A numerical simulation method for simulating the evolution of rock cracks under the action of a hob

Abstract

The present invention discloses a numerical simulation method for simulating the crack evolution of rock under the action of a hob, including: establishing a three-dimensional model of the hob and the rock; determining the simulation parameters of the three-dimensional model of the hob and the rock, including: rock material property parameters, hob material property parameters, material damage models, contact models between the hob model and the rock model, boundary conditions of the hob model and the rock model, solution methods, and output calculation parameters; using the open-source program Peridigm to calculate the model; importing the calculation results into Paraview for visualization processing. The present invention provides a new idea for simulating the damage evolution of rock under the action of a hob, and can well simulate the evolution of cracks in rock; at the same time, this method can achieve parallel computing, has multi-scale analysis capabilities, and has good application prospects in calculating large models at the engineering scale.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical engineering, and particularly to a numerical simulation method for simulating the crack evolution of rock under the action of a hob. Background Art

[0002] At present, during the construction of tunnels, TBM tunneling construction has been widely used in tunnel construction. TBM tunneling construction mainly relies on the hob at its foremost end to cut and break the rock on the tunnel face, and repeats this process to make the tunnel penetrate. For TBM construction technology, it is necessary to focus on the degree of damage of the rock on the tunnel face under the action of the cutter, study the mechanism of rock breaking by the hob, and provide a reference for the design of the TBM cutterhead. At present, the research methods for rock breaking by the hob mainly include two types: indoor tests and numerical simulations. Indoor test research mainly includes three types: hob penetration test, linear cutting test, and rotary cutting test. However, these tests not only have high requirements for equipment, increasing the test cost, but also it is difficult to actually observe the damage inside the rock. With the continuous development of computer technology, numerical simulation has become a research method chosen by many scholars due to its advantages such as low cost and good repeatability.

[0003] Currently, the numerical methods for studying rock breaking by the hob mainly include the finite element method and the discrete element method. Among them, when the finite element method simulates fracture problems, it is necessary to additionally introduce a crack propagation criterion, which has a certain interference on the final result; although the discrete element method does not have the requirement of continuity, there is no strict basis for determining the size of discrete particles. In summary, it can be seen that the numerical methods currently applied to the field of rock breaking by the hob have their own limitations. Summary of the Invention

[0004] The purpose of the present invention is to propose a numerical simulation method for simulating the crack evolution of rock under the action of a hob in view of the limitations of existing numerical methods, providing a new idea for the numerical research of rock breaking by the hob.

[0005] The technical solution of the present invention is as follows:

[0006] A numerical simulation method for simulating the crack evolution of rock under the action of a hob by using the peridynamics theory, including the following steps:

[0007] Step 1, establish a three-dimensional model of the hob and the rock;

[0008] Step 2, determine the simulation parameters of the three-dimensional model of the hob and the rock, including: rock material property parameters, hob material property parameters, material damage models, contact models between the hob model and the rock model, boundary conditions of the hob model and the rock model, solution methods, and output calculation parameters;

[0009] Step 3: Combine the simulation parameters and use the open-source program Peridigm to calculate the three-dimensional model of the hob and the rock, and visualize the calculation results to obtain the numerical simulation results of the rock crack evolution under the action of the hob.

[0010] Further, in the above Step 2, the rock material property data includes the material model of the rock, the density of the rock material, the Young's modulus, and the shear modulus; the hob material property data includes the material model of the hob, the density of the hob material, the Young's modulus, and the shear modulus.

[0011] Further, in the above Step 2, the damage model of the material is the damage model of the rock material, which is one of the critical elongation rate model, the time-dependent critical elongation rate model, and the interface perception model;

[0012] Further, in the above Step 2, the contact model between the hob model and the rock model is one of the short-range contact force model and the time-dependent short-range contact force model;

[0013] Further, in the above Step 2, the boundary conditions of the hob model and the rock model include: the velocity boundaries of the hob in the x, y, and z directions, and the displacement boundaries of the front, back, left, and right four faces of the rock model.

[0014] Further, in the above Step 2, the solution method includes the start time, end time, and integration method of the simulation.

[0015] Further, in the above Step 2, the calculated parameters output include the displacements of the hob and the rock respectively, the velocities of the hob and the rock respectively, the contact force between the hob and the rock, and the damage of the rock, etc.

[0016] Further, in the above Step 3, the open-source program Peridigm is used to calculate the three-dimensional model of the hob and the rock in parallel by region, and the calculated parameters output also include the processor number.

[0017] Further, in the visualization process, the cell data is converted into point data to enhance the visualization effect.

