Rockfill dam creep simulation analysis method and system based on implicit iteration

Abstract

The invention discloses a rock-fill dam creep simulation analysis method and system based on implicit iteration, and belongs to the technical field of rock-fill dam creep numerical simulation. According to an existing rock-fill dam creep simulation analysis scheme, model parameters depend on observation data of a rock-fill dam, universality is lacked, and expandability is poor. According to the rock-fill dam creep simulation analysis method based on implicit iteration, the object generation unit, the solution strategy setting unit, the rock-fill dam strain calculation unit and the implicit iteration calculation unit are constructed to complete rock-fill dam creep simulation analysis based on implicit iteration; therefore, the output of the nonlinear elastic model and the rock-fill dam creep model can be processed as an intermediate variable without depending on the specific expression forms and parameters of the nonlinear elastic model and the rock-fill dam creep model, so that the nonlinear elastic model and the rock-fill dam creep model can be coupled with the existing different nonlinear elastic model and the creep model; and the method has good expansibility and universality.

Description

Technical Field

[0001] The present invention relates to a method and system for creep simulation analysis of rockfill dams based on implicit iteration, belonging to the technical field of numerical simulation of rockfill dam creep. Background Art

[0002] The deformation of the face slab of a rockfill dam mainly stems from the deformation of the rockfill body. When the deformation of the rockfill body is too large, it may cause cracks in the face slab, thereby weakening the anti-seepage effect and even endangering the overall stability of the dam body. Therefore, accurately predicting the deformation of the rockfill body is the key to improving the accuracy of rockfill dam deformation prediction. The deformation of the rockfill body can be divided into instantaneous deformation and time-dependent deformation. Among them, the instantaneous deformation is mainly caused by the self-weight of the dam body and water pressure, while the time-dependent deformation is generated by the creep effect after the dam body is impounded. At present, the nonlinear elastic model is usually adopted in China to simulate the instantaneous deformation of the rockfill body, while less research has been done on the time-dependent deformation caused by rockfill creep.

[0003] A Chinese literature (Shen Changsong, Gu Ganchen. Discussion on parameter back-analysis and deformation law of concrete face rockfill dam [J]. Journal of Hohai University, 1996, 24(6): 13-19) discloses a scheme for discussion on parameter back-analysis and deformation law of a face rockfill dam. According to the deformation observation data of the Xibeikou concrete face rockfill dam during the construction period and operation period, a four-element model and a Duncan-Chang model are established by applying theories of hydraulic engineering, geotechnical mechanics, mathematical statistics, optimization, etc. Among them, the four-element model is a creep model of a rockfill dam, and the Duncan-Chang model is a nonlinear elastic model, so as to reasonably analyze the filling component, water pressure component and creep component of the dam body deformation in different periods. Furthermore, through a large number of finite element calculations, the relationship between each parameter in the Duncan-Chang model and the settlement deformation is found, and the value of the model parameter is determined.

[0004] The above scheme obtains relatively reasonable model parameters by comparing the observed data, resulting in the origin of the model parameters being highly dependent on the observed data of this rockfill dam. Therefore, the model parameters are only applicable to the Duncan-Chang model and the four-element model in this scenario, and cannot be applied to other scenarios, other nonlinear elastic models and rockfill dam creep models, lacking generality and having poor scalability.

[0005] Furthermore, the above scheme needs to collect a large amount of deformation observation data and requires a large number of finite element calculations to obtain the model parameters. The development process of the rockfill dam coupling model is relatively complex, and the amount of data to be processed is large, which is not conducive to the popularization and use of the rockfill dam creep simulation analysis scheme.

[0006] The information disclosed in this background art is only used to understand the background of the inventive concept of the present invention, so it may include information that does not constitute the prior art. Summary of the Invention

[0007] In view of the above problems or one of the above problems, the object of the present invention is to provide a method and system for creep simulation analysis of rockfill dams based on implicit iteration. By constructing an object generation unit, a solution strategy setting unit, a rockfill dam strain calculation unit, and an implicit iteration calculation unit, it is possible to not depend on the specific expression forms and parameters of the nonlinear elastic model and the rockfill dam creep model, and only treat the outputs of the nonlinear elastic model and the rockfill dam creep model as an intermediate variable. Therefore, it can be coupled with existing different nonlinear elastic models and creep models, has good scalability and versatility, can simplify the development process of the rockfill dam coupling model, requires a small amount of data to be processed, and is conducive to the development of rockfill dam numerical simulation technology.

[0008] To achieve the above object, the first technical solution of the present invention is: A method for creep simulation analysis of rockfill dams based on implicit iteration, including the following contents: Using a pre-constructed object generation unit, combined with the dam construction grading data and the dam body material information, a rockfill dam simulation object is established; Through a pre-constructed solution strategy setting unit, according to the rockfill dam simulation object and the dam construction grading data, an integral time step sequence is created; Adopting a pre-constructed rockfill dam strain calculation unit, applying the applied load to the rockfill dam simulation object, and based on the nonlinear elastic algorithm and the rockfill dam creep characteristics, the initial strain data of the rockfill dam is obtained, which is used to estimate the instantaneous deformation and aging deformation of the rockfill dam; Using a pre-constructed implicit iteration calculation unit, based on the integral time step sequence, implicit integration is performed on the initial strain data of the rockfill dam to obtain the dam settlement data, and the creep simulation analysis of the rockfill dam based on implicit iteration is completed.

