Salt rock self-healing characteristic discrete element simulation method and device

Abstract

The invention relates to the technical field of salt rock damage self-healing, in particular to a salt rock self-healing characteristic discrete element simulation method and device.The method comprises the steps that on the basis of a pre-constructed healing starting criterion of target salt rock, under the condition that it is detected that particles of a damage interface of the target salt rock meet a preset healing condition, the target salt rock is subjected to self-healing characteristic discrete element simulation; fracture contact among the particles is reconstructed into heavy bonding contact to endow new parallel bonding force among the particles, so that equivalent healing stress of the damaged interface of the target rock salt after healing is determined, and strain evolution of the volume of the damaged interface before healing and the volume after healing is quantified; and when it is detected that the strain evolution result meets a preset healing termination condition, generating a target salt rock self-healing characteristic discrete element simulation result. Therefore, the problems that in the prior art, after contact fracture between particles, bonding with strength cannot be established again, and the micro-mechanical recovery process of self-healing after salt rock damage cannot be truly reflected are solved.

Description

Technical Field

[0001] The present application relates to the technical field of salt rock damage self-healing, and in particular to a discrete element simulation method and device for salt rock self-healing characteristics. Background Art

[0002] Salt rock is widely used in underground energy storage and nuclear waste disposal. One of the most notable features of its mechanical behavior is the self-healing of microcracks under specific conditions, that is, the cracks can close again after damage and restore a certain strength. Mainstream salt rock mechanics simulations mostly use continuous medium methods, such as FEM (Finite Element Method) and FDM (Finite Difference Method). These methods regard the material as a continuum and are based on the stress-strain equivalent field. It is difficult to accurately characterize the entire process of "occurrence-evolution-closure" of cracks, especially the discreteness and nonlinearity of the crack regeneration and self-healing process. Therefore, the process of salt rock damage development can be analyzed by DEM (Discrete Element Method).

[0003] However, although the discrete element method in related technologies can simulate the occurrence and closure of cracks, once the contact between particles is broken, it is impossible to re-establish strong bonding. There is a lack of physical modeling of the recovery of mechanical connections between particles during the healing process, and it cannot truly reflect the micromechanical recovery process of self-healing of salt rock after damage. This reduces the physical authenticity and engineering prediction reliability of the self-healing behavior of salt rock in discrete element simulation, which urgently needs to be solved. Summary of the Invention

[0004] This application is based on the following problems and understandings made by the inventors:

[0005] First, the damage-healing mechanism of salt rock is primarily manifested as microcrack initiation, i.e., the propagation of microcracks between crystals under tensile or shear stress; damage propagation, i.e., the increase and penetration of cracks, manifested as mechanical property degradation and volume expansion; crack closure, i.e., under conditions of high pressure and low temperature, the crack surfaces re-contact, leading to crack filling due to ion migration and creep; and performance recovery, i.e., the gradual re-load of the closed region, manifested macroscopically as enhanced mechanical properties and volume compression. This process is dynamic, time-varying, and state-dependent, requiring simulation methods capable of timing control, crack identification, contact updating, and strength reconstruction.

[0006] Among them, Figure 1As shown, the conventional PFC (Particle Flow Code) discrete element model's shortcomings in simulating salt rock self-healing are as follows: Fracture formation can be simulated, but healing cannot be expressed: in traditional models, once particles break, contact disappears. While they can later re-contact, they will not re-bond. Furthermore, mechanical property recovery cannot be reestablished: even if contact is re-established, there will be no new parallel bonding forces. There is also no healing criterion: the model cannot determine whether, when, or how a crack can heal.

[0007] Therefore, relying solely on the traditional DEM model is unable to simulate the actual damage-healing process of salt rock and needs to be improved urgently.

[0008] The present application provides a discrete element simulation method and device for the self-healing characteristics of salt rock to solve the problems of the discrete element method in related technologies, such as the inability to re-establish strong bonding after contact between particles breaks, and the inability to truly reflect the micromechanical recovery process of self-healing of salt rock after damage, thereby reducing the physical authenticity and engineering prediction reliability of the self-healing behavior of salt rock in discrete element simulation.

[0009] A first aspect of the present application provides a discrete element simulation method for the self-healing characteristics of salt rock, comprising the following steps: based on a pre-constructed healing initiation criterion of a target salt rock, detecting whether the particles at the damaged interface of the target salt rock meet a preset healing condition; when it is detected that the particles meet the preset healing condition, reconstructing the fractured contact between the particles into a rebonding contact to impart a new parallel bonding force between the particles, and determining the equivalent healing stress after the damaged interface of the target salt rock is healed based on the new parallel bonding force between the particles; based on the equivalent healing stress after the healing of the damaged interface, quantifying the strain evolution of the volume of the damaged interface before healing and the volume after healing to obtain a strain evolution result, and generating a discrete element simulation result of the self-healing characteristics of the target salt rock when it is detected that the strain evolution result meets the preset healing termination condition.

