Abrasive water jet rock breaking simulation method based on DEM-CFD coupling method

Abstract

The invention discloses an abrasive water jet rock breaking simulation method based on a DEM-CFD coupling method. Establishing an EBPM bonded rock mass discrete element model through a discrete element DEM, and calibrating mesoscopic parameters through a virtual mechanical test; simulating a water-abrasive two-phase flow through fluid dynamics CFD, and adopting a Gidaspow drag force model; the DEM-CFD bidirectional interface realizes real-time coupling; carrying out post-treatment to extract an erosion morphology and a crack network; the method can effectively simulate the rock mass fracture process and the large deformation behavior in the water jet rock breaking process and reveal rock mass damage evolution from the microscopic scale, and can be widely applied to research of water jet assisted rock breaking in the fields of civil engineering, mining, petroleum energy, marine resources and the like.

Description

Technical Field

[0001] This invention relates to high-pressure water jet rock breaking technology, which can serve fields such as oil drilling engineering, tunnel excavation engineering, and deep-sea mining engineering. Specifically, it relates to a simulation method for abrasive water jet rock breaking based on the DEM-CFD coupling method. Background Technology

[0002] High-pressure water jetting has been widely used in oil drilling, mining, and tunneling. However, conventional continuous pure water jetting only generates water hammer pressure once, with low subsequent stagnation pressure, making it difficult to sustain damage. In recent years, some new high-pressure water jetting modes have emerged, such as pulsed high-pressure water jetting and abrasive water jetting. To accurately analyze the rock-breaking effect of jetting, analyzing the rock-breaking effect in actual engineering projects is the most direct method, but it is expensive and has poor repeatability. Physical experiments are also time-consuming and costly, and it is difficult to obtain information on the evolution of cracks within the rock mass. Numerical simulation methods, on the other hand, have advantages such as clear theory, good reproducibility, and the ability to analyze multiple factors, making them a feasible means of analyzing the rock-breaking effect of jetting.

[0003] Existing simulation methods mostly employ the finite element method (FEM) based on the continuous medium assumption, which struggles to realistically reproduce the intrinsic properties of rocks composed of discrete particles and their multi-scale coupled behaviors such as fracture, fragmentation, and erosion. Furthermore, traditional continuous pure water jets suffer from problems such as single water hammer pressure, rapid attenuation of stagnation pressure, and low rock-breaking efficiency. While pulsed water jets and abrasive water jets can improve efficiency, a unified numerical simulation framework is lacking to quantitatively compare the rock-breaking effects of different jet types.

[0004] Traditional finite element or SPH-FEM methods are based on the assumption of continuous medium, which makes it difficult to describe phenomena such as discontinuous rock fracture, particle spalling, and secondary crack propagation. Existing coupled algorithms often ignore the volume fraction, rotation, and grinding effects of high-concentration abrasive particles, resulting in large simulation and measurement errors.

[0005] Therefore, this invention provides a simulation method for abrasive waterjet rock breaking based on a DEM-CFD coupled approach. Based on molecular dynamics theory, the discrete element method (DEM) accurately describes the contact mechanics and motion evolution of discrete particles in the rock medium by establishing a particle ensemble model. This effectively simulates the rock fracture process and large deformation behavior, revealing the rock damage evolution at the microscopic scale. This invention, based on the coupling of computational fluid dynamics (CFD) and discrete element method (DEM), conducts numerical simulation studies on the rock breaking processes of continuous pure water jet, pulsed water jet, and abrasive water jet. It compares and analyzes the failure morphology, load changes, fracture bond distribution, erosion hole size, and surface fracture zone characteristics of rocks under different jet forms, providing a reference for the optimized design and engineering application of high-pressure water jet technology.