[0009] The present invention constructs an object generation unit, a solution strategy setting unit, a rockfill dam strain calculation unit, and an implicit iteration calculation unit. According to the rockfill dam simulation object and the dam construction grading data, an integral time step sequence is created; and based on the nonlinear elastic algorithm and the rockfill dam creep characteristics, the initial strain data of the rockfill dam is obtained; then implicit integration is performed on the initial strain data of the rockfill dam to obtain the dam settlement data, thereby completing the creep simulation analysis of the rockfill dam based on implicit iteration. Thus, it is possible to not depend on the specific expression forms and parameters of the nonlinear elastic model and the rockfill dam creep model, and only treat the outputs of the nonlinear elastic model and the rockfill dam creep model as an intermediate variable. Therefore, it can be coupled with existing different nonlinear elastic models and creep models, has good scalability and versatility, can simplify the development process of the rockfill dam coupling model, requires a small amount of data to be processed, is conducive to the development of rockfill dam numerical simulation technology, and is convenient for the popularization and use of the creep simulation analysis scheme of the rockfill dam.

[0010] As a preferred technical measure: The method for establishing a rockfill dam simulation object by using a pre-constructed object generation unit in combination with dam construction classification data and dam body material information is as follows: Obtain dam construction classification data and dam body material information; The dam construction classification data is information on the construction of the dam in time periods and sequences, including information on the constructed sections, the sections under construction, and the sections not yet constructed; The dam body material information includes foundation material information, transition layer material information, upstream rockfill layer material information, and downstream rockfill layer material information; Process the information on the constructed sections and the sections under construction to obtain a number of three-dimensional unstructured elements, and each integration point of each three-dimensional unstructured element contains 3 translational degrees of freedom; Based on the dam body material information, apply rockfill data to each three-dimensional unstructured element to obtain a rockfill dam simulation element for characterizing the actual filled rockfill in different sections; Couple a number of rockfill dam simulation elements to obtain a rockfill dam simulation object.

[0011] As a preferred technical measure: The method for creating an integral time step sequence by using a pre-constructed solution strategy setting unit according to the rockfill dam simulation object and the dam construction classification data is as follows: Obtain the global construction time of the rockfill dam according to the construction information of the rockfill dam simulation object; Based on the dam construction classification data, divide the global construction time into a number of construction classification periods; set an integral time step at the initial moment of each construction classification period, and align the integral time step with the change moment of the construction classification period to ensure that the time step is set at the moment of the replacement of the construction classification period; Based on the integral time step set at the initial moment, set a number of evenly distributed calculation time steps for the construction classification period; Adopt a non-uniform time step strategy to encrypt the calculation time steps in the early and late time periods of the new construction classification period to obtain multiple encrypted time steps; Sort the integral time steps, calculation time steps, and encrypted time steps of each construction classification period to obtain an integral time step sequence.

[0012] As a preferred technical measure: The method for obtaining the initial strain data of the rockfill dam by using a pre-constructed rockfill dam strain calculation unit, applying the applied load to the rockfill dam simulation object, and based on the non-linear elastic algorithm and the creep characteristics of the rockfill dam is as follows: Based on the creep characteristics of the rockfill dam simulation object, a creep calculation formula for the dam is constructed to describe the relationship between the creep strain tensor and the parameter vector, so as to estimate the time-dependent deformation of the rockfill dam; Obtain the applied load for the rockfill dam to be simulated and analyzed, and at the same time set the initial value of the parameter vector; Substitute the initial value of the parameter vector and the applied load into the dam creep calculation formula for simulation calculation to obtain the initial creep strain tensor; Based on the rockfill dam simulation object and the nonlinear elastic algorithm, a nonlinear elastic calculation formula is constructed to describe the relationship between the parameter group, stress tensor and strain tensor of the rockfill dam, so as to estimate the instantaneous deformation of the rockfill dam; Set the initial value of the parameter group; and substitute the initial value of the parameter group and the initial creep strain tensor into the nonlinear elastic calculation formula for simulation calculation to obtain the initial stress tensor; Summarize the initial creep stress tensor and the initial strain tensor to obtain the initial strain data of the rockfill dam.

[0013] As a preferred technical measure: The method of substituting the initial value of the parameter vector and the applied load into the dam creep calculation formula for simulation calculation to obtain the initial creep strain tensor is as follows: According to the creep characteristics of the rockfill dam simulation object, set the Young's modulus, Poisson's ratio, parameter vector and continuous time; Discretize the continuous time to obtain a number of time steps; For each time step, substitute the Young's modulus, Poisson's ratio and parameter vector into the dam creep calculation formula to obtain the creep strain increment corresponding to each time step; Based on the creep strain increment, determine the initial creep strain tensor.

