Discrete element servo method and device for multidirectional circulating single shear under different drainage conditions

Abstract

The invention relates to the technical field of numerical analysis, in particular to a discrete element servo method and device for multidirectional circulating simple shear under different drainage conditions, and the method comprises the steps: determining test parameters needing to be controlled, generating and consolidating a sample based on a target condition, and determining a shear stress target value of the multidirectional circulating simple shear, the method comprises the following steps: monitoring a stress tensor and a strain tensor of a sample, calculating a stress increment matrix and a strain increment matrix, correcting the stress increment matrix by using different drainage conditions to judge whether the monitored shear stress and volume strain are within a certain tolerance range, and if not, applying the corresponding strain increment to the sample so as to judge whether the monitored shear stress and volume strain are within the certain tolerance range. And iteration is carried out until loading is finished. Therefore, the problems that in the prior art, only the influence of partial drainage conditions and multi-directional circulating single shear on the mechanical behavior of the soil body is researched respectively, and the research on the comprehensive influence of the mechanical behavior of the soil body under the action of the partial drainage conditions and the multi-directional circulating single shear is insufficient are solved.

Description

Technical Field

[0001] The present application relates to the field of numerical analysis control technology, in particular to a discrete element servo method and device for multi-directional cyclic single shear under different drainage conditions. Background Art

[0002] In the related technology, on the one hand, excess pore water pressure and plastic shear strain are more easily accumulated in multi-directional cyclic shear experiments. The discrete element method is used to simulate the mechanical response of soil under different stress paths in the deviatoric stress plane. The polyhedral specimen configuration is used to ensure uniform stress during the simulation process, and the magnitude of each stress and strain component is obtained simultaneously in each calculation step.

[0003] On the other hand, the actual drainage condition on site may be neither fully drained nor undrained, but partially drained. In order to simulate the local drainage condition, proportional strain loading test is carried out on sand, that is, the ratio of axial strain to volumetric strain is kept constant during the whole loading process.

[0004] However, in the related technologies, only the effects of partial drainage conditions and multi-directional cyclic simple shear on the mechanical behavior of soil are studied separately. There is a problem of insufficient research on the comprehensive influence of partial drainage conditions and multi-directional cyclic simple shear on the mechanical behavior of soil, which urgently needs to be improved. Summary of the invention

[0005] The present application provides a discrete element servo method and device for multi-directional cyclic simple shear under different drainage conditions to solve the problem that in the related art, only the influence of partial drainage conditions and multi-directional cyclic simple shear on the mechanical behavior of soil is studied separately, resulting in insufficient research on the comprehensive influence of partial drainage conditions and multi-directional cyclic simple shear on the mechanical behavior of soil.

[0006] The first aspect of the present application provides a discrete element servo method for multi-directional cyclic simple shear under different drainage conditions, including the following steps: determining the test parameters that need to be controlled to generate and consolidate a specimen based on the target test conditions; determining the shear stress target value of the multi-directional cyclic single shear, and monitoring the stress tensor and strain tensor of the specimen to calculate the stress increment matrix required to achieve the shear stress target value; calculating the strain increment matrix corresponding to the stress increment matrix, and correcting the stress increment matrix using different drainage conditions to determine whether the monitored shear stress and volume strain are within a preset tolerance range; if not within the preset tolerance range, applying the corresponding strain increment to the specimen, and iterating until the loading is completed.

[0007] The embodiments of the present application can accurately describe the stress and strain changes of the soil during the test by monitoring the stress tensor and strain tensor of the sample and calculating the stress increment matrix and the strain increment matrix. Based on the monitoring results, it is determined whether the shear stress and volumetric strain are within the tolerance range, and iterative adjustments are made to continuously optimize the test results, thereby ensuring precise control of the mechanical behavior of the soil during the test, thereby improving the accuracy of the soil mechanical behavior data obtained.

[0008] Optionally, in an embodiment of the present application, it further includes: if it is not within the preset tolerance range, determining the next time step by a preset formula.

[0009] The embodiment of the present application can determine the next time step through a certain formula, and guide the test to develop in a direction that makes the shear stress and volumetric strain approach the tolerance range, thereby improving the accuracy of the test results.

[0010] Optionally, in one embodiment of the present application, the preset formula is:

[0011] σ xz(t) -σ xz =σ zx(t) -σ zx =0,σ xy(t) -σ xy =σ yx(t) -σ yx =0,σ yz(t) -σ yz =σ zy(t) -σ zy =0,

[0012] Among them, σ xz(t) , σ zx(t) is the target value of shear stress in the xz direction for multi-directional cyclic single shear, σ xz , σ zx is the stress tensor of multi-directional cyclic simple shear in the xz direction at a certain time step, σ xy(t) , σ yx(t) is the target value of shear stress in the xy direction for multi-directional cyclic single shear, σ xy , σ yx is the stress tensor of multi-directional cyclic simple shear in a certain time step in the xy direction, σ yz(t) , σ zy(t) is the target value of shear stress in the yz direction for multi-directional cyclic single shear, σ yz , σ zy is the stress tensor of multi-directional cyclic simple shear in the yz direction at a certain time step.

[0013] The embodiment of the present application can establish a step size formula based on the physical relationship between the stress tensor and the stress target value in the multi-directional cyclic single shear test, and perform test adjustments according to the formula, so that the experimental results are more consistent with physical reality, providing a basis for further expanding and improving the test method.