[0010] Optionally, in one embodiment of the present application, the healing initiation criterion based on the pre-constructed target salt rock is used to detect whether the particles on the damaged interface of the target salt rock meet the preset healing conditions, including: constructing the healing initiation criterion of the target salt rock based on the minimum principal stress and the von Mises stress; and detecting whether the particles on the damaged interface of the target salt rock meet the preset healing conditions based on the target flow potential function in the healing initiation criterion of the target salt rock.

[0011] Optionally, in one embodiment of the present application, determining the equivalent healing stress of the target salt rock after the damaged interface is healed based on the new parallel bonding force between the particles includes: calculating the macroscopic stress state of the target salt rock after the damaged interface is healed according to a preset healing equivalent stress formula, and converting the macroscopic stress state into a microscopic contact force between the particles of the damaged interface; using the microscopic contact force to determine the new parallel bonding force between the particles, so as to determine the equivalent healing stress of the target salt rock after the damaged interface is healed based on the new parallel bonding force between the particles.

[0012] Optionally, in one embodiment of the present application, when it is detected that the strain evolution result meets the preset healing termination condition, the target salt rock self-healing characteristic discrete element simulation result is generated, including: judging whether the increment of the volume strain after the damage interface is healed in the strain evolution result is less than a first preset threshold within the target time step, whether the number of cracks remains unchanged within the target time step, and whether the target unbalanced force is less than a second preset threshold; if the increment of the volume strain is less than the first preset threshold within the target time step, the number of cracks remains unchanged within the target time step, and the target unbalanced force is less than the second preset threshold, then generating the salt rock self-healing characteristic discrete element simulation result; if the increment of the volume strain is greater than or equal to the first preset threshold within the target time step, the number of cracks does not remain unchanged within the target time step, or the target unbalanced force is greater than or equal to the second preset threshold, then continuing the salt rock self-healing characteristic discrete element simulation.

[0013] Optionally, in one embodiment of the present application, the healing initiation criterion of the target salt rock is expressed as:

[0014]

[0015] Among them, F h is the target flow potential function, σ3 is the minimum principal stress, a6, a5 are model parameters, σ v is the vonMises stress.

[0016] Optionally, in one embodiment of the present application, the target healing equivalent stress formula is expressed as:

[0017]

[0018] Among them, I1 is the first stress invariant, x 10 is the equivalent healing parameter, and σ1 is the maximum principal stress.

[0019] A second aspect of the present application provides a discrete element simulation device for the self-healing characteristics of salt rock, including: a detection module for detecting whether the particles at the damaged interface of the target salt rock meet preset healing conditions based on a pre-constructed healing start criterion of the target salt rock; a determination module for reconstructing the broken contact between the particles into a re-bonding contact when it is detected that the particles meet the preset healing conditions, so as to impart new parallel bonding forces between the particles, and determining the equivalent healing stress after the damaged interface of the target salt rock is healed based on the new parallel bonding forces between the particles; a simulation module for quantifying the strain evolution of the volume before and after healing of the damaged interface based on the equivalent healing stress after healing of the damaged interface to obtain a strain evolution result, and generating a discrete element simulation result of the self-healing characteristics of the target salt rock when it is detected that the strain evolution result meets the preset healing termination condition.

[0020] Optionally, in one embodiment of the present application, the detection module includes: a construction unit for constructing a healing initiation criterion for the target salt rock based on the minimum principal stress and the von Mises stress; and a detection unit for detecting whether the particles at the damaged interface of the target salt rock meet the preset healing condition based on the target flow potential function in the healing initiation criterion of the target salt rock.

[0021] Optionally, in one embodiment of the present application, the determination module includes: a calculation unit, used to calculate the macroscopic stress state of the damaged interface of the target salt rock after healing according to a preset healing equivalent stress formula, and convert the macroscopic stress state into a microscopic contact force between particles of the damaged interface; a determination unit, used to use the microscopic contact force to determine the new parallel bonding force between the particles, so as to determine the equivalent healing stress after the damaged interface of the target salt rock is healed based on the new parallel bonding force between the particles.

[0022] Optionally, in one embodiment of the present application, the simulation module includes: a judgment unit, used to judge whether the increment of the volume strain after the damage interface is healed in the strain evolution result is less than a first preset threshold within the target time step, whether the number of cracks remains unchanged within the target time step, and whether the target unbalanced force is less than a second preset threshold; a first processing unit, used to generate the discrete element simulation result of the salt rock self-healing characteristics if the increment of the volume strain is less than the first preset threshold within the target time step, the number of cracks remains unchanged within the target time step, and the target unbalanced force is less than the second preset threshold; a second processing unit, used to continue the discrete element simulation of the salt rock self-healing characteristics if the increment of the volume strain is greater than or equal to the first preset threshold within the target time step, the number of cracks does not remain unchanged within the target time step, or the target unbalanced force is greater than or equal to the second preset threshold.

[0023] Optionally, in one embodiment of the present application, the healing initiation criterion of the target salt rock is expressed as:

[0024]

[0025] Among them, F h is the target flow potential function, σ3 is the minimum principal stress, a6, a5 are model parameters, σ v is the vonMises stress.

