CN117113517B

CN117113517B - Precast pile foundation pit supporting particle flow numerical simulation method and system

Info

Publication number: CN117113517B
Application number: CN202311372485.2A
Authority: CN
Inventors: 刘永超; 刘洁; 宋晓光; 李刚; 张阳; 陆鸿宇; 孙友为; 王玉琢
Original assignee: TIANJIN JIANCHENG JIYE GROUP CO Ltd
Current assignee: TIANJIN JIANCHENG JIYE GROUP CO Ltd
Priority date: 2023-10-23
Filing date: 2023-10-23
Publication date: 2024-01-23
Anticipated expiration: 2043-10-23
Also published as: CN117113517A

Abstract

The embodiment of the invention provides a precast pile foundation pit supporting particle flow numerical simulation method and system, wherein a precast pile foundation scheme is obtained, and a simulation target is determined according to the precast pile foundation scheme; establishing a macroscopic continuous medium model and a microscopic discrete particle model based on the simulation target; coupling the macroscopic continuous medium model and the microscopic discrete particle model to obtain a particle flow numerical simulation model; determining initial parameters according to the prefabricated pile foundation scheme; the initial parameters are input into the particle flow numerical simulation model to obtain a particle flow motion state, the behavior of the particle flow in the foundation pit supporting process of the precast pile can be more accurately simulated and predicted by establishing the coupling of the macroscopic continuous medium model and the microscopic discrete particle model, and the behavior of the particle flow can be obtained by inputting the behavior into the numerical simulation model, so that an important reference basis is provided for the design and construction of a foundation pit supporting scheme of the precast pile.

Description

Precast pile foundation pit supporting particle flow numerical simulation method and system

Technical Field

The invention relates to the technical field of mathematical modeling, in particular to a precast pile foundation pit supporting particle flow numerical simulation method and system.

Background

The precast pile foundation pit supporting particle flow numerical simulation is a technology for performing numerical simulation on the particle flow behavior in the precast pile foundation pit supporting process by using a computer simulation method. By establishing a mathematical model based on a physical mechanics principle, a mathematical equation of the model is solved by adopting a numerical calculation method, and the motion and deformation rule of the particle flow in the foundation pit supporting process of the precast pile is simulated. The precast pile foundation pit supporting particle flow numerical simulation can optimize the design scheme, reduce engineering risks, improve construction efficiency and have important engineering application value.

The simulation method can consider various mechanical factors such as the friction force among particles, the interaction force between the particles and the supporting structure, the shape and physical properties of the particles and the like. By adjusting model parameters and boundary conditions, the movement and deformation process of the particle flow under different conditions can be simulated, the stability and deformation condition of the supporting structure can be predicted, and references and guidance can be provided for engineering design and construction.

However, the particle flow simulation needs to consider the mutual coupling of various physical processes, such as the movement, deformation, interaction with a supporting structure and the like of particles, which involves the cross problem of a plurality of physical fields, has great modeling difficulty and can not provide accurate data for subsequent construction operations.

Disclosure of Invention

The embodiment of the invention provides a precast pile foundation pit supporting particle flow numerical simulation method and system, which can at least solve the problems that in the prior art, the particle flow simulation needs to consider the mutual coupling of a plurality of physical processes and the modeling difficulty is large.

In a first aspect, an embodiment of the present invention provides a method for numerically simulating a particle flow of a foundation pit support of a precast pile, including:

obtaining a prefabricated pile foundation scheme, and determining a simulation target according to the prefabricated pile foundation scheme;

establishing a macroscopic continuous medium model and a microscopic discrete particle model based on the simulation target;

coupling the macroscopic continuous medium model and the microscopic discrete particle model to obtain a particle flow numerical simulation model;

determining initial parameters according to the prefabricated pile foundation scheme;

and inputting the initial parameters into the particle flow numerical simulation model to obtain a particle flow motion state.

Optionally, the step of establishing a macroscopic continuous medium model and a microscopic discrete particle model based on the simulation target comprises:

establishing a macroscopic continuous medium model according to the simulation target to describe the macroscopic motion state of the particle flow, wherein the macroscopic continuous medium model has the following expression:

； (1)

； (2)

Where ρ is the density of the fluid, u is the velocity vector of the fluid, t is the time,is a gradient operator, σ is a stress tensor, g is a gravitational acceleration;

establishing a microscopic discrete particle model according to the simulation target to describe microscopic interaction among particles, wherein the expression of the microscopic discrete particle model is as follows:

F _ij = kn·δn _ij + ks·δs _ij +μ·Fn _ij ·δs _ij ； (3)

wherein F is _ij Is the interaction force between particles i and j, kn and ks are the normal and tangential spring constants between particles δn _ij And δs _ij Is the normal and tangential displacement between particles i and j, μ is the coefficient of friction between particles,Fn _ij is the normal contact force between particle i and particle j.

Optionally, the pre-pile foundation scheme includes a particle flow domain and a particle flow value corresponding to the particle flow domain, and the step of coupling the macroscopic continuous medium model and the microscopic discrete particle model to obtain a particle flow numerical simulation model includes:

dividing the particle basin into a macro grid and a micro grid;

solving the macroscopic continuous medium model on the macroscopic grid based on the particle flow value to obtain a macroscopic solution;

solving the microscopic discrete particle model on the microscopic grid based on the particle flow value to obtain a microscopic solution;

And taking the macroscopic solution as the input of the microscopic discrete particle model, and taking the microscopic solution as the input of the macroscopic continuous medium model to obtain the particle flow numerical simulation model.

Optionally, the step of solving the macroscopic continuous medium model on the macroscopic grid based on the particle flow value to obtain a macroscopic solution includes:

on the macro grid, the equation (3) is solved by using a numerical method, namely, the expression of the discrete form macro continuous medium model is as follows:

M(du/dt) + K·U = f； (4)

where M is the mass matrix of the fluid, t is the time, K is the stiffness matrix of the fluid, U is the vector of the velocity field, and f is the external force vector.

Optionally, the step of obtaining the particle flow numerical simulation model by taking the macroscopic solution as an input of the microscopic discrete particle model and taking the microscopic solution as an input of the macroscopic continuous medium model includes:

interpolating a velocity field of a macroscopic solution onto the microscopic mesh as one of the inputs to the discrete particle model;

calculating the movement and interaction force of particles on the micro grid by using a discrete element method, calculating the interaction force between the particles by using a formula (3), and updating the displacement of the particles;

Interpolating the particle displacement and interaction force on the micro grid onto the macro grid as one of the source items of the macro continuous medium model;

solving an equation of the macroscopic continuous medium model on the macroscopic grid, and calculating an external force vector according to a formula (4) by using a velocity field on the macroscopic grid and particle displacement and interaction force obtained by interpolation;

updating a speed field on the macro grid according to the equation solving result of the macro continuous medium model;

repeating the steps until the coupling solution between the macro grid and the micro grid converges, and obtaining the particle flow numerical simulation model.