[0014] Optionally, in one embodiment of the present application, the stress increment matrix is:

[0015]

[0016] Among them, Δσ ij(t) is the stress increment, σ yx(y) , σ xy(t) is the target shear stress value in the xy direction for multi-directional cyclic single shear, σ yx , σ xy is the stress tensor of multi-directional cyclic simple shear in a certain time step in the xy direction, σ zx(t) , σ xz(t) is the target value of shear stress in the xz direction for multi-directional cyclic single shear, σ zx , σ xz is the stress tensor of multi-directional cyclic simple shear in the xz direction at a certain time step, σ zy(t) , σ yz(t) is the target value of shear stress in the yz direction for multi-directional cyclic single shear, σ zy , σ yz is the stress tensor of multi-directional cyclic simple shear in the yz direction at a certain time step.

[0017] The embodiments of the present application can accurately describe the stress changes of the specimen in different directions during the multi-directional cyclic single shear process by clarifying the stress increment elements in each direction, accurately reflect the increase and decrease trend of stress in each direction, and provide a detailed data basis for the subsequent analysis of the deformation and characteristics of the soil.

[0018] Optionally, in one embodiment of the present application, the use of different drainage conditions to correct the stress increment matrix includes: calculating the invariant of the strain increment required to achieve the stress increment matrix to calculate the strain control matrix; and correcting the strain control matrix to obtain a corrected strain control matrix.

[0019] The embodiment of the present application can calculate the strain control matrix by calculating the invariant of the strain increment required to achieve the stress increment matrix, accurately reflecting the intrinsic connection between stress change and strain change. By correcting the strain control matrix, the test process is made more consistent with the mechanical behavior of the soil under actual drainage conditions, thereby improving the accuracy and practicality of the test results.

[0020] Optionally, in one embodiment of the present application, the modified strain control matrix is:

[0021]

[0022] Among them, Δε ij is the modified strain control matrix, dε xx is the length strain tensor due to stress change in the x direction, dε yy is the length strain tensor in the y direction due to stress change, dε zz is the length strain tensor due to stress change in the z direction, dε xy , dε yx is the strain tensor corresponding to the angle change between the x and y directions due to shear, dε xz , dε zx is the strain tensor corresponding to the angle change between the x and z directions due to shear, dε yz , dε zy is the strain tensor corresponding to the angular change between the y and z directions due to shear.

[0023] The embodiment of the present application can use a matrix form to represent the strain control matrix, which is convenient for mathematical calculation and analysis and improves the efficiency of calculation. At the same time, the matrix form is also convenient for implementation and processing in a computer program, which provides convenience for numerical simulation and automated analysis. The strain control matrix has a certain versatility and can be applied to different types of soil and different test conditions. As long as it meets the basic stress-strain transformation relationship and the setting principles of drainage conditions, the matrix can be used to control the deformation of the soil, thereby further expanding and improving the test method.

[0024] The second aspect of the present application provides a discrete element servo device for multi-directional cyclic single shear under different drainage conditions, including: a generation module, used to determine the test parameters that need to be controlled, so as to generate and consolidate the specimen based on the target test conditions; a first calculation module, used to determine the shear stress target value of the multi-directional cyclic single shear, and monitor the stress tensor and strain tensor of the specimen to calculate the stress increment matrix required to achieve the shear stress target value; a second calculation module, used to calculate the strain increment matrix corresponding to the stress increment matrix, and correct the stress increment matrix using different drainage conditions to determine whether the shear stress and volume strain obtained by monitoring are within a preset tolerance range; an iteration module, used to apply the corresponding strain increment to the specimen when it is not within the preset tolerance range, and iterate until the loading is completed.

[0025] The embodiments of the present application can monitor the stress tensor and strain tensor of the sample, calculate the stress increment matrix and the strain increment matrix, accurately describe the stress and strain changes of the soil during the test, judge whether the shear stress and volume strain are within the tolerance range based on the monitoring results, and make iterative adjustments to continuously optimize the test results, thereby ensuring precise control of the mechanical behavior of the soil during the test, thereby improving the accuracy of the soil mechanical behavior data obtained.

[0026] Optionally, in one embodiment of the present application, the iteration module includes: a judgment unit, configured to determine the next time step using a preset formula when the time step is not within the preset tolerance range.

[0027] The embodiment of the present application can determine the next time step through a certain formula, and guide the test to develop in a direction that makes the shear stress and volumetric strain approach the tolerance range, thereby improving the accuracy of the test results.

[0028] Optionally, in one embodiment of the present application, the preset formula is:

[0029] σ xz(t) -σ xz =σ zx(t) -σ zx =0,σ xy(t) -σ xy =σ yx(t) -σ yx =0,σ yz(t) -σ yz =σ zy(t) -σ zy =0,

[0030] Among them, σ xz(t) , σ zx(t) is the target value of shear stress in the xz direction for multi-directional cyclic single shear, σ xz , σ zx is the stress tensor of multi-directional cyclic simple shear in the xz direction at a certain time step, σ xy(t) , σ yx(t) is the target value of shear stress in the xy direction for multi-directional cyclic single shear, σ xy , σ yx is the stress tensor of multi-directional cyclic simple shear in a certain time step in the xy direction, σ yz(t) , σ zy(t) is the target value of shear stress in the yz direction for multi-directional cyclic single shear, σ yz , σ zy is the stress tensor of multi-directional cyclic simple shear in the yz direction at a certain time step.