[0014] As a preferred technical measure: The method of obtaining the dam settlement data is as follows: Step 1, based on the integral time step sequence, determine the time difference between adjacent time steps; Obtain the initial strain data of the rockfill dam, which includes the initial creep stress tensor and the initial strain tensor; Step 2, based on the initial creep stress tensor and the time difference, use the Newton-Raphson iterative integral to calculate the creep strain increment of a certain integral step; Step 3, according to the creep strain increment of a certain integral step, update the elastic strain increment of the current integral step in real time to obtain a new elastic strain increment; Step 4, based on the new elastic strain increment, strain displacement matrix, unit volume and linear elastic stiffness matrix, calculate the unit internal force vector of the rockfill dam simulation object; Step 5, summarize the internal force vectors of the elements into the global internal force vector; Step 6, perform a convergence judgment on the global internal force vector. When it converges, execute Step 7; when it does not converge, reduce the time difference by half and execute Step 2; Step 7, obtain the strain tensor based on the creep strain increment, and calculate the dam displacement information through the strain-displacement matrix; Step 8, based on the dam displacement information, filter out the vertical displacement value of the dam as the dam settlement data.

[0015] Furthermore, the linear elastic stiffness matrix is constructed based on the Poisson's ratio; the strain-displacement matrix consists of the shape functions and their derivatives of the grid nodes in the rockfill dam simulation object; the element volume is calculated by Gaussian integration.

[0016] As an optimal technical measure: The method for performing a convergence judgment on the global internal force vector is as follows: Obtain the applied load and convert the applied load into an applied load vector; Calculate the difference between the global internal force vector and the applied load vector; Judge whether the difference satisfies the relative convergence criterion and the absolute convergence criterion, which includes the following: Based on the relative threshold constant and the applied load vector, set the relative convergence reference value; Based on the absolute threshold constant, set the absolute convergence reference value; When the difference is less than the relative convergence reference value, that is, the relative convergence criterion is satisfied. At this time, the absolute convergence criterion is not judged, and the judgment result is convergence; When the difference is greater than the relative convergence reference value and at the same time the difference is less than the absolute convergence reference value, the judgment result is convergence; When the difference is greater than the relative convergence reference value and at the same time the difference is greater than the absolute convergence reference value, the judgment result is non-convergence.

[0017] As an optimal technical measure: The method for obtaining the dam settlement data is as follows: Step 1, based on the integral time step sequence, determine the time difference between adjacent time steps; Obtain the initial strain data of the rockfill dam, which includes the initial creep stress tensor and the initial strain tensor; Step 2, based on the initial creep stress tensor and the time difference, use the Newton-Raphson iterative integral to calculate the creep strain increment of a certain integral step; Step 3, calculate the total strain increment according to the displacement increment and the strain-displacement matrix; The displacement increment is a known quantity in the Newton-Raphson iterative integral, and the strain-displacement matrix consists of the shape functions and their derivatives of the grid nodes; Step 4: Subtract the total strain increment from the creep strain increment to obtain the elastic strain increment; Step 5: Calculate the internal force vector of the elements of the rockfill dam simulation object based on the elastic strain increment, strain-displacement matrix, element volume, and linear elastic stiffness matrix; Step 6: Aggregate the internal force vectors of the elements into the overall internal force vector; Step 7: Perform a convergence judgment on the overall internal force vector. When it converges, execute Step 8. When it does not converge, reduce the time difference by half and execute Step 2; Step 8: Obtain the strain tensor based on the creep strain increment, and obtain the dam displacement information through the strain-displacement matrix; Step 9: Screen out the vertical displacement values of the dam based on the dam displacement information to obtain the dam settlement data.

[0018] Furthermore, the linear elastic stiffness matrix is constructed based on the Poisson's ratio; the strain-displacement matrix is composed of the shape functions and their derivatives of the grid nodes in the rockfill dam simulation object; the element volume is obtained through Gaussian integration.

[0019] To achieve the above object, the second technical solution of the present invention is: A creep simulation analysis method for a rockfill dam based on implicit iteration, including the following steps: S1: Generate elements using a pre-constructed object, and establish a rockfill dam simulation object in combination with the dam construction grading data and the dam body material information; S2: Construct elements using a pre-constructed calculation model, and establish a nonlinear elastic model and a creep empirical parameter model based on the rockfill dam simulation object; S3: Set elements using a pre-constructed solution strategy, and create an integral time step sequence and initial state variables based on the nonlinear elastic model and the creep empirical parameter model; S4: Use a pre-constructed implicit iteration calculation element, substitute the initial state variables into the nonlinear elastic model and the creep empirical parameter model to obtain the initial strain data of the rockfill dam; then perform implicit integration on the initial strain data of the rockfill dam according to the integral time step sequence to obtain the dam settlement value, and complete the creep simulation analysis of the rockfill dam based on implicit iteration.

[0020] To achieve the above object, the third technical solution of the present invention is: A creep simulation analysis system for a rockfill dam based on implicit iteration, which includes: One or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors are caused to implement the above-mentioned creep simulation analysis method for a rockfill dam based on implicit iteration.

