Numerical simulation method and system based on rock mass fracture extension and seepage coupling

Abstract

The invention provides a numerical simulation method and system based on rock mass fracture extension and seepage coupling, and belongs to the field of rock mechanics. Rock is regarded as a set composed of particles and mechanical contact between the particles, and a triangulation network is constructed based on the circle center of each particle; according to the geometrical characteristics of the triangulation network, a seepage pipeline network containing the interior and the periphery is built, and network nodes and boundary nodes are determined; calculating the permeability coefficient according to the particle positions on the two sides of the pipeline, and forming a penetrating seepage channel and fracture network by taking the pipeline which is not 0 and penetrates through and is connected with boundary nodes as a passage pipeline; and constructing a flow conservation equation set based on network nodes, solving pore pressure by using a Jacobian iteration method, calculating fracture pressure, and applying the fracture pressure to the model to realize coupling of a stress field and a seepage field. According to the method, the advantages of particle discrete elements in calculation of rock mass fracture extension and the advantages of a pipeline network method in calculation of fracture seepage are fully exerted, and accurate simulation of rock mass fracture initiation extension, seepage channel recognition and seepage field calculation is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of rock mechanics, and in particular to a numerical simulation method and system based on coupling of rock mass fracture expansion and seepage. Background Art

[0002] Rock mass crack expansion, crack seepage and their coupling problems are widely present in the fields of water conservancy and hydropower engineering, slope engineering, tunnel engineering, mining engineering and underground energy storage engineering. The existing numerical simulation methods have some shortcomings in describing the coupling problems of rock mass crack expansion and seepage, which are reflected in: on the one hand, it is difficult to dynamically and accurately identify the seepage channel during the expansion of rock mass cracks; on the other hand, in the process of simulating the crack expansion driven by fluid pressure, it is impossible to accurately present its actual situation. These shortcomings seriously affect the accurate analysis and effective solution of related engineering problems. Summary of the invention

[0003] In order to solve the above problems, the present invention proposes a numerical simulation method and system based on the coupling of rock crack expansion and seepage, which gives full play to the advantages of particle discrete element method (DEM) in calculating rock crack expansion and pipeline network method (PNM) in calculating crack seepage, realizes the functions of rock crack expansion process simulation, dynamic identification of seepage channels, seepage field calculation and fluid pressure driven crack expansion, and realizes accurate simulation of rock crack initiation and expansion, seepage channel identification and seepage field calculation.

[0004] In order to achieve the above object, the present invention adopts the following technical solution: In a first aspect, the present invention provides a numerical simulation method based on the coupling of rock mass fracture expansion and seepage, comprising: Rock is considered as a collection of particles and their mutual mechanical contacts, and a Delaunay triangulation is constructed based on the center of each particle. According to the geometric features of triangles in the Delaunay triangulation network, a pipeline network including seepage pipelines inside the model and seepage pipelines outside the model is established; the endpoints of the seepage pipelines inside the model are pipeline network nodes, and the endpoints extending from the seepage pipelines outside the model are pipeline network boundary nodes; According to the relative positions of particles on both sides of the seepage pipe, the pipe permeability coefficient is calculated; The seepage pipe with a non-zero permeability coefficient is regarded as a passage pipe. If the passage pipe is connected and connected to the boundary nodes of the pipe network, a through-seepage channel is formed. The fracture network is obtained based on the through-seepage channel. The pipeline network nodes in the fracture network are obtained to construct the flow conservation equations, and the Jacobi iteration method is used to solve the node pore pressure; The fracture pressure is calculated based on the average pore pressure of two pipeline network nodes, and the fracture pressure is applied to the fracture network to achieve stress field-seepage field coupling.

[0005] Preferably, according to the geometric features of triangles in the Delaunay triangulation, a pipeline network including seepage pipelines inside the model and seepage pipelines outside the model is established; specifically, the method includes: connecting the centroids of any two adjacent triangles inside the Delaunay triangulation to form a seepage pipeline inside the model; and connecting the centroids of the triangles and the midpoints of the boundary edges at the outer boundary of the Delaunay triangulation, and extending the same distance in this direction to form a seepage pipeline outside the model.