[0031] The embodiment of the present application can establish a step size formula based on the physical relationship between the stress tensor and the stress target value in the multi-directional cyclic single shear test, and perform test adjustments according to the formula, so that the experimental results are more consistent with physical reality, providing a basis for further expanding and improving the test method.

[0032] Optionally, in one embodiment of the present application, the stress increment matrix is:

[0033]

[0034] Among them, Δσ ij(t) is the stress increment, σ yx(t) , σ xy(t) is the target shear stress value in the xy direction for multi-directional cyclic single shear, σ yx , σ xy is the stress tensor of multi-directional cyclic simple shear in a certain time step in the xy direction, σ zx(t) , σ xz(t) is the target value of shear stress in the xz direction for multi-directional cyclic single shear, σ zx , σ xz is the stress tensor of multi-directional cyclic simple shear in the xz direction at a certain time step, σ zy(t) , σ yz(t) is the target value of shear stress in the yz direction for multi-directional cyclic single shear, σ zy , σ yz is the stress tensor of multi-directional cyclic simple shear in the yz direction at a certain time step.

[0035] The embodiments of the present application can accurately describe the stress changes of the specimen in different directions during the multi-directional cyclic single shear process by clarifying the stress increment elements in each direction, accurately reflect the increase and decrease trend of stress in each direction, and provide a detailed data basis for the subsequent analysis of the deformation and characteristics of the soil.

[0036] Optionally, in one embodiment of the present application, the second calculation module includes: a first calculation unit, used to calculate the invariant of the strain increment required to achieve the stress increment matrix to calculate the strain control matrix; and a correction unit, used to correct the strain control matrix to obtain a corrected strain control matrix.

[0037] The embodiment of the present application can calculate the strain control matrix by calculating the invariant of the strain increment required to achieve the stress increment matrix, accurately reflecting the intrinsic connection between stress change and strain change. By correcting the strain control matrix, the test process is made more consistent with the mechanical behavior of the soil under actual drainage conditions, thereby improving the accuracy and practicality of the test results.

[0038] Optionally, in one embodiment of the present application, the modified strain control matrix is:

[0039]

[0040] Among them, Δε ij is the modified strain control matrix, dε xx is the length strain tensor due to stress change in the x direction, dε yy is the length strain tensor in the y direction due to stress change, dε zz is the length strain tensor due to stress change in the z direction, dε xy , dε yx is the strain tensor corresponding to the angle change between the x and y directions due to shear, dε xz , dε zx is the strain tensor corresponding to the angle change between the x and z directions due to shear, dε yz , dε zy is the strain tensor corresponding to the angular change between the y and z directions due to shear.

[0041] The embodiment of the present application can use a matrix form to represent the strain control matrix, which is convenient for mathematical calculation and analysis and improves the efficiency of calculation. At the same time, the matrix form is also convenient for implementation and processing in a computer program, which provides convenience for numerical simulation and automated analysis. The strain control matrix has a certain versatility and can be applied to different types of soil and different test conditions. As long as it meets the basic stress-strain transformation relationship and the setting principles of drainage conditions, the matrix can be used to control the deformation of the soil, thereby further expanding and improving the test method.

[0042] The third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement a discrete element servo method for multi-directional cyclic single shear under different drainage conditions as described in the above embodiments.

[0043] A fourth aspect of the present application provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the discrete element servo method for multi-directional cyclic single shear under different drainage conditions as described above.

[0044] The fifth aspect of the present application provides a computer program product, including a computer program, which, when executed, is used to implement the discrete element servo method of multi-directional cyclic single shear under different drainage conditions as described above.

[0045] The embodiments of the present application can monitor the stress tensor and strain tensor of the sample, calculate the stress increment matrix and the strain increment matrix, accurately describe the stress and strain changes of the soil during the test, and judge whether the shear stress and volumetric strain are within the tolerance range based on the monitoring results to guide the test in the direction of making the shear stress and volumetric strain approach the tolerance range, thereby improving the accuracy of the test results. By clarifying the stress increment elements in various directions, the stress changes of the sample in different directions during the multi-directional cyclic single shear process are accurately described, and the increase and decrease trends of stress in each direction are accurately reflected. By correcting the strain control matrix, the test process is made more consistent with the mechanical behavior of the soil under actual drainage conditions, thereby improving the accuracy and practicality of the test results.

[0046] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0048] Figure 1 It is a flow chart of a discrete element servo method for multi-directional cyclic single shear under different drainage conditions provided according to an embodiment of the present application;

[0049] Figure 2 A schematic diagram of a discrete element servo method for multi-directional cyclic single shear under different drainage conditions according to a specific embodiment of the present application for numerical simulation of a twenty-six-sided specimen;

[0050] Figure 3 It is a structural schematic diagram of a discrete element servo device for multi-directional cyclic single shear under different drainage conditions provided according to an embodiment of the present application;