Optionally, the step of updating the velocity field on the macro grid according to the equation solution to the macro continuous medium model includes:

calculating an equation solving result of the macroscopic continuous medium model based on a weighted average algorithm to update a speed field on the macroscopic grid, wherein the weighted average algorithm expression is as follows:

v _micro = ∑(w _i · v _macro i) / ∑w _i ； (5)

wherein v is _micro Representing velocity field values, v, on the macro grid _macro i represents the velocity field value, w, of the adjacent node on the macro grid _i Representing weights of the corresponding nodes, the weights being determined from the mass and distance of the discrete particle model.

Optionally, the step of inputting the initial parameters into the particle flow numerical simulation model to obtain a particle flow motion state includes:

inputting the initial parameters into a particle flow numerical simulation model, and performing iterative computation to obtain a coupling solution between the macroscopic continuous medium model and the microscopic discrete particle model;

and in each step of iteration, updating the particle flow motion state according to the coupling solution until a preset iteration stopping condition is reached.

In a second aspect, the embodiment of the invention further provides a precast pile foundation pit supporting particle flow numerical simulation system, which comprises:

the acquisition module is used for acquiring a prefabricated pile foundation scheme and determining a simulation target according to the prefabricated pile foundation scheme;

the establishing module is used for establishing a macroscopic continuous medium model and a microscopic discrete particle model based on the simulation target;

the coupling module is used for coupling the macroscopic continuous medium model and the microscopic discrete particle model to obtain a particle flow numerical simulation model;

the determining module is used for determining initial parameters according to the prefabricated pile foundation scheme;

and the output module is used for inputting the initial parameters into the particle flow numerical simulation model to obtain the particle flow motion state.

In a third aspect, an embodiment of the present invention further provides an electronic device, including a memory and a processor, where the memory stores a computer program, and the processor is configured to run the computer program to execute the precast pile foundation pit supporting particle stream numerical simulation method according to any one of the first aspect.

In a fourth aspect, an embodiment of the present invention further provides a readable storage medium, where a computer program is stored, where the computer program includes program code for controlling a process to execute a process, where the process includes any one of the precast pile foundation pit supporting particle stream numerical simulation methods according to the first aspect

According to the embodiment of the invention, the precast pile foundation scheme is obtained, and the simulation target is determined according to the precast pile foundation scheme; establishing a macroscopic continuous medium model and a microscopic discrete particle model based on the simulation target; coupling the macroscopic continuous medium model and the microscopic discrete particle model to obtain a particle flow numerical simulation model; determining initial parameters according to the prefabricated pile foundation scheme; the initial parameters are input into the particle flow numerical simulation model to obtain a particle flow motion state, the behavior of the particle flow in the precast pile foundation pit supporting process can be more accurately simulated and predicted by establishing the coupling of the macroscopic continuous medium model and the microscopic discrete particle model, the behavior of the particle flow can be obtained by inputting the behavior into the numerical simulation model, an important reference basis is provided for the design and construction of a precast pile foundation pit supporting scheme, and meanwhile, the method can simulate and analyze according to different precast pile foundation schemes and has higher applicability and flexibility.

The beneficial effects of the embodiments of the present invention may refer to technical effects corresponding to technical features in the specific implementation manner, and are not described herein.

Drawings

Fig. 1 is a flow chart of a numerical simulation method for a precast pile foundation pit supporting particle flow provided by an embodiment of the invention;

fig. 2 is a flow chart of another numerical simulation method for a precast pile foundation pit supporting particle flow provided by the embodiment of the invention;

fig. 3 is a schematic diagram of a precast pile foundation pit supporting particle flow numerical simulation system according to an embodiment of the present invention.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The technical scheme of the invention is described in detail below by specific examples. The following embodiments may be combined with each other, and some embodiments may not be repeated for the same or similar concepts or processes.

The precast pile foundation pit supporting particle flow numerical simulation is a technology for performing numerical simulation on the particle flow behavior in the precast pile foundation pit supporting process by using a computer simulation method. By establishing a mathematical model based on a physical mechanics principle, a mathematical equation of the model is solved by adopting a numerical calculation method, and the motion and deformation rule of the particle flow in the foundation pit supporting process of the precast pile is simulated.

In practical application, the technical field of precast pile foundation pit supporting particle flow numerical simulation has the problem of multiple physical couplings: particle flow simulation requires consideration of the mutual coupling of various physical processes, such as particle movement, deformation, interaction with supporting structures, etc. The method involves the crossing problem of a plurality of physical fields, and needs to comprehensively consider the influences of different factors to build a complex mathematical model.

Aiming at the problem of multi-physical coupling, in the field of precast pile foundation pit supporting particle flow numerical simulation, the embodiment of the invention provides a multi-scale simulation method: by dividing the particle flow simulation into a macroscopic scale and a microscopic scale coupling simulation, physical processes and interactions at different scales can be more accurately considered. Macro-scale simulation may be used to predict overall behavior, while micro-scale simulation may be used to study particle-level details.

Based on this, the embodiment of the invention provides a precast pile foundation pit supporting particle flow numerical simulation method, as shown in fig. 1, including:

step S1: obtaining a prefabricated pile foundation scheme, and determining a simulation target according to the prefabricated pile foundation scheme;

in this step, the precast pile foundation scheme means a scheme for supporting and stabilizing a foundation pit by making concrete piles or reinforced concrete piles or the like in advance in a foundation pit supporting process. The simulation target refers to a target to be achieved in numerical simulation, such as predicting a motion state of a particle flow, evaluating stability of a precast pile foundation, and the like.

In practical application, the prefabricated pile foundation scheme can be determined according to engineering requirements and site conditions, such as selecting the type, the size, the arrangement position and the like of the prefabricated pile, and the foundation and the guidance can be provided for subsequent numerical simulation by acquiring the prefabricated pile foundation scheme and determining the simulation target, so that the simulation result is ensured to be consistent with the actual engineering requirements.