[0006] Preferably, the calculation of the pipeline permeability coefficient according to the relative positions of particles on both sides of the seepage pipeline specifically includes: Assume that the pipe permeability coefficient and its corresponding particle spacing satisfy the cubic law; ; in, is the pipeline permeability coefficient; is the correction factor; is the particle spacing, are the distances between two particles in the x and y directions respectively; is the acceleration due to gravity; is the kinematic viscosity of the fluid.

[0007] Preferably, in the entire pipeline network system, all the seepage pipelines directly connected to the pipelines determined to be passage pipelines are passage pipelines, and then it is determined that the passage pipelines are connected.

[0008] Preferably, there is fissure seepage in the through seepage channel, which is used to dynamically identify the rock seepage channel based on the distribution characteristics of the fissures.

[0009] Preferably, the step of acquiring pipeline network nodes in the fracture network to construct a flow conservation equation group and using Jacobi iteration method to solve the node pore pressure specifically includes: According to the law of flow conservation, the flow conservation equation is constructed for the pipeline network nodes in the fracture network; All flow conservation equations in the fracture network are combined to form a flow conservation equation group; Based on the flow conservation equations, the relationship between the pore pressure of the pipeline network node and the pore pressure of the three connected nodes is obtained, and the Jacobi iteration method is used to solve the pore pressure: ; in, is the node hole pressure, For the The particle spacing corresponding to the pipeline connected to the node is For the The pore pressure of the nodes connected to this node; For the The length of the pipe connected to the node.

[0010] Preferably, the method calculates the fracture pressure based on the average pore pressure of two pipeline network nodes, applies the fracture pressure to the fracture network, calculates the fracture expansion process, and updates the particle displacement and permeability coefficient to realize the stress field-seepage field coupling; specifically includes: The fracture pressure is applied to the pipe length of the discrete element model of the particle on average, and the fracture expansion process driven by the fracture fluid pressure is numerically calculated to achieve the fracture expansion simulation under the action of fluid pressure, that is, the coupling of flow field to force field. Based on the fracture extension simulation results and particle displacement, the pipeline permeability coefficient is calculated and updated to simulate the process of fracture extension, that is, the coupling of the force field to the flow field.

[0011] In a second aspect, the present invention provides a numerical simulation system based on rock mass fracture expansion and seepage coupling, comprising: The particle modeling module is configured to regard the rock as a collection of particles and their mechanical contacts, and to construct a Delaunay triangulation based on the center of each particle; The pipeline network modeling module is configured to establish a pipeline network including internal seepage pipelines and external seepage pipelines of the model according to the geometric characteristics of triangles in the Delaunay triangulation network; the endpoints of the internal seepage pipelines of the model are pipeline network nodes, and the endpoints extending from the external seepage pipelines of the model are pipeline network boundary nodes; A permeability coefficient calculation module is configured to calculate the pipeline permeability coefficient according to the relative positions of particles on both sides of the seepage pipeline; The fracture network establishment module is configured to use the seepage pipeline with a pipeline permeability coefficient not being 0 as a passage pipeline, and if the passage pipeline is connected and connected to the boundary node of the pipeline network, a through-seepage channel is formed; and a fracture network is obtained based on the through-seepage channel; The pore pressure calculation module is configured to obtain the pipeline network nodes in the fracture network to construct the flow conservation equations and solve the node pore pressure using the Jacobi iteration method; The coupling simulation module is configured to calculate the fracture pressure based on the average pore pressure of two pipeline network nodes, apply the fracture pressure to the fracture network, and realize the stress field-seepage field coupling.

[0012] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of a numerical simulation method based on coupling of rock fracture extension and seepage as described in the first aspect.

