CN105956314A - Numerical test method capable of creating different earth-rock mixing ratios - Google Patents

Abstract

The invention discloses a numerical test method for generating different soil-rock mixing ratios. Firstly, a Flac3d model whose unit number is N*N is generated. After determining the soil-rock mixing ratio, the initial model unit is divided into soil and stone, and written into the Flac3d calculation file. The numerical test is carried out by using Flac3d software, and the test curve is simulated by statistics of axial load and axial displacement. The present invention can not only solve the problem of model establishment, but also overcome the problems of sampling difficulty, sample disturbance, and large discreteness of results in the study of real test parameters. Engineering numerical simulation provides services with strong practicability.

Description

A Numerical Test Method for Generating Different Soil-rock Mixing Ratio

technical field

The invention belongs to the field of civil engineering numerical analysis, in particular to a numerical test method for generating different soil-rock mixing ratios.

Background technique

The accumulation body belongs to a discontinuous and heterogeneous binary medium, which is a special geological body between soil and rock mass, and people's research on it is still in exploration. The mechanical properties of accumulations not only depend on the physical and mechanical properties of soil and stone, but also are controlled by their internal structural characteristics. Factors such as soil-rock mixing ratio, stone gradation, stone shape, and stone tendency all have an impact on the mechanical properties of accumulations. greater impact. However, the physical and mechanical parameters of the accumulation body determined by the laboratory have shortcomings such as sampling disturbance, inconsistent soil-rock mixing characteristics of each sample, and large experimental errors, resulting in large dispersion and weak regularity of the test results. More importantly, the laboratory test block is limited by its scale and cannot well reflect the influence of soil-rock mixing characteristics on the physical and mechanical properties of the accumulation body.

The numerical method to study the parameters of accumulations has developed rapidly in recent years. This type of method can well overcome the difficulty of sampling, sample disturbance, large dispersion of results, and small test scale compared with the internal structure of accumulations in the study of real test parameters. And other issues. There are two major problems in the study of accumulation parameters by numerical method: (1) The problem of model establishment, that is, according to the internal structural parameters of the accumulation (such as: soil-rock mixing ratio, stone gradation, stone shape, stone tendency, etc.) The pile test block required by the numerical test; (2) Which numerical calculation method is used to simulate the real pile parameter test.

Contents of the invention

Aiming at the deficiencies of the prior art, the invention provides a numerical test method for generating different soil-rock mixing ratios, which is convenient for modeling and fast in convergence.

The present invention adopts following technical scheme:

A numerical test method for generating different soil-rock mixing ratios, comprising the following steps:

The first step: Generate the Flac3d model with the number of units being N*N: define that the number of units in the model is composed of N*N squares, the size of the model is 1*1*1/N(m), and the coordinates of the unit nodes and The nodes corresponding to each unit are numbered and assigned initial values, and the coordinates of the assigned nodes are written into the file Fracture.flac3d;

Step 2: Divide the initial model unit into soil and rock, and write the nodes and their corresponding coordinates, units and their corresponding node numbers into the Flac3d calculation file in order to generate different soil-rock mixing ratios numerical model of

Step 3: Import the constructed Flac3d file into Flac3d software, group it, and assign parameters to the grouped models, set boundary conditions, constrain the top and bottom of the model in the y direction, and then apply confining pressure in a displacement manner Loading, counting the axial load and axial displacement in each calculation step, and simulating the test curve.

Preferably, the first step of numbering the model units and nodes includes the following steps: the unit number increases from left to right from the bottom, then the unit number of the jth row i column is N*j+i, each A unit corresponds to 8 nodes, and its corresponding coordinates are N*(j-1)+i, N*(j-1)+i+1; N*(j-1)+i+N, N*(j -1)+i+N+1, N*N+N*(j-1)+i, N*N+N*(j-1)+i+1, N*N+N*(j-1 )+i+N, N*N+N*(j-1)+i+N+1.