[0018] The beneficial effects of the present invention are:

[0019] 1. The governing equation of the peridynamics method (Peridigm open-source program) is in integral form, which overcomes the drawback that it is difficult to obtain a solution at the crack tip in traditional methods. Therefore, it can simulate the fracture problem of rock under the action of a TBM hob;

[0020] 2. Since peridynamics is composed of integral form to form its governing equation, parallel computing can be realized to improve its computing efficiency. Therefore, it has certain potential for solving tunnel engineering scale models;

[0021] 3. Peridynamics itself is a dynamic algorithm that can simulate the dynamic contact process between two objects. Therefore, it can simulate the contact process between the hob and the rock, and thus can simulate the mode of rock damage under a certain penetration degree of the hob.

[0022] 4. Constitutive relations in classical mechanics can be embedded in the framework of the peridynamics method to achieve more complex material relations. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the rock-breaking model of the hob of the present invention.

[0024] Figure 2 It is a parallel computing partition diagram of the rock-breaking model of the hob of the present invention.

[0025] Figure 3 It is the damage mode of the rock when the penetration depth of the hob is 0.05 mm of the present invention.

[0026] Figure 4 It is the damage mode of the rock when the penetration depth of the hob is 0.08 mm of the present invention.

[0027] Figure 5 It is the damage mode of the rock when the penetration depth of the hob is 0.11 mm of the present invention.

[0028] Figure 6 It is the damage mode of the rock when the penetration depth of the hob is 0.16 mm of the present invention. Detailed Embodiment

[0029] The present invention will be further described below in conjunction with the drawings and specific embodiments. The following embodiments will refer to the rock-breaking model established by Zhai Shufang to prove the feasibility and implementation steps of simulating the crack evolution of rock under the action of a hob using the peridynamics theory:

[0030] Step 1: Establish a three-dimensional model of the hob and the rock equivalent to the reference document. The particle spacing of the model is set to 1 mm, as shown in the attached... Figure 1 ... illustration; among them, the equivalent model size of the hob is 15 mm × 10 mm × 8 mm, and the equivalent size of the rock is 100 mm × 100 mm × 10 mm. At the same time, a virtual boundary composed of three layers of particles needs to be established to apply the boundary conditions of the model.

[0031] Step 2: Determine the simulation parameters of the three-dimensional model of the hob and the rock, including: rock material property parameters, hob material property parameters, material damage models, contact models between the hob model and the rock model, boundary conditions of the hob model and the rock model, solution methods, and output calculation parameters, etc.; specifically, it includes the following steps:

[0032] Step 2.1, determine the rock material property parameters: The rock material property parameters include the material model of the rock, the density of the rock material, Young's modulus and shear modulus. In this embodiment, the material model of the rock is the LPS model, and the density is 2600 kg / m 3 , Young's modulus is 82.5 GPa, and shear modulus is 32.0 GPa;

[0033] Step 2.2, determine the cutter material property parameters: The cutter material property parameters include the material model of the cutter, the density of the cutter material, Young's modulus and shear modulus. In this embodiment, the material model of the cutter is the LPS model, and the density is 7700 kg / m 3 , Young's modulus is 160.0 GPa, and shear modulus is 78.3 GPa;

[0034] Step 2.3, select the damage model of the material: Select a suitable damage model and input relevant parameters; In this embodiment, the critical elongation rate model is selected. The physical meaning of this model is that when the elongation rate of the connection bond between particles exceeds a critical value, the connection bond will break, and the degree of particle damage is calculated by statistically analyzing the percentage of broken connection bonds;

[0035] Step 2.4, assign the material properties obtained in Step 2.1 and Step 2.2 and the damage model established in Step 2.3 to the three-dimensional model established in Step 1 respectively; Since the stiffness of the cutter is much greater than that of the rock specimen, the damage model is assigned to the rock specimen, assuming that no damage occurs to the cutter model.

[0036] Step 2.5, establish the contact model between the cutter model and the rock model, and set the required parameters; In this embodiment, the short-range contact force model is selected to simulate the dynamic contact between the cutter and the rock;

[0037] Step 2.6, establish the boundary conditions of the cutter model and the rock model; Specifically, set the velocity of the cutter in the y direction to -0.01 m / s, and the velocities in the x and z directions to 0; Set the virtual boundaries on the front and back of the rock model to have a displacement of 0 in the z direction to restore the plane strain state in the reference literature; Set the virtual boundaries on the left and right sides of the rock model to have displacements of 0 in the z and x directions to restore the state of lateral constraint in the reference literature; Set the virtual boundary at the bottom of the rock model to have a displacement of 0 in the y direction;

[0038] Step 2.7, select the solution method: including the start time, end time and integration method of the simulation; In this embodiment, the start time of the simulation is 0.0 s, the end time of the simulation is 0.02 s, and the integration method is selected as explicit time integration;

[0039] Step 2.8, set the output part; including the output file type, file name, output frequency, and output variables; the output file type is ExodusII, the output frequency is 200, and the output calculation parameters include: the displacements of the hob and the rock respectively, the velocities of the hob and the rock respectively, the processor number, the contact force between the hob and the rock, the damage of the rock, etc.;

[0040] Write the above simulation parameters into a file.