[0021] Compared with the existing technical solutions, the present invention has the following beneficial effects: By constructing an object generation unit, a solution strategy setting unit, a rockfill dam strain calculation unit, and an implicit iteration calculation unit, the present invention creates an integral time step sequence according to the rockfill dam simulation object and the dam construction grading data; and based on the nonlinear elastic algorithm and the creep characteristics of the rockfill dam, obtains the initial strain data of the rockfill dam; then performs implicit integration on the initial strain data of the rockfill dam to obtain the dam settlement data, thereby completing the creep simulation analysis of the rockfill dam based on implicit iteration. Thus, it is possible to not rely on the specific expression forms and parameters of the nonlinear elastic model and the rockfill dam creep model, and only treat the outputs of the nonlinear elastic model and the rockfill dam creep model as an intermediate variable. Therefore, it can be coupled with existing different nonlinear elastic models and creep models, has good scalability and versatility, can simplify the development process of the rockfill dam coupling model, requires a small amount of data to be processed, is beneficial to the development of the rockfill dam numerical simulation technology, and is convenient for the popularization and use of the rockfill dam creep simulation analysis scheme. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic flow chart of a method for creep simulation analysis of a rockfill dam according to the present invention; Figure 2 It is a schematic diagram of a grid and material partition of a certain rockfill dam according to the present invention; Figure 3 It is a schematic diagram of generating a settlement contour map of a certain rockfill dam by applying the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0024] On the contrary, the present invention covers any alternatives, modifications, equivalent methods and solutions made within the spirit and scope of the present invention defined by the claims. Further, in order to enable the public to better understand the present invention, some specific details are described in detail in the following detailed description of the present invention. Those skilled in the art can fully understand the present invention without the description of these details.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The term "or / and" used herein includes any and all combinations of one or more of the related listed items.

[0026] As shown Figure 1 in the following, the first specific embodiment of the creep simulation analysis method for rockfill dams based on implicit iteration of the present invention: A creep simulation analysis method for rockfill dams based on implicit iteration includes the following: Using a pre-constructed object generation unit, combining the dam construction grading data and the dam body material information, to establish a rockfill dam simulation object; Through a pre-constructed solution strategy setting unit, according to the rockfill dam simulation object and the dam construction grading data, to create an integral time step sequence; Adopting a pre-constructed rockfill dam strain calculation unit, applying the applied load to the rockfill dam simulation object, and based on the non-linear elastic algorithm and the creep characteristics of the rockfill dam, to obtain the initial strain data of the rockfill dam for predicting the instantaneous deformation and aging deformation of the rockfill dam; Using a pre-constructed implicit iteration calculation unit, based on the integral time step sequence, to perform implicit integration on the initial strain data of the rockfill dam to obtain the dam settlement data, and complete the creep simulation analysis of the rockfill dam based on implicit iteration.

[0027] The second specific embodiment of the creep simulation analysis method for rockfill dams based on implicit iteration of the present invention: A creep simulation analysis method for rockfill dams based on implicit iteration includes the following steps: S1: Using a pre-constructed object generation unit, combining the dam construction grading data and the dam body material information, to establish a rockfill dam simulation object; S2: Using a pre-constructed calculation model construction unit, according to the rockfill dam simulation object, to establish a non-linear elastic model and a creep empirical parameter model; S3: Using a pre-constructed solution strategy setting unit, based on the non-linear elastic model and the creep empirical parameter model, to create an integral time step sequence and an initial state variable; S4: Using a pre-constructed implicit iteration calculation unit, substituting the initial state variable into the non-linear elastic model and the creep empirical parameter model to obtain the initial strain data of the rockfill dam; then performing implicit integration on the initial strain data of the rockfill dam according to the integral time step sequence to obtain the dam settlement value, and complete the creep simulation analysis of the rockfill dam based on implicit iteration.

[0028] The third specific embodiment of the creep simulation analysis method for rockfill dams based on implicit iteration of the present invention: The creep simulation analysis method for rockfill dams based on implicit iteration is a numerical simulation calculation method capable of performing creep coupling analysis of rockfill dams, and it includes the following steps: S1: Combining the dam construction grading and the dam body material zoning to establish a finite element model of the rockfill dam.

[0029] S2: Select a suitable non - linear elastic model and a creep empirical parameter model.

[0030] S3: Create a reasonable integral time - step sequence and store the initial state variables of the elastic model and the creep model.

[0031] S4: For each time step, perform implicit integration according to the integration strategy until the convergence condition is met.

[0032] S5: Judge the time - step sequence. If the maximum time step has been reached, stop; otherwise, judge and update the state variables of the elastic model and the creep model respectively, update the time step, and return to S4 for execution.

[0033] In step S1 of this embodiment, the finite - element model of the rock - fill dam adopts three - dimensional unstructured elements, and each element integration point contains 3 translational degrees of freedom. Creating in combination with the dam construction grading means that the dam is constructed according to different material zones in a certain time period and sequence. During the construction period, the dam can be divided into the constructed zone, the zone under construction, and the unconstructed zone. The constructed - zone part of the finite - element model remains unchanged during this period, the part of the zone under construction is updated during this time period, and the geometric model of the unconstructed - zone part is not considered during this time period. Since the rock - fill materials filled in different material zones are different, non - linear elastic models and creep empirical parameter models that conform to the actual filling materials are applied to each zone.

[0034] In step S2 of this embodiment, the non - linear elastic model can be expressed as 、 , where and are the Young's modulus and Poisson's ratio of this elastic model respectively, where 、 、 are the stress tensor, strain tensor, and parameter group respectively.

[0035] The strain tensor is obtained through the displacement gradient tensor and its transposed symmetric part, and its calculation formula is as follows:

[0036] where is the displacement component, and further the strain tensor can be expressed as:

[0037] where , and are the normal strain components in the x - direction, y - direction, and z - direction of the stress tensor respectively, , and are the shear strain components in the x-y direction, the x-z direction, and the y-z direction, respectively.