[0006] The current status of domestic research on the creep characteristics of rock masses reinforced by anchor cables is as follows:

[0007] 1. The paper "Coupled CEL-FDEM modeling of rock failure induced by high-pressure waterjet" uses the CEL-FDEM coupled method to simulate the fracturing of rock by high-pressure water jet. The results show that when high-pressure water jet impacts rock, it produces energy attenuation and a water cushion effect. The rock failure time is on the order of milliseconds, and the symmetrical cracks in the rock are mainly caused by tensile forces. (See Engineering Fracture Mechanics, 2023, 277. Zenghui L, Zhengkuo M, Kai L, et al.)

[0008] 2. The paper "Numerical research on the dynamic rock-breaking process of impact drilling with multi-nozzle waterjets" studied the influence of multi-nozzle jets on the stress changes on the rock surface and the dynamic damage evolution of rock fracturing using the ALE-FEM algorithm. The results showed that nozzle jets with different inclination angles exhibited different rock-breaking modes, mainly tensile failure and radial shear fracture caused by water jet impact. Multi-nozzle jet rock breaking can be divided into four stages: elastic deformation stage, plastic deformation stage, micro-fracture stage, and complete failure stage. (See Journal of Petroleum Science and Engineering, 2021, 207. Lipeng H, Yanbao L, Kai S, et al.)

[0009] 3. The paper "Numerical simulation on rock fragmentation by discontinuous water-jet using coupled SPH / FEA method" simulates the rock fragmentation process of water jet impact using the SPH-FEA coupling method. It compares the rock fragmentation states under continuous and discontinuous water jet impact. The results show that, under the same energy, discontinuous water jets have better rock-breaking performance than continuous water jets. (See Powder Technology, 2017, 312248-259. Jiang H, Liu Z, Gao K.)

[0010] 4. The paper "Numerical research on rock cutting by abrasive jet under confining pressure based on SPH-FEM method" studies the process of abrasive jet cutting rock under confining pressure based on the SPH-FEM method. The results show that rock failure is mainly caused by compressive stress and shear stress, while crack propagation is mainly caused by tensile stress. (See Powder Technology, 2024, 433119196. Huihe Z, Hongxiang J, Hongsheng L, et al.)

[0011] In some research results, the finite element method based on the continuous medium theory is often used, which cannot accurately reflect the rock fracture characteristics. However, the method of this invention accurately describes the contact mechanical behavior and motion evolution law between discrete particles in the rock medium by establishing a particle assembly model. It can effectively simulate the rock mass fracture process and large deformation behavior and reveal the rock mass damage evolution at the microscale. Summary of the Invention

[0012] To overcome the shortcomings of existing technologies, this invention provides a simulation method for abrasive waterjet rock breaking based on the DEM-CFD coupling method.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] The simulation method for abrasive waterjet rock breaking based on DEM-CFD coupling method is as follows:

[0015] (1) Establish the liquid phase control equation for the simulation of abrasive water jet rock breaking;

[0016] (2) Establish the solid phase control equation for the simulation of abrasive water jet rock breaking;

[0017] (3) Establish a fluid-structure interaction algorithm for solid-liquid two-phase flow simulation of abrasive water jet rock breaking;

[0018] (4) Perform discrete element modeling of rock for water jet rock breaking and calibrate the microscopic parameters of the bond bond;

[0019] (5) Three jet methods were used to simulate water jet rock breaking: high pressure pure water continuous jet (CWJ), pulsed water jet (PWJ) and abrasive water jet (AWJ) to explore the rock breaking effect of water jet.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This invention is based on the discrete element method coupled with fluid dynamics. By establishing a particle ensemble model, it accurately describes the contact mechanical behavior and motion evolution law between discrete particles in rock media. It can effectively simulate the rock mass fracture process and large deformation behavior during water jet rock breaking and reveal the rock mass damage evolution at the microscale.

[0022] 2. This invention method can be widely applied to the research of water jet-assisted rock breaking in fields such as civil engineering, mining, petroleum energy, and marine resources, and has a wide range of applications. Attached Figure Description

[0023] Figure 1 Figures are attached to the abstract;

[0024] Figure 2 This is a schematic diagram of the EBPM binder particle model;

[0025] Figure 3 This is a schematic diagram of the DEM-CFD coupling principle;

[0026] Figure 4 Figures showing the failure morphology of rock samples under uniaxial compression and Brazilian splitting tests.

