CN111709148B - A discrete element numerical simulation method for hydraulic erosion damage of cohesive sandy soil - Google Patents

A discrete element numerical simulation method for hydraulic erosion damage of cohesive sandy soil Download PDF

Info

Publication number
CN111709148B
CN111709148B CN202010575284.2A CN202010575284A CN111709148B CN 111709148 B CN111709148 B CN 111709148B CN 202010575284 A CN202010575284 A CN 202010575284A CN 111709148 B CN111709148 B CN 111709148B
Authority
CN
China
Prior art keywords
hydraulic
aggregate
cohesive
model
strength
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CN202010575284.2A
Other languages
Chinese (zh)
Other versions
CN111709148A (en
Inventor
黄达
黄文波
裴向军
宋宜祥
岑夺丰
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hebei University of Technology
Original Assignee
Hebei University of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hebei University of Technology filed Critical Hebei University of Technology
Priority to CN202010575284.2A priority Critical patent/CN111709148B/en
Publication of CN111709148A publication Critical patent/CN111709148A/en
Application granted granted Critical
Publication of CN111709148B publication Critical patent/CN111709148B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2111/00—Details relating to CAD techniques
    • G06F2111/10—Numerical modelling
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Evolutionary Computation (AREA)
  • Geometry (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
  • Management, Administration, Business Operations System, And Electronic Commerce (AREA)

Abstract

本发明公开了一种粘性砂土水力侵蚀破坏的离散元数值模拟方法，包括建立初始计算空间区域和粘性砂土数值模型；数值模型的初始化和应力平衡；编制基于时间效应的强度退化准则线性粘结接触模型，用以模拟粘性砂土中骨料颗粒之间的粘土相；选择接触模型作为骨料颗粒之间接触的细观力学模型，再对接触模型的细观参数进行取值；通过直剪强度试验对数值模型进行校准；建立流场模拟粘性砂土的水力侵蚀破坏过程；获取水力侵蚀破坏试验数值模拟结果。本发明通过离散元模拟粘性砂土水力侵蚀破坏，简化了思路，在尽可能降低计算量、提高计算效率的情况下，可以在细观层面较为真实的模拟粘性砂土水力侵蚀破坏过程，观察和记录土颗粒的运移情况，结果准确。

Figure 202010575284

The invention discloses a discrete element numerical simulation method for the hydraulic erosion damage of cohesive sandy soil, which includes establishing an initial calculation space area and a cohesive sandy soil numerical model; initialization and stress balance of the numerical model; The contact model is used to simulate the clay phase between the aggregate particles in the cohesive sand; the contact model is selected as the meso-mechanical model of the contact between the aggregate particles, and then the meso-parameters of the contact model are valued; The shear strength test is used to calibrate the numerical model; the flow field is established to simulate the hydraulic erosion failure process of the cohesive sand; the numerical simulation results of the hydraulic erosion failure test are obtained. The present invention simulates the hydraulic erosion damage of viscous sand through discrete elements, which simplifies the thinking. Under the condition of reducing the calculation amount as much as possible and improving the calculation efficiency, the hydraulic erosion damage process of the viscous sand can be simulated more realistically at the mesoscopic level. The migration of soil particles was recorded, and the results were accurate.

