Modeling method of fiber concrete discrete element model

Abstract

The invention belongs to the technical field of discrete element simulation, and relates to a modeling method of a fiber concrete discrete element model, which comprises the following steps: S1, constructing a mortar matrix material model; s2, forming a target put fiber template; s3, putting fibers into the mortar matrix material model according to the target fiber putting template and reaching a preset target value; s4, randomly taking a fiber and calculating a linear equation where a fiber segment is located; s5, further calculating the vertical distance from the mortar particle unit to the fiber line segment; S6, redistributing a group name to the mortar particle unit; s7, traversing each fiber, and redistributing group names to all mortar particle units; and S8, redistributing strength parameters of the contact model to complete model construction. According to the method, the fiber is regarded as a two-dimensional line segment, random generation and quantitative feeding of the fiber in the fiber concrete model are achieved, the reinforcement effect of the fiber is simulated, and accurate characterization of a fiber entity is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of discrete element simulation, and relates to a modeling method of a fiber concrete discrete element model. Background Art

[0002] Fiber-reinforced concrete is a new type of concrete material that uses traditional concrete as its matrix and fibers as its reinforcement. By incorporating fibers into concrete and evenly distributing them throughout the concrete, it can block cracking and bridge force transmission in the tensile zone of the concrete material, reducing stress peaks in the tensile zone, effectively enhancing the integrity of the concrete and the toughness of the matrix, and meeting the high-strength and high-toughness performance requirements of concrete flexural members in actual engineering. Cement-stabilized crushed stone, as a concrete material, has been widely used as a representative semi-rigid material in the base and subbase layers of highways at all levels. To enhance the crack resistance of water-stabilized crushed stone, some researchers have attempted to improve the fatigue cracking resistance of water-stabilized base layers by adding basalt fibers, polypropylene fibers, polyvinyl alcohol fibers, or mixed fibers.

[0003] The evaluation of the mechanical properties of fiber-reinforced concrete currently relies primarily on indoor testing to create specimens with varying fiber dosages and types, and then comprehensively assess their crack resistance and toughening effects by measuring the differences in mechanical properties. However, for a multiphase composite material like fiber-reinforced concrete, its microstructure directly influences its macroscopic mechanical properties. Therefore, in order to understand the mechanism of fiber toughening and provide a foundation for optimizing and improving the crack resistance of fiber-reinforced concrete, it is necessary to analyze its crack resistance and toughening mechanisms from a microscopic perspective.

[0004] However, for concrete materials, due to their diverse types, diverse geometric forms, and complex mechanical environment, conventional testing methods are unable to establish the connection between microstructure and macroscopic mechanical properties, and traditional mechanical theories are also difficult to obtain mathematical analytical solutions. Against this background, with the development of computer simulation technology, micro-scale fracture simulation has become an important means to reveal the cracking mechanism of composite materials.

[0005] Among current numerical simulation methods, the discrete element method (DEM) can effectively solve the problem of large deformation motion in discontinuous systems and has been widely used in revealing the cumulative damage and failure mechanism of micro- and meso-media under complex conditions. For micro-scale research on fiber concrete, the current method mainly uses solid modeling to achieve numerical simulation of fine fibers. For example, patent document CN116644573A discloses a three-dimensional meso-scale simulation method for the crack resistance of fiber concrete based on discrete elements. The simulation method includes: establishing an actual three-dimensional model of the target fiber concrete using various levels of coarse aggregate and fiber; randomly generating fiber particles at different angles in the target space and placing aggregate; using the bond strength between fibers, aggregates, and mortar as input, establishing a bond contact relationship between the particles in the target fiber concrete model to generate fiber concrete specimens; consolidating and loading the fiber concrete specimens to perform initial equilibrium state analysis; applying boundary conditions to the fiber concrete specimens, and measuring the fracture mechanical properties of the fiber concrete by applying external loads through a three-point bending test. However, due to the small size of the fiber phase and the large difference in scale from other phases of concrete materials, it is difficult to achieve accurate characterization of the microfiber body, and thus it is impossible to study the mechanical behavior of fiber concrete at the microscopic scale; in addition, the huge difference in particle size leads to low model operation efficiency and difficulty in converging the operation results. Summary of the Invention

[0006] In view of the technical problem that it is difficult to achieve accurate characterization of fine fiber bodies in existing fiber concrete simulations, the present invention provides a modeling method for a fiber concrete discrete element model.