[0051] Figure 4 The figure is a structural example diagram of an electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0052] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0053] The following describes the discrete element servo method, device and electronic device of multi-directional cyclic single shear under different drainage conditions of the embodiment of the present application with reference to the accompanying drawings. In view of the related technologies mentioned in the above background technology center, only the influence of partial drainage conditions and multi-directional cyclic single shear on the mechanical behavior of soil is studied separately, resulting in insufficient research on the comprehensive influence of partial drainage conditions and multi-directional cyclic single shear on the mechanical behavior of soil. The present application provides a discrete element servo method of multi-directional cyclic single shear under different drainage conditions. In this method, the test parameters that need to be controlled can be determined to ensure that the test starts from the starting point of accurate planning, and then the shear stress target value of the multi-directional cyclic single shear is determined, and the stress tensor and strain tensor of the sample are monitored to calculate the required stress increment matrix. Then, the strain increment matrix corresponding to the stress increment matrix is ​​calculated, and the stress increment matrix is ​​corrected using different drainage conditions. At the same time, it is judged whether the shear stress and volume strain obtained by monitoring are within the tolerance range. If they are not within the tolerance range, the accuracy and reliability of the test results are guaranteed by correction and judgment. This solves the problem that in related technologies, only the effects of partial drainage conditions and multi-directional cyclic simple shear on the mechanical behavior of soil are studied separately, resulting in insufficient research on the comprehensive influence of partial drainage conditions and multi-directional cyclic simple shear on the mechanical behavior of soil.

[0054] Specifically, Figure 1 A schematic flow chart of a discrete element servo method for multi-directional cyclic single shear under different drainage conditions provided in an embodiment of the present application.

[0055] like Figure 1 As shown, the discrete element servo method for multi-directional cyclic single shear under different drainage conditions includes the following steps:

[0056] In step S101 , the test parameters that need to be controlled are determined so as to generate and consolidate the specimens based on the target test conditions.

[0057] It is understandable that when conducting any scientific experiment, it is crucial to clearly define the test parameters that need to be controlled. The test parameters will directly affect the process and results of the test. For the discrete element servo method of multi-directional cyclic single shear under different drainage conditions involved in this application, determining appropriate test parameters is the basis for ensuring that the test can accurately simulate the mechanical behavior of soil in an actual engineering environment.

[0058] In the embodiment of the present application, α is a loading control parameter of proportional strain loading, which is:

[0059]

[0060] Among them, ε v is the volume strain of the sample, ε q is the generalized shear strain.

[0061] Specifically,

[0062] ε v =ε xx +ε yy +ε zz ,

[0063]

[0064] Among them, ε xx is the strain tensor in the x direction, ε yy is the strain tensor in the y direction, ε zz is the strain tensor in the z direction, ε xy is the strain tensor in the x and y directions, ε yz is the strain tensor in the y and z directions, ε xz are the strain tensors in the x and z directions.

[0065] In the actual implementation process, when α = 0, the sample is not drained; when α>0, the sample is over-drained and the volume shrinks; when α<0, the sample is expanded and drained, and the volume expands. Further, according to the required test conditions, such as but not limited to relative density, initial confining pressure, etc., a 26-sided sample is made and consolidated. The 26-sided sample is as follows: Figure 2 shown.

[0066] The embodiment of the present application provides a clear calculation formula for the control parameter α and a calculation formula based on the strain tensor. The drainage state of the sample can be clearly judged by the value of α, which simplifies the judgment process of the drainage of the sample and improves the efficiency and accuracy of monitoring the sample state during the test. The icosahedral-shaped sample has better spatial representativeness and more accurately reflects the mechanical behavior of the soil under multi-directional stress conditions.

[0067] In step S102, the shear stress target value of the multi-directional cyclic single shear is determined, and the stress tensor and strain tensor of the sample are monitored to calculate the stress increment matrix required to achieve the shear stress target value.

[0068] It is understandable that the shear stress target value is the expected shear stress value that is pre-set in the test. This value is usually determined based on actual engineering requirements, theoretical analysis or experience as a target parameter of the test. The stress tensor is a mathematical tool used to describe the stress state at a point inside an object. In soil mechanics, the stress tensor contains multiple stress components, reflecting the normal stress and shear stress that the soil is subjected to in different directions. The strain tensor is used to describe the strain state at a point inside an object. It contains multiple strain components, reflecting the deformation of the soil in different directions.

[0069] In the embodiment of the present application, the stress increment matrix is:

[0070]

[0071] Among them, Δσ ij(t) is the stress increment, σ yx(t) , σ xy(t) is the target shear stress value in the xy direction for multi-directional cyclic single shear, σ yx , σ xy is the stress tensor of multi-directional cyclic simple shear in a certain time step in the xy direction, σ zx(t) , σ xz(t) is the target value of shear stress in the xz direction for multi-directional cyclic single shear, σ zx , σ xz is the stress tensor of multi-directional cyclic simple shear in the xz direction at a certain time step, σ zy(t) , σ yz(t) is the target value of shear stress in the yz direction for multi-directional cyclic single shear, σ zy , σ yz is the stress tensor of multi-directional cyclic simple shear in the yz direction at a certain time step.

[0072] In the actual implementation process, the target value of controlling the shear stress at different times is:

[0073] σ xz(t) =σ zx(t) =CRS max,1 P′0sin(ω1θ+k1)

[0074] σ yz(t) =σ zy(t) =CRS max,2 P′0sin(ω2θ+k2)

[0075] Among them, σ xz(t) , σ zx(t) is the target value of shear stress in the xz direction for multi-directional cyclic single shear, σ yz(t) , σ zy(t) is the target value of shear stress in the yz direction for multi-directional cyclic single shear, CRS max,1 、CRS max,2 is the cyclic shear stress ratio, P′0 is the average effective normal stress before the start of cyclic shear, σ xz(t) , σ zx(t) The cycle period is σ yz(t) , σ zy(t) The cycle period is

[0076] Specifically, when σ xz(t) , σ zx(t) and σ yz(t) , σ zy(t) When one of the pairs is zero, it is a one-way cyclic simple shear; when σ xz(t), σ zx(t) and σ yz(t) , σ zy(t) When both are not zero, it is cyclic simple shear.