[0013] Fourthly, the present invention provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps in a numerical simulation method based on the coupling of rock mass fracture propagation and seepage described in the first aspect are implemented.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention regards the rock as a collection of particle models and contacts, constructs a Delaunay triangular mesh based on the centers of particle nodes, and then establishes a seepage pipeline network, accurately calculates the pipeline permeability coefficient, and finds out the through seepage channels to form a fracture network. Among them, the pipeline network is reasonably constructed according to the characteristics of triangles in the Delaunay triangular mesh, the permeability coefficient is calculated considering the positions of particles on both sides of the seepage pipeline, the Jacobi iterative method is used to solve the pore pressure of nodes in the fracture network, and the fracture pressure is calculated and applied through the average pore pressure value to realize the coupling of the stress field and the seepage field. It can dynamically identify the seepage channels, solve the problem that it is difficult for the existing methods to dynamically and accurately identify the seepage channels during the fracture propagation process, and can also accurately present the situation of fluid pressure driving fracture propagation, overcoming the deficiencies of the existing simulation methods in describing the coupling problem, and providing a more accurate and effective analysis tool for engineering such as water conservancy, slope, tunnel, mine, and underground energy storage. It provides a new idea for the seepage-stress coupling simulation during the rock mass fracture propagation process, develops and promotes the numerical simulation technology method in the field of rock mechanics, and can be used in fields such as the sealing analysis of underground crude oil storage and underground gas storage, the stability analysis of fractured rock mass slopes under rainfall infiltration conditions, the stability analysis and water inrush calculation of rock tunnels.

[0015] The advantages of the additional aspects of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute a limitation to the present invention.

[0017] Figure 1 It is the main flowchart of a numerical simulation method based on the coupling of rock mass fracture propagation and seepage provided by an embodiment of the present invention; Figure 2 It is the schematic flowchart of a numerical simulation method based on the coupling of rock mass fracture propagation and seepage provided by an embodiment of the present invention; Figure 3 It is the schematic diagram of the unified geometric model of the particle model and the pipeline network model provided by an embodiment of the present invention; Figure 4 It is the schematic diagram of the calculation of the pipeline permeability coefficient provided by an embodiment of the present invention; Figure 5 Schematic diagram of mechanical failure provided by the embodiment of the present invention; among them, (a) is the fissure distribution map after rock failure; (b) is the radial displacement map of particles after rock failure. Figure 6 Seepage situation after rock failure provided by the embodiment of the present invention; among them, (a) is the water head distribution map after rock failure; (b) is the flow velocity distribution map after rock failure. Specific implementation manners

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] Considering that in the numerical simulation study of rock mass fissure expansion, the simulation of the rock mass fissure expansion process is the basis. Because the expansion of fissures will change the structure of the rock mass, and then affect the formation and change of seepage channels, it is closely related to the dynamic identification of seepage channels. The dynamic identification of seepage channels provides key structural information for the calculation of the seepage field. Only by accurately identifying the seepage channels can an effective seepage field calculation be carried out. And the fluid pressure-driven fissure expansion reflects the effect of the seepage field (fluid pressure is an important parameter of the seepage field) on the fissure expansion, that is, the change of the seepage field will cause the change of the fluid pressure, and then drive the further expansion of the fissures.

[0020] It can be seen that in actual rock mass engineering, the expansion of fissures will change the permeability of the rock mass, thus affecting seepage; and the fluid pressure generated by seepage will in turn affect the expansion of fissures. The two interact and influence each other, forming a coupling relationship. The numerical simulation method provided by the present invention aims to accurately simulate this coupling process, that is, to simultaneously consider the mutual influence of fissure expansion and seepage, so as to more realistically reflect the mechanical and hydraulic characteristics of the rock mass in actual engineering.

