Method and system for predicting loading deformation of overburden foundation gravel materials

Abstract

The present invention proposes a method and system for predicting the loading deformation of overburden foundation sand and gravel materials. The method includes conducting triaxial shear tests on graded, formed sand and gravel samples to obtain axial strain, volumetric strain, and deviatoric stress; establishing a tangent elastic modulus relationship for material strain softening based on the deviatoric stress and axial strain; calculating lateral strain based on the axial strain and volumetric strain, and establishing a Poisson's ratio relationship for the material's dilatancy properties based on the lateral strain and axial strain; constructing a constitutive model based on the tangent elastic modulus relationship and the Poisson's ratio relationship; and using the constitutive model to predict simulated data of the overburden foundation sand and gravel material, predicting how the deviatoric stress and volumetric strain change with the axial strain during loading, to obtain prediction results. This method effectively predicts the loading deformation characteristics of overburden foundation sand and gravel materials, minimizing the deviation between the predicted and actual results.

Description

Technical Field

[0001] The present invention belongs to the technical field of sand and gravel material detection, and in particular to a method and system for predicting the loading deformation of sand and gravel materials in overburden foundations. Background Art

[0002] Overburden gravel foundations are a typical dam foundation condition. The mechanical properties of this material are crucial to the stress-deformation characteristics of the dam foundation, impacting the coordinated safety and control of dam deformation. Compared to dams built directly on bedrock, dams built on overburden foundations generally experience greater settlement deformation, which can exacerbate uncoordinated deformation within the dam body or between the dam body and the impermeable structure, impacting dam operational safety. Unlike conventional dam rockfill materials, overburden foundations have loose structures, uneven gradations, and complex physical and mechanical properties. Furthermore, silt is present on the surface of the stratum. Traditional constitutive models for overburden materials, such as the Duncan-Zhang model, predict the stress-deformation characteristics of dam rockfill materials. However, these predictions fail to account for the stress-strain characteristics of the overburden material caused by strain softening and dilatancy. This leads to significant discrepancies between the predicted results and actual laboratory measurements, resulting in inaccurate estimates of the overburden deformation characteristics and impacting the assessment of the coordinated safety of dam deformation. Summary of the Invention

[0003] In order to solve the problem that the existing prediction of overburden materials is based on the stress and deformation characteristics of dam rockfill materials, resulting in large deviations in the prediction results and inaccurate prediction data, the present invention provides a method and system for predicting the loading deformation of overburden foundation gravel materials.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] The present invention proposes a method for predicting the loading deformation of overburden foundation gravel materials, comprising the following steps:

[0006] The axial strain was obtained by triaxial shear test based on the obtained graded gravel samples. , volumetric strain and deviatoric stress ;

[0007] Based on the deviatoric stress and the axial strain The tangent elastic modulus relationship is obtained by constructing the strain softening of the material;

[0008] Based on the axial strain and volumetric strain Calculated lateral strain , based on the lateral strain With the axial strain Establish the Poisson's ratio relationship of the material's dilatancy properties;

[0009] Constructing a constitutive model based on the tangent elastic modulus relationship and the Poisson's ratio relationship;

[0010] The constitutive model is used to predict the simulation data of the overburden foundation gravel material, and the changes of the deviatoric stress and the volumetric strain with the axial strain during the loading process are predicted to obtain a prediction result.

[0011] Preferably, obtaining the graded and formed sand and gravel sample includes:

[0012] Obtain the gradation of the raw materials of sand and gravel for the overburden foundation;

[0013] Scaling the gradation of the overburden foundation sand and gravel raw materials by a mixing method to obtain the scaled gradation of the overburden foundation sand and gravel raw materials;

[0014] Screening the scaled gradation of the overburden foundation sand and gravel raw materials to determine a reasonable gradation used in a triaxial shear test, thereby obtaining graded shaped sand and gravel raw materials;

[0015] Obtaining gradation data, volume data, and dry density data of the graded and formed sand and gravel raw materials to determine the total mass of the covering layer sand and gravel materials;

[0016] Grouping the graded formed sand and gravel raw materials to obtain multiple test groups, and determining the quality of the graded formed sand and gravel raw materials in each test group;

[0017] Based on the different sludge contents preset in each test group, a plurality of test comparison groups are obtained;

[0018] Samples were prepared for a plurality of the experimental comparison groups to obtain graded formed sand and gravel samples.