Step S2: establishing a macroscopic continuous medium model and a microscopic discrete particle model based on the simulation target;

in this step, the macroscopic continuous medium model refers to the fact that the precast pile foundation region is regarded as a continuous medium, and the mechanical behavior of the precast pile foundation region is described by a macroscopic mechanical equation. The microscopic discrete particle model refers to the discretization of the pre-pile area into a number of particles, which simulate the behavior of a particle stream by analyzing interactions between the particles.

In practical application, a macroscopic continuous medium model is established by using a macroscopic mechanics theory based on a precast pile foundation scheme and a simulation target, such as a finite element method or a boundary element method. Meanwhile, a discrete element method or a particle dynamics method is used for establishing a microscopic discrete particle model, and the mechanical behavior of a precast pile foundation area and the motion characteristics of particle flow can be analyzed by establishing a macroscopic continuous medium model and a microscopic discrete particle model, so that a foundation is provided for subsequent numerical simulation.

Step S3: coupling the macroscopic continuous medium model and the microscopic discrete particle model to obtain a particle flow numerical simulation model;

in this step, coupling means that the macroscopic continuous medium model and the microscopic discrete particle model are combined to jointly describe the mechanical behavior of the precast pile foundation region. The particle flow number simulation model refers to the motion state of the particle flow, which is predicted by numerical simulation calculation through coupling a macroscopic model and a microscopic model.

In practical application, the macroscopic continuous medium model and the microscopic discrete particle model can be coupled, and a multi-scale method or a mixing method and the like can be adopted. For example, the whole mechanical analysis is carried out on the particle flow through a macroscopic model, the interaction among particles is finely analyzed through a microscopic model, and the mechanical behavior of the precast pile foundation area can be more accurately described through coupling the macroscopic model and the microscopic model, so that the simulation precision of the motion state of the particle flow is improved.

Step S4: determining initial parameters according to the prefabricated pile foundation scheme;

in this step, the initial parameters refer to initial conditions and parameters required at the start of the particle flow value simulation, such as initial position, velocity, density, and the like of the particles.

In practical application, initial parameters are determined according to the precast pile foundation scheme, such as setting the initial position of the particles above the precast pile foundation, giving the initial speed and density of the particles, and the like, and by determining the initial parameters according to the precast pile foundation scheme, numerical simulation can be closer to practical conditions, and accuracy of simulation results is improved.

Step S5: inputting the initial parameters into the particle flow numerical simulation model to obtain a particle flow motion state;

in this step, the particle flow motion state refers to a state in which the position, speed, deformation, etc. of particles in the precast pile base region change with time.

In practical application, the initial parameters are input into a particle flow numerical simulation model, and numerical calculation is performed to obtain the motion state of the particle flow along with time, such as displacement, speed, stress distribution and the like of the particles. The motion state of the particle flow is obtained through numerical simulation, the stability of the prefabricated pile foundation can be evaluated, and references and guidance are provided for engineering design and construction.

The principle of the multi-scale simulation method provided by the embodiment of the invention is to couple together a macroscopic continuous medium model and a microscopic discrete particle model so as to consider the macroscopic behavior and microscopic interaction of particle flow at the same time. The following steps are specifically implemented:

Macroscopic continuous medium model: first, a macroscopic continuous media model is built to describe the macroscopic behavior of the particle stream. This model describes the flow of a particle stream at the perspective of a continuous medium, typically based on mass conservation equations and momentum conservation equations. In this model, the particle flow is considered as a continuous fluid whose behavior is described by macroscopic physical quantities such as flow rate, density, and stress.

Microcosmic discrete particle model: second, a microscopic discrete particle model is created to describe microscopic interactions between particles. This model is generally based on interactions and rules of motion between particles, describing the behavior of particle flow in discrete particle units. In this model, each particle has its own position, velocity, mass, etc. and is affected by the interaction forces.

The coupling method comprises the following steps: the macroscopic continuous medium model and the microscopic discrete particle model are coupled together to take into account both macroscopic and microscopic physical laws. This can be achieved in several ways:

a. multiscale grid: spatially, the particle basin is divided into a macro grid and a micro grid. The macro-grid is used to solve the equations of the continuous medium model, while the micro-grid is used to solve the equations of the discrete particle model. By transferring information between the two dimensions, a coupling between macroscopic and microscopic is achieved.

b. Sub-domain coupling: the particle basin is divided into a macroscopic sub-domain and a microscopic sub-domain. And simulating by using a continuous medium model and a discrete particle model in each subdomain respectively, and transmitting information between subdomains through boundary conditions to realize the coupling between macroscopic and microscopic.

c. Time domain coupling: the simulation was performed using alternating continuous medium models and discrete particle models over time. First, the change in macroscopic physical quantities is solved using a continuous medium model, and then the motions and interactions of the particles are calculated in a discrete particle model, taking these physical quantities as inputs. And gradually obtaining the coupling solution between the macroscopic and microscopic through iterative calculation.

To sum up, step S2, a step of establishing a macroscopic continuous medium model and a microscopic discrete particle model based on the simulation target, includes:

； (1)

； (2)

where ρ is the density of the fluid, u is the velocity vector of the fluid, t is the time,is a gradient operator, σ is the stress tensor, g is the gravitational acceleration.

F _ij = kn·δn _ij + ks·δs _ij +μ·Fn _ij ·δs _ij ； (3)

Wherein F is _ij Is the interaction force between particles i and j, kn and ks are the normal and tangential spring constants between particles δn _ij And δs _ij Is the normal and tangential displacement between particles i and j, μ is the coefficient of friction between particles, fn _ij The normal contact force between the particles i and j is the normal contact force, and in addition, it should be noted that the addition in the formula only represents the superposition of forces, and the situation that three forces are subtracted can occur in the actual situation, which is specific to the actual situation, and the embodiment of the invention is not repeated.

In addition, in yet another embodiment provided by the present invention, the step of coupling the macroscopic continuous medium model and the microscopic discrete particle model to obtain a particle flow numerical simulation model if the pre-pile foundation solution includes a particle flow domain and a particle flow numerical value corresponding thereto, as shown in fig. 2, includes:

step S31, dividing the particle basin into a macro grid and a micro grid;

step S32, solving the macroscopic continuous medium model on the macroscopic grid based on the particle flow value to obtain a macroscopic solution;

step S33, solving the microscopic discrete particle model on the microscopic grid based on the particle flow value to obtain a microscopic solution;

And step S34, taking the macroscopic solution as the input of the microscopic discrete particle model, and taking the microscopic solution as the input of the macroscopic continuous medium model to obtain the particle flow numerical simulation model.