[0021] Embodiment 1 As Figure 1 shown, this embodiment discloses a numerical simulation method based on the coupling of rock mass fissure expansion and seepage, including the following steps: S1: Regarding the rock as a set composed of particles and their mechanical contacts with each other, constructing a Delaunay triangulation based on the centers of each particle; S2: According to the geometric characteristics of the triangles in the Delaunay triangulation, establishing a pipeline network including internal seepage pipelines and external seepage pipelines of the model; the endpoints of the internal seepage pipelines of the model are the pipeline network nodes, and the endpoints extended from the external seepage pipelines of the model are the pipeline network boundary nodes; S3: Calculating the pipeline permeability according to the relative positions of the particles on both sides of the seepage pipeline; S4: Consider the seepage pipes with a non-zero pipe permeability as passage pipes. When the passage pipes are connected and linked to the boundary nodes of the pipe network, a connected seepage channel is formed. Based on the connected seepage channel, a fracture network is obtained. S5: Obtain the pipe network nodes in the fracture network to construct a flow conservation equation set, and use the Jacobi iterative method to solve the pore pressure at the nodes. S6: Calculate the fracture pressure based on the average pore pressure of two pipe network nodes, and apply the fracture pressure to the fracture network to achieve the coupling of the stress field and the seepage field.

[0022] Next, in combination with Figure 2 , a numerical simulation method based on the coupling of rock mass fracture propagation and seepage disclosed in this embodiment will be described in detail.

[0023] In S1, preferably, this embodiment is developed based on the development environment of the particle discrete element (DEM) commercial software PFC 2D . As Figure 3 shown, the rock mass is regarded as a collection composed of particles and their mechanical contacts with each other. Taking the centers of the particle circles (spheres) of the particle model as nodes, a Delaunay triangulation is constructed using the point-by-point insertion method.

[0024] It should be understood that those skilled in the art can choose other software for development according to needs.

[0025] The Delaunay triangulation is a collection of a series of connected but non-overlapping triangles, and the circumcircles of these triangles do not contain any other points in this plane region. The subsequent seepage pipe network constructed based on this triangulation can accurately track the changes in the internal structure of the rock mass and provide an accurate geometric framework for dynamically identifying seepage channels.

[0026] In S2, a pipe network model is constructed. For the common edges inside the triangulation, connect the centroids of two adjacent triangles to construct seepage pipes to describe the potential seepage existing between the particles at both ends of the common edge. For the boundaries outside the triangulation, connect the centroid of the triangle where it is located and the midpoint of the edge, and extend the same distance in this direction to form seepage pipes to describe the potential seepage existing between the particles at both ends of the edge. The extended endpoints of the seepage pipes are the boundaries of the pipe network, used to apply pore pressure boundary conditions. Establish a geometric model that unifies the particle model and the pipe network model.

[0027] In this embodiment, a pipe network model is constructed based on the Delaunay triangulation. By connecting the centroids of adjacent triangles to form internal seepage pipes and constructing extended seepage pipes outside the triangulation, the potential seepage paths inside and at the boundary of the rock mass are comprehensively covered.

[0028] This construction method establishes the connection between the pipe permeability coefficient and the particle displacement. When the rock mass fracture expands and causes particle displacement, the pipe permeability coefficient can be updated synchronously.

[0029] For example, the generation of new fractures will cause large displacements of the particles on both sides of the fractures, increasing the corresponding pipe seepage coefficient and then forming new passage pipes. At the same time, the clear pipe network nodes and boundary nodes provide a clear structure for subsequent application of boundary conditions and flow calculation, enabling the accurate capture of the formation and evolution process of seepage channels during the simulation process, and effectively solving the problem that it is difficult for traditional methods to dynamically track the changes of seepage channels.

[0030] In S3, it is defined that the permeability coefficient of the pipe is determined by the distance between the particles on both sides, and a quantitative relationship between the particle position (displacement) characteristics and the pipe permeability coefficient is established, such as Figure 4 shown. It is assumed that the pipe permeability coefficient and its corresponding particle spacing satisfy the cubic law:

[0031] In the formula, is the pipe permeability coefficient; is the correction coefficient; is the particle spacing, are the spacings of the two particles in the x and y directions respectively; is the acceleration of gravity; is the kinematic viscosity coefficient of the fluid.