Figure 202010575284

Description

Discrete element numerical simulation method for hydraulic erosion damage of cohesive sand
Technical Field
The invention relates to the field of geotechnical engineering soil body hydraulic erosion damage numerical simulation, in particular to a discrete element numerical simulation method for hydraulic erosion damage of cohesive sand soil.
Background
Human beings live in water by choice from ancient times, rivers breed civilizations of human beings, but human beings are benefited by rivers and are also troubled by disasters brought by the rivers. In order to resist the attack of river flooding, the flow path of human along river and river building embankment engineering is restricted in a set range. However, the potential problem of osmotic damage of the dikes and dams has a great safety hazard while benefiting mankind. In addition, China is also an area deeply affected by geological disasters such as landslides, and rainfall and reservoir water have the greatest influence on the landslides. Therefore, the research on the hydraulic erosion damage is of great significance in the aspects of bank and dam engineering or in the aspects of soil erosion, slope stability and other scientific problems.
When the hydraulic erosion damage of rock and soil mass is researched, the research cannot be completed by using an analytical method, and an experimental method and a numerical simulation calculation method are often adopted. Although the experimental research of seepage erosion can provide a large amount of precious research data, a large amount of manpower and material resources are needed, the experimental period is often quite long, the research efficiency is low, meanwhile, the variables are not easy to control, and errors are easily generated, so the obtained experimental result is often limited, and the relevant parameters for analyzing the seepage erosion damage can be obtained only by processing. In addition, the hydraulic erosion damage of the soil body often occurs in the soil body, the discovery and real-time observation and recording during experiments are not easy, the development process of the erosion damage and related parameters in the erosion process can be observed and recorded at any time through the numerical simulation method, and meanwhile, the numerical simulation method has good reproducibility, so that the numerical simulation method has great advantages in researching the hydraulic erosion damage.
As a complex bulk material, the soil body cannot be simply considered as a continuous medium due to the anisotropy on a microscopic structure and the randomness of a pore structure. The discrete element program can consider the structural randomness of the microscopic category, well consider the interaction among the microscopic particles, and truly reflect the migration and loss of the soil particles, so that the problem of infiltration erosion damage of the soil can be better simulated.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to solve the technical problem of providing a discrete element numerical simulation method for hydraulic erosion damage of cohesive sandy soil.
The technical scheme for solving the technical problem is to provide a discrete element numerical simulation method for hydraulic erosion damage of cohesive sandy soil, which is characterized by comprising the following steps of:
step 1, establishing an initial calculation space area and a cohesive sand numerical model;
step 2, initializing a numerical model and balancing stress;
step 3, compiling a time effect-based strength degradation criterion linear bonding contact model for simulating a clay phase among aggregate particles in the cohesive sand soil; the process of hydraulic erosion of the clay phase can be seen as a reduction in the cohesive strength of the contact pattern;
step 4, selecting a contact model as a mesoscopic mechanical model for contact between aggregate particles, and then taking values of mesoscopic parameters of the contact model;
step 5, calibrating the numerical model through a direct shear strength test;
step 6, establishing a flow field to simulate the hydraulic erosion damage process of the viscous sand;
and 7, obtaining a numerical simulation result of the hydraulic erosion damage test.
Compared with the prior art, the invention has the beneficial effects that: the invention simulates the cohesive sandy soil hydraulic erosion damage through the discrete elements, simplifies the thought, can simulate the cohesive sandy soil hydraulic erosion damage process relatively truly on a microscopical level under the conditions of reducing the calculated amount as much as possible and improving the calculation efficiency, observes and records the migration condition of soil particles, and has accurate result.
Drawings
FIG. 1 is a graph of the clay loss process of a true percolation attack in a prior art system;
FIG. 2 is a diagram of the cohesive sand hydraulic erosion damage process in the discrete element numerical model of the present invention;
FIG. 3 is a schematic view of an aggregate particle and its contact according to the present invention;
FIG. 4 is a diagram showing the actual dimensions of a test piece in example 1 of the present invention;
FIG. 5 is a graph of particle grading in accordance with example 1 of the present invention;
FIG. 6 is a schematic diagram of a numerical model of cohesive sand produced from three particle grading curves according to example 1 of the present invention;
FIG. 7 is a graph showing the results of the direct shear strength test in example 1 of the present invention;
FIG. 8 is a plot of the particle size distribution of the soil particles lost during the hydraulic erosion simulation of example 1 of the present invention:
FIG. 9 is a diagram illustrating the hole erosion process in example 1 of the present invention;
FIG. 10 is a hydraulic gradient-erosion rate graph of example 1 of the present invention.
Detailed Description
The present invention will be further described with reference to the following examples and accompanying drawings. The specific examples are only intended to illustrate the invention in further detail and do not limit the scope of protection of the claims of the present application.
The invention provides a discrete element numerical simulation method (short method) for hydraulic erosion damage of cohesive sand, which is characterized by comprising the following steps:
step 1, establishing an initial calculation space area and a cohesive sand numerical model (numerical model for short): generating a corresponding initial calculation space region based on PFC3D software; then, in the initial calculation space region, according to the gradation of the cohesive sandy soil aggregate phase to be simulated, spherical particles representing the aggregate phase are generated according to the sequence of the size range from large to small, so that the generation of the aggregate particles is realized, and the generation position is randomly selected, thereby obtaining a cohesive sandy soil numerical model;
the viscous sandy soil consists of sandy soil aggregate and clay phase wrapped around the aggregate; the aggregate particles and the clay phase are uniformly distributed in the numerical model, and the aggregate particles are wrapped by the clay phase;
step 2, initialization and stress balance of the numerical model: setting a gravity field and calculating and solving corresponding unbalanced force until the stress balance or average unbalanced force in the numerical model meets the set requirement;
step 3, compiling a time effect-based strength degradation criterion linear bonding contact model (contact model for short) by utilizing a Python language or a C + + language to simulate a clay phase among aggregate particles in the cohesive sand;
step 4, selecting a contact model in PFC3D software as a mesoscopic mechanical model for contact between aggregate particles, and then taking values of mesoscopic parameters of the contact model;
the mesoscopic parameters comprise strength degradation criterion based on time effect, linear bonding rigidity ratio, linear bonding modulus, linear bonding normal strength, linear bonding cohesion and the like;
step 5, calibrating the numerical model through a direct shear strength test: performing a direct shear strength test on the cohesive sand test piece indoors by adopting a direct shear apparatus, and acquiring a stress-strain curve and corresponding macroscopic mechanical parameters of the cohesive sand test piece for calibration of numerical simulation; when the shear strength of the numerical model and the error between the stress-strain curve and the indoor test result are within a set range, the obtained microscopic parameters are considered to be reasonable, and the constructed numerical model can truly reflect the actual macroscopic mechanical property of the numerical model;