In the embodiment of the invention, the particle drainage basin refers to the space range of discrete particles in the precast pile base region, the macro grid refers to the grid which divides the particle drainage basin into a plurality of macro regions and establishes a macro model in each region, and the micro grid refers to the grid which divides the particle drainage basin into a plurality of micro regions and establishes a discrete particle model in each region.

In practical application, dividing a particle river basin into a macro grid and a micro grid, and solving on the macro grid according to the macro continuous medium model to obtain a macro solution; solving on a micro grid according to the micro discrete particle model to obtain a micro solution; and finally, by coupling the macroscopic model and the microscopic model, the mechanical behavior of the precast pile foundation area and the motion characteristic of the particle flow can be more comprehensively described, and the accuracy of numerical simulation is improved. Meanwhile, the particle drainage basin is divided into a macro grid and a micro grid, so that the calculated amount can be reduced, and the calculation efficiency is improved.

Then, the step of solving the macroscopic continuous medium model on the macroscopic grid based on the particle flow value to obtain a macroscopic solution includes:

M(du/dt) + K·U = f； (4)

The coupling method comprises the following steps:

the coupling of the macroscopic continuous medium model and the microscopic discrete particle model is realized by adopting a multi-scale grid method. The particle basin is divided into a macro grid for solving the equation of the continuous medium model and a micro grid for solving the equation of the discrete particle model.

The expression of the macroscopic continuous medium model on the macroscopic grid, i.e. in discrete form, is as follows

M(du/dt) + K·U = f ； (4)

Wherein M is the mass matrix of the fluid, t is time, formula (4) shows that the time evolution K of the velocity field in the macroscopic medium model is the stiffness matrix of the fluid, U is the vector of the velocity field, and f is the external force vector.

On the microscopic grid, the discrete element method is used to solve the equation of the discrete particle model. The discrete element method may calculate the movement and interaction force of the particles by iteration, wherein the interaction force may be calculated according to formula (3).

Information is transferred between the two dimensions, and the coupling between the macro and micro is realized. By interpolating the velocity field on the macro grid onto the micro grid, one of the inputs to the discrete particle model. At the same time, the displacement and interaction force of particles on the micro grid are interpolated to the macro grid as one of the source items of the continuous medium model. And gradually obtaining the coupling solution between the macroscopic and microscopic through iterative calculation.

Further, the step of obtaining the particle flow numerical simulation model by taking the macroscopic solution as an input of the microscopic discrete particle model and taking the microscopic solution as an input of the macroscopic continuous medium model comprises the following steps:

step A, interpolating a velocity field of a macroscopic solution onto the microscopic grid as one of the inputs of the discrete particle model;

step B, calculating the movement and interaction force of particles on the micro grid by using a discrete element method, calculating the interaction force between the particles by using a formula (3), and updating the displacement of the particles;

step C, interpolating the particle displacement and interaction force on the micro grid to the macro grid as one of source items of the macro continuous medium model;

Step D, solving an equation of the macroscopic continuous medium model on the macroscopic grid, and calculating an external force vector by using a velocity field on the macroscopic grid and particle displacement and interaction force obtained by interpolation according to a formula (4);

e, updating a speed field on the macro grid according to an equation solving result of the macro continuous medium model;

and F, repeating the steps until the coupling solution between the macro grid and the micro grid converges, and obtaining the particle flow numerical simulation model.

In a further embodiment provided by the invention, the coupling between macroscopic and microscopic is achieved based on the above-mentioned steps, i.e. transferring information between the two dimensions. By interpolating the velocity field on the macro grid onto the micro grid, one of the inputs to the discrete particle model. At the same time, the displacement and interaction force of particles on the micro grid are interpolated to the macro grid as one of the source items of the continuous medium model. The coupling solution between the macro and the micro is obtained step by step through iterative calculation, and the calculation results of the velocity field interpolation and the interaction force interpolation in the step directly influence the accuracy of coupling, so that the velocity field interpolation and the interaction force interpolation are two key steps in the coupling process of information transmission between the macro and the micro.

Based on this, the step of updating the velocity field on the macro grid according to the result of the equation solution to the macro continuous medium model, comprises:

v _micro = ∑(w _i · v _macro i) / ∑w _i ； (5)

For this weight, on the microscopic grid, the corresponding velocity field value is calculated by means of weighted averaging from the position information in the discrete particle model. The weight of the weighted average can be determined according to the mass and distance of the discrete particle model, and the specific calculation method is as follows:

for weights w in interaction force interpolation _i Can be determined based on the mass and distance of the discrete particle model. The method comprises the following specific steps:

the distance between the particles is determined. In a discrete particle model, each particle has a position coordinate, and the distance between the particles can be determined by calculating the Euclidean distance between the particles;

The mass between the particles is determined. In a discrete particle model, each particle has a mass value that can be determined based on the volume and density of the particle;

calculating the weight w _i . Depending on the mass and distance of the discrete particle model, different formulas may be used to calculate the weights. The general weight calculation formula is as follows:

a) Linear weights: the weights are calculated using a linear function, i.e. the weights are linear with distance.

w _i = (d _max - d _i ) / (d _max - d _min ) ；

Wherein d _i Represents the distance between particles, d _max And d _min Representing maximum distance and minimum distance, respectively. The weight approaches 0 as the distance between particles approaches the maximum distance; the weight approaches 1 as the distance approaches the minimum distance.

b) Gaussian weight: the weights are calculated using a gaussian function, i.e. the weights are related to the gaussian distribution of distances.

w _i = exp(-(d _i ^2) / (2 · σ^2)) ；

Where d_i represents the distance between particles and σ represents the standard deviation of the gaussian function. When the distance between particles is closer to 0, the weight approaches 1; the weight approaches 0 as the distance gets farther from 0.

c) Other weight calculation methods: other weight calculation methods, such as exponential weights, polynomial weights, etc., may also be employed depending on the particular problem and need.

According to the weight calculation method described above, the interaction force can be interpolated from the micro grid into the macro grid. The specific calculation formula is as follows:

F _macro = ∑(w _i · F _micro i) / ∑w _i ；

Wherein F is _macro Representing interaction forces on the micro grid, F _micro i represents the interaction force of adjacent particles on the micro grid, w _i Representing the weight of the corresponding node.

Through the interpolation calculation, information can be transmitted between the macro and the micro, so that the coupling solution between the macro and the micro is realized, meanwhile, the linear weight and the Gaussian weight can be combined in a weighted average mode, and the optimal weight solution is calculated, and the method comprises the following specific steps:

the linear weights and gaussian weights are calculated. And respectively calculating linear weight and Gaussian weight according to the linear weight formula and the Gaussian weight formula.