[0019] Preferably, preparing samples for a plurality of said test comparison groups comprises:

[0020] Arrange the latex film in a triaxial shear tester and load the PVC plate, fix the sample preparation cylinder, and place a filter screen on the base of the triaxial shear tester;

[0021] The test and comparison group is placed in the sample preparation cylinder of the triaxial shear testing machine, and the graded and formed sand and gravel raw materials in the test and comparison group are loaded in multiple layers. The graded and formed sand and gravel raw materials in each layer are vibrated to a preset height. After the loading is completed, a filter screen and a permeable plate are placed on top, and then vacuuming and negative pressure are applied in sequence to obtain an initial sample;

[0022] placing the initial sample into a pressure chamber, injecting water into the pressure chamber, saturating the initial sample to obtain a saturated sample;

[0023] Different confining pressures were applied to the saturated samples. , reaching the specified confining pressure After that, the sample is consolidated and the volume strain reading is observed. When the volume strain reading is stable, the consolidation is considered to be complete, and the graded formed gravel sample is obtained. The graded formed gravel sample is subjected to a triaxial shear test to obtain different confining pressures. The axial strain under the condition , volumetric strain and the deviatoric stress .

[0024] Preferably, the graded gravel samples are subjected to triaxial shear tests to obtain the values ​​of different confining pressures. The axial strain under the condition , volumetric strain and the deviatoric stress ,include

[0025] Based on the preset shear conditions, the graded gravel samples were subjected to a consolidation and drainage triaxial shear test, and the confining pressures were recorded. Axial load and axial strain curves, volumetric strain and axial strain curves under different conditions;

[0026] Observe different confining pressures The axial load and axial strain curve, the volumetric strain and axial strain curve under the conditions;

[0027] If there is a peak in the axial load and axial strain curve and the volumetric strain and axial strain curve, the test is terminated when the axial strain reaches 4% after the peak value appears, and the test data is obtained;

[0028] If there is no peak in the axial load and axial strain curve and the volumetric strain and axial strain curve, the test is terminated when the shearing is continued until the axial strain reaches 15%, and the test data is obtained;

[0029] Based on the test data, different confining pressures are obtained. The axial strain under the condition and the deviatoric stress .

[0030] Preferably, the shearing condition is a shear rate of 1.0-2.0 mm / min.

[0031] Preferably, based on the axial strain and the deviatoric stress Determine the tangent elastic modulus relationship for strain softening of materials, including:

[0032] Based on standard atmospheric pressure With different confining pressure Determine the shear strength and the initial modulus of the overburden gravel material ;

[0033] Based on the shear strength , the axial strain and the initial modulus Determine the test constant;

[0034] The axial strain is determined based on the test constants and the deviatoric stress Relationship, the axial-deviatoric stress relationship is obtained;

[0035] The tangent elastic modulus of the material strain softening is determined based on the axial-deviatoric stress relationship and the test constants. relation;

[0036]

[0037] in, is the axial strain corresponding to the shear strength, is the initial modulus of the overburden gravel material, is the axial strain, is the peak deviatoric stress.

[0038] Preferably, the axial-deviatoric stress relationship is:

[0039]

[0040] in, is the deviatoric stress; is the axial strain; is the first experimental constant, is the second experimental constant, is the third experimental constant;

[0041] The first test constant , the second experimental constant , the third test constant The determination process is:

[0042]

[0043] in, is the axial strain corresponding to the shear strength, is the peak deviatoric stress, is the initial modulus of the overburden gravel material.

[0044] Preferably, based on the axial strain and volumetric strain Calculated lateral strain , based on the lateral strain With the axial strain Establish the Poisson's ratio relationship for the dilatancy of materials, including:

[0045] Based on standard atmospheric pressure With different confining pressure Determine the fifth experimental constant ;

[0046] Based on the fifth experimental constant , the standard atmospheric pressure With different confining pressure Determine the fourth experimental constant ;

[0047] Based on the volume strain and the axial strain Calculated lateral strain ;

[0048] Based on the fourth experimental constant , the fifth test constant , the axial strain and the lateral strain The relationship between the lateral strain and the axial strain is determined, and the lateral strain-axial strain relationship is obtained;

[0049] The Poisson's ratio of the material dilatancy characteristic is established based on the lateral strain-axial strain relationship. relation;

[0050]

[0051] in, is the fourth experimental constant, is the fifth experimental constant, is the axial strain.