[0077] Furthermore, the stress tensor of the sample at this time step is monitored. and the strain tensor Thus, the generalized shear strain ε at this time step can be calculated q According to the loading control parameter α of proportional strain loading, the target volume strain ε can be calculated v(t) =α·ε q , the true volume strain ε v(true) =ε xx +ε yy +ε zz .

[0078] Furthermore, actively giving up control xx , σ yy and σ zz , the target stress tensor for this time step can be obtained from the target values ​​of shear stress at different times. In order to achieve the target stress state, a stress increment Δσ needs to be applied to the specimen boundary. ij(t) =σ ij(t) -σ ij , that is, the stress increment matrix is

[0079] The embodiment of the present application can control the target value of shear stress at different times with a clear formula, so that it can be flexibly adjusted according to different test requirements, better simulate the stress conditions of soil in different actual engineering scenarios, and use stress tensor and strain tensor to describe the stress and strain state inside the soil, which can comprehensively and accurately reflect the stress and deformation conditions of the soil in different directions.

[0080] In step S103, the strain increment matrix corresponding to the stress increment matrix is ​​calculated, and the stress increment matrix is ​​corrected using different drainage conditions to determine whether the monitored shear stress and volumetric strain are within a preset tolerance range.

[0081] It can be understood that the preset tolerance range refers to the range of allowable fluctuations of a certain mechanical or physical quantity that is preset during engineering analysis or monitoring. For shear stress and volumetric strain, the preset tolerance range refers to the range in which shear stress and volumetric strain are allowed to vary within a certain numerical range.

[0082] Optionally, in one embodiment of the present application, the stress increment matrix is ​​corrected using different drainage conditions, including: calculating the invariant of the strain increment required to achieve the stress increment matrix to calculate the strain control matrix; and correcting the strain control matrix to obtain a corrected strain control matrix.

[0083] In the embodiment of the present application, the modified strain control matrix is:

[0084]

[0085]

[0086] Among them, Δε ij is the modified strain control matrix, dε xx is the length strain tensor due to stress change in the x direction, dε yy is the length strain tensor in the y direction due to stress change, dε zz is the length strain tensor due to stress change in the z direction, dε xy , dε yx is the strain tensor corresponding to the angle change between the x and y directions due to shear, dε xz , dε zx is the strain tensor corresponding to the angle change between the x and z directions due to shear, dε yz , dε zy is the strain tensor corresponding to the angular change between the y and z directions due to shear.

[0087] In some cases, to achieve the stress increment matrix Δσ ij(t) The required strain increment matrix, in order to make the specimen follow the multi-directional cyclic single shear stress path, is the stress increment Δσ ij(t) Expressed in the form of c(Δσ) I (In three-dimensional problems, I = 1, 2, 3), the invariant of the strain increment can be obtained through the isotropic elastic stress-strain relationship, that is, Hooke's law:

[0088]

[0089] Among them, (Δε) I is the size of the strain increment, (Δα Δε ) I is the direction of strain increment, E is the elastic modulus of the specimen, and v is the Poisson's ratio of the specimen.

[0090] The strain control matrix is ​​calculated as:

[0091]

[0092] The calculated ε v(t) and the true volumetric strain ε v(true) Different, there is a difference, ε v(t) -ε v(true) , so it is necessary to adjust dε in the strain control matrix xx , dε yy , dε zz Correction is performed to obtain the corrected strain control matrix.

[0093] In the embodiment of the present application, the relevant strain control matrix elements can be corrected according to the difference between the volume strain and the true volume strain, thereby improving the accuracy of the entire analysis result.

[0094] In step S104, if it is not within the preset tolerance range, the corresponding strain increment is applied to the sample and iterated until the loading is completed.

[0095] It can be understood that "out of tolerance" means that when the monitored shear stress and volumetric strain values ​​exceed the preset reasonable fluctuation range, the mechanical state of the sample does not meet the expected standards, there may be potential safety hazards or it may not meet the design requirements. It is necessary to apply strain and repeat the above steps until the requirements are finally met.

[0096] In some cases, if it is not within the preset tolerance range, the next time step is determined by a preset formula, which is:

[0097] σ xz(t) -σ xz =σ zx(t) -σ zx =0,σ xy(t) -σ xy =σ yx(t) -σ yx =0,σ yz(t) -σ yz =σ zy(t) -σ zy =0,

[0098] Among them, σ xz(t) , σ zx(t) is the target value of shear stress in the xz direction for multi-directional cyclic single shear, σ xz , σ zx is the stress tensor of multi-directional cyclic simple shear in the xz direction at a certain time step, σ xy(t) , σ yx(t) is the target value of shear stress in the xy direction for multi-directional cyclic single shear, σ xy , σ yx is the stress tensor of multi-directional cyclic simple shear in a certain time step in the xy direction, σ yz(t) , σzy(t) is the target value of shear stress in the yz direction for multi-directional cyclic single shear, σ yz , σ zy is the stress tensor of multi-directional cyclic simple shear in the yz direction at a certain time step.

[0099] The modified strain control matrix Δε ij Apply to the sample and repeat steps S102 to S104 until it is within the tolerance range. In other cases, if it is within the tolerance range, the target shear stress is kept unchanged.