[0007] The present invention constructs a new virtual modeling method, regards the fiber as a two-dimensional line segment, realizes the random generation and quantitative placement of fibers in the fiber concrete model; and simulates the reinforcement effect of the fiber to achieve accurate characterization of the fiber entity, and studies the crack resistance and toughening mechanism of fiber concrete materials from a microscopic scale.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A modeling method for a fiber concrete discrete element model comprises the following steps:

[0010] S1. Constructing a mortar matrix material model;

[0011] S2. Constructing a fiber geometry template and forming a target delivery fiber template according to the set fiber geometry parameters;

[0012] S3, using a self-identification algorithm, randomly placing fibers in the mortar matrix material model according to the target fiber placement template until the number of fibers placed reaches a preset target value;

[0013] S4. Randomly select a fiber from the mortar matrix material model where the fiber is placed and calculate the equation of the straight line where the fiber segment lies;

[0014] S5. Traverse each mortar particle unit in the mortar matrix material model, read the center coordinate C (x3, y3) of the mortar particle unit, and calculate the vertical distance h from the mortar particle unit to the fiber segment;

[0015] S6. Set the fiber reinforcement width range t of the mortar matrix material model, and reassign the "fiber mortar" group name to the mortar particle units with a vertical distance h≤t;

[0016] S7, traverse each fiber and repeat steps S4 to S6 to complete the reassignment of group names for all mortar particle units;

[0017] S8. Redistribute the adjacent mortar particle units within the "fiber mortar" group name, redistribute the contact model strength parameters, simulate the fiber reinforcement strength, and complete the construction of the fiber concrete discrete element model.

[0018] It is further defined that in step S1, the process of constructing the mortar matrix material model is:

[0019] S1.1. Use discrete element PFC 2D software to establish a coordinate system, define the boundary area, fill the closed boundary area with mortar matrix material, and uniformly assign the "mortar" group name to form a mortar phase particle system;

[0020] S1.2. Then, a contact model between mortar particles is set, and various model parameters of the contact model are set to form a mortar matrix material model.

[0021] It is further defined that in step S1.1, the mortar matrix material is composed of a number of regularly arranged mortar "ball" particles bonded together; the diameter of the mortar "ball" particles is 0.2 mm.

[0022] It is further defined that in step S1.2, the contact model is a parallel bonding contact model;

[0023] The model parameters of the parallel bond contact model include the effective modulus E of the contact bond * , stiffness ratio k * , tensile strength T F and shear strength S F , effective modulus of parallel bonding Stiffness ratio tensile strength and bond strength

[0024] Further defined, the specific process of step S2 is:

[0025] S2.1. Use two-dimensional line segments to represent the geometry of virtual fibers in the mortar matrix material model and define them by length, inclination and center position to form a geometric template of the fibers.

[0026] S2.2. In the fiber geometry template, set the length parameters, inclination parameters, and center position parameters of a single fiber to form the geometry parameters of the fiber, and convert the fiber geometry parameters into a target delivery fiber template.

[0027] It is further defined that in step S2.2, the inclination parameter and the center position parameter are both defined using Gaussian distribution or uniform distribution; the length parameter range is [fsmin, fsmax]; fsmin represents the minimum length value of the target fiber, and fsmax represents the maximum length value of the target fiber.