[0032] Traditional methods usually adopt a fixed permeability coefficient and cannot reflect the dynamic changes of seepage characteristics during the stress and deformation process of the rock mass. In this embodiment, a quantitative relationship between the particle position (displacement) characteristics and the pipe permeability coefficient is established. When the rock mass is stressed and causes the particle spacing to change, the permeability coefficient will be dynamically adjusted accordingly. Since the change of the permeability coefficient directly affects the flow resistance and flow distribution of the fluid, this dynamic adjustment mechanism enables more accurate simulation of the fluid flow in the rock mass when simulating the fracture expansion driven by fluid pressure.

[0033] In S4, search for the pipes with non-zero permeability coefficients in the pipe network, which are the passage pipes. When the passage pipes are connected and connected to the boundary nodes of the pipe network, a through-flow seepage channel is formed, generating fracture seepage, and realizing the dynamic identification of the rock mass seepage channel based on the fracture distribution characteristics. The dynamic identification refers to identifying the change process of the fractures and obtaining the fracture network.

[0034] This embodiment achieves dynamic and accurate identification of rock seepage channels by screening the passage pipes based on the pipe permeability coefficient and determining the through seepage channels and fracture networks. Since the pipe permeability coefficient is dynamically related to the relative position of the particles, when the rock fractures expand or close, the permeability coefficient will change accordingly, resulting in changes in the distribution and connectivity of the passage pipes. This dynamic identification method based on actual physical processes can accurately capture the formation and evolution of seepage channels in rock mass under different stress stages and deformation states. Compared with traditional methods, it can more realistically reflect the fracture development and seepage laws inside the rock mass, provide an accurate model basis for subsequent simulation of fluid pressure-driven fracture expansion, and avoid simulation errors caused by the inability to accurately identify seepage channels.

[0035] In S5, for each non-boundary node in the fracture network, there are three pipes converging at this point. Based on the law of flow conservation (i.e., the outflow of water from this node is equal to the inflow), the flow conservation equation for this point is established, and its unknown quantity is the pore pressure of this node and the adjacent nodes connected to this node. The equations of each node on the seepage channel are combined to form a system of equations with the node pore pressure as the unknown quantity.

[0036] According to the law of conservation of flow, the relationship between the pore pressure of each non-boundary node and the pore pressure of the three connected nodes is shown in Equation 2. Therefore, the Jacobi iteration method is used to solve the pore pressure equations, and the calculation error is taken as .

[0037]

[0038] In the formula, is the node hole pressure, For the The particle spacing corresponding to the pipeline connected to the node is For the The pore pressure of the nodes connected to this node; For the The length of the pipe connected to the node.

[0039] This embodiment constructs a group of flow conservation equations based on the pipeline network nodes in the fracture network, fully considering the flow relationship between each node in the fracture network, and ensuring the accuracy of the pore pressure calculation; and the Jacobi iteration method has the characteristics of fast convergence speed and good calculation stability, and can obtain high-precision node pore pressure solutions in a short time. Accurate pore pressure calculation results provide key data for subsequent calculation of fracture pressure and simulation of stress field-seepage field coupling, so that the simulation process can more realistically reflect the distribution and transmission of fluid pressure in the rock mass, thereby more accurately simulating the actual process of fluid pressure driving fracture expansion.

[0040] In S6, the fracture pressure is calculated based on the average pore pressure of two pipeline network nodes, the fracture pressure is applied to the fracture network, the fracture propagation process is calculated, and the particle displacement and permeability coefficient are updated to achieve the coupling of the stress field and the seepage field. Specifically, it includes: For each pipeline, the average value of the pore pressures at its two nodes is taken to calculate the fracture pressure, which is evenly applied to the particle model along the pipeline length to promote fracture propagation. Numerically calculate the process of fracture propagation driven by the fracture fluid pressure to achieve the simulation of fracture propagation under the action of fluid pressure, that is, the coupling of the flow field to the force field; Based on the fracture propagation simulation results and the particle displacement, calculate and update the pipeline permeability coefficient to achieve the simulation of the change of the pipeline permeability coefficient during the fracture propagation process, that is, the coupling of the force field to the flow field.