[0027] Figure 5 This is a comparison chart of stress-strain curves;

[0028] Figure 6 Diagram of a high-pressure pure water jet rock-breaking model;

[0029] Figure 7 A diagram of an abrasive waterjet model (including abrasive particles);

[0030] Figure 8 Three jet velocity-time curves;

[0031] Figure 9 A comparison diagram of simulated and experimental damage morphologies;

[0032] Figure 10 Damage morphology diagrams of different jet patterns at 200 μs;

[0033] Figure 11 Simulation diagram of the compressive stress zone generated in rock after impact by CWJ, PWJ, and AWJ;

[0034] Figure 12 The graph shows the compressive stress variation at the reference point for three jet calculation models.

[0035] Figure 13 A graph showing the number of bond fractures over time;

[0036] Figure 14 A comparison chart of erosion hole depth / diameter / volume;

[0037] Figure 15 This is a comparison diagram of the simulated and experimental fractured zone on the rock surface. Detailed Implementation

[0038] The simulation method for abrasive waterjet rock breaking based on DEM-CFD coupling method is as follows:

[0039] 1. Establish the liquid phase governing equations for simulating abrasive waterjet rock breaking. The specific method is as follows:

[0040] In the water jet rock-breaking model

[0041] The Dense Discrete Phase Model (DDPM) from the Euler multiphase flow model is used to handle the volume fraction of the particulate phase for numerical simulation calculations of solid-liquid two-phase flow.

[0042] mass conservation equation:

[0043]

[0044] Momentum conservation equation:

[0045]

[0046] In the formula: α l It is the volume fraction of the fluid phase; ρ l It is the density of the fluid phase; It is the Hamiltonian operator; v l τ is the velocity of the fluid phase; p is the pressure shared by all phases; l It is the stress-strain tensor of the fluid phase; g is the acceleration due to gravity; F pf It is the force exerted by particles on a fluid;

[0047] The drag force model selected is the Gidaspow model, and the drag force acting on the particle is:

[0048]

[0049] In the formula, d s It is the particle diameter of the solid phase; α s It is the volume fraction of the solid phase; K sl It is the fluid-structure interaction coefficient;

[0050] When α l >0.8, fluid-structure interaction coefficient:

[0051]

[0052] in,

[0053]

[0054] When α l ≤0.8, fluid-structure exchange coefficient:

[0055]

[0056] in,

[0057]

[0058] Where: μ l It is the dynamic viscosity of the fluid phase; α l It is the volume fraction of the fluid phase.

[0059] 2. Establish the solid phase governing equations for simulating abrasive waterjet rock breaking. The specific method is as follows:

[0060] In the water jet rock-breaking model, the solid phase governing equations are derived as follows:

[0061] In discrete element method (DEM) simulations, each particle has six degrees of freedom, which are divided into translational and rotational motions. Newton's second law is typically used to calculate the particle's acceleration, while the particle's velocity and displacement are obtained through numerical integration of the governing equations for its translational and rotational motions.

[0062] Particle motion equations:

[0063]

[0064] In the formula: m is the particle mass; I is the particle moment of inertia; v is the particle linear velocity; ω is the particle angular velocity; F c It is the vector sum of the normal contact force and the tangential contact force; F d It is the drag force; g is the acceleration due to gravity; T c It is the contact torque caused by the contact force;

[0065] Assuming the force on the particle remains constant within a time step, the linear velocity and angular velocity of the particle can be obtained by numerical integration based on the governing equations of its translational and rotational motions:

[0066]

[0067] Integrating the above equation, we can obtain the linear and angular displacements of the particles:

[0068] u(t+Δt)=u(t)+v(t)Δt (12)

[0069] θ(t+Δt)=θ(t)+ω(t)Δt (13)