[0100] The following is a detailed description of a specific embodiment. In this embodiment, the force on the wall boundary of the 26-sided sample is obtained by volume averaging, and the formula is as follows:

[0101]

[0102] in, The coordinates of the wall acting on the specimen boundary are The concentrated force at point β of the sample 1 is shown in Figure 1. v is the volume of sample 1, i, j = x, y, z, and thus σ can be calculated. xx , σ yy , σ zz , σ xy , σ yx , σ xz , σ zx , σ yz , σ zy .

[0103] The strain tensor is obtained by using the Biot strain calculation method. The sample boundary has 26 planes. First, the shape gradient matrix D is calculated. ij :

[0104]

[0105] in, is the i coordinate of the centroid of one of the twenty-six planes, ΔS is the area of ​​the plane, V is the volume of the sample in the initial configuration, N j is the j component of the unit normal vector of the plane of the specimen in the initial configuration, i, j = x, y, z.

[0106] Then the strain is calculated:

[0107] ε ij =δ ij -D ij

[0108] in, From this we can calculate ε xx , ε yy , εzz , ε xy , ε yx , ε xz , ε zx , ε yz , ε zy .

[0109] Determine the loading control parameter a of proportional strain loading, which is an important parameter for controlling the drainage state. At the same time, clarify the various test conditions required for the test specimen, such as specimen size, relative density, and initial confining pressure. Generate a 26-hedron-shaped specimen 1 according to the test conditions and consolidate it.

[0110] First, determine the target value of shear stress at different times: xz(t) =σ zx(t) =CRS max,1 p0′sin(ω1θ+k1),σ yz(t) =σ zy(t) =CRS max,2 p0′sin(ω2θ+k2),σ xy(t) =σ yx(t) =0.

[0111] Detect the stress tensor of sample 1 at this time step and the strain tensor Thus, the generalized shear strain at this time step can be calculated According to the loading control parameter α of proportional strain loading, the target volume strain ε can be calculated v(t) =α·ε q , the true volume strain ε v(true) =ε xx +ε yy +ε zz .

[0112] Then, voluntarily give up control xx , σ yy and σ zz , the target stress tensor for this time step can be known from the target values ​​of shear stress at different times The stress tensor σ obtained by monitoring at this time step is known ij In order to achieve the target stress state, a stress increment Δσ needs to be applied to the specimen boundary. ij(t) =σ ij(t) -σ ij , that is, the stress increment matrix is

[0113] In order to achieve this stress increment, Hooke's law is used to calculate the strain increment, and the stress increment Δσ ij(t) Expressed in the form of c(Δσ) I(In three-dimensional problems, I = 1, 2, and 3). The invariant of the strain increment can be obtained from the isotropic elastic stress-strain relationship, namely Hooke's law:

[0114]

[0115] Among them, (Δε) I is the size of the strain increment, (Δα Δε ) I is the direction of strain increment, E is the elastic modulus of the sample, and υ is the Poisson's ratio of the sample.

[0116] The calculated strain control matrix is:

[0117] Δε ij The bidirectional cyclic shear of the sample can be controlled. In order to control the partial drainage of the sample, Δε ij The correction is made so that the target volume strain ε at this time step is v(t) and the true volumetric strain ε v(true) The same, the difference ε v(t) -ε v(true) Evenly distributed to dε xx , dε yy and dε zz , the strain control matrix is ​​corrected and the strain control matrix is ​​obtained as follows:

[0118] The real shear stress and volume strain of sample 1 are monitored and compared with the target shear stress and volume strain to determine whether they are within the tolerance range, that is, to determine:

[0119]

[0120] If not, make the next time step σ xz(t) -σ xz =σ zx(t) -σ zx =0,σ xy(t) -σ xy =σ yx(t) -σ yx =0,σ yz(t) -σ yz =σ zy(t) -σ zy =0, if , the target shear stress remains unchanged.

[0121] Finally, the modified strain control matrix Δε ij Apply to the sample and repeat the above steps. The strain control matrix Δε is known ij , by ε ij =δ ij -Dij The updated deformation gradient matrix D can be obtained ij , based on the updated D ij , since the center point O of the specimen remains unchanged, the centroid of each boundary surface before and after the specimen is deformed satisfies:

[0122] x oi =D ij X oj

[0123] Among them, x oi is the centroid position of the sample boundary surface before deformation, X oj is the centroid position of the boundary surface of the deformed specimen. It can be seen that in order to achieve the strain control matrix Δε ij , the movement patterns of the twenty-six boundary walls of Sample 1.

[0124] According to the discrete element servo method of multi-directional cyclic single shear under different drainage conditions proposed in the embodiment of the present application, the test parameters that need to be controlled can be determined to ensure that the test starts from a precisely planned starting point, and then the shear stress target value of the multi-directional cyclic single shear is determined, and the stress tensor and strain tensor of the specimen are monitored to calculate the required stress increment matrix. Then, the strain increment matrix corresponding to the stress increment matrix is ​​calculated, and the stress increment matrix is ​​corrected using different drainage conditions. At the same time, it is judged whether the shear stress and volume strain obtained by monitoring are within the tolerance range. If they are not within the tolerance range, the accuracy and reliability of the test results are guaranteed through correction and judgment.

[0125] Next, a discrete element servo device for multi-directional cyclic single shear under different drainage conditions proposed in an embodiment of the present application will be described with reference to the accompanying drawings.

