, characterized in that, The plastic multiplier is: In the formula, It is a plastic multiplier; For the fourth-order elastic stiffness tensor of the material; For strain increment; Let be the plastic potential function; The correlation coefficient is the expansion angle. It is the expansion angle; This represents the volumetric strain increment; This represents the increment of shear plastic strain.

7. The method for refined characterization of blasting damage zone and calculation of surrounding rock load according to claim 6, characterized in that, The tensile damage factor is: The compression-shear damage factor is: In the formula, It is a tensile damage factor; It is the first material constant; This is the second material constant; For volumetric tensile strain; The critical tensile strain; For fracture toughness; Density of the rock; For longitudinal wave velocity; The maximum volumetric strain rate; The principal components of the tensile strain tensor; It is the compression-shear damage factor; It is the third material constant; It is the fourth material constant; This is the equivalent compression-shear strain; The critical compressive-shear strain; The duration of the blasting load; The principal components of the compression-shear strain tensor are given.

8. The method for refined characterization of blasting damage zone and calculation of surrounding rock load according to claim 1, characterized in that, The method of assessing the damage zoning of tunnel surrounding rock based on the tensile damage factor and the compressive-shear damage factor to obtain tensile damage zone, compressive-shear damage zone, and refined zoning composed of the tensile damage zone and the compressive-shear damage zone includes: Obtain the tensile damage factor threshold and the compressive-shear damage factor threshold; The region with a tensile damage factor greater than or equal to the tensile damage factor threshold is determined as the tensile damage region; The region where the compression-shear damage factor is greater than or equal to the compression-shear damage factor threshold is determined as the compression-shear damage region; The tensile damage zone and the compressive shear damage zone together constitute the refined partitioning.

9. The method for refined characterization of blasting damage zone and calculation of surrounding rock load according to claim 1, characterized in that, The surrounding rock load is: In the formula, For surrounding rock load; Density of the rock; It is the acceleration due to gravity; The loose rock mass is in the compression-shear damage zone; Deformed rock mass in the tension damage zone; The load contribution function for the tensile damage zone; The load contribution function for the compression-shear damage zone; The depth of damage; For tunnel span; This represents the deformation stress influence coefficient in the tensile damage zone.

10. A system for refined characterization of blasting damage zones and calculation of surrounding rock loads, characterized in that, include: The numerical model construction and solution unit is used to obtain working condition parameters related to tunnel blasting excavation, construct a numerical model based on the working condition parameters, and solve the numerical model to obtain the strain increment of the tunnel surrounding rock under blasting load. The dual-scalar tensile-compressive damage constitutive model calculation unit is used to input the strain increment into the strain rate-related dual-scalar tensile-compressive damage constitutive model to obtain the tensile damage factor and the compressive-shear damage factor. The dual-scalar tensile-compressive damage constitutive model defines tensile damage variables and compressive-shear damage variables respectively, and establishes the damage evolution law related to the tensile strain tensor and compressive-shear strain tensor and strain rate based on the tensile and compressive-shear decomposition of stress tensor and strain tensor, respectively, so as to independently characterize the tensile damage mechanism and compressive-shear damage mechanism of the material. The damage zone fine assessment unit is used to assess the damage zoning of the tunnel surrounding rock based on the tensile damage factor and the compressive shear damage factor, and to obtain the tensile damage zone, the compressive shear damage zone, and the fine zoning composed of the tensile damage zone and the compressive shear damage zone. The surrounding rock load determination unit is used to determine the surrounding rock load based on the tensile damage zone and the compressive shear damage zone.

Images