step 6, establishing a flow field to simulate the hydraulic erosion damage process of the viscous sand: establishing a corresponding flow field through a CFD module coupled in the PFC3D, carrying out grid division, calculating the interaction force of fluid-aggregate particles, and simulating the hydraulic erosion damage process of the viscous sandy soil;
step 7, obtaining a numerical simulation result of the hydraulic erosion damage test: arranging a measuring ball to measure corresponding porosity; and obtaining the soil mass lost in the hydraulic erosion damage process, the particle size distribution of the aggregate particles, the erosion rate, the hydraulic tangential shear force among the aggregate particles and the like by traversing the aggregate particles in the numerical model.
Further, in the step 3, the aggregate is represented by spherical particles in the PFC3D, and the clay phase is represented by a contact model of the absence of solids among the aggregate particles; the process of hydraulic erosion of the clay phase can be regarded as a process of degradation of the cohesive strength between the aggregate particles, i.e. the hydraulic erosion process can be equivalently replaced by a reduction of the cohesive strength of the contact pattern (as shown in fig. 2).
In step 3, the adhesive strength of the contact model is determined by the following steps:
(1) determining the mass of the clay phase:
Mclay＝Mgrain*ξ (2)
in formula 2), MclayAnd MgrainRespectively representing the quality of a clay phase and an aggregate phase in the numerical model, and xi representing the proportion of the clay phase and the aggregate phase;
the clay phase surrounding each aggregate particle is proportional to the surface area of the aggregate particle, i.e.
Figure BDA0002551121980000031
In formula 3), mj_clayIs the mass of the clay phase around the aggregate particle j; r isjThe radius of the aggregate particles j is shown, and N is the total number of the aggregate particles in the numerical model;
(2) the introduction parameter λ represents the bond strength, which has the physical meaning of the bond strength provided per unit mass of clay, so that the total bond strength around the aggregate particle j is:
Figure BDA0002551121980000041
in formula 4), shear _ sjShear force between aggregate particles, tensile _ sjIs the tension between aggregate particles, lambdacohIs a cohesive strength coefficient, λtenIs the tensile strength coefficient; lambda, lambdacohAnd λtenThe value of (2) is obtained by the direct shear strength test in the step (5), so that the numerical model can reflect the macroscopic mechanical properties of the real viscous sand, such as the bonding strength, the internal friction angle and the like;
(3) there are several contacts around aggregate particle j that together make up the overall bond strength of the clay phase around aggregate particle j, where the bond strength of a single contact is expressed as:
Figure BDA0002551121980000042
in formula 5), CiAnd TiThe bonding strength of the contact i (shown in FIG. 3) between the aggregate particles j and kThe strength and the tensile strength of the steel,
Figure BDA0002551121980000043
and
Figure BDA0002551121980000044
the aggregate particles j and k, respectively.
The erosion rate of the cohesive sandy soil hydraulic erosion damage is approximately linear in relation to the hydraulic tangential shear force of the aggregate particle surface, and the correlation can be expressed as follows:
Figure BDA0002551121980000045
in the formula 1), a is an erosion rate per unit surface area (kg/m)2/s)；kerSurface erosion coefficient (s/m); tau is the hydraulic tangential shear force on the surface of the aggregate particles; tau iscCritical hydraulic tangential shear force; b is an empirical coefficient (usually taken approximately 1);
after the flow field of step 6 is applied to the numerical model, the degradation rate of the bonding strength of the contact model of step 3 can be obtained by the following formula:
Figure BDA0002551121980000051
in formula 6), rkIs the radius, τ, of the aggregate particle kjAnd τkThe hydraulic tangential shear force of the particle j and the particle k in the flow field is respectively.
In step 6, simulating the hydraulic erosion damage process of the viscous sandy soil as follows:
(1) initializing a CFD module of PFC3D, reading initial conditions, fluid parameters and CFD meshes, and calculating porosity and drag force;
(2) the PFC3D sends data to a CFD solver, the CFD solver calculates data such as fluid speed, pressure gradient, dynamic viscosity, density and porosity, and then the PFC3D solver reads corresponding data to the PFC 3D;
(3) calculating the hydraulic tangential shear force borne by each aggregate particle according to a control equation, and judging whether the hydraulic tangential shear force is greater than a critical hydraulic tangential shear force; if the hydraulic tangential shear force is larger than the critical hydraulic tangential shear force, the hydraulic erosion damage occurs, and the step 4) is carried out; if the hydraulic tangential shear force is less than or equal to the critical hydraulic tangential shear force, the time step is increased by one step, and the step 2) is returned for recalculation;
(4) judging whether particle loss exists in the numerical model, if the particle loss exists, increasing the time step by one step, and returning to the step 2) to continue calculation; if no particle loss or hydraulic erosion has not occurred, the procedure is ended.
In step 6, in order to improve the calculation efficiency, shorten the calculation time, and ensure the simulation accuracy, the selection criteria of the time step in the numerical simulation process are as follows:
Figure BDA0002551121980000052
in formula 7), Δ tmin、Δtmid、ΔtmaxAnd Δ t represents a minimum time step, an intermediate time step, a maximum time step, and an actual time step, respectively; rlow、RhighAnd RuRespectively representing the ratio of the low-level unbalanced force, the high-level unbalanced force and the actual maximum unbalanced force in the numerical model.
Example 1
In this embodiment, the size of the sample for the cavitation erosion test is 112mm × 224mmm × 112mm (as shown in FIG. 4), and a cavity with a diameter of 20mm is present in the middle.
In step 1, respective cohesive sand numerical models are generated according to the aggregate phase grading curve shown in fig. 5, and as shown in fig. 6, three cohesive sand numerical models are generated from left to right for grading curves with fractal dimensions D of 1.7, 2.0 and 2.5, respectively;
in step 4, the mesoscopic parameters comprise strength degradation criterion based on time effect, linear bonding rigidity ratio, linear bonding modulus, linear bonding normal strength and linear bonding normal strengthCohesion and the like, and the specific parameters are as follows: the density of aggregate particles is 2500kg/m3Contact modulus of aggregate particles Ec＝1.0×107Pa, linear bond modulus Eb＝1.0×107Pa, linear bond stiffness ratio kn/ksWhen the ratio of the clay to the specific surface area is 1.0, the ratio ζ of the clay phase is 0.3, the coefficient b of the bonding radius range is 1.0, and the coefficient l of the linear bonding strength iscoh、lten＝2.0×104N/kg, fluid density 1000kg/m3Hydrodynamic viscosity μf＝0.001Pa·s；
In step 5, the direct shear strength test result is shown in fig. 7, the shear strength of the numerical model and the error between the stress-strain curve and the indoor test result are within the set range, the obtained microscopic parameters are reasonable, and the constructed numerical model can truly reflect the actual macroscopic mechanical property of the numerical model.
In step 7, taking the particle size distribution with fractal dimension D of 1.7 as an example, the soil mass lost in the hydraulic erosion damage process and the particle size distribution of aggregate particles obtained by traversing the aggregate particles in the numerical model are shown in fig. 8, the pore erosion development process is shown in fig. 9, and the erosion rate is shown in fig. 10.
In this embodiment, Δ tmin＝1.0×10-3s，Δtmid＝1s，Δtmax＝500s，Rlow＝5×10-4，Rhigh＝5×10-3。
Nothing in this specification is said to apply to the prior art.