And setting a weight fusion parameter. A weight fusion parameter is introduced for adjusting the weight ratio between the linear weight and the Gaussian weight. A value in the range 0, 1 may be set to indicate the relative importance between the linear weight and the gaussian weight.

And calculating an optimal weight solution. And calculating an optimal weight solution according to the weight fusion parameters. The specific calculation formula is as follows:

w _best = α · w _linear + (1 - α) · w _gaussian ；

wherein w is _best Represents the optimal weight solution, w _linear Represents a linear weight, w _gaussian And represents a gaussian weight, and alpha represents a weight fusion parameter.

Through the above steps, an optimal weight solution can be obtained and applied to weight calculation in interaction force interpolation. Thus, the contribution of the linear weight and the Gaussian weight can be comprehensively considered, and a more accurate interpolation result is obtained. It should be noted that the choice of the weight fusion parameters should be adjusted according to specific problems and requirements to obtain an optimal weight solution.

In yet another embodiment of the present invention, the step of inputting the initial parameters into the particle flow numerical simulation model to obtain a particle flow motion state includes:

In the embodiment of the invention, iterative calculation refers to successive approximation of a desired result by repeating calculation a plurality of times. The iteration stopping condition refers to judging whether the condition for stopping the iteration is met or not in the iterative calculation process, for example, the maximum iteration times or the error meeting the requirement are met.

Specific examples: and inputting the initial parameters into a particle flow numerical simulation model, and performing iterative calculation to obtain a coupling solution between the macroscopic continuous medium model and the microscopic discrete particle model. In each iteration, the motion state of the particle stream is updated according to the coupling solution, such as updating the position, speed, stress distribution, etc. of the particles. And repeating iterative calculation until reaching a preset iteration stopping condition.

The real motion state of the particle flow can be approximated gradually through iterative calculation and updating of the coupling solution, and the accuracy of numerical simulation is improved. Meanwhile, by setting the iteration stopping condition, the calculation accuracy and calculation amount can be controlled, and the calculation efficiency is improved.

The invention also provides a complete embodiment of the precast pile foundation pit supporting particle flow numerical simulation method in practical application, so as to realize the self-adaption of engineering characteristics in the precast pile foundation supporting process, and the concrete implementation modes are as follows:

in the coupling process, the thought of multi-scale grid coupling, sub-domain coupling and time domain coupling can be simultaneously considered so as to comprehensively utilize the advantages of macroscopic and microscopic models. The method comprises the following specific steps:

1. determining a scheme of the prefabricated pile foundation and determining a simulation target;

the method comprises the steps of determining a precast pile foundation scheme and determining a simulation target according to actual engineering requirements and soil conditions, and then determining the simulation target, for example, predicting dynamic changes of particle flow in the pile foundation construction process.

2. Establishing a macroscopic continuous medium model and a microscopic discrete particle model:

building a macroscopic continuous medium model: establishing a macroscopic continuous medium model to describe macroscopic motion states of the particle stream:

； (1)

Equation (1) is a mass conservation equation, which indicates that the rate of change of the mass of the fluid in space is 0.

； (2)

Equation (2) is a conservation of momentum equation, representing that the rate of change of the momentum of the fluid in space is equal to the sum of the external force and the internal force, where ρ is the density of the fluid, u is the velocity vector of the fluid, t is time,is a gradient operator, σ is the stress tensor, g is the force of gravity plusSpeed.

Establishing a microcosmic discrete particle model: establishing a microscopic discrete particle model according to interaction force among particles:

F _ij = kn·δn _ij + ks·δs _ij +μ·Fn _ij ·δs _ij ；(3)

in this step, equation (3) is an interaction force equation between particles, describing spring force, friction force, and normal contact force between particles. Wherein F is _ij Is the interaction force between particles i and j, kn and ks are the normal and tangential spring constants between particles δn _ij And δs _ij Is the normal and tangential displacement between particles i and j, μ is the coefficient of friction between particles, fn _ij Is the normal contact force between particle i and particle j

3. Coupling the macroscopic continuous medium model and the microscopic discrete particle model:

in the step, a particle river basin is divided into a macro grid and a micro grid, a macro continuous medium model is solved on the macro grid to obtain a macro solution, a micro discrete particle model is solved on the micro grid to obtain a micro solution, the macro solution is used as the input of the micro discrete particle model, and the micro solution is used as the input of the macro continuous medium model to obtain a particle flow number simulation model.

4. A step of solving a macroscopic solution based on a macroscopic continuous medium model on a macroscopic grid:

solving a discrete form macroscopic continuous medium model on the macroscopic grid by using a finite element method or a finite volume method and other numerical methods, wherein the discrete form macroscopic continuous medium model expression is as follows: m (du/dt) +k·u=f. Where M is the mass matrix of the fluid, t is the time, K is the stiffness matrix of the fluid, U is the vector of the velocity field, and f is the external force vector.

5. A step of taking the macroscopic solution as an input of a microscopic discrete particle model and taking the microscopic solution as an input of a macroscopic continuous medium model:

in this step, a macroscopic solution velocity field is interpolated onto a microscopic mesh as one of inputs of a discrete particle model, motions and interaction forces of particles are calculated on the microscopic mesh using a discrete element method, the interaction forces between particles are calculated according to formula (3), and displacements of the particles are updated, the particle displacements and interaction forces on the microscopic mesh are interpolated onto a macroscopic mesh as one of source items of a macroscopic continuous medium model, equations of the macroscopic continuous medium model are solved on the macroscopic mesh, and an external force vector is calculated according to formula (4) using the velocity field on the macroscopic mesh and the interpolated particle displacements and interaction forces.

6. Updating the velocity field on the macro grid:

calculating the calculation result of the macroscopic flow field based on a weighted average algorithm to update the velocity field on the macroscopic grid, wherein the expression of the weighted average algorithm is as follows v _micro = ∑(w _i · v _macro i) / ∑w _i . Wherein v is _micro Representing velocity field values, v, on the macro grid _macro i represents the velocity field value, w, of the adjacent node on the macro grid _i Representing weights of the corresponding nodes, the weights being determined from the mass and distance of the discrete particle model.

7. Iteratively calculating the motion state of the particle flow:

and inputting initial parameters into a particle flow numerical simulation model, performing iterative calculation on a coupling solution between the macroscopic continuous medium model and the microscopic discrete particle model, and updating the particle flow motion state according to the coupling solution in each step of iteration until a preset iteration stopping condition is reached.