[0052] Preferably, the tangent elastic modulus based on the strain softening of the material Relationship and Poisson's ratio of the material dilatancy properties The constitutive model obtained by relationship construction is:

[0053]

[0054] in, is the axial strain corresponding to the shear strength, is the initial modulus of the overburden gravel material, is the tangent elastic modulus of the overburden gravel material, is the shear strength, ,and is the experimental constant, is the Poisson's ratio of the overburden gravel material, is the deviatoric stress.

[0055] The present invention proposes a system for constructing a loading and deformation constitutive model of overburden foundation sand and gravel materials, comprising:

[0056] The first processing unit is configured to:

[0057] Used to obtain axial strain by triaxial shear test based on the obtained graded gravel specimens , volumetric strain and deviatoric stress ;

[0058] The second processing unit is configured to:

[0059] For the deviatoric stress based on and the axial strain The tangent elastic modulus relationship is obtained by constructing the strain softening of the material;

[0060] The third processing unit is configured to:

[0061] For the axial strain based on and volumetric strain Calculated lateral strain , based on the lateral strain With the axial strain Establish the Poisson's ratio relationship of the material's dilatancy properties;

[0062] The fourth processing unit is configured to:

[0063] Used to construct a constitutive model based on the tangent elastic modulus relationship and the Poisson's ratio relationship;

[0064] The prediction unit is configured as follows:

[0065] Predicting the simulated data of the overburden foundation gravel material using the constitutive model, predicting the changes of the deviatoric stress and the volumetric strain with the axial strain during the loading process, and obtaining a prediction result;

[0066] Output unit, configured as:

[0067] Used to output prediction results.

[0068] Compared with the prior art, the present invention has the following beneficial technical effects:

[0069] The present invention proposes a method for predicting the loading deformation of gravel materials for overburden foundations. This method uses triaxial shear tests to accurately obtain axial strain and deviatoric stress data of graded and formed gravel specimens. By constructing a tangent elastic modulus relationship, the mechanical properties of the material in the strain softening stage are successfully revealed. By calculating the lateral strain and establishing a relationship with the axial strain, the Poisson's ratio of the material is quantitatively determined. The constitutive model constructed by integrating the tangent elastic modulus relationship and the Poisson's ratio relationship can comprehensively reflect the strain softening and shear dilatancy characteristics of the gravel materials for overburden foundations during loading. When predicting through the constitutive model, the influence of strain softening and shear dilatancy on the loading deformation of the gravel materials for overburden foundations is taken into account, thereby improving the accuracy and reliability of the prediction, achieving effective prediction of the loading deformation characteristics of the gravel materials for overburden foundations, reducing the deviation between the predicted results and the actual results, and providing accurate data support for the deformation coordination of dams on overburden foundations.

[0070] Furthermore, this method makes it easier to conduct tests under laboratory conditions through scaling. At the same time, a reasonable test gradation is determined through screening, which improves the reliability of the test results. The total mass of the sample is determined by accurately measuring the gradation data, volume data and dry density data of the raw materials, and the samples are grouped and prepared. Different silt contents are set for comparative tests, which helps to deeply analyze the impact of silt content on material properties and provides rich and comprehensive data support for constitutive model construction and loading deformation prediction. Therefore, when predictions are made through the constructed constitutive model, the predicted structure obtained is more reliable and accurate.

[0071] Furthermore, this method effectively ensures the uniformity and density of the sample by arranging latex membranes, PVC boards and filter screens, and using the vibration method to load the raw materials in layers. After vacuuming and loading negative pressure treatment, the initial sample is obtained, and the stability and reliability of the sample are further improved through saturation treatment. During the process of applying different confining pressures and consolidation, the volume strain readings are strictly monitored to ensure that the sample reaches a stable state, thereby obtaining high-quality graded molded sand and gravel samples, improving the accuracy and repeatability of the test, and obtaining accurate axial strain and deviatoric stress data.

[0072] Furthermore, the triaxial shear test conducted on graded formed sand and gravel specimens in this method accurately recorded the axial load-axial strain curves and the volumetric strain-axial strain curves under different confining pressures through carefully controlled consolidation and drainage conditions and strict monitoring methods. If a peak appeared on the curve, monitoring was continued after the peak until the axial strain increased by 4%. If no peak appeared, shearing was terminated when the axial strain reached 15%. This ensured the integrity and accuracy of the test data, fully reflected the mechanical response characteristics of the material under different confining pressures, and accurately obtained the axial strain and deviatoric stress under different confining pressures.