[0070] In the formula: u is the displacement produced by translational motion; θ is the displacement produced by rotational motion;

[0071] The Edinburgh Bonded Particle Model (EBPM) accurately reflects the mechanical behavior of cemented materials. The EBPM model assumes that all particles are rigid spheres. Due to the spherical nature, there is only one contact point between any two particles. At the particle contact point, there are two types of contact: bonded contact and unbonded contact. At the bonded contact, the Timoshenko Beam Bonded-Contact Model (TBBM) is used. This model assumes that the particles are rigidly connected by a Timoshenko beam element, and the mechanical behavior of the bond follows the Timoshenko beam element theory. Each end of the bond shares the same six degrees of freedom with the particles. When two particles first come into contact or the bond breaks, the Hertz-Mindlin Contact Model (HMCM) is formed to describe the force-displacement relationship at the unbonded contact point. Figure 2 This is a schematic diagram of the EBPM binder particle model.

[0072] 3. Establish a fluid-structure interaction algorithm for simulating solid-liquid two-phase flow in abrasive waterjet rock breaking. The specific method is as follows:

[0073] In the water jet rock-breaking model, DEM-CFD bidirectional coupling is achieved through the FLUENT-EDEM interface. During the fluid-structure interaction calculation, the CFD and DEM software separately solve for fluid phase and particle phase information, respectively, and the coupling interface facilitates information transmission to achieve coupling. At the start of the CFD-DEM coupling, the DEM is used to solve for particle position, velocity, and other information within the coupled computational domain using the particle contact force model and particle motion equations. This information is then transferred to the CFD software via the coupling interface to solve for the Navier-Stokes mass conservation equation and momentum conservation equation. The DPM model is then used to calculate the fluid pressure, drag force, and velocity of each particle within the coupled computational domain. The obtained information is used as input parameters for the next iteration step, and the above process is repeated to finally obtain the dynamic characteristics of the flow field and particle motion. A schematic diagram of the DEM-CFD coupling principle is shown below. Figure 3 .

[0074] 4. Perform discrete element modeling of the rock during water jet rock breaking and calibrate the microscopic parameters of the bond bonds. The specific method is as follows:

[0075] The discrete element method (DEM) model of the rock adopted the EBPM bonded grain model. The microscopic parameters of the bond were calibrated by uniaxial compression and Brazilian splitting tests to ensure that the macroscopic uniaxial compressive strength, tensile strength, and elastic modulus were all within the error range. Figure 4 Failure morphology diagrams of rock specimens under uniaxial compression and Brazilian splitting tests. Figure 5 Comparison of stress-strain curves.

[0076] 5. Three jetting methods were used to simulate water jet rock breaking: continuous pure water jet, pulsed water jet, and abrasive jet. The rock breaking effect of water jet was investigated. The specific methods are as follows:

[0077] Continuous pure water jet with constant velocity; pulsed water jet with square wave, fixed period, and 50% duty cycle; abrasive water jet with abrasive particles added to the continuous aqueous phase at a volume fraction of 20%–30%, see [link to relevant documentation]. Figures 6-8 ;

[0078] The quantitative evaluation of the rock-breaking effect of the three jet types was completed using the following indicators: final depth of the erosion hole, compressive stress-time curve at the impact point, total number of bond fractures, diameter and volume of the erosion hole, and area of ​​the surface fracture zone. The results were compared with indoor granite erosion tests. Figures 9-15 .

[0079] Specific Implementation Cases

[0080] I. Software Environment

[0081] Numerical simulation of water jet rock breaking was performed using EDEM (2022) and ANSYS Fluent (2022R1) simulation software. A DPM-based coupling interface (version 2.2) was selected for information transmission to achieve bidirectional coupling. At the start of the coupled simulation, EDEM calculated the particle position, velocity, and other information within the coupled computational domain and transmitted this information to Fluent through the DPM-based coupling interface (version 2.2). Fluent initialized the flow field and solved the Navier-Stokes mass conservation equation and momentum conservation equation. Using the DPM model, it calculated the fluid pressure, drag force, and velocity of each particle within the coupled computational domain and fed this information back to EDEM through the coupling interface. EDEM updated the particle motion equations and fed them back to Fluent. This process was repeated until the coupled simulation was completed.