[0126] Figure 3 It is a block diagram of a discrete element servo device for multi-directional cyclic single shear under different drainage conditions of an embodiment of the present application.

[0127] like Figure 3 As shown, the discrete element servo device 10 for multi-directional cyclic single shear under different drainage conditions includes: a generation module 100, a first calculation module 200, a second calculation module 300 and an iteration module 400.

[0128] Specifically, the generation module 100 is used to determine the test parameters that need to be controlled so as to generate and consolidate the specimen based on the target test conditions.

[0129] The first calculation module 200 is used to determine the shear stress target value of multi-directional cyclic single shear and monitor the stress tensor and strain tensor of the sample to calculate the stress increment matrix required to achieve the shear stress target value.

[0130] The second calculation module 300 is used to calculate the strain increment matrix corresponding to the stress increment matrix, and to modify the stress increment matrix using different drainage conditions to determine whether the monitored shear stress and volumetric strain are within a preset tolerance range.

[0131] The iteration module 400 is used to apply the corresponding strain increment to the sample when the strain is not within the preset tolerance range, and iterate until the loading is completed.

[0132] Optionally, in an embodiment of the present application, the iteration module 400 further includes: a judgment unit, configured to determine the next time step using a preset formula when the time step is not within the preset tolerance range.

[0133] Optionally, in one embodiment of the present application, the preset formula is:

[0134] σ xz(t) -σ xz =σ zx(t) -σ zx =0,σ xy(t) -σ xy =σ yx(t) -σ yx =0,σ yz(t) -σ yz =σ zy(t) -σ zy =0,

[0135] Among them, σ xz(t) , σ zx(t) is the target value of shear stress in the xz direction for multi-directional cyclic single shear, σ xz , σ zx is the stress tensor of multi-directional cyclic simple shear in the xz direction at a certain time step, σ xy(t) , σ yx(t) is the target value of shear stress in the xy direction for multi-directional cyclic single shear, σ xy , σ yx is the stress tensor of multi-directional cyclic simple shear in a certain time step in the xy direction, σ yz(t) , σ zy(t) is the target value of shear stress in the yz direction for multi-directional cyclic single shear, σ yz , σ zy is the stress tensor of multi-directional cyclic simple shear in the yz direction at a certain time step.

[0136] Optionally, in one embodiment of the present application, the stress increment matrix is:

[0137]

[0138] Among them, Δσ ij(t)is the stress increment, σ yx(t) , σ xy(t) is the target shear stress value in the xy direction for multi-directional cyclic single shear, σ yx , σ xy is the stress tensor of multi-directional cyclic simple shear in a certain time step in the xy direction, σ zx(t) , σ xz(t) is the target value of shear stress in the xz direction for multi-directional cyclic single shear, σ zx , σ xz is the stress tensor of multi-directional cyclic simple shear in the xz direction at a certain time step, σ zy(t) , σ yz(t) is the target value of shear stress in the yz direction for multi-directional cyclic single shear, σ zy , σ yz is the stress tensor of multi-directional cyclic simple shear in the yz direction at a certain time step.

[0139] Optionally, in one embodiment of the present application, the second calculation module 300 includes: a first calculation unit and a correction unit.

[0140] The first calculation unit is used to calculate the invariant of the strain increment required to achieve the stress increment matrix, so as to calculate the strain control matrix.

[0141] The correction unit is used to correct the strain control matrix to obtain a corrected strain control matrix.

[0142] Optionally, in one embodiment of the present application, the modified strain control matrix is:

[0143]

[0144] Among them, Δε ij is the modified strain control matrix, dε xx is the length strain tensor due to stress change in the x direction, dε yy is the length strain tensor in the y direction due to stress change, dε zz is the length strain tensor due to stress change in the z direction, dε xy , dε yx is the strain tensor corresponding to the angle change between the x and y directions due to shear, dε xz , dε zx is the strain tensor corresponding to the angle change between the x and z directions due to shear, dε yz , dε zy is the strain tensor corresponding to the angular change between the y and z directions due to shear.

[0145] It should be noted that the above explanation of the discrete element servo method embodiment of multi-directional cyclic single shear under different drainage conditions is also applicable to the discrete element servo device of multi-directional cyclic single shear under different drainage conditions of this embodiment, and will not be repeated here.

[0146] According to the discrete element servo device for multi-directional cyclic single shear under different drainage conditions proposed in the embodiment of the present application, the test parameters that need to be controlled can be determined to ensure that the test starts from a precisely planned starting point, and then the shear stress target value of the multi-directional cyclic single shear is determined, and the stress tensor and strain tensor of the specimen are monitored to calculate the required stress increment matrix. Then, the strain increment matrix corresponding to the stress increment matrix is ​​calculated, and the stress increment matrix is ​​corrected using different drainage conditions. At the same time, it is judged whether the shear stress and volume strain obtained by monitoring are within the tolerance range. If they are not within the tolerance range, the accuracy and reliability of the test results are guaranteed through correction and judgment.

[0147] Figure 4 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0148] Memory 401 , processor 402 , and a computer program stored in the memory 401 and executable on the processor 402 .

[0149] When the processor 402 executes the program, the discrete element servo method for multi-directional cyclic single shear under different drainage conditions provided in the above embodiments is implemented.

[0150] Furthermore, the electronic device further comprises:

[0151] The communication interface 403 is used for communication between the memory 401 and the processor 402 .