[0028] Further defined, step S4 specifically includes:

[0029] S4.1. Select a fiber and read the center coordinates O(x0, y0), length L, and inclination angle θ of the fiber;

[0030] S4.2. Calculate the coordinates of the fiber's endpoints A (x1, y1) and B (x2, y2) as follows:

[0031]

[0032]

[0033] S4.3. Based on the coordinates of endpoints A and B, calculate the equation of the line where the fiber segment lies. The expression is as follows:

[0034]

[0035] Where,

[0036] It is further defined that in step S5, the vertical distance h from the mortar particle unit to the fiber segment is calculated as follows:

[0037]

[0038] It is further defined that in step S5, the mortar particle unit center coordinate C is read to meet the following requirements:

[0039]

[0040] It is further defined that in step S6, the reinforcement width range t of the fiber to the mortar matrix material model is 0.1 mm.

[0041] The beneficial effects of the present invention are:

[0042] 1. The present invention discloses a modeling method for a fiber-reinforced concrete discrete element model. This method, through a self-identification algorithm, achieves the quantitative and random placement of microfibers within a mortar matrix material model according to fiber content and target length. This method is automatically controlled and quantitatively controllable, significantly improving modeling efficiency and accuracy. Furthermore, by considering the influence of fiber reinforcement width and direction, the method can more realistically reproduce the fiber reinforcement effect under real conditions, achieving precise characterization of microfiber entities in fiber-reinforced concrete. This provides a highly accurate basic analytical model for exploring the microscopic fracture behavior and reinforcement toughening mechanisms of fiber-reinforced concrete.

[0043] 2. The present invention calculates the vertical distance h from the mortar particle unit to the fiber line segment, and according to the reinforcement width range t of the fiber to the mortar matrix material model, reallocates the mortar particle units with the vertical distance h≤t to the group name of "fiber mortar", and further reallocates the contact model strength parameters of the adjacent mortar particle units within the reallocated "fiber mortar" group name to simulate the reinforcement strength of the fiber. At the same time, it can also realize the characterization of the different influencing widths and directions of the fibers, providing an accurate basic analysis model for further exploring the microscopic fracture behavior and reinforcement toughening mechanism of fiber concrete.

[0044] 3. This invention develops a new virtual modeling method based on the discrete element simulation platform to realize the construction of fiber and concrete models, providing practical verification and technical reference for the research on the micro-model construction of fiber concrete materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Flowchart of the method for constructing discrete element model of fiber reinforced concrete;

[0046] Figure 2 The schematic diagram of the fiber structure is represented by two-dimensional line segments;

[0047] Figure 3 Schematic diagram of the regular arrangement of mortar "balls";

[0048] Figure 4 Schematic diagram of the two-dimensional discrete element model of fiber concrete;

[0049] Figure 5 Schematic diagram of the characterization of the fiber reinforcement width range (0.1 mm);

[0050] Figure 6 Schematic diagram for representing the fiber reinforcement direction. DETAILED DESCRIPTION

[0051] See also Figure 1The present invention provides a modeling method for a fiber concrete discrete element model, comprising the following steps:

[0052] S1. Use discrete element PFC 2D software to construct the mortar matrix material model.

[0053] In step S1 of the present invention, the process of constructing the mortar matrix material model is:

[0054] S1.1. Use discrete element PFC 2D software to establish a coordinate system, define the boundary area, fill the closed boundary area with mortar matrix material, and uniformly assign the "mortar" group name to form a mortar phase particle system;

[0055] S1.2. Then, a contact model between mortar particles is set, and various model parameters of the contact model are set to form a mortar matrix material model.

[0056] Specifically, in step S1.1, the mortar matrix material is composed of a number of regularly arranged mortar "ball" particles bonded together; the diameter of the mortar "ball" particles is 0.2 mm.

[0057] Specifically, in step S1.1, the shape and size of the boundary region refer to the shape and size of the discrete element virtual specimen.

[0058] In step S1.1, the mortar matrix material is preferably a regularly arranged mortar "ball" particle array, which can be implemented using either a "cubic" or "hexagonal" arrangement. Each mortar "ball" particle has the same diameter. The mortar matrix material is composed of several mortar "ball" particles bonded together. For microscopic simulation purposes, the mortar "ball" particle diameter is 0.2 mm.

[0059] Specifically, in step S1.2, the contact model is a parallel bonding contact model.