Claims (7)

1.一种粘性砂土水力侵蚀破坏的离散元数值模拟方法，其特征在于该方法包括以下步骤：1. a discrete element numerical simulation method of viscous sandy soil hydraulic erosion damage is characterized in that the method comprises the following steps: 步骤1、在孔洞侵蚀试验中生成初始计算空间区域；然后在初始计算空间区域内，根据所要模拟的粘性砂土骨料相的级配D＝1.4、1.5、1.6、1.7、1.8、1.9、2.0、2.1、2.3、2.5和2.7，按照粒径范围先大后小的顺序生成代表骨料相的球体颗粒，并随机选择产生位置，从而得到分形维数D＝1.7、2.0和2.5的级配曲线生成的三个粘性砂土数值模型；Step 1. Generate an initial calculation space area in the cavity erosion test; then in the initial calculation space area, according to the gradation of the cohesive sand aggregate phase to be simulated D = 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 , 2.1, 2.3, 2.5 and 2.7, the spherical particles representing the aggregate phase are generated according to the order of the particle size range, and the generation position is randomly selected to obtain the gradation curves of fractal dimension D=1.7, 2.0 and 2.5 Three numerical models of cohesive sand are generated; 步骤2、数值模型的初始化和应力平衡；Step 2. Initialization of the numerical model and stress balance; 步骤3、编制基于时间效应的强度退化准则线性粘结接触模型，用以模拟粘性砂土中骨料颗粒之间的粘土相；粘土相的水力侵蚀过程可视为接触模型的粘结强度的减小；Step 3. Compile a linear bond contact model based on the strength degradation criterion based on time effect to simulate the clay phase between the aggregate particles in the cohesive sand; the hydraulic erosion process of the clay phase can be regarded as the reduction of the bond strength of the contact model. Small; 步骤4、选择接触模型作为骨料颗粒之间接触的细观力学模型，再对接触模型的细观参数进行取值；Step 4. Select the contact model as the meso-mechanical model of the contact between the aggregate particles, and then select the meso-parameters of the contact model; 细观参数包括基于时间效应的强度退化准则、线性粘结刚度比、线性粘结模量、线性粘结法向强度和线性粘结内聚力；骨料颗粒密度为2500kg/m3，骨料颗粒接触模量Ec＝1.0×107Pa，线性粘结模量Eb＝1.0×107Pa，线性粘结刚度比kn/ks＝1.0，粘土相比例ζ＝0.3，粘结半径范围系数b＝1.0，线性粘结强度系数lcoh、lten＝2.0×104N/kg，流体密度为1000kg/m3，流体动力粘度μf＝0.001Pa·s；The meso parameters include strength degradation criterion based on time effect, linear bond stiffness ratio, linear bond modulus, linear bond normal strength and linear bond cohesion; the aggregate particle density is 2500kg/m 3 , the aggregate particle contact Modulus E c =1.0×10 7 Pa, linear bond modulus E b =1.0×10 7 Pa, linear bond stiffness ratio k n /ks =1.0, clay phase ratio ζ=0.3, bond radius range factor b=1.0, linear bond strength coefficients l coh , l ten =2.0×10 4 N/kg, fluid density is 1000kg/m 3 , fluid dynamic viscosity μ f =0.001Pa·s; 步骤5、通过直剪强度试验对数值模型进行校准；Step 5. Calibrate the numerical model through the direct shear strength test; 步骤6、建立流场模拟粘性砂土的水力侵蚀破坏过程；Step 6. Establish a flow field to simulate the hydraulic erosion and damage process of cohesive sand; 时间步的选择标准如下：The selection criteria for time steps are as follows:
Figure FDA0002943960870000011
Figure FDA0002943960870000011
 式7)中，Δtmin、Δtmid、Δtmax和Δt分别表示最小时间步长、中等时间步长、最大时间步长和实际时间步长；Rlow、Rhigh和Ru分别表示数值模型中低水平不平衡力比值、高水平不平衡力比值和实际最大不平衡力比值；Δtmin＝1.0×10-3s，Δtmid＝1s，Δtmax＝500s，Rlow＝5×10-4，Rhigh＝5×10-3；In Equation 7), Δt min , Δt mid , Δt max and Δt represent the minimum time step, medium time step, maximum time step and actual time step, respectively; R low , R high and R u respectively represent the Low level unbalance force ratio, high level unbalance force ratio and actual maximum unbalance force ratio; Δt min = 1.0×10 -3 s, Δt mid = 1s, Δt max = 500s, R low = 5×10 -4 , R high = 5×10 −3 ; 步骤7、获取水力侵蚀破坏试验数值模拟结果；在分形维数D＝1.7的颗粒级配中，布设测量球测量相应的孔隙率；通过遍历数值模型中的骨料颗粒得到水力侵蚀破坏过程中损失的土体质量、骨料颗粒粒径分布、侵蚀速率和颗粒间的水力切向剪切力；平均侵蚀速率q＝1.8424×103.2106i-6.3297，其中i为水力梯度。Step 7. Obtain the numerical simulation results of the hydraulic erosion damage test; in the particle gradation with fractal dimension D=1.7, a measuring ball is arranged to measure the corresponding porosity; the loss in the process of hydraulic erosion damage is obtained by traversing the aggregate particles in the numerical model The soil mass, aggregate particle size distribution, erosion rate and hydraulic tangential shear force between particles; average erosion rate q=1.8424×10 3.2106i -6.3297, where i is the hydraulic gradient. 