[0026] Optionally, in one embodiment of the present application, the target healing equivalent stress formula is expressed as:

[0027]

[0028] Among them, I1 is the first stress invariant, x 10 is the equivalent healing parameter, and σ1 is the maximum principal stress.

[0029] A third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the discrete element simulation method for the self-healing characteristics of salt rock as described in the above embodiment.

[0030] A fourth aspect of the present application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above discrete element simulation method for the self-healing characteristics of salt rock.

[0031] A fifth aspect of the present application provides a computer program product, including a computer program, which, when executed, is used to implement the above discrete element simulation method for the self-healing characteristics of salt rock.

[0032] The embodiment of the present application can be based on the pre-constructed healing initiation criteria of the target salt rock. When it is detected that the particles at the damaged interface of the target salt rock meet the healing conditions, the broken contact between the particles is reconstructed as a re-bonded contact to give the particles a new parallel bonding force, thereby determining the equivalent healing stress after the damaged interface is healed, and then quantifying the strain evolution of the volume before and after the healing of the damaged interface. When it is detected that the strain evolution results meet the healing termination conditions, the discrete element simulation results of the target salt rock self-healing characteristics are generated, thereby truly reflecting the micromechanical recovery process of the salt rock self-healing after damage, and effectively improving the physical authenticity and engineering prediction reliability of the salt rock self-healing behavior in the discrete element simulation. Thus, the problem that the discrete element method in the related art cannot re-establish strong bonding after the contact between the particles is broken and cannot truly reflect the micromechanical recovery process of the salt rock self-healing after damage is solved.

[0033] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0035] Figure 1 Schematic diagram comparing general re-contact and healing re-contact in PFC in the related art;

[0036] Figure 2 This is a flow chart of a discrete element simulation method for salt rock self-healing characteristics provided according to an embodiment of the present application;

[0037] Figure 3 Schematic diagram of the short-term strength (A), expansion boundary (B) and healing boundary (C) of salt rock according to a specific embodiment of the present application;

[0038] Figure 4 This is a schematic diagram of the interparticles after injury and after healing according to a specific embodiment of the present application;

[0039] Figure 5 This is a schematic diagram of the changes in the number of cracks and body strain during the healing process of a specific embodiment of the present application;

[0040] Figure 6 This is a schematic structural diagram of a discrete element simulation device for salt rock self-healing characteristics provided in accordance with an embodiment of the present application;

[0041] Figure 7 A schematic diagram of the structure of an electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0042] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0043] The following describes a discrete element simulation method and device for the self-healing characteristics of salt rock according to an embodiment of the present application with reference to the accompanying drawings. In view of the problems that the discrete element method in the related art mentioned in the background technology center cannot re-establish strong bonding after the contact between particles is broken, cannot truly reflect the micromechanical recovery process of self-healing of salt rock after damage, and reduces the physical authenticity and engineering prediction reliability of the self-healing behavior of salt rock in discrete element simulation, the present application provides a discrete element simulation method for the self-healing characteristics of salt rock. In this method, based on a pre-constructed healing initiation criterion of the target salt rock, when it is detected that the particles at the damaged interface of the target salt rock meet the healing conditions, the broken contact between the particles is reconstructed as a re-bonding contact to give new parallel bonding forces between the particles, thereby determining the equivalent healing stress after the damage interface is healed, and then quantifying the strain evolution of the volume before and after the healing of the damaged interface. When it is detected that the strain evolution result meets the healing termination condition, the target salt rock self-healing characteristics discrete element simulation result is generated, thereby truly reflecting the micromechanical recovery process of self-healing of salt rock after damage, effectively improving the physical authenticity and engineering prediction reliability of the self-healing behavior of salt rock in discrete element simulation. This solves the problem that the discrete element method in related technologies cannot re-establish strong bonding after the contact between particles breaks, and cannot truly reflect the micromechanical recovery process of self-healing of salt rock after damage.

[0044] Specifically, Figure 1 A schematic flow chart of a discrete element simulation method for the self-healing characteristics of salt rock provided in an embodiment of the present application.

[0045] like Figure 1 As shown, the discrete element simulation method for the self-healing characteristics of salt rock includes the following steps:

[0046] In step S101, based on the pre-established healing initiation criterion of the target salt rock, it is detected whether the particles at the damaged interface of the target salt rock meet the preset healing conditions.

[0047] In the embodiment of the present application, the target salt rock is the salt rock currently undergoing discrete element simulation of self-healing characteristics.

[0048] It can be understood that the embodiment of the present application can pre-construct the healing initiation criterion of the target salt rock based on the minimum principal stress and von Mises stress in the following steps, so that it can be detected whether the particles at the damaged interface of the target salt rock meet certain healing conditions according to the healing initiation criterion. For example, the flow potential function can be used to determine whether the damage is healed, which effectively improves the executability of the discrete element simulation of the self-healing characteristics of the salt rock.