[0060] The model parameters of the parallel bond contact model include the effective modulus of contact bond E * , stiffness ratio k * , tensile strength T F and shear strength S F , effective modulus of parallel bonding Stiffness ratio tensile strength and bond strength

[0061] S2. Construct a fiber geometry template and form a target delivery fiber template according to the set fiber geometry parameters.

[0062] Further defined, the specific process of step S2 is:

[0063] S2.1. Use two-dimensional line segments to represent the geometry of virtual fibers in the mortar matrix material model and define them by length, inclination, and center position to form a geometric template of the fibers.

[0064] S2.2. In the fiber geometry template, set the length parameters, inclination parameters, and center position parameters of a single fiber to form the geometry parameters of the fiber, and convert the fiber geometry parameters into a target delivery fiber template.

[0065] Specifically, in step S2.2, the inclination parameters and center position parameters are defined using gauss (Gaussian distribution) and uniform (uniform distribution); the length parameter is controlled by the "slimit" keyword, and the length parameter range is [fsmin, fsmax]; fsmin represents the minimum length value of the target fiber, and fsmax represents the maximum length value of the target fiber.

[0066] S3. Using a self-identification algorithm, randomly place fibers in the mortar matrix material model according to the target fiber placement template until the number of fibers placed reaches a preset target value.

[0067] S4. Randomly select a fiber from the mortar matrix material model where the fiber is placed and calculate the equation of the straight line where the fiber segment lies.

[0068] Step S4 specifically includes:

[0069] S4.1. Select a fiber and read the center coordinates O(x0, y0), length L, and inclination angle θ of the fiber;

[0070] S4.2. Calculate the coordinates of the fiber's endpoints A (x1, y1) and B (x2, y2) as follows:

[0071]

[0072] S4.3. Based on the coordinates of endpoints A and B, calculate the equation of the line where the fiber segment lies. The expression is as follows:

[0073]

[0074] Where,

[0075] S5. Traverse each mortar particle unit in the mortar matrix material model, read the center coordinate C (x3, y3) of the mortar particle unit, and calculate the vertical distance h from the mortar particle unit to the fiber segment.

[0076] In step S5 of the present invention, the vertical distance h from the mortar particle unit to the fiber segment is calculated as follows:

[0077]

[0078] Specifically, in step S5, since each mortar is traversed, in order to improve the calculation efficiency of the vertical distance h between the mortar particle unit and the fiber segment, when participating in the calculation of the above formula (6), the mortar particle unit center coordinate C is read to meet the following requirements:

[0079]

[0080] S6. Set the fiber reinforcement width range t of the mortar matrix material model, and reallocate the “fiber mortar” group name to the mortar particle units with a vertical distance h ≤ t.

[0081] In particular, the reinforcement width range of each fiber can be set according to user needs.

[0082] Preferably, the reinforcement width range t of the fiber to the mortar matrix material model is 0.1 mm.

[0083] S7. Traverse each fiber and repeat steps S4 to S6 to complete the reassignment of group names for all mortar particle units.

[0084] S8. Redistribute the adjacent mortar particle units within the "fiber mortar" group name, redistribute the contact model strength parameters, simulate the fiber reinforcement strength, and complete the construction of the fiber concrete discrete element model.

[0085] The following describes the implementation steps of the present invention in detail by taking a two-dimensional circular specimen as an example and combining with the accompanying drawings, but it cannot be used as a limitation on the protection scope of the present invention.

[0086] Example

[0087] In this embodiment, the diameter of the two-dimensional circular test piece is selected to be 150 mm.

[0088] This embodiment provides a modeling method for a fiber concrete discrete element model to achieve accurate simulation of fine fibers. The modeling method includes the following steps:

[0089] 1. Use discrete element PFC 2D software to build the mortar matrix material model

[0090] Step 1. Use the discrete element PFC 2D software to establish a coordinate system. Use the "wall" command to generate a circular boundary wall with a radius of 75 mm as the model boundary area. In the closed boundary area, regularly arrange mortar "ball" particles (i.e., mortar matrix material) with a diameter of d and uniformly assign the "mortar" group name ("mortar" group name) to form a mortar phase particle system to simulate the mortar entity of concrete.