2.根据权利要求1所述的粘性砂土水力侵蚀破坏的离散元数值模拟方法，其特征在于步骤2具体是：通过设置重力场并计算求解相应的不平衡力，直至数值模型内部的应力平衡或平均不平衡力达到设置要求。2. the discrete element numerical simulation method of viscous sandy soil hydraulic erosion damage according to claim 1 is characterized in that step 2 is specifically: by setting gravity field and calculating and solving corresponding unbalanced force, until the stress balance inside the numerical model Or the average unbalanced force reaches the set requirement. 3.根据权利要求1所述的粘性砂土水力侵蚀破坏的离散元数值模拟方法，其特征在于步骤3中，接触模型的粘结强度通过以下步骤确定：3. the discrete element numerical simulation method of viscous sandy soil hydraulic erosion damage according to claim 1 is characterized in that in step 3, the bond strength of the contact model is determined by the following steps: (1)确定粘土相质量：(1) Determine the quality of the clay phase: Mclay＝Mgrain*ξ (2)M clay =M grain *ξ (2) 式2)中，Mclay和Mgrain分别表示数值模型中粘土相和骨料相的质量，ξ表示粘土相和骨料相的比例；In formula 2), M clay and M grain represent the mass of clay phase and aggregate phase in the numerical model, respectively, and ξ represents the ratio of clay phase and aggregate phase; 每个骨料颗粒周围包裹的粘土相与骨料颗粒表面积成比例，即The clay phase surrounding each aggregate particle is proportional to the aggregate particle surface area, i.e.
Figure FDA0002943960870000021
Figure FDA0002943960870000021
 式3)中，mj_clay为骨料颗粒j周围的粘土相质量；rj为骨料颗粒j的半径，N为数值模型中的骨料颗粒总数；In formula 3), m j_clay is the mass of the clay phase around the aggregate particle j; r j is the radius of the aggregate particle j, and N is the total number of aggregate particles in the numerical model; (2)引入参数λ表示粘结强度，其物理意义为每单位质量的粘土所提供的粘结强度，则骨料颗粒j周围的总粘结强度为：(2) The parameter λ is introduced to represent the bond strength, and its physical meaning is the bond strength provided by each unit mass of clay, then the total bond strength around the aggregate particle j is:
Figure FDA0002943960870000022
Figure FDA0002943960870000022
 式4)中，shear_sj为骨料颗粒间剪切力，tensile_sj为骨料颗粒间拉力，λcoh为粘聚力强度系数，λten为拉力强度系数；λ、λcoh和λten由步骤5中的直剪强度试验获得；In formula 4), shear_s j is the shear force between aggregate particles, tension_s j is the tensile force between aggregate particles, λ coh is the cohesion strength coefficient, λ ten is the tensile strength coefficient; λ, λ coh and λ ten are determined by the step The direct shear strength test in 5 is obtained; (3)骨料颗粒j周围有若干个接触，共同组成骨料颗粒j周围粘土相的总粘结强度，其中单个接触的粘结强度表示为：(3) There are several contacts around the aggregate particle j, which together form the total bond strength of the clay phase around the aggregate particle j, where the bond strength of a single contact is expressed as:
Figure FDA0002943960870000023
Figure FDA0002943960870000023
 式5)中，Ci和Ti分别为骨料颗粒j和骨料颗粒k之间接触i的粘结强度和抗拉强度，
Figure FDA0002943960870000031
和
Figure FDA0002943960870000032
分别为骨料颗粒j和骨料颗粒k的总接触。In formula 5), C i and T i are the bond strength and tensile strength of the contact i between the aggregate particle j and the aggregate particle k, respectively,
Figure FDA0002943960870000031
and
Figure FDA0002943960870000032
are the total contact of aggregate particles j and aggregate particles k, respectively. 4.根据权利要求3所述的粘性砂土水力侵蚀破坏的离散元数值模拟方法，其特征在于粘性砂土水力侵蚀破坏的侵蚀速率与骨料颗粒表面的水力切向剪切力的关系如下：4. the discrete element numerical simulation method of cohesive sandy soil hydraulic erosion damage according to claim 3, it is characterized in that the relation between the erosion rate of cohesive sandy soil hydraulic erosion damage and the hydraulic tangential shear force of aggregate particle surface is as follows:
Figure FDA0002943960870000033
Figure FDA0002943960870000033
 式1)中，a为单位表面积的侵蚀速率；ker为表面侵蚀系数；τ为骨料颗粒表面的水力切向剪切力；τc为临界水力切向剪切力；b为经验系数；In formula 1), a is the erosion rate per unit surface area; ker is the surface erosion coefficient; τ is the hydraulic tangential shear force on the surface of the aggregate particle; τ c is the critical hydraulic tangential shear force; b is the empirical coefficient; 当步骤6的流场作用于数值模型后，步骤3的接触模型粘结强度的退化速率可由下式获得：When the flow field in step 6 acts on the numerical model, the degradation rate of the bond strength of the contact model in step 3 can be obtained by the following formula:
Figure FDA0002943960870000034
Figure FDA0002943960870000034
 式6)中，rk为骨料颗粒k的半径，τj和τk分别为骨料颗粒j和骨料颗粒k在流场中所受的水力切向剪切力。In formula 6), r k is the radius of the aggregate particle k, and τ j and τ k are the hydraulic tangential shear force of the aggregate particle j and the aggregate particle k in the flow field, respectively. 5.根据权利要求1所述的粘性砂土水力侵蚀破坏的离散元数值模拟方法，其特征在于步骤5具体是：在室内对粘性砂土试件进行直剪强度试验，并获取其应力-应变曲线及相应的宏观力学参数；当数值模型的抗剪强度以及应力-应变曲线与室内试验结果的误差在设定范围以内，则所取细观参数合理，所构建的数值模型可以真实反映其实际宏观力学性能。5. the discrete element numerical simulation method of the hydraulic erosion damage of cohesive sand soil according to claim 1, it is characterized in that step 5 is specifically: carry out direct shear strength test to cohesive sand soil test piece indoors, and obtain its stress-strain curve and the corresponding macro-mechanical parameters; when the shear strength of the numerical model and the error between the stress-strain curve and the laboratory test results are within the set range, the meso-parameters taken are reasonable, and the constructed numerical model can truly reflect the actual Macro mechanical properties. 6.根据权利要求1所述的粘性砂土水力侵蚀破坏的离散元数值模拟方法，其特征在于步骤6具体是：建立相应的流场并进行网格划分，计算流体-骨料颗粒的相互作用力，模拟粘性砂土的水力侵蚀破坏过程。6. The discrete element numerical simulation method of viscous sandy soil hydraulic erosion damage according to claim 1, is characterized in that step 6 is specifically: establish corresponding flow field and carry out grid division, calculate the interaction of fluid-aggregate particle force to simulate the hydraulic erosion failure process of cohesive sandy soil. 7.根据权利要求1或6所述的粘性砂土水力侵蚀破坏的离散元数值模拟方法，其特征在于步骤6中，粘性砂土的水力侵蚀破坏过程模拟如下：7. the discrete element numerical simulation method of cohesive sandy soil hydraulic erosion damage according to claim 1 and 6 is characterized in that in step 6, the hydraulic erosion damage process of cohesive sandy soil is simulated as follows: (1)初始化PFC3D的CFD模块，读取初始条件，流体参数和CFD网格，计算孔隙度和拖拽力；(1) Initialize the CFD module of PFC3D, read initial conditions, fluid parameters and CFD grids, and calculate porosity and drag force; (2)PFC3D发送数据到CFD求解器，CFD求解器计算流体速度、压力梯度、动力粘度、密度和孔隙率等数据，然后PFC3D求解器读取相应的数据至PFC3D中；(2) PFC3D sends data to the CFD solver, the CFD solver calculates data such as fluid velocity, pressure gradient, dynamic viscosity, density and porosity, and then the PFC3D solver reads the corresponding data into PFC3D; (3)根据控制方程计算每个骨料颗粒所受水力切向剪切力，并判断水力切向剪切力是否大于临界水力切向剪切力；若水力切向剪切力＞临界水力切向剪切力，则水力侵蚀破坏发生，进入步骤4)；若水力切向剪切力≤临界水力切向剪切力，则时间步增加一步，返回步骤2)重新计算；(3) Calculate the hydraulic tangential shear force on each aggregate particle according to the control equation, and judge whether the hydraulic tangential shear force is greater than the critical hydraulic tangential shear force; if the hydraulic tangential shear force > the critical hydraulic shear force If the hydraulic tangential shear force is less than or equal to the critical hydraulic tangential shear force, then the time step increases by one step, and returns to step 2) for recalculation; (4)判断数值模型中是否存在颗粒损失，若有颗粒损失则时间步增加一步，返回步骤2)继续计算；若无颗粒损失或水力侵蚀未发生则结束程序。(4) Determine whether there is particle loss in the numerical model, if there is particle loss, increase the time step by one step, and return to step 2) to continue the calculation; if there is no particle loss or hydraulic erosion occurs, end the program.
CN202010575284.2A 2020-06-22 2020-06-22 A discrete element numerical simulation method for hydraulic erosion damage of cohesive sandy soil Expired - Fee Related CN111709148B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010575284.2A CN111709148B (en) 2020-06-22 2020-06-22 A discrete element numerical simulation method for hydraulic erosion damage of cohesive sandy soil