[0041] In this embodiment, the fracture pressure is obtained by calculating the average pore pressure of two pipeline network nodes and applied to the particle discrete element model where the pipeline is located, simulating the process of fracture propagation driven by fluid pressure and considering the action of the flow field on the force field. At the same time, based on the fracture propagation simulation results, the particle displacement and permeability coefficient are updated to achieve the feedback of the force field on the flow field. This two-way coupling mechanism enables the simulation process to comprehensively consider the interaction relationship between rock mass fracture propagation and seepage. Through this dynamic coupling process, the mechanical behavior of the rock mass under complex stress and seepage conditions can be more accurately simulated.

[0042] The rock mass fracture propagation and seepage coupling simulation method (DEM-PMM) formed in this embodiment is a cyclic dynamic simulation process. During the calculation process, as Figure 2 shown, steps S2 - S6 are executed cyclically, and by continuously updating the model parameters, identifying the seepage channels, calculating the pore pressure, and realizing the coupling of the fields, the accurate simulation of the rock mass fracture propagation and seepage coupling process is achieved.

[0043] To verify the effect of this embodiment, as Figure 5 、 6 shown, these experimental results are all obtained based on the numerical simulation method (DEM - PMM) of rock mass fracture propagation and seepage coupling proposed in this embodiment. By using this method, as Figure 5 shown in a, the internal fracture distribution of the rock after the triaxial compression test of the rock under the confining pressure of 2 MPa is successfully simulated, accurately presenting that the rock forms through-going fractures after failure and mainly shows tensile-shear failure. As Figure 5 shown in b, the particle displacement on both sides of the main fracture of the rock develops away from the fracture after the rock failure, resulting in the phenomenon of an increase in the fracture width.

[0044] As Figure 6As shown in Figure a, it is the head distribution during the rock seepage process with a 30m water head difference after the failure of the rock triaxial compression test under a confining pressure of 2MPa. That is, in terms of seepage simulation, it accurately shows that the rock seepage mainly occurs along the through-going fractures, forming a seepage channel. Figure 6 Figure b shows the velocity distribution. The through-going fractures formed after the rock failure form the main seepage channels, and the greater the width of the fractures, the greater the velocity, which reflects the relationship between the fracture width and the velocity.

[0045] These simulation results are consistent with the existing research, fully verifying the accuracy and reliability of the method proposed in this embodiment in simulating the coupling process of rock mass fracture propagation and seepage. It can not only effectively capture the mechanical behavior and seepage characteristics of rock mass under complex stress and seepage conditions, but also has significant advantages over traditional simulation methods in dynamically identifying seepage channels and accurately presenting fluid pressure-driven fracture propagation, providing a more scientific and effective means for the analysis of rock mass fracture problems in related engineering fields.

[0046] This specific embodiment forms a closed-loop interaction relationship among functions such as simulating the rock mass fracture propagation process, dynamically identifying seepage channels, calculating the seepage field, and fluid pressure-driven fracture propagation, jointly constituting a comprehensive simulation of the coupling problem of rock mass fracture propagation and seepage. By breaking through traditional limitations, it accurately captures the coupling process of rock mass fracture propagation and seepage. Through the careful construction of the seepage pipeline network, it realizes the dynamic and accurate identification of seepage channels, making up for the deficiencies of existing methods in this regard. When simulating fluid pressure-driven fracture propagation, based on the accurately calculated pore pressure and fracture pressure, it truly restores the actual situation. This method greatly improves the accuracy and reliability of the simulation, provides a scientific basis for engineering fields such as water conservancy and hydropower, mines, etc. in analyzing rock mass fracture-related problems, helps to optimize engineering designs, reduce construction risks, and ensure the safe and stable operation of projects.