[0091] The circular boundary wall is completed using the following procedure.

[0092] [ini_pos=vector(0,0)]

[0093] geometry set circle

[0094] geometry generate circle position@ini_pos rad 75e-3

[0095] wall import geometry circle

[0096] See also Figure 3 ,In step 1, the regular arrangement of the mortar "ball" particles can be either "cubic" or "hexagonal".

[0097] In particular, in order to achieve the purpose of microscopic simulation, the diameter of the mortar "ball" particles in step 1 is preferably 0.2 mm.

[0098] The shape and size of the model boundary area refer to the shape and size of the discrete element virtual specimen.

[0099] Step 2: Set the contact model between mortar phase particles to the parallel bond contact model built into the PFC 2D software, and set the various parameters of the parallel bond contact model (Table 1) to form a mortar matrix material model.

[0100] Table 1 Parameters of the parallel bonding contact model of mortar “ball” particles

[0101]

[0102]

[0103] ball group'mortar'range radius 0.2e-3

[0104] contact model linearpbond range group'mortar'

[0105] contact method deformability emod 0.2e8 krat 3.0range group'mortar'

[0106] contact method pb_deform emod 0.16e8 krat 0.94range group'mortar'

[0107] contact property pb_ten 0.63e6 pb_coh 1.26e6 range group'mortar'

[0108] clean

[0109] 2. Construct a fiber geometry template and form a target delivery fiber template based on the set fiber geometry parameters.

[0110] Step 3: Use one or two-dimensional line segments to represent the geometry of virtual fibers in the mortar matrix material model (see Figure 2 ) and is defined by length, inclination and center position to form a fiber geometry template.

[0111] Step 4. In the fiber geometry template, set the length range of a single fiber to [0.3e-2, 3.0e-2], the inclination angle to "uniform", and the center position to "uniform" to form the geometric parameters of the fiber. Then, use the "dfn templatecreate" command to convert the fiber geometry parameters into the target fiber template "Fiber".

[0112] dfn template create name Fiber orientation uniform position uniformsize uniform slimit 0.3e-2 3.0e-2

[0113] 3. Using a self-identification algorithm, fibers are randomly placed in the mortar matrix material model according to the target fiber placement template until the number of fibers placed reaches the preset target value.

[0114] In step 5, the self-identification algorithm is written using the Fish function. According to the "Fiber" fiber template generated in step 4, the "dfn generate" command is run to randomly place the target fiber "Fiber" in the mortar matrix model in step 2.

[0115] dfn generate template name Fiber genbox-75e-3 75e-3 -75e-3 75e-3nfrac 1

[0116] Step 6: Set the total number of fibers to be placed to 20, and repeat steps 4 to 5 in a counting cycle until all fibers are prefabricated and placed (see Figure 4 ).

[0117] In this step, the fiber preparation and placement are completed using the following procedures.

[0118]

[0119] The delivery termination condition is defined by the keyword "nfrac". When the number of generated fibers reaches the target value, the delivery is stopped.

[0120] 4. Randomly select a fiber from the mortar matrix material model with the fiber placed and calculate the equation of the straight line where the fiber segment lies.

[0121] Step 7: Randomly select a fiber, represented by "Fib", and read the center position coordinates O(x0, y0), length L and inclination angle θ of the fiber. The return values are pos, len, and angle respectively.

[0122] The center position coordinates O(x0, y0), length L and inclination angle θ of the fiber are read using the following procedure.

[0123] pos=vector(dfn.fracture.pos.x(Fib),dfn.fracture.pos.y(Fib))

[0124] len = dfn.fracture.len(Fib)

[0125] angle=dfn.fracture.dip(Fib)*math.degrad

[0126] Step 8: Calculate the coordinates of the fiber endpoints A(x1, y1) and B(x2, y2) as follows:

[0127]

[0128] During implementation, the coordinates of endpoint A (x1, y1) and endpoint B (x2, y2) are calculated through the following programming.