[0082] II. Model Establishment and Parameter Setting

[0083] 1. Rock model parameter calibration

[0084] To accurately simulate the rock-breaking process of high-pressure water jet based on the CFD-DEM coupling method, it is necessary to accurately model the discrete element rock model. The parameters of the rock material were calibrated through uniaxial compression test and Brazilian splitting test. This paper takes granite as the research object. The target values ​​of the macroscopic mechanical parameters of the rock are based on the values ​​selected by the water jet rock-breaking laboratory test in Liu Bin et al. "Experimental Study on Rock Breaking Effect of Abrasive Pulse Jet" as shown in Table 1 (see Liu Bin, Zhang Jiancheng, Zhang Bo, et al. Experimental Study on Rock Breaking Effect of Abrasive Pulse Jet [J]. Journal of Hydroelectric Engineering, 2024, 43(08):14-21).

[0085] The uniaxial compression test model consists of a cylindrical specimen with a diameter of 15 mm and a height of 30 mm. Loading is achieved by controlling the speed of the upper and lower pressure loading plates to obtain the compressive strength and elastic modulus of the specimen. The Brazilian splitting test model consists of a cylindrical specimen with a diameter of 30 mm and a thickness of 15 mm. Line loads are applied to the side of the cylinder through two loading elements to obtain the tensile strength and elastic modulus of the specimen. The specimen failure results of the uniaxial compression numerical simulation test and the Brazilian splitting test after final parameter calibration are as follows: Figure 4 As shown, the stress-strain curve is as follows: Figure 5 As shown in Table 2, the macroscopic mechanical parameters obtained from the indoor test of the selected granite are compared with those obtained from the numerical simulation. The calibrated parameters of the particles, pressure plate and bonding bond are shown in Tables 3 and 4.

[0086] Table 1 Mechanical parameters of granite

[0087]

[0088] Table 2 Macroscopic parameters of rocks from indoor tests and numerical simulations

[0089]

[0090] Table 3. Parameters of Particles and Loading Plate

[0091]

[0092] Table 4 EBPM Bond Parameters

[0093]

[0094] 2. Calculation model and software settings

[0095] The model for water jet impacting rock uses a 40mm×40mm×18mm cuboid with a particle radius of 0.5mm and a porosity of 0.37. The rock particles are bonded using the EBPM bonding model. Particle parameters, as well as interparticle bonding, friction coefficient, and coefficient of restitution, are obtained through parameter calibration. A confining pressure of 20MPa is applied to the rock model to establish a high-pressure pure water continuous water jet rock-breaking model. Figure 6 As shown.

[0096] In the abrasive waterjet impact rock model, ignoring the different shapes of the abrasive particles, the abrasive particles are set as spheres with a radius of 0.2 mm and a particle density of 4000 kg / m³. 3 With Poisson's ratio set to 0.25 and shear modulus set to 17.7 GPa, the abrasive jet rock-breaking model is as follows: Figure 7 As shown in Table 5, the interaction coefficients between the abrasive, rock particles, and the wall are shown in Table 5.

[0097] Table 5 Interaction coefficients

[0098]

[0099] 3. Nozzle Model Establishment

[0100] The high-pressure water jet nozzle has a diameter of 2mm, uses a velocity inlet, and the nozzle wall is configured with a no-slip boundary condition, while the remaining wall surfaces are configured as pressure outlets. The velocity variations of the three high-pressure water jets over time are shown below. Figure 8 As shown, the jet velocities of the high-pressure pure water continuous jet (CWJ) and the abrasive water jet (AWJ) are both set to 632 m / s, and the peak jet velocity of the pulsed water jet (PWJ) is also set to 632 m / s, with a period of 30 μs.