[0047] Embodiment 2 This embodiment provides a numerical simulation system based on the coupling of rock mass fracture propagation and seepage, including: A particle model modeling module, configured to regard the rock as a collection composed of particles and their mechanical contacts, and construct a Delaunay triangulation based on the centers of each particle; A pipeline network modeling module, configured to establish a pipeline network including internal seepage pipelines and external seepage pipelines of the model according to the geometric characteristics of triangles in the Delaunay triangulation; the endpoints of the internal seepage pipelines of the model are pipeline network nodes, and the endpoints extended from the external seepage pipelines of the model are pipeline network boundary nodes; A permeability coefficient calculation module, configured to calculate the pipeline permeability coefficient according to the relative positions of particles on both sides of the seepage pipeline; The fracture network establishment module is configured to use the seepage pipes with non-zero pipe permeability as passage pipes. When the passage pipes are connected and connected to the boundary nodes of the pipe network, a through-flow seepage channel is formed; a fracture network is obtained based on the through-flow seepage channel; The pore pressure calculation module is configured to obtain the pipe network nodes in the fracture network to construct a flow conservation equation set, and use the Jacobi iterative method to solve the node pore pressure; The coupled simulation module is configured to calculate the fracture pressure based on the average pore pressure of two pipe network nodes, apply the fracture pressure to the fracture network, and realize the coupling of the stress field and the seepage field.

[0048] Embodiment III This embodiment provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, it implements the steps in a numerical simulation method based on the coupling of rock mass fracture propagation and seepage as described in Embodiment I above.

[0049] Embodiment IV This embodiment provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the steps in a numerical simulation method based on the coupling of rock mass fracture propagation and seepage as described in Embodiment I above.

[0050] The steps or modules involved in Embodiments II to IV above correspond to those in Embodiment I. For the specific implementation manners, reference may be made to the relevant description part of Embodiment I. The term "computer-readable storage medium" should be understood to include a single medium or multiple media including one or more instruction sets; it should also be understood to include any medium that can store, encode, or carry an instruction set for execution by a processor and enable the processor to execute any method in the present invention.

[0051] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A numerical simulation method based on the coupling of rock mass fracture expansion and seepage, characterized in that: include: Rock is considered as a collection of particles and their mutual mechanical contacts, and a Delaunay triangulation is constructed based on the center of each particle. According to the geometric features of triangles in the Delaunay triangulation network, a pipeline network including seepage pipelines inside the model and seepage pipelines outside the model is established; the endpoints of the seepage pipelines inside the model are pipeline network nodes, and the endpoints extending from the seepage pipelines outside the model are pipeline network boundary nodes; According to the relative positions of particles on both sides of the seepage pipe, the pipe permeability coefficient is calculated; The seepage pipe with a non-zero permeability coefficient is regarded as a passage pipe. If the passage pipe is connected and connected to the boundary nodes of the pipe network, a through-seepage channel is formed. The fracture network is obtained based on the through-seepage channel. The pipeline network nodes in the fracture network are obtained to construct the flow conservation equations, and the Jacobi iteration method is used to solve the node pore pressure; The fracture pressure is calculated based on the average pore pressure of two pipeline network nodes, and the fracture pressure is applied to the fracture network to achieve stress field-seepage field coupling.

2. A numerical simulation method based on rock mass fracture expansion and seepage coupling according to claim 1, characterized in that: The method establishes a pipeline network including an internal seepage pipeline of the model and an external seepage pipeline of the model according to the geometric characteristics of the triangles in the Delaunay triangulation network. Specifically, the method comprises: connecting the centroids of any two adjacent triangles inside the Delaunay triangulation network to form an internal seepage pipeline of the model; and connecting the centroids of the triangles and the midpoints of the boundary edges at the outer boundary of the Delaunay triangulation network, and extending the same distance in this direction to form an external seepage pipeline of the model.