[0129] local posx1=dfn.fracture.pos.x(Fib)+math.cos(angle)*len / 2

[0130] local posy1=dfn.fracture.pos.y(Fib)+math.sin((angle)*len / 2

[0131] local posx2=dfn.fracture.pos.x(Fib)-math.cos((angle)*len / 2

[0132] local posy2=dfn.fracture.pos.y(Fib)-math.sin((angle)*len / 2

[0133] Step 9: Calculate the equation of the straight line where the fiber "Fib" in step 7 is located based on the actual positions of the coordinates of the endpoints A and B in step 8.

[0134] The equation of a line is expressed as follows:

[0135]

[0136] Where,

[0137] 5. Traverse each mortar particle unit in the mortar matrix material model, read the center coordinates C(x3,y3) of the mortar particle unit, and calculate the vertical distance h from the mortar particle unit to the fiber segment.

[0138] The vertical distance h from the mortar particle unit to the fiber line segment is calculated as follows:

[0139]

[0140] In step S5, the center coordinate C of the mortar particle unit must meet the following requirements when reading:

[0141]

[0142] During implementation, the vertical distance h from the mortar particle unit to the fiber line segment is calculated using the following programming method.

[0143]

[0144] 6. Set the fiber reinforcement width range t of the mortar matrix material model, and reassign the "fiber mortar" group name to the mortar particle units with a vertical distance h ≤ t.

[0145] Step 10: Set the fiber reinforcement width range t to 0.1 mm (see Figure 5 ), according to the vertical distance h between the mortar particle unit and the fiber, determine whether the mortar particle unit is a fiber-reinforced mortar particle, and reassign the fiber-reinforced mortar particles to the "FiberContact" group name (also called the "fiber mortar" group name).

[0146] Since the reinforcement width range t of the fiber to the mortar matrix material is preferably 0.1 mm, that is, when the vertical distance from the mortar particle unit to the fiber is less than or equal to 0.1 mm, the mortar particles can be regarded as mortar particles reinforced with fibers and are assigned the group name of "fiber mortar".

[0147] 7. Traverse each fiber and repeat the corresponding steps 4 to 6 above to complete the reassignment of group names for all mortar particle units.

[0148] Step 11: traverse each fiber and repeat steps 8 to 10 to complete the group name assignment for all fiber-reinforced mortar particles.

[0149] 8. Redistribute the adjacent mortar particle units within the "fiber mortar" group name, redistribute the contact model strength parameters, simulate the fiber reinforcement strength, and complete the construction of the fiber concrete discrete element model.

[0150] Step 12: Redistribute the contact model strength parameters (see Table 2) of the adjacent mortar units in the “FiberContact” group name to simulate the strength improvement effect of fiber reinforcement and complete the construction of the fiber concrete discrete element model.

[0151] Table 2 Parameters of the parallel bonding contact model of fiber reinforced “ball” particles

[0152]

[0153] See also Figure 6 In this embodiment, the fiber reinforcement direction is realized by traversing the mortar particle units with the "FiberContact" group name in step 10, selecting two adjacent mortar units, ball1 and ball2, obtaining the particle center coordinates (ballx1, bally1) and (ballx2, bally2), and judging the positions of the two adjacent particles ball1 and ball2 relative to the fiber segment. If they are on the same side, they are defined as the same-side reinforcement particle units, and the mortar particles are assigned the "FiberYContact" group name. If they are on both sides, they are defined as the opposite-side reinforcement particle units, and the mortar particles are assigned the "FiberXContact" group name; the mortar particles and the mortar particles are in the "MortarContact" group name; thereby realizing the characterization of different reinforcement directions of the fiber-reinforced mortar particles.

[0154] Specifically, the fiber reinforcement direction is realized through the following programming procedure.