[0038] Stress tensor is obtained by the action of the elastic stiffness tensor on the strain tensor The specific calculation formula is as follows:

[0039] Stress tensor can be expressed as:

[0040] where , and are the normal stress components in the x direction, the y direction, and the z direction of the stress tensor, respectively, , and are the shear stress components in the x-y direction, the x-z direction, and the y-z direction, respectively.

[0041] This model parameter set can be expressed as:

[0042] where is the th parameter of this model, is the total number of parameters of this model.

[0043] For rockfill dams, its nonlinear elastic model describes the relationship between the Young's modulus , Poisson's ratio and the element stress tensor as well as the strain tensor of the rockfill.

[0044] The creep model can be expressed as , where is the creep strain tensor, , are the Young's modulus and Poisson's ratio, respectively, is the time, is the parameter vector of the creep model, which can be expressed as:

[0045] where is the th parameter of this model, and M is the total number of parameters of this model.

[0046] For a rockfill dam, the creep parameter model describes the creep strain tensor and physical parameters and time The strain tensor output by the creep parameter model is involved in the calculation of the stress tensor of the nonlinear elastic model.

[0047] In the finite element calculation, continuous time is discretized. For the th time step, the expression of the creep model is as follows:

[0048] where is the creep strain tensor at the th time step, , is the increment of creep strain, and represent the elastic modulus, Poisson's ratio and time step value at the th time step respectively.

[0049] In this embodiment S3, the time step sequence needs to be set according to the dam construction grading. During the construction process, the dam construction grading usually proceeds according to a certain time period. Therefore, the time step needs to be aligned with the change moment of the construction grading. Set a global construction time , and divide it into construction grading periods . Set the time step at the initial moment of each construction grading period to ensure that the time step is set at the moment of construction grading period replacement. Before and after the replacement of different construction grading periods, the time step needs to be reasonably refined. Adopt a non-uniform time step strategy. Divide the first 10% - 20% time period of the new dam construction grading period into 10 - 20 time steps; divide the last 10% - 20% time period into 12 - 15 time steps, and each time step length accounts for about 1.2% - 1.5% of the whole period. Save the state parameters related to the element state in the parameter vectors of the elastic model and the creep model at the initial time step to ensure that they can be updated in subsequent time steps.

[0050] In this embodiment S4, for the th time step , its time difference from the th time step is . At time step , the stress tensor and strain tensor of the known unit Gauss integration point are available. Three methods can be selected to calculate the The stress tensor at one time step and the strain tensor .

[0051] The first way assumes that the Young's modulus and Poisson's ratio of the non-linear elastic model within remain unchanged and the creep strain increment is invariant. The Young's modulus and Poisson's ratio of the elastic model are taken as and respectively. According to the creep model, the calculation formula of the creep strain increment is as follows: , where is the creep strain increment at the th time step, is the creep strain tensor at the th time step, and represent the elastic modulus, Poisson's ratio and time step value at the th time step respectively, is the known creep model parameter vector at the th time step.

[0052] Calculate the elastic stress tensor of in accordance with the linear elastic method. Its calculation formula is as follows:

[0053] where is the elastic strain increment, is the stress tensor at the i-th time step, is the total strain tensor, is the known linear elastic stiffness matrix at the i-th time step.

[0054] The expression of the linear elastic stiffness matrix is as follows:

[0055] where and are the Young's modulus and Poisson's ratio at the th integration step.

[0056] The second way assumes that the creep strain increment within is invariant. Its expression is as follows:

[0057] For the non-linear elastic model, the Newton-Raphson iterative integration is used to calculate the elastic stress tensor, that is, the new stress tensor is calculated according to the stiffness update matrix, and the expression of the stiffness update matrix is as follows:

[0058] where the elastic strain increment is the total strain increment minus the creep strain increment , and the specific expression is as follows:

[0059]

[0060] where, is the total strain increment, is the displacement increment, which is a known quantity in the Newton-Raphson iterative integration, is the strain-displacement matrix, which is composed of the shape functions and their derivatives of the model mesh nodes.

[0061] The stiffness matrix is updated in real time according to the current nd integration step in the iterative integration, and its expression is as follows:

[0062] where, and are the Young's modulus and Poisson's ratio of the rd integration step, which are given by the non-linear elastic model.

[0063] The third method assumes that the Young's modulus and Poisson's ratio of the non-linear elastic model remain unchanged within , and the Newton-Raphson iterative integration is used to calculate the creep strain increment of the creep model. The calculation formula for the creep strain increment of the

[0064] The elastic strain increment is updated in real time according to the creep strain increment of the current st integration step in the iterative integration, and its expression is as follows: .

[0065] At time , the internal force vector of the element is calculated and summarized as the global internal force vector . The calculation formula for the internal force vector of the element is as follows:

[0066] wherein represents the volume of the element, which is calculated by Gaussian integration.