Through the steps of the precast pile foundation pit supporting particle flow numerical simulation method, the supporting effect of the precast pile foundation pit can be evaluated, the precast pile foundation scheme is optimized, and the safety and the efficiency of construction are improved.

In the 7 steps, the thought of sub-domain coupling and time domain coupling is mainly embodied in the step 3 and the step 5.

In step 3, the macroscopic continuous medium model and the microscopic discrete particle model are coupled, the macroscopic continuous medium model and the microscopic discrete particle model are respectively subjected to numerical solution by dividing the macroscopic grid and the microscopic grid in the particle drainage basin, the macroscopic solution is used as the input of the microscopic discrete particle model, and the microscopic solution is used as the input of the macroscopic continuous medium model, so that the coupling between subdomains is realized.

In step 5, in the step of solving the macroscopic solution based on the macroscopic continuous medium model on the macroscopic grid, the velocity field of the macroscopic solution is interpolated onto the microscopic grid as the input of the discrete particle model, and the motion and interaction force of the particles are calculated on the microscopic grid by using the discrete element method, and then the displacement and interaction force of the particles on the microscopic grid are interpolated onto the macroscopic grid as one of the source items of the macroscopic continuous medium model. In this way, the macroscopic continuous medium model and the microscopic discrete particle model are coupled in the time domain, and the coupling in the time domain is realized by iteratively calculating the coupling solution between the macroscopic continuous medium model and the microscopic discrete particle model.

However, in the process of supporting the prefabricated pile foundation, deformation of the pile body is often ignored, but only the sudden situation in the actual operation process can not be truly reflected by purely considering numerical simulation of the particle flow, and the improvement thought based on the specific embodiment can be as follows:

in step 2, when determining a simulation target according to the precast pile foundation scheme, pile deformation factors including rigidity, deformation characteristics and the like of the pile are considered. The rigidity and deformation data of the pile body can be obtained through on-site actual measurement or numerical simulation and used as an important parameter in a simulation target.

In step 3, when the macroscopic continuous medium model and the microscopic discrete particle model are established based on the simulation target, the rigidity and deformation characteristics of the pile body are considered. In a macroscopic continuous medium model, the pile body can be regarded as a rigid body or an elastic body and forces and deformations of its interaction with the soil body are incorporated into the model. In the microscopic discrete particle model, the pile body can be regarded as discrete particles, and interaction force and displacement between the pile body and other particles are considered.

In step 5, the macroscopic solution is used as an input of the microscopic discrete particle model, and the rigidity and deformation characteristics of the pile body are considered. When solving the equation of the macroscopic continuous medium model on the macroscopic grid, the external force vector can be calculated according to the rigidity and deformation characteristics of the pile body and taken into consideration. When the motion and interaction force of the particles are calculated on the micro grid by using a discrete element method, the interaction force and displacement between the pile body and other particles can be considered.

By considering the rigidity and deformation characteristics of the pile body, the interaction between the pile body and the soil body is brought into simulation, and particle flow and pile body deformation in the foundation pit supporting process of the precast pile can be more accurately simulated. Therefore, a more reliable simulation result can be provided for engineering practice and used for designing and optimizing a precast pile foundation pit supporting scheme.

Examples:

in step 2, when determining the simulation target according to the prefabricated pile foundation scheme, considering the pile deformation factor, the elastic modulus and the shear modulus of the pile can be introduced as parameters in the simulation target. Assuming that the pile body in the precast pile foundation has linear elasticity (specifically according to practical situations), the elastic modulus E and the shear modulus G of the pile body can be calculated by the following formulas:

E = ν(2G + E) / (1 - ν)；

G = E / (2(1 + ν))；

where v is poisson's ratio.

In step 3, when the macroscopic continuous medium model and the microscopic discrete particle model are established based on the simulation target, the rigidity and deformation characteristics of the pile body are considered. In the macroscopic continuous medium model, the rigidity and deformation of the pile body can be incorporated into the model, the deformation behavior of the pile body is described by an elastic theory, and the rigidity and deformation of the pile body can be represented by using a bending moment-curvature relationship, namely, m=eiθ″, where M is a bending moment, E is an elastic modulus, I is a section moment of inertia, and θ″ is a curvature. In the microscopic discrete particle model, the pile body can be regarded as discrete particles, and the interaction force and displacement between the pile body and other particles are considered, and the stiffness and deformation of the pile body can be described according to a spring-particle model, i.e. f=kδu, where F is the interaction force, k is the spring stiffness, δu is the displacement difference.

In step 5, the macroscopic solution is used as an input of the microscopic discrete particle model, and the rigidity and deformation characteristics of the pile body are considered. When solving the equation of the macroscopic continuous medium model on the macroscopic grid, the interaction between the pile body and the soil body can be incorporated into the model by introducing the rigidity and deformation parameters of the pile body. Specifically, the effect of the pile on the soil mass may be considered when calculating the external force vector. The stress of the pile body on the soil body can be calculated by the following formula:

σ = Eε + M·y / I；

wherein sigma is stress, E is elastic modulus, epsilon is strain, M is bending moment, y is longitudinal distance of the pile body, and I is section moment of inertia. Thus, the influence of the rigidity of the pile body on the stress distribution of the soil body can be considered.

When the motion and interaction force of the particles are calculated on the micro grid by using a discrete element method, the interaction force and displacement between the pile body and other particles can be considered. In particular, the spring rate and displacement differences between the pile body and other particles may be taken into account when calculating the interaction force. The interaction force between the pile body and other particles can be calculated by the following formula:

F _ij = kδu +μFn _ij ·δs；

wherein F is _ij K is the spring rate, δu is the displacement difference, μ is the coefficient of friction between particles, fn _ij For normal contact force δs is tangential displacement. This allows for consideration of the effect of the stiffness of the pile on the interaction forces between the particles.

By considering the rigidity and deformation characteristics of the pile body, the interaction between the pile body and the soil body is brought into simulation, and particle flow and pile body deformation in the foundation pit supporting process of the precast pile can be more accurately simulated. Thus, more reliable simulation results can be provided for engineering practice and used for designing and optimizing a precast pile foundation scheme.

In addition, in step 7, a particle flow numerical simulation model is input according to the initial parameters, and the coupling solution between the macroscopic continuous medium model and the microscopic discrete particle model is calculated in an iterative mode. In each iteration step, the particle flow motion state is updated according to the coupling solution until a preset iteration stopping condition is reached. Iterative methods, such as explicit or implicit time integration methods, can be used to solve for the coupling solution of the macroscopic continuous medium model and the microscopic discrete particle model. In each iteration, the motion state of the particle flow, including the position, the speed, the interaction force and the like of the particles, is updated according to the macroscopic solution and the microscopic solution at the current moment.