[0101] 4. Experimental verification

[0102] To verify the accuracy of the simulation results, the jet velocity of the high-pressure water jet nozzle was set to 420 m / s based on the above model, and a numerical simulation of high-pressure water jet rock breaking was carried out. Figure 9 The simulation results demonstrate the failure modes of rocks under the fixed-point impact of high-pressure water jets; by comparing the simulation results with the failure modes obtained from experiments, the accuracy of the simulation results can be determined.

[0103] III. Implementation Results

[0104] 3.1 Analysis of Failure Mode

[0105] Rock breaking simulations were performed using high-pressure pure water continuous jet (CWJ), abrasive water jet (AWJ), and pulsed water jet (PWJ) respectively. The failure modes were analyzed, and the schematic diagram of rock failure mode after impact is shown in the figure. Figure 10 As shown.

[0106] 3.2 Load Analysis

[0107] Simulation results of the compressive stress zone generated in rocks after CWJ, PWJ, and AWJ impacts are as follows: Figure 11 As shown.

[0108] Using the central region of the rock particles in the water jet rock-breaking model as reference points, the compressive stress on these particles is analyzed. The compressive stress variation curves at the reference points of the three jet calculation models are shown below. Figure 12 As shown.

[0109] 3.3 Analysis of Broken Bonds

[0110] As the water jet continuously impacts the rock, the bonding bonds break down as follows: Figure 13 As shown.

[0111] 3.4 Analysis of the shape and size of erosion holes

[0112] In discrete element simulation, the size of the erosion holes in a high-pressure water jet rock-breaking model is measured by recording the displacement of particles. The sizes of the erosion holes obtained from three different jet impacts on the rock are shown below. Figure 14 As shown.

[0113] 3.5 Rock Surface Fracture Zone

[0114] The fracture zone produced by high-pressure water jet impact on the rock surface and the experimental results are compared. Figure 15 As shown.

Claims

1. A simulation method for abrasive waterjet rock breaking based on DEM-CFD coupling, characterized in that, The implementation steps are as follows: (1) Establish the liquid phase control equation for the simulation of abrasive water jet rock breaking; (2) Establish the solid phase control equation for the simulation of abrasive water jet rock breaking; (3) Establish a fluid-structure interaction algorithm for solid-liquid two-phase flow simulation of abrasive water jet rock breaking; (4) Perform discrete element modeling of rock for water jet rock breaking and calibrate the microscopic parameters of the bond bond; (5) Three jet methods were used to simulate water jet rock breaking: high pressure pure water continuous jet (CWJ), pulsed water jet (PWJ) and abrasive water jet (AWJ) to explore the rock breaking effect of water jet.

2. The method according to claim 1, characterized in that, The specific method for establishing the liquid phase control equations for simulating abrasive waterjet rock breaking is as follows: In the water jet rock breaking model, the DDPM (Dense Discrete Phase Model) model from the Euler multiphase flow model is used to handle the volume fraction of the particle phase and to perform numerical simulation calculations of solid-liquid two-phase flow. mass conservation equation: Momentum conservation equation: In the formula: α l It is the volume fraction of the fluid phase; ρ l It is the density of the fluid phase; It is the Hamiltonian operator; v l τ is the velocity of the fluid phase; p is the pressure shared by all phases; l is the stress-strain tensor of the fluid phase; g is the acceleration due to gravity. F pf It is the force exerted by particles on a fluid; The drag force model selected is Gidaspowmodel, and the drag force acting on the particle is: In the formula, d s It is the particle diameter of the solid phase; α s It is the volume fraction of the solid phase; K sl It is the fluid-structure interaction coefficient; When α l >0.8, fluid-structure interaction coefficient: in, When α l ≤0.8, fluid-structure exchange coefficient: in, Where: μ l It is the dynamic viscosity of the fluid phase; α l It is the volume fraction of the fluid phase.