[0067] Judge whether the difference from the applied load vector satisfies the relative convergence criterion and the absolute convergence criterion. When the relative convergence criterion is satisfied, the absolute convergence criterion is not judged; when the relative convergence criterion is not satisfied, the absolute convergence criterion is judged. If the absolute convergence criterion is not satisfied, try to halve the time difference and then recalculate the strain tensor and the stress tensor , and their calculation formulas are as follows:

[0068] The relative convergence criterion is:

[0069] wherein is the relative threshold constant, usually taken as .

[0070] The absolute convergence criterion is:

[0071] wherein is the absolute threshold constant, which is user-defined and usually taken as .

[0072] In this embodiment S5, further, judge whether is equal to the maximum time. If they are equal, end the calculation process; otherwise, update and save the Young's modulus and Poisson's ratio of the nonlinear elastic model, update their respective state variables and according to the specific expressions of the nonlinear elastic model and the creep model, let and execute S4.

[0073] A specific embodiment of applying the present invention to simulate and analyze a certain concrete face rockfill dam: The method for numerically simulating a certain concrete face rockfill dam is as follows: Step 1: Take a certain concrete face rockfill dam in Central China as an example. The designed maximum dam height of this rockfill dam is 114 m, the top width is 10 m, the dam crest length is 328 m, and the upstream and downstream slope ratios of the rockfill dam are both . According to the dam construction zoning and material zoning, the dam body is divided into 4 zones, namely the foundation, transition layer, upstream rockfill zone, and downstream rockfill zone, as shown in Figure 2As shown, the construction is carried out in the order of the transition layer, the upstream rockfill layer, and the downstream rockfill layer.

[0074] Step 2: Select the Duncan-Chang E-B model widely used in engineering as the nonlinear elastic model, and select the nine-parameter power function rheological model as the creep model. Among them, the Young's modulus in the Duncan-Chang E-B model has the following expression:

[0075] where , , are known test parameters, the value range of is 0.78 - 0.89, the value range of is 1150 - 1800, the value range of n is 0.35 - 0.47, and are the first principal stress and the third principal stress respectively, is the Mohr-Coulomb yield stress, , and can be calculated from the stress tensor, is the atmospheric pressure.

[0076] The Poisson's ratio has the following expression:

[0077] where and are known test parameters, the value range of is 550 - 640, the value range of is 0.2 - 0.4.

[0078] The axial creep in the nine-parameter power function creep model has the following expression:

[0079]

[0080] where is the atmospheric pressure, and its value is ; is the characteristic time, and its value is 1 hour; is the confining pressure, is the stress level, and can be calculated from the integration point stress tensor, is the axial creep stress ratio coefficient; , , and are known test parameters, ranges from 0.2745 to 1.3546, ranges from 0.2247 to 0.7968, ranges from 0.1107 to 0.1457, ranges from 0.3568 to 1.0253.

[0081] Volume creep The expression is as follows:

[0082] where , , , and are known test parameters, where ranges from 0.3149 to 0.4879, ranges from 0.5698 to 1.9872, ranges from 0.1779 to 0.3989, ranges from 0.9156 to 1.4526, ranges from 0.0606 to 0.0899.

[0083] Respectively, find the time derivatives of axial creep and volume creep and write them in difference format. The specific expressions are as follows:

[0084]

[0085] where is the axial creep increment; is the volume creep increment.

[0086] Furthermore, the creep stress increment can be written as:

[0087] where is the unit fourth-order tensor, is the deviatoric stress tensor, is the von Mises equivalent stress, and can be calculated from

[0088] Step 3: Create a reasonable time series according to the construction sequence and construction period ​, is the total number of discrete time steps. And the state variables of the Duncan E-B model and the nine-parameter creep model are saved at the initial moment. For the Duncan E-B model, the expressions of its state variables are as follows:

[0089] For the creep model, the expressions of its state variables are as follows:

[0090]

[0091] Step 4: Integrate according to the first way of the integration strategy. It is considered that within the time period, the Young's modulus and Poisson's ratio of the Duncan E-B model remain unchanged and the creep strain tensor of the nine-parameter creep model remains unchanged. Calculate the stress tensor at the moment in a linear elastic manner and perform convergence judgment. If the relative convergence criterion is satisfied, end Step 4. Otherwise, divide the time from to into , , moments. The calculation formula for the time difference is as follows:

[0092] Starting from the moment, calculate the stress tensor and strain tensor at the moment according to the new time series. The stress tensor acts on the strain tensor through the elastic stiffness matrix tensor. The calculation formula for the strain tensor is as follows:

[0093] where is the total strain increment.

[0094] Furthermore, according to the strain tensor, the displacement of the dam is obtained through the strain-displacement matrix.

[0095] Step 5: Judge whether is equal to . If they are equal, stop the calculation. Otherwise, update the state variables , of the Duncan E-B model and the state variables , and of the nine-parameter creep model respectively, and update the value of to , and re-execute Step 4.

[0096] The finally calculated contour map of the settlement distribution of the rockfill dam is as shown in Figure 3 the figure. Taking the maximum value of the absolute value of the vertical numerical component in the displacement result as the maximum dam settlement value, with the unit of meter (m), it can be found that the maximum dam settlement value after coupling the creep model occurs in the middle and lower parts of the dam, with a reasonable distribution and a numerical value close to the experimental monitoring result, which proves the rationality of the calculation method of coupling the nonlinear elastic model and the creep model in the present invention.