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010575284.2A CN111709148B (en) 2020-06-22 2020-06-22 A discrete element numerical simulation method for hydraulic erosion damage of cohesive sandy soil

Publications (2)

Publication Number Publication Date
CN111709148A CN111709148A (en) 2020-09-25
CN111709148B true CN111709148B (en) 2021-04-06

Family

ID=72541696

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010575284.2A Expired - Fee Related CN111709148B (en) 2020-06-22 2020-06-22 A discrete element numerical simulation method for hydraulic erosion damage of cohesive sandy soil

Country Status (1)

Country Link
CN (1) CN111709148B (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113075106B (en) * 2021-03-26 2022-11-11 桂林理工大学 A method for determining hydraulic parameters and water inflow in the erosion stage of gravel soil
CN113221476B (en) * 2021-04-23 2024-04-09 湘潭大学 Concrete flow behavior prediction method based on discrete elements
CN113191004B (en) * 2021-05-09 2022-08-30 甘肃省地震局 Method for calculating internal rigidity of loess soil body
CN113221431B (en) * 2021-05-14 2022-05-06 湖北理工学院 Numerical simulation method of compression permeability test based on particle discrete element and lattice Boltzmann
CN113237722B (en) * 2021-05-26 2022-04-22 中国水利水电科学研究院 Soil internal erosion deformation response simulation method
CN113720992B (en) * 2021-07-12 2022-08-02 河海大学 A method of simulating the effect of rainfall on rock and soil mass by using the raindrop method
CN113569398B (en) * 2021-07-19 2024-09-03 湖南农业大学 Grouting process simulation method, grouting process simulation system and readable storage medium