[0155]

[0156]

[0157] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications made without departing from the technical principles of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A modeling method for a fiber concrete discrete element model, characterized in that: The following steps are involved: S1. Constructing a mortar matrix material model; S2. Constructing a fiber geometry template and forming a target delivery fiber template according to the set fiber geometry parameters; S3, using a self-identification algorithm, randomly placing fibers in the mortar matrix material model according to the target fiber placement template until the number of fibers placed reaches a preset target value; S4. Randomly select a fiber from the mortar matrix material model where the fiber is placed and calculate the equation of the straight line where the fiber segment lies; S5. Traverse each mortar particle unit in the mortar matrix material model, read the center coordinate C (x3, y3) of the mortar particle unit, and calculate the vertical distance h from the mortar particle unit to the fiber segment; S6. Set the fiber reinforcement width range t of the mortar matrix material model, and reassign the "fiber mortar" group name to the mortar particle units with a vertical distance h≤t; S7, traverse each fiber and repeat steps S4 to S6 to complete the reassignment of group names for all mortar particle units; S8. Redistribute the adjacent mortar particle units within the "fiber mortar" group name, redistribute the contact model strength parameters, simulate the fiber reinforcement strength, and complete the construction of the fiber concrete discrete element model.

2. The modeling method of the fiber concrete discrete element model according to claim 1, characterized in that: In step S1, the process of constructing the mortar matrix material model is: S1.

1. Use discrete element PFC 2D software to establish a coordinate system, define the boundary area, fill the closed boundary area with mortar matrix material, and uniformly assign the "Mortar" group name to form a mortar phase particle system; S1.

2. Then, a contact model between mortar particles is set, and various model parameters of the contact model are set to form a mortar matrix material model.

3. The modeling method of the fiber concrete discrete element model according to claim 2, characterized in that: In step S1.1, the mortar matrix material is composed of a number of regularly arranged mortar "ball" particles bonded together; the diameter of the mortar "ball" particles is 0.2 mm.

4. The modeling method of the fiber concrete discrete element model according to claim 2, characterized in that: In step S1.2, the contact model is a parallel bonding contact model; The model parameters of the parallel bond contact model include the effective modulus E of the contact bond * , stiffness ratio k * , tensile strength T F and shear strength S F , effective modulus of parallel bonding Stiffness ratio tensile strength and bond strength 5. The modeling method of the fiber concrete discrete element model according to claim 1, characterized in that: The specific process of step S2 is: S2.

1. Use two-dimensional line segments to represent the geometry of virtual fibers in the mortar matrix material model and define them by length, inclination, and center position to form a geometric template of the fibers. S2.

2. In the fiber geometry template, set the length parameters, inclination parameters, and center position parameters of a single fiber to form the geometry parameters of the fiber, and convert the fiber geometry parameters into a target delivery fiber template.

6. The modeling method of the fiber concrete discrete element model according to claim 5, characterized in that: In step S2.2, the inclination parameter and the center position parameter are both defined using Gaussian distribution or uniform distribution; the length parameter range is [fsmin, fsmax]; fsmin represents the minimum length value of the target fiber, and fsmax represents the maximum length value of the target fiber.

7. The modeling method of the fiber concrete discrete element model according to claim 1, characterized in that: Step S4 specifically includes: S4.

1. Select a fiber and read the center coordinates O(x0, y0), length L, and inclination angle θ of the fiber; S4.

2. Calculate the coordinates of the fiber's endpoints A (x1, y1) and B (x2, y2) as follows: S4.

3. Based on the coordinates of endpoints A and B, calculate the equation of the line where the fiber segment lies. The expression is as follows: Where, 8. The modeling method of fiber concrete discrete element model according to claim 1, characterized in that: In step S5, the vertical distance h from the mortar particle unit to the fiber segment is calculated as follows:

9. The modeling method of fiber concrete discrete element model according to claim 8, characterized in that: In step S5, the mortar particle unit center coordinates C are read to meet the following requirements:

10. The modeling method of fiber concrete discrete element model according to claim 9, characterized in that: In step S6, the reinforcement width range t of the fiber to the mortar matrix material model is 0.1 mm.

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