[0049] In one embodiment of the present application, based on a pre-constructed healing initiation criterion of the target salt rock, whether the particles at the damaged interface of the target salt rock meet the preset healing conditions is detected, including: constructing the healing initiation criterion of the target salt rock based on the minimum principal stress and the vonMises stress; and detecting whether the particles at the damaged interface of the target salt rock meet the preset healing conditions based on the target flow potential function in the healing initiation criterion of the target salt rock.

[0050] In the actual implementation process, the Huo / Lux model combines the damage theory of continuum mechanics and is based on the Lobby2 rheological model, integrating the diffusion and displacement, damage and damage healing, and strain hardening and recovery in salt rock deformation in a phenomenological way. Therefore, in the Huo / Lux model, the total strain rate By the elastic part and the inelastic part Right now:

[0051]

[0052] where the elastic strain rate is given by Hooke's law:

[0053]

[0054] Among them, s ij is the deviatoric stress, I1 is the first stress invariant, K is the bulk modulus, D is the damage parameter, defined as D = damage area / total area, G is the shear modulus, δ ij is the Kronecker product.

[0055] The inelastic strain rate includes viscoplastic volumetric strain rate, damage expansion and healing contraction, namely:

[0056]

[0057] in, is the viscoplastic volume strain rate, To expand the damage, To heal and shrink.

[0058] Since the various parts are linearly superimposed, the present embodiment only focuses on the shrinkage caused by healing:

[0059]

[0060] Among them, ε Vol is the dilatancy strain, F h is the flow potential function, F * is the stress reference value, here we take F * =1MPa,Q h is the plastic potential function caused by damage healing, σ ij is the stress tensor, ε Vol is the dilatancy strain, a 11 、a 12 、a 13 are model parameters respectively.

[0061] In the above formula, <x>is the switch function, that is:

[0062]

[0063] In the above formula, the flow potential function F h It determines whether the strain rate caused by healing is activated. Therefore, the flow potential function is considered as the criterion for damage healing in PFC, that is:

[0064]

[0065] Among them, σ3 is the minimum principal stress, a6, a5 are model parameters, σ v is the von Mises stress.

[0066] When F h >0 indicates that the injury has healed. h When <0, it means that damage healing cannot occur. Where σ3 is the minimum principal stress, a6 and a5 are model parameters, where a6 = 67.0 MPa and a5 = 0.055 MPa -1 ,σ v is the von Mises stress, that is:

[0067]

[0068] Among them, σ1, σ2, and σ3 are the first, second, and third principal stresses, respectively.

[0069] Since PFC is a discrete particle system, it is necessary to redefine the stress state of the continuous medium of the particle aggregate. Therefore, the REV (Representative Elementary Volume) method based on the averaging concept can be used to represent the stress state of the particle system and expressed in the form of a tensor product, that is:

[0070]

[0071] Among them, V is the size of REV, is the set of REV internal contacts, is the contact reaction force, is the branch vector. This method is implemented in PFC by measuring the circle, and the calculation formula is:

[0072]

[0073] in, is the mean stress, F (c) is the contact force vector, L (c) is the branch vector connecting the centers of mass of the two objects in contact, N c is the number of contacts in the measurement area.

[0074] Therefore, the embodiment of the present application can use the stress state calculated by the representative element volume (REV) method as a basis, combine the minimum principal stress and the von Mises stress to construct the healing initiation criterion, and use the target flow potential function to further refine the detection of healing conditions, thereby achieving accurate simulation and control of the self-healing behavior of salt rock.

[0075] In step S102, when it is detected that the preset healing conditions are met between the particles, the broken contact between the particles is reconstructed into a rebonded contact to give the particles new parallel bonding forces, and based on the new parallel bonding forces between the particles, the equivalent healing stress of the damaged interface of the target salt rock after healing is determined.

[0076] It is understandable that the embodiment of the present application can reconstruct the fracture contact between the particles into a rebonded contact when it is detected that the healing conditions in the above steps are met between the particles, so as to give the particles a new parallel bonding force. Then, the MDCF (Multimechanism Deformation Coupled Fracture) can be used as a reference to introduce an equivalent healing stress to describe the strength change of the healing area. For example, after the damaged part of the salt rock is healed, its mechanical properties will also change. Therefore, MDCF can be proposed based on MD (Multimechanism Deformation). In the MDCF model, the healing equivalent stress formula is used to evaluate the material strength and stress state after the damage is healed. This formula can more accurately describe the material behavior after the damage is healed by considering the influence of the first invariant and principal stress of the stress tensor, that is:

[0077]

[0078] in, is the healing equivalent stress, I1 is the first stress invariant, x 10 is the equivalent healing parameter. This formula shows that the healing equivalent stress depends not only on the first invariant of the stress tensor, but also on the principal stress. By introducing the coefficient x 10 , which can describe the healing behavior of materials under different stress states. In simulating the self-healing process of salt rock damage, this formula can be used to calculate the equivalent stress after healing, thereby evaluating the damage healing effect and mechanical properties of the material.