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102799713A (en) * 2012-06-26 2012-11-28 武汉大学 Numerical simulation method for hydraulic fracture of core wall of rock-fill dam
CN108009363A (en) * 2017-12-04 2018-05-08 中铁二院工程集团有限责任公司 A kind of mud-rock flow washes away the computational methods of bridge pier
CN108088982A (en) * 2018-01-20 2018-05-29 上海交通大学 Simulate the Experimental Method in Laboratory of fine grained seepage inflow erosion inside deep aquifers sand
CN109344482A (en) * 2018-09-21 2019-02-15 河北工业大学 A numerical simulation method for aging degradation of carbonate rock mechanical properties under water action
CN109446706A (en) * 2018-11-09 2019-03-08 西南石油大学 A kind of method that determining pulse fiber sand fracturing support bolus lays form

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110006714A (en) * 2019-01-25 2019-07-12 绍兴文理学院 A kind of sample making apparatus for the three axis samples that simulation overall process corrodes

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102799713A (en) * 2012-06-26 2012-11-28 武汉大学 Numerical simulation method for hydraulic fracture of core wall of rock-fill dam
CN108009363A (en) * 2017-12-04 2018-05-08 中铁二院工程集团有限责任公司 A kind of mud-rock flow washes away the computational methods of bridge pier
CN108088982A (en) * 2018-01-20 2018-05-29 上海交通大学 Simulate the Experimental Method in Laboratory of fine grained seepage inflow erosion inside deep aquifers sand
CN109344482A (en) * 2018-09-21 2019-02-15 河北工业大学 A numerical simulation method for aging degradation of carbonate rock mechanical properties under water action
CN109446706A (en) * 2018-11-09 2019-03-08 西南石油大学 A kind of method that determining pulse fiber sand fracturing support bolus lays form

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
"A DEM-based approach for modeling the evolution process of seepage-induced erosion in clayey sand";Dong Ming Gu et al.;《Acta Geotechnica》;20190619;1629-1640页 *
"Development of a DEM-Based Method for Modeling the Water-Induced Failure Process of Rock from Laboratory to Engineering-Scale";Xuecheng Gao et al.;《ASCE》;20200417;1-13页 *
"富水砂层中隧道渗蚀灾害的初步细观模拟分析";龙莹莹 等;《现代隧道技术》;20181115;501-508页 *

Also Published As

Publication number Publication date
CN111709148A (en) 2020-09-25

Similar Documents

Publication Publication Date Title
CN111709148B (en) A discrete element numerical simulation method for hydraulic erosion damage of cohesive sandy soil
Salgado et al. Shear strength and stiffness of silty sand
Guoxing et al. Experimental investigation on fluid characteristics of medium dense saturated fine sand in pre-and post-liquefaction
Yang et al. Cavity expansion in unsaturated soils exhibiting hydraulic hysteresis considering three drainage conditions
Shahir et al. Employing a variable permeability model in numerical simulation of saturated sand behavior under earthquake loading
CN112485106B (en) Physical model layered preparation and test method for controlling soil body state parameters
Alnuaim et al. Performance of micropiled raft in clay subjected to vertical concentrated load: Centrifuge modeling
Matsumaru et al. Three-phase seepage-deformation coupled analysis about unsaturated embankment damaged by earthquake
CN111553098A (en) A method and device for numerical simulation of seepage failure type inrush water process
Park et al. Laboratory Experiment and Numerical Analysis on the Precursory Hydraulic Process of Rainfall‐Induced Slope Failure
Grabe et al. Coupled deformation–seepage analysis of dynamic capacity tests on open-ended piles in saturated sand
Kato et al. Numerical evaluation of liquefaction resistance for desaturated sands
Malekmakan et al. Investigation of liquefaction‐induced lateral spreading of gently sloping grounds using a variable permeability model
Abo-Youssef et al. Numerical modelling of passive loaded pile group in multilayered soil
Yin et al. Non‐uniqueness of critical state line in compression and extension conditions
Trinh Coupled and uncoupled approaches for the estimation of 1-d heave in expansive soils due to transient rainfall infiltration: a case study in central Vietnam
CN114638178A (en) A discrete element-based simulation method for the migration of loose sandstone particles
CN113761764A (en) DEM-CFD coupling control simulation method for compaction grouting process
CN113011062A (en) Transformer substation foundation treatment numerical simulation analysis method
Tafreshi et al. Cyclic loading on foundation to evaluate the coefficient of elastic uniform compression of sand
CN116705185A (en) Method for determining relevant parameters of density of rock-fill material of earth-rock dam by additional mass method
Fredlund The practice of unsaturated soil mechanics
Bouckovalas et al. Kinematic interaction of piles in laterally spreading ground
Rojas et al. Simulating undrained tests on unsaturated soils
Ding et al. Friction anlysis of large diameter steel cylinder penetration process using 3D-DEM

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CF01 Termination of patent right due to non-payment of annual fee
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20210406