3. A numerical simulation method based on rock mass fracture expansion and seepage coupling according to claim 1, characterized in that: The calculation of the pipeline permeability coefficient according to the relative positions of particles on both sides of the seepage pipeline specifically includes: Assume that the pipe permeability coefficient and its corresponding particle spacing satisfy the cubic law; ； in, is the pipeline permeability coefficient; is the correction factor; is the particle spacing, are the distances between two particles in the x and y directions respectively; is the acceleration due to gravity; is the kinematic viscosity of the fluid.

4. A numerical simulation method based on rock mass fracture expansion and seepage coupling according to claim 1, characterized in that: In the entire pipeline network system, if all the seepage pipes directly connected to the passage pipes identified as passage pipes are passage pipes, then the passage pipes are deemed to be connected.

5. The numerical simulation method based on the coupling of rock mass fracture expansion and seepage according to claim 1, characterized in that: The through seepage channel has fracture seepage, which is used to dynamically identify the rock mass seepage channel based on fracture distribution characteristics.

6. A numerical simulation method based on rock mass fracture expansion and seepage coupling according to claim 1, characterized in that: The method of obtaining pipeline network nodes in the fracture network to construct a flow conservation equation group and using the Jacobi iteration method to solve the node pore pressure specifically includes: According to the law of flow conservation, the flow conservation equation is constructed for the pipeline network nodes in the fracture network; All flow conservation equations in the fracture network are combined to form a flow conservation equation group; Based on the flow conservation equations, the relationship between the pore pressure of the pipeline network node and the pore pressure of the three connected nodes is obtained, and the Jacobi iteration method is used to solve the pore pressure: ； in, is the node hole pressure, For the The particle spacing corresponding to the pipeline connected to the node is For the The pore pressure of the nodes connected to this node; For the The length of the pipe connected to the node.

7. A numerical simulation method based on rock mass fracture expansion and seepage coupling according to claim 1, characterized in that: The method calculates the fracture pressure based on the average pore pressure of the two pipeline network nodes, applies the fracture pressure to the fracture network, calculates the fracture expansion process, and updates the particle displacement and permeability coefficient to realize the stress field-seepage field coupling; specifically includes: The fracture pressure is applied to the pipe length of the discrete element model of the particle on average, and the fracture expansion process driven by the fracture fluid pressure is numerically calculated to achieve the fracture expansion simulation under the action of fluid pressure, that is, the coupling of flow field to force field. Based on the fracture extension simulation results and particle displacement, the pipeline permeability coefficient is calculated and updated to simulate the process of fracture extension, that is, the coupling of force field to flow field.

8. A numerical simulation system based on the coupling of rock mass fracture expansion and seepage, characterized in that: include: The particle modeling module is configured to regard the rock as a collection of particles and their mechanical contacts, and construct a Delaunay triangulation based on the center of each particle; The pipeline network modeling module is configured to establish a pipeline network including internal seepage pipelines and external seepage pipelines of the model according to the geometric characteristics of triangles in the Delaunay triangulation network; the endpoints of the internal seepage pipelines of the model are pipeline network nodes, and the endpoints extending from the external seepage pipelines of the model are pipeline network boundary nodes; A permeability coefficient calculation module is configured to calculate the pipeline permeability coefficient according to the relative positions of particles on both sides of the seepage pipeline; The fracture network establishment module is configured to use the seepage pipeline with a pipeline permeability coefficient not being 0 as a passage pipeline, and if the passage pipeline is connected and connected to the boundary node of the pipeline network, a through-seepage channel is formed; and a fracture network is obtained based on the through-seepage channel; The pore pressure calculation module is configured to obtain the pipeline network nodes in the fracture network to construct the flow conservation equations and solve the node pore pressure using the Jacobi iteration method; The coupling simulation module is configured to calculate the fracture pressure based on the average pore pressure of two pipeline network nodes, apply the fracture pressure to the fracture network, and realize the stress field-seepage field coupling.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of a numerical simulation method based on coupling of rock fracture extension and seepage as described in any one of claims 1 to 7 are implemented.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps in the numerical simulation method based on the coupling of rock fracture extension and seepage as described in any one of claims 1 to 7 are implemented.

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