[0079] Among them, in one embodiment of the present application, based on the new parallel bonding force between particles, the equivalent healing stress of the damaged interface of the target salt rock after healing is determined, including: calculating the macroscopic stress state of the damaged interface of the target salt rock after healing according to a preset healing equivalent stress formula, and converting the macroscopic stress state into the microscopic contact force between particles of the damaged interface; using the microscopic contact force to determine the new parallel bonding force between particles, so as to determine the equivalent healing stress of the damaged interface of the target salt rock after healing based on the new parallel bonding force between particles.

[0080] As a possible implementation, in particle flow code (PFC) simulations, force transmission is achieved through microscopic contact forces between particles. However, the healing equivalent stress formula in the MDCF model is based on a description of a continuous macroscopic stress state. Parameters such as the principal stress involved in the healing equivalent stress formula are derived from the calculation of the macroscopic stress tensor. Therefore, in order to apply the healing equivalent stress in the MDCF model to PFC simulations, it is necessary to link the macroscopic stress state with the microscopic contact forces.

[0081] Assume that the two spheres are in contact through a radius of The circular flat contact area interacts microscopically, and the normal force of the bond after healing can be expressed as:

[0082]

[0083] in, is the normal healing equivalent stress, is the area of ​​the contact region, in two-dimensional case Substituting formula (1.10) into the equation, we can obtain:

[0084]

[0085] Therefore, the total parallel bond force after healing is:

[0086]

[0087] in, is the parallel bond tangential stiffness, δ s is the tangential displacement.

[0088] In step S103, based on the equivalent healing stress after the damage interface is healed, the strain evolution of the volume before and after the damage interface is healed is quantified to obtain the strain evolution result. When it is detected that the strain evolution result meets the preset healing termination condition, the discrete element simulation result of the target salt rock self-healing characteristics is generated.

[0089] It can be understood that the embodiments of the present application can use the boundary particle method to track the strain behavior of the sample based on the equivalent healing stress after the damage interface is healed, and quantify the strain evolution of the volume before and after the damage interface is healed to obtain the strain evolution results. When it is detected that the strain evolution results meet the healing termination conditions, for example, when it is detected that the strain evolution results meet the triple healing termination criteria of strain stability, stable number of cracks, and unbalanced force less than a certain threshold, adaptive healing termination control can be performed to generate discrete element simulation results of the target salt rock self-healing characteristics, thereby truly reflecting the micromechanical recovery process of salt rock self-healing after damage, and effectively improving the physical authenticity and engineering prediction reliability of salt rock self-healing behavior in discrete element simulation.

[0090] Optionally, in one embodiment of the present application, when it is detected that the strain evolution result meets the preset healing termination condition, a target salt rock self-healing characteristic discrete element simulation result is generated, including: judging whether the increment of the volume strain after the damage interface is healed in the strain evolution result is less than a first preset threshold within the target time step, whether the number of cracks remains unchanged within the target time step, and whether the target unbalanced force is less than a second preset threshold; if the increment of the volume strain is less than the first preset threshold within the target time step, the number of cracks remains unchanged within the target time step, and the target unbalanced force is less than the second preset threshold, then the salt rock self-healing characteristic discrete element simulation result is generated; if the increment of the volume strain is greater than or equal to the first preset threshold within the target time step, the number of cracks does not remain unchanged within the target time step, or the target unbalanced force is greater than or equal to the second preset threshold, then the salt rock self-healing characteristic discrete element simulation continues.

[0091] It should be noted that the self-healing of salt rock damage is a complex process involving many factors such as time, stress, temperature, and chemical potential energy. Limited by current numerical simulation technology, it is difficult to consider all these factors during the research process. Therefore, this application draws on the ideas of phenomenology and focuses on studying the differences in mechanical properties before and after healing. At the same time, from the perspectives of mechanical equilibrium, damage stability, and energy dissipation, the following healing termination conditions suitable for discrete element numerical simulation methods are proposed:

[0092] First, the volume strain does not change significantly within 1e5 time steps, i.e. |ε (t+1) -ε t |≤0.1%;

[0093] Since volume expansion is the result of injury, and the result of healing is the reduction of volume expansion, e.g. Figure 3 As shown in Figure 2, when the damage stress exceeds the expansion strength, the volume expansion will increase under the action of shear stress and tensile stress.

[0094] This process can be measured using the expansion recovery rate Indicates that:

[0095]

[0096] Among them, ε Vol is the volume expansion, ε Vol <0,a 11 、a 12 、a 13 、a 14 are model parameters respectively.

[0097] ε v =ε x +ε y (1.15)

[0098] Among them, ε v is the volume strain, ε x is the radial strain, ε y is the axial strain.

[0099] In PFC2D, the boundary particle method is used to calculate strain. That is:

[0100]

[0101] Among them, d r ,d l ,d t ,d b are the displacements of the right, left, upper and lower boundaries of the specimen, respectively; L and H are the width and height of the specimen, respectively (the center of the specimen is at the origin).

[0102] Although volumetric strain is not equivalent to dilatancy strain, this application uses the trend of volumetric strain as an approximate indicator of dilatancy, considering the difficulty of directly obtaining dilatancy strain in the PFC model. Furthermore, during the healing process of salt rock, crack closure is accompanied by volumetric contraction, a characteristic consistent with dilatancy suppression. Therefore, if the increment is less than 0.1% for 1e5 consecutive time steps, the volumetric deformation is considered stable, and dilatancy can be approximately considered to have terminated.