Preferably, the first step is to assign values to the unit node coordinates on the main view of the model, including the following steps: setting the x, y, and z coordinates of the j-th row and i-column node to be 1.0*i/(N-1), a[ N*j+i][1]＝1.0*j/(N-1), a[N*j+i][2]＝0.0, to assign values to the coordinates of the unit nodes on the back of the model, its regular feature is that The x, y, and z coordinates of the nodes in row j and column i are 1.0*i/(N-1), a[N*j+i][1]=1.0*j/(N-1), a[N *j+i][2]=1.0/(N-1).

Preferably, the second step is to randomly select sum units on the Flac3d model, define their properties as soil, and change the soil-rock mixing ratio by changing the value of sum to generate different numerical models.

Preferably, the third step uses the mohr-coulomb constitutive model for numerical calculation.

Beneficial effects: the present invention quickly generates models of different soil-rock mixing ratios by determining the soil-rock mixing ratio, and performs numerical test simulation through Flac3d, which can not only solve the problem of model establishment, but also overcome sampling difficulties, sample disturbances, and discrete results in the study of real test parameters At the same time, the finite difference method is used for modeling convenience and fast convergence.

Description of drawings

Fig. 1 is a design flow chart of the present invention;

Figure 2 is a Flac3d hexahedral block grid;

Fig. 3 is that the stone content of earth-rock mixture is 50% model figure;

Fig. 4 is that the stone content of earth-rock mixture is 60% model figure;

Fig. 5 is a model diagram of 90% stone content of the soil-rock mixture;

Figure 6 is a diagram of the relationship between axial stress and axial strain for different soil-rock mixing ratios.

detailed description

The present invention is described in detail below in conjunction with accompanying drawing and specific embodiment:

A numerical test method for generating different soil-rock mixing ratios, as shown in Figure 1, includes the following steps:

Step 1: Generate a Flac3d model with N*N units, and the size of the model is 1*1*1/N(m). details as follows:

a. Number the model units and nodes. The unit numbering rule is to increase from left to right from the bottom layer. The unit number of the jth row i column is N*j+i, and each unit corresponds to 8 nodes. The corresponding coordinates are N*(j-1)+i, N*(j-1)+i+1; N*(j-1)+i+N, N*(j-1)+i+N +1, N*N+N*(j-1)+i, N*N+N*(j-1)+i+1, N*N+N*(j-1)+i+N, N *N+N*(j-1)+i+N+1;

b Assign values to the coordinates of the unit nodes on the main view of the model. The regularity is that the x, y, and z coordinates of the nodes in the jth row and column i are 1.0*i/(N-1), a[N*j+i ][1]＝1.0*j/(N-1), a[N*j+i][2]＝0.0, assign values to the coordinates of the unit nodes on the back of the model. Node x, y, z coordinates are 1.0*i/(N-1), a[N*j+i][1]=1.0*j/(N-1), a[N*j+i] [2]=1.0/(N-1).

The above steps are completed by programming in C language, as shown in Figure 2, the nodes of the Flac3d model have a unique arrangement format, assign initial values to the coordinates of the unit nodes and the corresponding nodes of each unit, and use the array a[2*N*N ][3]={0} and node[N*N][8]={0}.

First, assign the coordinates of the unit nodes on the main view of the model, and the programming is as follows:

Secondly, calculate and assign the coordinates of the node nodes on the back of the model, and the programming is as follows:

Finally, write the assigned node coordinates into the file Fracture.flac3d. Since Flac3d has its own data format, the programming is completed as follows:

Step 2: Divide the initial model unit into soil and rock, and write it into the Flac3d calculation file. By changing the value of sum, the soil-rock mixing ratio can be changed to generate numerical models of different soil-rock mixing ratios. details as follows:

First write the nodes and their corresponding coordinates, then write the units and their corresponding node numbers, and finally perform grouping, determine the soil-rock mixing ratio, and use random distribution for grouping (randomly selected on the basis of the model generated in the first step sum units, and its attribute is defined as soil in the subsequent processing), in order to avoid repeated selection of units, recursive thinking is used to re-select the repeated units.

The specific programming is as follows:

Step 3: Import the constructed Flac3d file into Flac3d software, use Flac3d software to conduct numerical experiments, and simulate the test curves by counting axial load and axial displacement. details as follows:

First, import the FLAC3d files into the model FLAC3d software, group them, and assign parameters to the grouped models. Select the mohr-coulomb constitutive model.