[0152] The memory 401 is used to store computer programs that can be executed on the processor 402 .

[0153] The memory 401 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0154] If the memory 401, the processor 402 and the communication interface 403 are implemented independently, the communication interface 403, the memory 401 and the processor 402 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 4 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0155] Optionally, in a specific implementation, if the memory 401, the processor 402 and the communication interface 403 are integrated on a chip, the memory 401, the processor 402 and the communication interface 403 can communicate with each other through an internal interface.

[0156] The processor 402 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0157] The embodiment of the present application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the discrete element servo method of multi-directional cyclic single shear under different drainage conditions as described above.

[0158] An embodiment of the present application also provides a computer program product, including a computer program, which, when executed, is used to implement the discrete element servo method of multi-directional cyclic single shear under different drainage conditions as described above.

[0159] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0160] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0161] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0162] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or N wirings (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways as necessary and then storing it in a computer memory.

[0163] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0164] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0165] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0166] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A discrete element servo method for multi-directional cyclic single shear under different drainage conditions, characterized in that: The following steps are involved: Determine the test parameters that need to be controlled to generate and consolidate the specimens based on the target test conditions; Determining a shear stress target value of multi-directional cyclic single shear, and monitoring the stress tensor and strain tensor of the specimen to calculate a stress increment matrix required to achieve the shear stress target value; Calculating the strain increment matrix corresponding to the stress increment matrix, and correcting the stress increment matrix using different drainage conditions to determine whether the monitored shear stress and volume strain are within a preset tolerance range; If it is not within the preset tolerance range, the corresponding strain increment is applied to the specimen and iterated until the loading is completed.

2. The method according to claim 1, characterized in that Also includes: If it is not within the preset tolerance range, the next time step is determined by a preset formula.

3. The method according to claim 2, characterized in that: The preset formula is: s xz(t) -s xz =s zx(t) -s zx =0、σ xy(t) -s xy =s yx(t) -s yx =0、σ yz(t) -s yz =s zy(t) -s zy =0, Among them, σ xz(t) , σ zx(t) is the target value of shear stress in the xz direction for multi-directional cyclic single shear, σ xz , σ zx is the stress tensor of multi-directional cyclic simple shear in the xz direction at a certain time step, σ xy(t) , σ yx(t) is the target value of shear stress in the xy direction for multi-directional cyclic single shear, σ xy , σ yx is the stress tensor of multi-directional cyclic simple shear in a certain time step in the xy direction, σ yz(t) , σ zy(t) is the target value of shear stress in the yz direction for multi-directional cyclic single shear, σ yz , σ zy is the stress tensor of multi-directional cyclic simple shear in the yz direction at a certain time step.

4. The method according to claim 3, characterized in that The stress increment matrix is: Among them, Δσ ij(t) is the stress increment, σ yx(t) , σ xy(t) is the target shear stress value in the xy direction for multi-directional cyclic single shear, σ yx , σ xy is the stress tensor of multi-directional cyclic simple shear in a certain time step in the xy direction, σ zx(t) , σ xz(t) is the target value of shear stress in the xz direction for multi-directional cyclic single shear, σ zx , σ xz is the stress tensor of multi-directional cyclic simple shear in the xz direction at a certain time step, σ zy(t) , σ yz(t) is the target value of shear stress in the yz direction for multi-directional cyclic single shear, σ zy , σ yz is the stress tensor of multi-directional cyclic simple shear in the yz direction at a certain time step.

5. The method according to claim 1, characterized in that The method of modifying the stress increment matrix using different drainage conditions includes: calculating the invariants of the strain increments required to achieve the stress increment matrix to calculate the strain control matrix; The strain control matrix is ​​corrected to obtain a corrected strain control matrix.

6. The method according to claim 5, characterized in that The modified strain control matrix is: Among them, Δε ij is the modified strain control matrix, dε xx is the length strain tensor due to stress change in the x direction, dε yy is the length strain tensor in the y direction due to stress change, dε zz is the length strain tensor due to stress change in the z direction, dε xy , dε yx is the strain tensor corresponding to the angle change between the x and y directions due to shear, dε xz , dε zx is the strain tensor corresponding to the angle change between the x and z directions due to shear, dε yz , dε zy is the strain tensor corresponding to the angular change between the y and z directions due to shear.

7. A discrete element servo device for multi-directional cyclic single shear under different drainage conditions, characterized in that: include: A generation module is used to determine the test parameters that need to be controlled in order to generate and consolidate the specimens based on the target test conditions; A first calculation module is used to determine a shear stress target value of multi-directional cyclic single shear and monitor the stress tensor and strain tensor of the sample to calculate a stress increment matrix required to achieve the shear stress target value; A second calculation module is used to calculate the strain increment matrix corresponding to the stress increment matrix, and to modify the stress increment matrix using different drainage conditions to determine whether the monitored shear stress and volume strain are within a preset tolerance range; The iteration module is used for applying the corresponding strain increment to the sample when the strain is not within the preset tolerance range, and iterating until the loading is completed.

8. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement a discrete element servo method for multi-directional cyclic single shear under different drainage conditions as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement a discrete element servo method for multi-directional cyclic single shear under different drainage conditions as described in any one of claims 1 to 6.

10. A computer program product, characterized in that It comprises a computer program, characterized in that the computer program is executed to implement a discrete element servo method for multi-directional cyclic single shear under different drainage conditions as described in any one of claims 1-6.

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