[0103] Secondly, in the continuous 1×10 5 Within a time step, the number of cracks no longer changes;

[0104] like Figure 4 As shown in the figure, whether it is damage or healing, the most intuitive change is the generation and closure of microcracks, that is, the change in the number of cracks. As the damage progresses, the microcracks inside the specimen go through the stages of initiation, development, and penetration, and the number of cracks increases further, eventually leading to failure. Take the parallel bond model in PFC as an example: when the parallel bond normal force When the parallel bond tensile strength is greater than the contact tensile strength, tensile failure occurs; when the parallel bond tangential force Shear failure occurs when its parallel bond shear strength is exceeded.

[0105] In contrast to the damage process, when previously damaged particles come into contact again and meet a certain healing criterion (Equation (1.17)), the crack can be considered to have closed, that is:

[0106]

[0107] Among them, R c is the particle distance, R h For healing spacing.

[0108] In this application, the contact that is rebonded after fracture may be referred to as rebonded contact. The biggest difference between rebonded contact and general contact regenerated after fracture is that its parallel bonding state (pb_state) is bonded and has parallel bonding force (pb_force). Therefore, rebonded contact can withstand tension and bending moment. The magnitude of the parallel bonding force of rebonded contact is equivalently given according to (1.13).

[0109] Again, the average unbalanced force ratio of the particle system is <1e-4;

[0110] The system's AFR (Average Force Ratio) is an important indicator for measuring whether the model as a whole has achieved quasi-static mechanical equilibrium. In PFC, it is defined as the ratio of the sum of the unbalanced force components on all particles to the sum of the total applied force, expressed as:

[0111]

[0112] Among them, f i is the component of the force for each particle, <v i >=|v x |+|v y |+|v z | is the Manhattan norm, and n is the total number of particles.

[0113] This metric is a reliable measure of the overall convergence of the system. The AFR directly quantifies the imbalance in forces between particles in the system, reflecting the system's current "non-equilibrium" state, consistent with the natural tendency of salt bodies to converge toward static equilibrium during healing.

[0114] Therefore, if Figure 5 As shown, when the increment of volumetric strain is less than the corresponding threshold within the target time step, the number of cracks remains unchanged within the target time step, and the target unbalanced force is less than the corresponding threshold, the embodiment of the present application can write the above three conditions as a healing termination function and solve them using the fish-halt keyword until all conditions are met and the healing is terminated; when one of the above three conditions is not met, the discrete element simulation of the self-healing characteristics of salt rock continues, so that the present application can completely reproduce the full-cycle mechanical evolution process of "initiation-development-through-closure" of salt rock cracks, effectively make up for the defects of existing continuous and traditional discrete methods in "self-healing mechanism simulation", and can accurately capture the mechanical stability state of the salt rock self-healing process, thereby improving the physical authenticity and engineering application reliability of the simulation results.

[0115] According to the discrete element simulation method of the self-healing characteristics of salt rock proposed in the embodiment of the present application, based on the pre-constructed healing initiation criterion of the target salt rock, when it is detected that the particles at the damaged interface of the target salt rock meet the healing conditions, the broken contact between the particles can be reconstructed as a re-bonded contact to give the particles a new parallel bonding force, thereby determining the equivalent healing stress after the damaged interface is healed, and then quantifying the strain evolution of the volume before and after the healing of the damaged interface, and when it is detected that the strain evolution result meets the healing termination condition, the discrete element simulation result of the self-healing characteristics of the target salt rock is generated, thereby truly reflecting the micromechanical recovery process of the self-healing of the salt rock after damage, and effectively improving the physical authenticity and engineering prediction reliability of the self-healing behavior of the salt rock in the discrete element simulation. Thus, the problem that the discrete element method in the related art cannot re-establish a strong bond after the contact between the particles is broken and cannot truly reflect the micromechanical recovery process of the self-healing of the salt rock after damage is solved.

[0116] Next, a discrete element simulation device for the self-healing characteristics of salt rock proposed in accordance with an embodiment of the present application will be described with reference to the accompanying drawings.

[0117] Figure 6 Schematic diagram of a discrete element simulation device for self-healing characteristics of salt rock according to an embodiment of the present application.

[0118] like Figure 6 As shown, the salt rock self-healing characteristic discrete element simulation device 10 includes: a detection module 100, a determination module 200 and a simulation module 300.

[0119] Specifically, the detection module 100 is used to detect whether the particles at the damaged interface of the target salt rock meet the preset healing conditions based on the pre-constructed healing initiation criterion of the target salt rock.

[0120] The determination module 200 is used to reconstruct the broken contact between the particles into a rebonded contact when it is detected that the preset healing conditions between the particles are met, so as to give the particles new parallel bonding forces, and determine the equivalent healing stress of the damaged interface of the target salt rock after healing based on the new parallel bonding forces between the particles.