Through the steps, the pile deformation factors are considered, so that a more real simulation result can be obtained: in the process of supporting a precast pile foundation pit, deformation of a pile body is a non-negligible factor. By considering the deformation characteristics of the pile body, the flow behavior of the soil body and the deformation condition of the pile body in the foundation pit supporting process of the precast pile can be more truly simulated. Thus, a more accurate simulation result can be obtained, and the reliability of the simulation result is improved; the interaction between the pile body and the soil body is more accurate: the deformation of the pile body can influence the stress distribution and deformation of the soil body, so that the flowing behavior of particles is influenced. By taking into account the stiffness and deformation parameters of the pile body, the interaction between the pile body and the soil body can be described more accurately. Thus, the interaction process of the pile body and the soil body can be more accurately simulated, and the accuracy of the simulation result is improved; finally, by simulating the deformation condition of the pile body in the foundation pit supporting process of the precast pile, the influence of different pile body design schemes on the soil body flow and the pile body deformation can be evaluated. By comparing simulation results of different design schemes, the design of the pile body can be optimized, so that the pile body is more suitable for actual engineering requirements. Therefore, the effect and the safety of the foundation pit support of the precast pile can be improved. A numerical simulation method of a macroscopic continuous medium model and a microscopic discrete particle model which comprehensively consider the precast pile foundation pit supporting particle flow can be established. The method can more accurately simulate the particle flowing behavior and the deformation condition of the pile body in the foundation pit supporting process of the precast pile, and provides reliable simulation results for engineering design and optimization. Meanwhile, the coupling resolving process of the method can gradually converge through iterative computation, and accuracy and stability of a simulation result are ensured.

Similarly, in different working conditions, factors to be considered in the embodiment of the invention are different, and the invention also provides a mode for correcting the coupling model based on the soil mechanical model based on the common condition of different soil properties in the working conditions so as to improve the accuracy of the numerical simulation of the particle flow.

The specific implementation mode is as follows:

one possible coupling mode is to combine a precast pile foundation pit supporting particle flow numerical simulation method with a soil body mechanical model, in the coupling mode, the embodiment of the invention can take the mechanical effect of particle flow on the soil body into consideration based on the result of the particle flow numerical simulation model, and the concrete design is as follows:

1. in the particle flow numerical simulation model, the motion state and the interaction force of the particle flow are obtained.

2. And calculating the acting force of the particles on the soil body according to the result of the particle flow numerical simulation model.

3. And (5) taking the acting force of the particles on the soil body as a boundary condition and inputting the acting force into the soil body mechanical model.

4. In the soil mechanics model, the acting force of particles on the soil is considered, and the deformation and stress distribution of the soil are calculated.

5. And feeding back the result of the soil body mechanical model to the particle flow number simulation model, and updating the motion state and interaction force of particles.

6. Repeating the steps until the simulation result converges.

By coupling the particle flow numerical simulation model with the soil body mechanical model, the interaction between particles and the soil body in the foundation pit supporting process of the precast pile can be more accurately simulated. The coupling mode can provide more comprehensive information, help us understand the mechanical behavior between the particle flow and the soil body, and optimize the precast pile foundation pit support design.

The following is an example of one possible step and related calculation formula:

step 1, solving a particle flow numerical simulation model:

a. the velocity field of the macroscopic solution is interpolated onto the microscopic mesh as one of the inputs to the discrete particle model.

b. And calculating the movement and interaction force of the particles on the microscopic grid by using a discrete element method and the like, calculating the interaction force between the particles by using a formula (3), and updating the displacement of the particles.

c. The displacement and interaction force of particles on the micro grid are interpolated onto the macro grid as one of the source items of the macro continuous medium model.

d. Solving an equation of a macroscopic continuous medium model on the macroscopic grid, and calculating an external force vector by using the equation (4) and combining a velocity field on the macroscopic grid and particle displacement and interaction force obtained by interpolation.

e. And updating the speed field on the macro grid according to the calculation result of the macro flow field.

Step 2, solving a soil body mechanical model:

a. and calculating the acting force of the particles on the soil body according to the result of the particle flow numerical simulation model. The contact force model may be used for calculation.

In a discrete particle model, the force of each particle i can be calculated by the following formula:

F_i = ∑(F _ij ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein F is _ij Is the interaction force between particle i and adjacent particle j.

Examples: assuming two adjacent particles i and j are present, the interaction force between them can be calculated by means of a spring model, with the formula:

F _ij = k _ij · δx _ij ；

wherein k is _ij Is the spring rate between particles i and j, δx _ij Is the displacement between particle i and particle j.

b. And (5) taking the acting force of the particles on the soil body as a boundary condition and inputting the acting force into the soil body mechanical model.

In the soil body mechanical model, the acting force of the particles on the soil body can be used as one of boundary conditions to simulate the mechanical action of the particles on the soil body. The specific boundary conditions depend on the soil mechanics model employed.

Examples: assuming that an elastic model is adopted, the acting force of the particles on the soil body can be used as a boundary condition to be applied on the boundary of the soil body so as to simulate the mechanical action of the particles on the soil body.

c. In the soil mechanics model, the acting force of particles on the soil is considered, and the deformation and stress distribution of the soil are calculated.

According to the soil mechanics model adopted, the deformation and stress distribution of the soil can be calculated by using a proper equation. For example, for elastic models, the stress and deformation of the soil mass can be calculated using elastomechanical equations.

Examples: assuming an elastic model, the relationship between stress and strain can be expressed as:

σ = E ·ε；

wherein sigma is stress, E is elastic modulus of the soil body, and epsilon is strain of the soil body.

Step 3, coupling iteration process:

a. and feeding back the result of the soil body mechanical model to the particle flow number simulation model, and updating the motion state and interaction force of particles.

According to the soil displacement and stress distribution obtained by calculation of the soil mechanics model, the motion state and interaction force of particles in the particle flow number simulation model can be updated.

Examples: assuming that the soil displacement calculated by the soil mechanical model is u and the stress distribution is sigma. According to the calculation result of the soil body mechanical model, the displacement and interaction force of particles in the particle flow number simulation model can be updated. For example, the position of the particles may be updated according to the displacement u, and the interaction force between the particles may be updated according to the stress σ.

b. And (5) repeating the step 1 and the step 2 until the simulation result converges.