[0073] Furthermore, by comprehensively considering standard atmospheric pressure, shear strength under different confining pressures, and the initial modulus of the material, this method can accurately determine the test constants, and then construct a relationship model between axial strain and deviatoric stress, and then determine the tangent elastic modulus relationship of the material strain softening. This improves the understanding of the mechanical properties of materials in the strain softening stage, provides a powerful tool for accurately predicting the behavior of materials under complex stress states, and thus makes the prediction results more accurate and reliable.

[0074] Furthermore, by introducing the third and fourth experimental constants, this method accurately establishes the relationship between lateral strain and axial strain, determines the Poisson's ratio relationship of the material's shear dilatancy, and provides a quantitative indicator for evaluating the material's shear dilatancy. By establishing the Poisson's ratio relationship, the deformation characteristics of the material under complex stress conditions can be more accurately predicted, so that the deviation between the predicted results and the actual results is small, providing accurate data support for the deformation coordination of the dam on the overburden foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 A schematic flow chart of the method for predicting the loading deformation characteristics of overburden foundation gravel materials provided by the present invention;

[0076] Figure 2 A schematic diagram of the gradation of gravel materials used in the method for predicting the loading and deformation characteristics of gravel materials for overburden foundations provided by the present invention;

[0077] Figure 3 Schematic diagram of the triaxial testing device for materials used in the method for predicting the loading and deformation characteristics of overburden foundation gravel materials provided by the present invention;

[0078] Figure 4 Schematic diagram of the relationship between the deviatoric stress, volumetric strain and axial strain of the material under the condition of 0% silt content in the method for predicting the loading deformation characteristics of the overburden foundation gravel material provided by the present invention;

[0079] Figure 5 Schematic diagram of the relationship between the deviatoric stress, volumetric strain and axial strain of the material under the condition of 6% silt content in the method for predicting the loading deformation characteristics of the overburden foundation gravel material provided by the present invention;

[0080] Figure 6 A schematic diagram showing a comparison between the deviatoric stress and axial strain results predicted by the constitutive model and the test results in the method for predicting the loading deformation characteristics of the overburden foundation gravel material provided by the present invention;

[0081] Figure 7 This is a schematic diagram comparing the volume strain and axial strain results predicted by the constitutive model in the method for predicting the loading deformation characteristics of overburden foundation gravel materials provided by the present invention with the test results. DETAILED DESCRIPTION

[0082] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0083] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0084] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0085] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0086] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0087] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0088] See also Figure 1 The present invention proposes a method for predicting the loading deformation of overburden foundation gravel materials, comprising the following steps:

[0089] The axial strain was obtained by triaxial shear test based on the obtained graded gravel samples. , volumetric strain and deviatoric stress ;

[0090] Specifically, raw materials for the overburden foundation sand and gravel are obtained from an actual engineering site, the gradation of the raw materials for the overburden foundation sand and gravel is analyzed, and the gradation of the raw materials for the overburden foundation sand and gravel is scaled down by a mixing method according to the size limitation of the test instrument to obtain the scaled gradation of the raw materials for the overburden foundation sand and gravel used in the test;

[0091] Screen the scaled gradation of the overburden foundation sand and gravel raw materials to determine the reasonable gradation used in the triaxial shear test and obtain the graded shaped sand and gravel raw materials;

[0092] Obtain the gradation data, volume data and dry density data of the graded gravel raw materials. In this embodiment, the dry density is 2.2 g / cm 3 , the relative density is 0.85; the total mass of the covering layer sand and gravel material is determined; the graded molding sand and gravel raw materials are grouped and divided into 5 equal parts to obtain 5 test groups, and the mass of the graded molding sand and gravel raw materials in each test group is determined; based on each test group, the silt content is set to 0%, silt content is 2%, silt content is 4% and silt content is 6%, respectively, to obtain multiple test comparison groups.

[0093] Samples were prepared for a plurality of the experimental comparison groups to obtain graded formed sand and gravel samples.

[0094] Specifically, the base of the coarse-grained soil triaxial shear testing machine SZ30-4DA was cleaned. To reduce the impact of boundary effects on the specimen and protect the specimen from damage, a 3 mm thick latex film was placed around it. Then, the latex film and PVC board were fixed to the sample preparation cylinder, and a filter screen was placed on the base of the triaxial shear testing machine.