[0121] The simulation module 300 is used to quantify the strain evolution of the volume before and after the healing of the damaged interface based on the equivalent healing stress after the healing of the damaged interface to obtain the strain evolution results, and generate discrete element simulation results of the target salt rock self-healing characteristics when it is detected that the strain evolution results meet the preset healing termination conditions.

[0122] Optionally, in one embodiment of the present application, the detection module 100 includes: a construction unit and a detection unit.

[0123] Among them, the construction unit is used to construct the healing initiation criterion of the target salt rock based on the minimum principal stress and von Mises stress.

[0124] The detection unit is used to detect whether the particles at the damaged interface of the target salt rock meet the preset healing conditions based on the target flow potential function in the healing start criterion of the target salt rock.

[0125] Optionally, in one embodiment of the present application, the determination module 200 includes: a calculation unit and a determination unit.

[0126] Among them, the calculation unit is used to calculate the macroscopic stress state of the damaged interface of the target salt rock after healing according to the preset healing equivalent stress formula, and convert the macroscopic stress state into the microscopic contact force between the particles of the damaged interface.

[0127] A unit is determined for determining the new parallel bonding force between particles by using the microscopic contact force, so as to determine the equivalent healing stress of the damaged interface of the target salt rock after healing based on the new parallel bonding force between particles.

[0128] Optionally, in one embodiment of the present application, the simulation module 300 includes: a judgment unit, a first processing unit and a second processing unit.

[0129] Among them, the judgment unit is used to judge whether the increment of the volume strain after the damage interface heals in the strain evolution result is less than a first preset threshold within the target time step, whether the number of cracks remains unchanged within the target time step, and whether the target unbalanced force is less than a second preset threshold.

[0130] The first processing unit is used to generate a discrete element simulation result of the self-healing characteristics of salt rock if the increment of the volume strain is less than a first preset threshold within a target time step, the number of cracks remains unchanged within the target time step, and the target unbalanced force is less than a second preset threshold.

[0131] The second processing unit is used to continue the discrete element simulation of the self-healing characteristics of salt rock if the increment of volume strain is greater than or equal to the first preset threshold within the target time step, the number of cracks does not remain unchanged within the target time step, or the target unbalanced force is greater than or equal to the second preset threshold.

[0132] Optionally, in one embodiment of the present application, the healing initiation criterion of the target salt rock is expressed as:

[0133]

[0134] Among them, F h is the target flow potential function, σ3 is the minimum principal stress, a6, a5 are model parameters, σ v is the von Mises stress.

[0135] Optionally, in one embodiment of the present application, the target healing equivalent stress formula is expressed as:

[0136]

[0137] Among them, I1 is the first stress invariant, x 10 is the equivalent healing parameter, and σ1 is the maximum principal stress.

[0138] It should be noted that the above explanation of the embodiment of the discrete element simulation method for salt rock self-healing characteristics is also applicable to the discrete element simulation device for salt rock self-healing characteristics of this embodiment, and will not be repeated here.

[0139] According to the discrete element simulation device for the self-healing characteristics of salt rock proposed in the embodiment of the present application, based on the pre-constructed healing initiation criteria of the target salt rock, when it is detected that the particles at the damaged interface of the target salt rock meet the healing conditions, the broken contact between the particles can be reconstructed as a rebonded contact to give the particles a new parallel bonding force, thereby determining the equivalent healing stress after the damaged interface is healed, and then quantifying the strain evolution of the volume before and after the healing of the damaged interface, and when it is detected that the strain evolution result meets the healing termination conditions, the discrete element simulation result of the self-healing characteristics of the target salt rock is generated, thereby truly reflecting the micromechanical recovery process of the self-healing of the salt rock after damage, and effectively improving the physical authenticity and engineering prediction reliability of the self-healing behavior of the salt rock in the discrete element simulation. Thus, the problem that the discrete element method in the related art cannot re-establish a strong bond after the contact between the particles is broken and cannot truly reflect the micromechanical recovery process of the self-healing of the salt rock after damage is solved.

[0140] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0141] Memory 701 , processor 702 , and computer programs stored in the memory 701 and executable on the processor 702 .

[0142] When the processor 702 executes the program, the discrete element simulation method for the self-healing characteristics of salt rock provided in the above embodiment is implemented.

[0143] Furthermore, the electronic device further includes:

[0144] The communication interface 703 is used for communication between the memory 701 and the processor 702 .

[0145] The memory 701 is used to store computer programs that can be run on the processor 702 .

[0146] The memory 701 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0147] If the memory 701, processor 702, and communication interface 703 are implemented independently, the communication interface 703, memory 701, and processor 702 can be connected to each other via a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. Buses can be divided into address buses, data buses, control buses, etc. For ease of representation, 7 Figure 7 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0148] Optionally, in a specific implementation, if the memory 701, the processor 702 and the communication interface 703 are integrated on a chip, the memory 701, the processor 702 and the communication interface 703 can communicate with each other through an internal interface.

[0149] The processor 702 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0150] This embodiment also provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the discrete element simulation method for the self-healing characteristics of salt rock as described above is implemented.