Then set the boundary conditions, constrain the top and bottom of the model in the y direction, and then apply the confining pressure to load according to the displacement.

Finally, the axial load and axial displacement in each calculation step are counted, and the stress-displacement test curve is drawn.

Application example: Apply the above method to the soil-rock mixture model, where the parameters of the stone are: bulk modulus 25Gpa, shear modulus 12Gpa, density 2900kg/m ³ , cohesion 4Gpa, friction angle 45°, tensile strength The strength is 2Mpa, the dilation angle is 15°; the parameters of the soil are: bulk modulus 40Mpa, shear modulus 15Mpa, density 2200kg/m ³ , cohesion 0.08Mpa, friction angle 28°, tensile strength 9Kpa, shear The expansion angle is 10°.

Specific steps are as follows:

(1) Generate different soil-rock mixture ratio models through C language programming according to the above method.

(2) Import the generated model into the Flac3d software, adopt the mohr-coulomb original model, and load at a loading rate of 5*10 ^-5 m/step. During the calculation process, the axial load and axial displacement are counted. As shown in Figure 3-5, they are model diagrams of soil-rock mixture with stone content of 50%, 60% and 90%, respectively.

(3) The results of step (2) are plotted and displayed, as shown in Figure 6, which shows the relationship between axial stress and axial strain.

Claims (5)

1. A numerical test method that generates different soil-rock mixing ratios, is characterized in that, comprises the following steps: The first step: Generate the Flac3d model with the number of units being N*N: define that the number of units in the model is composed of N*N squares, the size of the model is 1*1*1/N(m), and the coordinates of the unit nodes and The nodes corresponding to each unit are numbered and assigned initial values, and the coordinates of the assigned nodes are written into the file Fracture.flac3d; Step 2: Divide the initial model unit into soil and rock, and write the nodes and their corresponding coordinates, units and their corresponding node numbers into the Flac3d calculation file in order to generate different soil-rock mixing ratios numerical model of Step 3: Import the constructed Flac3d file into Flac3d software, group it, and assign parameters to the grouped models, set boundary conditions, constrain the top and bottom of the model in the y direction, and then apply confining pressure in a displacement manner Loading, counting the axial load and axial displacement in each calculation step, and simulating the test curve. 2. the numerical test method that generates different soil-rock mixing ratios according to claim 1, is characterized in that, the first step is numbered to model unit and node and comprises the following steps: unit numbering is to start from the bottom layer from left to right successively Increase, the unit number of the jth row i column is N*j+i, each unit corresponds to 8 nodes, and its corresponding coordinates are N*(j-1)+i, N*(j-1)+ i+1; N*(j-1)+i+N, N*(j-1)+i+N+1, N*N+N*(j-1)+i, N*N+N* (j-1)+i+1, N*N+N*(j-1)+i+N, N*N+N*(j-1)+i+N+1. 3. the numerical test method that generates different soil-rock mixing ratios according to claim 2, is characterized in that, the first step assigns the unit node coordinates on the main view of the model and comprises the following steps: setting the node of j row i column The x, y, and z coordinates are 1.0*i/(N-1), a[N*j+i][1]=1.0*j/(N-1), a[N*j+i][2 ]=0.0, assign values to the coordinates of the unit nodes on the back of the model, and its regular feature is that the x, y, and z coordinates of the nodes in the j-th row and i-column are 1.0*i/(N-1), a[N*j +i][1]=1.0*j/(N-1), a[N*j+i][2]=1.0/(N-1). 4. the numerical test method that generates different soil-rock mixing ratios according to claim 1, is characterized in that, the second step is to select sum units at random on the Flac3d model, and its attribute is defined as soil mass, by changing the value of sum Values change the soil-rock mixture ratio, generating different numerical models. 5. the numerical test method that generates different soil-rock mixing ratios according to claim 1, is characterized in that, the 3rd step adopts mohr-coulomb constitutive model to carry out numerical calculation.