[0095] The test comparison group was loaded into the sample preparation cylinder in the triaxial shear testing machine SZ30-4D, and the graded molded sand and gravel raw materials in the test comparison group were loaded in multiple layers, that is, the graded molded sand and gravel raw materials with the same silt content were loaded into the sample preparation cylinder in multiple layers, and the graded molded sand and gravel raw materials of each layer were vibrated to reach a preset height. In this embodiment, the preset height was 60 mm, and then the next layer of material was loaded. After the material was loaded, a filter screen and a permeable plate were placed above the material, and then vacuum was applied and negative pressure was applied. When the instrument displayed a negative pressure of -30 kPa, the sample preparation cylinder was removed to obtain an initial sample; the initial sample sample was placed in a pressure chamber, and water was injected into the pressure chamber. When the water was full, a trial contact was performed, and the initial sample was saturated to obtain a saturated sample. The sample was saturated by both air extraction and water head saturation to ensure that the confining pressure was 30 kPa higher than the pore pressure.

[0096] Apply different confining pressures to the saturated specimens , according to relevant engineering experience, confining pressure Select four confining pressure levels of 0.4 MPa, 0.8 MPa, 1.2 MPa and 1.6 MPa respectively to reach the specified confining pressure After that, the sample is consolidated and the volume strain reading is observed. When the volume strain reading is stable, the consolidation is considered to be complete, and the graded formed gravel sample is obtained. The graded formed gravel sample is subjected to a triaxial shear test to obtain different confining pressures. Axial strain under conditions , volumetric strain and deviatoric stress .

[0097] The triaxial shear test of graded gravel samples was carried out to obtain the results of different confining pressures. Axial strain under conditions , volumetric strain and the deviatoric stress ,include:

[0098] Based on the preset shear conditions, the consolidated drained triaxial shear test was carried out on the graded gravel samples. Figure 3As shown, it includes a piston 1, a top plate 2, a first permeable stone 3, a first filter screen 4, a second filter screen 5, a second permeable stone 6, a drain valve 7, an air pressure sensor 8, a confining pressure gauge 9, and a latex film 10. The gravel material is placed between the first filter screen 4 and the second filter screen 5 in the sample preparation cylinder, the first permeable stone 3 is placed on the upper part of the first filter screen 4, the top plate 2 is installed on the upper end of the first permeable stone 3, the piston 1 is pressed on the top plate 2, and the second permeable stone 6 is placed on the bottom of the second filter screen 5. The latex film 10 is paved outside the sample preparation cylinder in the equipment so that the latex film 10 covers the sample preparation cylinder, the first permeable stone 3, the second permeable stone 6, the first filter screen 4 and the second filter screen 5. The equipment is also equipped with a drain valve 7, an air pressure sensor 8, and a confining pressure gauge 9 to record different confining pressures. Axial load and axial strain curves, volume strain and axial strain curves under different confining pressures The axial load and axial strain curves, volumetric strain and axial strain curves under different conditions are obtained; if there are peaks in the axial load and axial strain curves, the test is terminated when the axial strain reaches 4% after the peak, and the test data is obtained; if there are no peaks in the axial load and axial strain curves, the test is terminated when the shearing reaches 15%, and the test data is obtained; based on the test data, the results of the experiment under different silt content and different confining pressure are obtained. Axial strain during action , volumetric strain and deviatoric stress ,like Figure 4 and Figure 5 The shearing condition is that the shear rate is 1.0~2.0 mm / min.

[0099] Based on different silt content conditions and different confining pressure Deviatoric stress during operation and axial strain The tangent elastic modulus relationship is obtained by constructing the strain softening of the material;

[0100] Specifically, based on standard atmospheric pressure With different confining pressure , determine the peak deviatoric stress and the initial modulus of the overburden gravel material ;

[0101] The determination process is:

[0102] (1)

[0103] in, is the standard atmospheric pressure, 、 、 and It is a parameter related to the tangential modulus of sand and gravel materials and is determined by the consolidated drained triaxial shear test;

[0104] Based on the deviatoric stress peak , axial strain and initial modulus Determine the test constants, the test constants are the first test constant , the second experimental constant and the third experimental constant ;

[0105] First experimental constant , the second experimental constant and the third experimental constant The determination process is:

[0106] (2)

[0107] in, is the axial strain corresponding to the shear strength, is the peak deviatoric stress, is the initial modulus of the overburden gravel material.