3. The specific method for establishing the solid phase control equation for simulating abrasive waterjet rock breaking according to claim 1 is as follows: In the water jet rock-breaking model, the solid phase governing equations are derived as follows: In discrete element method (DEM) simulations, each particle has six degrees of freedom, which are divided into translational and rotational motions. Newton's second law is typically used to calculate the particle's acceleration, while the particle's velocity and displacement are obtained through numerical integration of the governing equations for its translational and rotational motions. Particle motion equations: In the formula: m is the particle mass; I is the particle moment of inertia; v is the particle linear velocity; ω is the particle angular velocity; F c It is the vector sum of the normal contact force and the tangential contact force; F d It is the drag force; g is the acceleration due to gravity; T c It is the contact torque caused by the contact force; Assuming the force on the particle remains constant within a time step, the linear velocity and angular velocity of the particle can be obtained by numerical integration based on the governing equations of its translational and rotational motions: Integrating the above equation, we can obtain the linear and angular displacements of the particles: u(t+Δt)=u(t)+v(t)Δt (12) θ(t+Δt)=θ(t)+ω(t)Δt (13) In the formula: u is the displacement produced by translational motion; θ is the displacement produced by rotational motion; The Edinburgh Bonded Particle Model (EBPM) accurately reflects the mechanical behavior of cemented materials. The EBPM model assumes that all particles are rigid spheres. Due to the spherical nature, there is only one contact point between any two particles. At the particle contact point, there are two types of contact: bonded contact and unbonded contact. At the bonded contact, the Timoshenko Beam Bonded-Contact Model (TBBM) is used. This model assumes that the particles are rigidly connected by a Timoshenko beam element, and the mechanical behavior of the bond follows the Timoshenko beam element theory. Each end of the bond shares the same six degrees of freedom with the particles. When two particles first come into contact or the bond breaks, the Hertz-Mindlin Contact Model (HMCM) is formed to describe the force-displacement relationship at the unbonded contact point.

4. The fluid-structure interaction algorithm for simulating solid-liquid two-phase flow in abrasive waterjet rock breaking, as described in claim 1, is as follows: In the water jet rock-breaking model, the DEM-CFD bidirectional coupling is completed through the FLUENT-EDEM interface. During the fluid-structure interaction calculation, the CFD software and the DEM software solve for fluid phase information and particle phase information separately, and the information is transmitted through the coupling interface to achieve coupling. At the beginning of the CFD-DEM coupling, the DEM is used to solve for information such as particle position and velocity in the coupled calculation domain through the particle contact force model and particle motion equation. The information is transmitted to the CFD software through the coupling interface to solve the Navier-Stokes mass conservation equation and momentum conservation equation. The DPM model is used to calculate the fluid pressure, drag force and velocity of each particle in the coupled calculation domain. The obtained information is used as the input parameters for the next iteration step, and the above process is repeated to finally obtain the dynamic characteristics of the flow field and particle motion.

5. The method for performing discrete element modeling of rock for water jet rock breaking according to claim 1, and for calibrating the microscopic parameters of the bonding bonds, is as follows: The discrete element modeling of the rock adopts the EBPM bonded particle model. The microscopic parameters of the bond are calibrated by uniaxial compression and Brazilian splitting tests to ensure that the macroscopic uniaxial compressive strength, tensile strength and elastic modulus are all within the error range.

6. The water jet rock-breaking simulation using three jet methods as described in claim 1—continuous pure water jet, pulsed water jet, and abrasive jet—is used to investigate the water jet rock-breaking effect. The specific method is as follows: Continuous pure water jet with constant velocity; pulsed water jet with square wave, fixed period, and 50% duty cycle; abrasive water jet with abrasive particles added to the continuous aqueous phase at a volume fraction of 20%–30%. The rock-breaking effect of the three jet types was quantitatively evaluated using the following indicators: final depth of the erosion hole, pressure-time curve at the impact point, total number of bond fractures, diameter and volume of the erosion hole, and area of ​​the surface fracture zone, and compared with indoor granite erosion tests.

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