[0151] This embodiment also provides a computer program product, including a computer program. When the computer program is executed, it is used to implement the above discrete element simulation method for salt rock self-healing characteristics.

[0152] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0153] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0154] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing a custom logical function or process step, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed in a different order than shown or discussed, including performing functions in a substantially simultaneous manner or in a reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application pertain.

[0155] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or N wires (electronic devices), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program can be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing it in other suitable ways as necessary, and then storing it in a computer memory.

[0156] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiment, the N steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, it can be implemented using any one or a combination of the following technologies known in the art: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0157] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0158] In addition, the functional units in the various embodiments of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into a module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0159] The storage medium mentioned above may be a read-only memory, a magnetic disk, or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application. Persons skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.< / x>

Claims

1. A discrete element simulation method for salt rock self-healing characteristics, characterized by: The following steps are involved: Based on the pre-established healing initiation criterion of the target salt rock, detecting whether the particles at the damaged interface of the target salt rock meet the preset healing conditions; When it is detected that the preset healing condition is satisfied between the particles, the broken contact between the particles is reconstructed into a rebonded contact to impart a new parallel bonding force between the particles, and based on the new parallel bonding force between the particles, an equivalent healing stress after the damaged interface of the target salt rock is healed is determined; Based on the equivalent healing stress after the damage interface is healed, the strain evolution of the volume of the damage interface before and after healing is quantified to obtain the strain evolution result. When it is detected that the strain evolution result meets the preset healing termination condition, the discrete element simulation result of the self-healing characteristics of the target salt rock is generated.

2. The method according to claim 1, characterized in that The healing initiation criterion of the target salt rock constructed in advance is used to detect whether the particles at the damaged interface of the target salt rock meet the preset healing conditions, including: Based on the minimum principal stress and von Mises stress, a healing initiation criterion of the target salt rock is constructed; Based on the target flow potential function in the healing initiation criterion of the target salt rock, it is detected whether the particles at the damaged interface of the target salt rock meet the preset healing condition.

3. The method according to claim 1, characterized in that The determining of the equivalent healing stress of the damaged interface of the target salt rock after healing based on the new parallel bonding force between the particles includes: Calculating the macroscopic stress state of the damaged interface of the target salt rock after healing according to a preset healing equivalent stress formula, and converting the macroscopic stress state into the microscopic contact force between particles of the damaged interface; The new parallel bonding force between the particles is determined by using the microscopic contact force, so as to determine the equivalent healing stress of the damaged interface of the target salt rock after healing based on the new parallel bonding force between the particles.

4. The method according to claim 1, wherein When it is detected that the strain evolution result satisfies a preset healing termination condition, generating a discrete element simulation result of the target salt rock self-healing characteristic includes: Determining whether an increment of the volumetric strain after the damaged interface heals in the strain evolution result is less than a first preset threshold within a target time step, whether the number of cracks remains unchanged within the target time step, and whether a target unbalanced force is less than a second preset threshold; If the increment of the volumetric strain is less than the first preset threshold within the target time step, the number of the cracks remains unchanged within the target time step, and the target unbalanced force is less than the second preset threshold, then generating the discrete element simulation result of the salt rock self-healing characteristics; If the increment of the volumetric strain is greater than or equal to the first preset threshold within the target time step, the number of cracks does not remain unchanged within the target time step, or the target unbalanced force is greater than or equal to the second preset threshold, the discrete element simulation of the salt rock self-healing characteristics continues.

5. The method according to claim 2, characterized in that The healing initiation criterion of the target salt rock is expressed as: Among them, F h is the target flow potential function, σ3 is the minimum principal stress, a6, a5 are model parameters, σ v is the von Mises stress.

6. The method according to claim 3, characterized in that The target healing equivalent stress formula is expressed as: Among them, I1 is the first stress invariant, x 10 is the equivalent healing parameter, and σ1 is the maximum principal stress.

7. A discrete element simulation device for salt rock self-healing characteristics, characterized in that: include: A detection module is used to detect whether the particles at the damaged interface of the target salt rock meet the preset healing conditions based on the pre-established healing initiation criterion of the target salt rock; a determination module configured to, upon detecting that the preset healing condition is satisfied between the particles, reconstruct the fractured contact between the particles into a rebonded contact to impart new parallel bonding forces between the particles, and determine, based on the new parallel bonding forces between the particles, an equivalent healing stress after the damaged interface of the target salt rock is healed; A simulation module is used to quantify the strain evolution of the volume of the damaged interface before and after healing based on the equivalent healing stress after the damaged interface is healed to obtain a strain evolution result, and generate a discrete element simulation result of the self-healing characteristics of the target salt rock when it is detected that the strain evolution result meets a preset healing termination condition.

8. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the discrete element simulation method for the self-healing characteristics of salt rock according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the discrete element simulation method for the self-healing characteristics of salt rock according to any one of claims 1 to 6.

10. A computer program product comprising a computer program, characterized in that The computer program is executed by a processor to implement the discrete element simulation method for salt rock self-healing characteristics as described in any one of claims 1 to 6.

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