[0041] Step 3, use the open-source program Peridigm to calculate the model; specifically including the following steps:

[0042] Step 3.1, put the three-dimensional model of the hob and the rock established in Step 1 and the calculation file of the model written in Step 2 into the same folder;

[0043] Step 3.2, partition the model established in Step 1 to achieve parallel computing; the number of partitions of the model can be set artificially and is determined by the performance of the computing platform used. To improve the computing efficiency, the model established in Step 1 is divided into 120 parts for parallel operation with 120 cores. As shown in the appendix Figure 2 shown, where different colors represent the processor numbers;

[0044] Step 3.3, open a terminal in the folder described in Step 3.1, run Peridigm, and calculate the model. In the present invention, the compilation and operation of Peridigm are carried out on the Ubuntu system;

[0045] Step 4, import the calculation results into Paraview for visualization processing; convert the cell data into point data, and then use the Glyph module to enhance the visualization effect of the calculation results; the damage maps of the penetration depths of the hob being 0.05mm, 0.08mm, 0.11mm, and 0.16mm calculated by the present invention are shown in the appendix Figures 3-6 .

[0046] The model size, material parameters, and loading conditions of the embodiments of the present invention all refer to the paper "Zhai Shufang, Zhou Xiaoping, Bi Jing. Generalized Particle Dynamics Numerical Simulation of TBM Cutter Rock Breaking [J]. Rock and Soil Mechanics, 2018, 39(07): 2699–2707." to prove the rationality of the present invention for calculating this problem.

[0047] It should be noted that the above embodiments are only used to illustrate the advantages and operation processes of the present invention, and do not limit the scope of use of the present invention. Other forms of simulation carried out by those skilled in the art based on the present invention fall within the protection scope of the present invention.

Claims

1. A numerical simulation method for simulating the crack evolution of rock under the action of a hob, characterized in that, it includes the following steps: Step 1, establish a three-dimensional model of the hob and the rock; Step 2, determine the simulation parameters of the three-dimensional model of the hob and the rock, including: rock material property parameters, hob material property parameters, material damage models, contact models between the hob model and the rock model, boundary conditions of the hob model and the rock model, solution methods, and output calculation parameters; specifically including the following steps: Step 2.1, determine the rock material property parameters: The rock material property parameters include the material model of the rock, the density of the rock material, Young's modulus and shear modulus; Step 2.2, determine the hob material property parameters: The hob material property parameters include the material model of the hob, the density of the hob material, Young's modulus and shear modulus; Step 2.3, select the material damage model: Select a suitable damage model and input relevant parameters; Step 2.4, assign the material properties obtained in Step 2.1 and Step 2.2 and the damage model established in Step 2.3 to the three-dimensional model established in Step 1 respectively; Step 2.5, establish a contact model between the hob model and the rock model and set the required parameters; Step 2.6, establish the boundary conditions of the hob model and the rock model; Step 2.7, select the solution method; Step 2.8, set the output part; including the output file type, file name, output frequency, and output variables; Step 3, combine the simulation parameters, and use the open-source program Peridigm to perform simulation calculations on the three-dimensional model of the hob and the rock, and visualize the calculation results to obtain the numerical simulation results of the crack evolution of the rock under the action of the hob.

2. A numerical simulation method for simulating the crack evolution of rock under the action of a hob according to claim 1, characterized in that, in Step 2, the material damage model is the damage model of the rock material, which is one of the critical elongation rate model, time-dependent critical elongation rate model, and interface perception model.

3. A numerical simulation method for simulating the crack evolution of rock under the action of a hob according to claim 1, characterized in that, in Step 2, the contact model between the hob model and the rock model is one of the short-range contact force model and the time-dependent short-range contact force model.

4. A numerical simulation method for simulating the crack evolution of rock under the action of a hob according to claim 1, characterized in that, in Step 2, the boundary conditions of the hob model and the rock model include: the velocity boundaries of the hob in the x, y, and z directions, and the displacement boundaries of the front, back, left, and right four faces of the rock model.

5. A numerical simulation method for simulating the crack evolution of rock under the action of a hob according to claim 1, characterized in that, in Step 2, the solution method includes the start time, end time, and integration method of the simulation.

6. A numerical simulation method for simulating the crack evolution of rock under the action of a hob according to claim 1, characterized in that, in Step 2, the output calculation parameters include the displacements of the hob and the rock respectively, the velocities of the hob and the rock respectively, the contact force between the hob and the rock, and the damage of the rock.

7. A numerical simulation method for simulating the evolution of rock cracks under the action of a hob, according to claim 1, characterized in that, in step 3, the open-source program Peridigm is used to perform parallel calculations on the partition of the three-dimensional model of the hob and the rock.

8. A numerical simulation method for simulating the evolution of rock cracks under the action of a hob, according to claim 1, characterized in that, in the visualization process, the cell data can be converted into point data to enhance the visualization effect.

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