[0097] An equipment embodiment applying the method of the present invention: An electronic device, which includes: One or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors are caused to implement the above-mentioned method for creep simulation analysis of a rockfill dam based on implicit iteration.

[0098] A computer medium embodiment applying the method of the present invention: A computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, it implements the above-mentioned method for creep simulation analysis of a rockfill dam based on implicit iteration.

[0099] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, and computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, optical storage, etc.) containing computer-usable program code.

[0100] The present application is described according to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products of the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the specified functions in Figure 1 one process or multiple processes or / and blocks Figure 1 one block or multiple blocks.

[0101] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction device that implements the functions specified in one or more processes or / and blocks Figure 1 in one or more processes or / and blocks Figure 1 specified in the function.

[0102] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes or / and blocks Figure 1 in one or more processes or / and blocks Figure 1 specified in the function.

[0103] The unit in this application is an object that constitutes an objective description of the morphological structure by means of an entity or a virtual representation. The object is not equal to an object and is not limited to entities and virtuals. It can be a data processing function, a software program, a processing mode, a usage method, an operation mode, a work process, an application process, electronic hardware, a circuit module, a processing system, a system imitation, or a simulation object.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still modify or equivalently replace the specific implementation manners of the present invention. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A creep simulation analysis method for rockfill dams based on implicit iteration, characterized by: including the following: Using a pre-constructed object generation unit, combining the dam construction grading data and the dam body material information to establish a rockfill dam simulation object; Through a pre-constructed solution strategy setting unit, according to the rockfill dam simulation object and the dam construction grading data, create an integral time step sequence; Adopt a pre-constructed rockfill dam strain calculation unit, apply the applied load to the rockfill dam simulation object, and based on the non-linear elastic algorithm and the creep characteristics of the rockfill dam, obtain the initial strain data of the rockfill dam for predicting the instantaneous deformation and aging deformation of the rockfill dam; Use a pre-constructed implicit iteration calculation unit, based on the integral time step sequence, perform implicit integration on the initial strain data of the rockfill dam to obtain the dam settlement data, and complete the creep simulation analysis of the rockfill dam based on implicit iteration.

2. The creep simulation analysis method for rockfill dams based on implicit iteration according to claim 1, characterized by: The method of using a pre-constructed object generation unit to establish a rockfill dam simulation object in combination with the dam construction grading data and the dam body material information is as follows: Obtain the dam construction grading data and the dam body material information; The dam construction grading data is the information of the dam construction in time periods and sequences, which includes the information of the constructed sections, the sections under construction, and the sections not yet constructed; The dam body material information includes the foundation material information, the transition layer material information, the upstream rockfill layer material information, and the downstream rockfill layer material information; Process the information of the constructed sections and the sections under construction to obtain a number of three-dimensional unstructured elements, and each integration point of each three-dimensional unstructured element contains 3 translational degrees of freedom; Based on the dam body material information, apply the rockfill data to each three-dimensional unstructured element to obtain a rockfill dam simulation element for characterizing the actual filled rockfill in different sections; Couple a number of rockfill dam simulation elements to obtain a rockfill dam simulation object.

3. The creep simulation analysis method for rockfill dams based on implicit iteration according to claim 1, characterized by: The method of creating an integral time step sequence through a pre-constructed solution strategy setting unit according to the rockfill dam simulation object and the dam construction grading data is as follows: According to the construction information of the rockfill dam simulation object, obtain the global construction time of the rockfill dam; Based on the dam construction grading data, divide the global construction time into several construction grading periods; set an integral time step at the initial moment of each construction grading period, and align the integral time step with the change moment of the construction grading period to ensure that the time step is set at the moment of construction grading period replacement; Based on the integral time step set at the initial moment, set a number of evenly distributed calculation time steps for the construction grading period; Adopt a non-uniform time step strategy to encrypt the calculation time steps in the early and late time periods of the new construction grading period to obtain multiple encrypted time steps; Sort the integral time steps, calculation time steps, and encrypted time steps of each construction grading period to obtain an integral time step sequence.

4. A creep simulation analysis method for rockfill dams based on implicit iteration, characterized in that: The method of applying the applied load to the rockfill dam simulation object using a pre-constructed strain calculation unit for the rockfill dam and obtaining the initial strain data of the rockfill dam based on the non-linear elastic algorithm and the creep characteristics of the rockfill dam is as follows: Based on the creep characteristics of the rockfill dam of the rockfill dam simulation object, a dam creep calculation formula is constructed to describe the relationship between the creep strain tensor and the parameter vector to estimate the aging deformation of the rockfill dam; Obtain the applied load to be simulated and analyzed for the rockfill dam, and at the same time set the initial value of the parameter vector; Substitute the initial value of the parameter vector and the applied load into the dam creep calculation formula for simulation calculation to obtain the initial creep strain tensor; Based on the rockfill dam simulation object and the non-linear elastic algorithm, a non-linear elastic calculation formula is constructed to describe the relationship between the parameter group, stress tensor and strain tensor of the rockfill dam to estimate the instantaneous deformation of the rockfill dam; Set the initial value of the parameter group; And substitute the initial value of the parameter group and the initial creep strain tensor into the non-linear elastic calculation formula for simulation calculation to obtain the initial stress tensor; Summarize the initial creep stress tensor and the initial strain tensor to obtain the initial strain data of the rockfill dam.