And (3) repeating the step (1) and the step (2) through iterative calculation until the coupling solution between the particle flow number simulation model and the soil body mechanical model reaches a convergence state. The convergence condition can be defined according to the actual situation and the simulation requirement.

Examples: in each iteration, firstly, calculating the motion state and interaction force of particles according to the particle flow numerical simulation model, and then feeding back the calculation result of the soil body mechanical model to the particle flow numerical simulation model for updating. Then, the calculation of the particle flow numerical simulation model is performed again until the coupling solution between the two models converges. The convergence condition may be defined according to the stability and simulation accuracy of the particle flow, for example, when the amount of change in the displacement or stress is set to be smaller than a certain threshold value, the convergence state is considered to be reached.

Besides the coupling with the soil mechanics model, we can also consider the coupling with models in other fields. For example, a particle flow value simulation model may be coupled with a water flow model to simulate the effect of water flow on particle flow. Or coupling the particle flow numerical simulation model with the chemical reaction model to simulate a chemical reaction process in the particle flow. The coupling mode can help us to more fully understand and analyze various complex physical phenomena in the foundation pit supporting process of the precast pile.

In still another embodiment of the present invention, there is provided a precast pile foundation pit supporting particle flow numerical simulation system, as shown in fig. 3, including:

the acquisition module 01 is used for acquiring a prefabricated pile foundation scheme and determining a simulation target according to the prefabricated pile foundation scheme;

a building module 02, configured to build a macroscopic continuous medium model and a microscopic discrete particle model based on the simulation target;

the coupling module 03 is used for coupling the macroscopic continuous medium model and the microscopic discrete particle model to obtain a particle flow numerical simulation model;

the determining module 04 is used for determining initial parameters according to the prefabricated pile foundation scheme;

and the output module 05 is used for inputting the initial parameters into the particle flow numerical simulation model to obtain the particle flow motion state.

The embodiment of the invention also provides electronic equipment, which comprises:

a processor;

a memory for storing processor-executable instructions;

wherein the processor is configured to invoke the instructions stored in the memory to perform the method described previously.

In a fourth aspect of an embodiment of the present invention,

there is provided a computer readable storage medium having stored thereon computer program instructions which, when executed by a processor, implement the method as described above.

The present invention may be a method, apparatus, system, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for performing various aspects of the present invention.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. The utility model provides a precast pile foundation ditch support granule flow numerical simulation method which characterized in that includes:

inputting the initial parameters into the particle flow numerical simulation model to obtain a particle flow motion state;

a step of establishing a macroscopic continuous medium model and a microscopic discrete particle model based on the simulation target, comprising:

▽·(ρu) = 0 ； (1)

ρ(∂u/∂t + u·▽u) = ▽·σ + ρg ； (2)

where ρ is the density of the fluid, u is the velocity vector of the fluid, t is time, v is the gradient operator, σ is the stress tensor, g is the gravitational acceleration;

F _ij = kn·δn _ij + ks·δs _ij +μ·Fn _ij ·δs _ij ； (3)

wherein F is _ij Is the interaction force between particles i and j, kn and ks are the normal and tangential spring constants between particles δn _ij And δs _ij Is the normal and tangential displacement between particles i and j, μ is the coefficient of friction between particles, fn _ij Is the normal contact force between particle i and particle j;

the pre-pile foundation scheme comprises a particle flow domain and a particle flow value corresponding to the particle flow domain, and the step of coupling the macroscopic continuous medium model and the microscopic discrete particle model to obtain a particle flow value simulation model comprises the following steps:

Dividing the particle basin into a macro grid and a micro grid;

taking the macroscopic solution as the input of the microscopic discrete particle model, and taking the microscopic solution as the input of the macroscopic continuous medium model to obtain the particle flow numerical simulation model;

solving the macroscopic continuous medium model on the macroscopic grid based on the particle flow value to obtain a macroscopic solution, wherein the method comprises the following steps:

M(du/dt) + K·U = f； (4)

2. The method for numerical simulation of the particle flow of the foundation pit support of the precast pile according to claim 1, wherein the step of obtaining the numerical simulation model of the particle flow by taking the macroscopic solution as the input of the microscopic discrete particle model and taking the microscopic solution as the input of the macroscopic continuous medium model comprises the following steps:

3. The method for numerical simulation of precast pile foundation pit supporting particle flow according to claim 2, wherein the step of updating the velocity field on the macro grid according to the result of solving the equation of the macro continuous medium model comprises:

v _micro = ∑(w _i · v _macro i) / ∑w _i ； (5)

4. The method for simulating the particle flow numerical simulation of the foundation pit support of the precast pile according to claim 1, wherein the step of inputting the initial parameters into the particle flow numerical simulation model to obtain the particle flow motion state comprises the following steps:

5. The utility model provides a precast pile foundation ditch support granule flow numerical simulation system which characterized in that includes:

the output module is used for inputting the initial parameters into the particle flow numerical simulation model to obtain a particle flow motion state;

the establishing module is specifically configured to establish a macroscopic continuous medium model according to the simulation target so as to describe a macroscopic motion state of the particle flow, where an expression of the macroscopic continuous medium model is as follows:

▽·(ρu) = 0 ； (1)

ρ(∂u/∂t + u·▽u) = ▽·σ + ρg ； (2)

F _ij = kn·δn _ij + ks·δs _ij +μ·Fn _ij ·δs _ij ； (3)

the prefabricated pile foundation scheme comprises a particle drainage basin and a particle flow value corresponding to the particle drainage basin, and the coupling module is specifically used for dividing the particle drainage basin into a macroscopic grid and a microscopic grid; solving the macroscopic continuous medium model on the macroscopic grid based on the particle flow value to obtain a macroscopic solution; solving the microscopic discrete particle model on the microscopic grid based on the particle flow value to obtain a microscopic solution; taking the macroscopic solution as the input of the microscopic discrete particle model, and taking the microscopic solution as the input of the macroscopic continuous medium model to obtain the particle flow numerical simulation model;

the coupling module is further configured to solve, on the macro grid, the formula (3) using a numerical method, that is, the expression of the discrete form macro continuous medium model is as follows:

M(du/dt) + K·U = f； (4)

6. An electronic device comprising a memory and a processor, wherein the memory has stored therein a computer program, the processor being arranged to run the computer program to perform the precast pile foundation pit supporting particle stream numerical simulation method of any one of claims 1 to 4.

7. A readable storage medium, characterized in that the readable storage medium has stored therein a computer program comprising program code for controlling a process to perform a process comprising the precast pile foundation pit supporting particle stream numerical simulation method according to any one of claims 1 to 4.