5. A creep simulation analysis method for rockfill dams based on implicit iteration, characterized in that: The method of substituting the initial value of the parameter vector and the applied load into the dam creep calculation formula for simulation calculation to obtain the initial creep strain tensor is as follows: According to the creep characteristics of the rockfill dam of the rockfill dam simulation object, set the Young's modulus, Poisson's ratio, parameter vector and continuous time; Discretize the continuous time to obtain a number of time steps; For each time step, substitute the Young's modulus, Poisson's ratio and parameter vector into the dam creep calculation formula to obtain the creep strain increment corresponding to each time step; Based on the creep strain increment, determine the initial creep strain tensor.

6. A creep simulation analysis method for rockfill dams based on implicit iteration, characterized in that: The method of obtaining the dam settlement data is as follows: Step 1, based on the integral time step sequence, determine the time difference between adjacent time steps; Obtain the initial strain data of the rockfill dam, which includes the initial creep stress tensor and the initial strain tensor; Step 2, based on the initial creep stress tensor and the time difference, use Newton-Raphson iterative integration to calculate the creep strain increment of a certain integration step; Step 3, according to the creep strain increment of a certain integration step, update the elastic strain increment of the current integration step in real time to obtain a new elastic strain increment; Step 4, based on the new elastic strain increment, strain displacement matrix, unit volume and linear elastic stiffness matrix, calculate the unit internal force vector of the rockfill dam simulation object; Step 5, summarize the unit internal force vectors into an overall internal force vector; Step 6, perform a convergence judgment on the overall internal force vector. When it converges, execute Step 7; when it does not converge, reduce the time difference by half and execute Step 2; Step 7, according to the creep strain increment, obtain the strain tensor and obtain the dam displacement information through the strain displacement matrix; Step 8: According to the dam displacement information, the vertical displacement value of the dam is selected as the dam settlement data.

7. The rockfill dam creep simulation analysis method based on implicit iteration according to claim 6, characterized in that: The method for judging the convergence of the overall internal force vector is as follows: Obtaining applied loads and converting applied loads into applied load vectors; Calculate the difference between the global internal force vector and the applied load vector; Determine whether the difference meets the relative convergence criterion and the absolute convergence criterion, which includes the following: Setting a relative convergence reference value based on a relative threshold constant and an applied load vector; Based on the absolute threshold constant, set the absolute convergence benchmark value; When the difference is less than the relative convergence reference value, the relative convergence criterion is met. At this time, the absolute convergence criterion is not judged and the judgment result is convergence; When the difference is greater than the relative convergence reference value and less than the absolute convergence reference value, the result is convergence; When the difference is greater than the relative convergence reference value and the difference is greater than the absolute convergence reference value, the judgment result is non-convergence.

8. The rockfill dam creep simulation analysis method based on implicit iteration according to claim 1, characterized in that: The method to obtain dam settlement data is as follows: Step 1, based on the integrated time step sequence, determine the time difference between adjacent time steps; Obtaining initial strain data of the rockfill dam, which includes initial creep stress tensor and initial strain tensor; Step 2, based on the initial creep stress tensor and the time difference, use Newton-Raphson iterative integration to calculate the creep strain increment of a certain integration step; Step 3, calculating the total strain increment according to the displacement increment and the strain displacement matrix; The displacement increment is a known quantity in the Newton-Raphson iterative integral, and the strain-displacement matrix consists of the shape functions of the mesh nodes and their derivatives; Step 4, subtract the total strain increment from the creep strain increment to obtain the elastic strain increment; Step 5, calculating the unit internal force vector of the rockfill dam simulation object based on the elastic strain increment, the strain displacement matrix, the unit volume and the linear elastic stiffness matrix; Step 6, summarizing the unit internal force vectors into an overall internal force vector; Step 7, judging the convergence of the overall internal force vector, and executing step 8 if converged, and if not converged, reducing the time difference by half and executing step 2; Step 8, obtaining the strain tensor according to the creep strain increment, and obtaining the dam displacement information through the strain displacement matrix; Step 9: According to the dam displacement information, the vertical displacement value of the dam is screened out to obtain the dam settlement data.

9. A creep simulation analysis method for rockfill dam based on implicit iteration, characterized by: The following steps are involved: S1: Use the pre-built object generation unit, combined with the dam construction classification data and dam material information to establish the rockfill dam simulation object; S2: Using the pre-built computational model construction unit, a nonlinear elastic model and a creep empirical parameter model are established according to the rockfill dam simulation object; S3: Use the pre-built solution strategy to set up the unit, create the integration time step sequence and initial state variables based on the nonlinear elastic model and the creep empirical parameter model; S4: Substitute the initial state variables into the nonlinear elastic model and the creep empirical parameter model by using the pre-constructed implicit iterative calculation unit to obtain the initial strain data of the rockfill dam; Then, perform implicit integration on the initial strain data of the rockfill dam according to the integral time step sequence to obtain the dam settlement value, and complete the creep simulation analysis of the rockfill dam based on implicit iteration.

10. A creep simulation analysis system of a rockfill dam based on implicit iteration, characterized in that: It includes: One or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors are caused to implement a creep simulation analysis method of a rockfill dam based on implicit iteration as described in any one of claims 1-9.

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