[0108] Based on the first experimental constant , the second experimental constant and the third experimental constant Determine the axial strain and deviatoric stress Relationship, the axial-deviatoric stress relationship is obtained;

[0109] The expression of the axial-deviatoric stress relationship is:

[0110] (3)

[0111] in, is the deviatoric stress; is the axial strain; is the first experimental constant, is the second experimental constant, is the third experimental constant;

[0112] Determine the tangent elastic modulus of the material strain softening based on the axial-deviatoric stress relationship and test constants relation;

[0113] Tangent elastic modulus of the material The expression of the relationship is:

[0114] (4)

[0115] Expression (4) combined with expression (3) yields the final tangent elastic modulus: relation:

[0116] (5)

[0117] in, is the axial strain corresponding to the shear strength, is the initial modulus of the overburden gravel material, is the axial strain, is the peak deviatoric stress.

[0118] Based on different silt content conditions and different confining pressure Axial strain during action and volumetric strain Calculated lateral strain , based on lateral strain With the axial strain Establish the Poisson's ratio relationship of the material's dilatancy properties;

[0119] Based on standard atmospheric pressure With different confining pressure Determine the fifth experimental constant Among them, according to the test results, the fifth test constant under different silt contents and There is a strong power function relationship between them, and the fifth experimental constant is determined The process is:

[0120] (6)

[0121] in, is the standard atmospheric pressure, is a parameter related to the tangential modulus of sand and gravel materials, determined by the consolidated drained triaxial shear test. is the length of the graded gravel specimen;

[0122] Based on the fifth experimental constant , standard atmospheric pressure With different confining pressure Determine the fourth experimental constant Among them, according to the test results, under different sludge contents and There is a strong linear relationship between them, and the fourth experimental constant is determined The process is;

[0123] (6)

[0124] in, is the standard atmospheric pressure, and is a parameter related to the tangential modulus of sand and gravel materials, determined by the consolidated drained triaxial shear test. is the fifth experimental constant.

[0125] Based on volumetric strain and axial strain Calculated lateral strain ;

[0126] The calculation process is:

[0127] (7)

[0128] in, is the axial strain, is the volume strain;

[0129] Based on the fourth experimental constant , the fifth experimental constant , axial strain and lateral strain The relationship between the lateral strain and the axial strain is determined, and the lateral strain-axial strain relationship is obtained;

[0130] The relationship between lateral strain and axial strain is:

[0131] ; (8)

[0132] in, is the axial strain, is the lateral strain, is the fourth experimental constant, is the fifth experimental constant;

[0133] Poisson's ratio of material dilatancy based on the relationship between lateral strain and axial strain relation;

[0134] (9)

[0135] in, is the fourth experimental constant, is the fifth experimental constant, is the axial strain.

[0136] The expression of the constitutive model is:

[0137] (10)

[0138] in, is the axial strain corresponding to the shear strength, is the initial modulus of the overburden gravel material, is the tangent elastic modulus of the overburden gravel material, is the peak deviatoric stress, ,and is the experimental constant, is the Poisson's ratio of the overburden gravel material, is the deviatoric stress.

[0139] The constitutive model is embedded in numerical software, and the triaxial test numerical simulation of the overburden gravel material is carried out using the numerical software. The simulation data of the overburden foundation gravel material is predicted, and the changes of the deviatoric stress and volumetric strain with the axial strain during the loading process are predicted to obtain the prediction results.

[0140] The prediction results obtained by the above method are verified by conducting indoor tests on the overburden gravel material to obtain test results; the test results are compared with the prediction results to verify the validity of the established constitutive model, such as Figure 6 and Figure 7 As shown in the figure, the predicted results under different confining pressures agree well with the experimental results. The predicted deviatoric stress-axial strain curves exhibit a similar pattern to the experimental curves, with the deviatoric stress growth rate gradually decreasing, reaching zero at the peak stress point, and ultimately exhibiting a certain degree of negative growth. The established model effectively simulates the strain-softening characteristics of the overburden material. The predicted volumetric strain of the overburden material first increases and then decreases, with the specimen first contracting and then dilating. This is consistent with the experimental results, demonstrating that the model can describe the dilatancy characteristics and that this method can accurately predict the strain-softening characteristics of overburden sand and gravel materials.

[0141] The present invention proposes a system for constructing a loading deformation constitutive model of overburden foundation gravel materials, which is characterized by including

[0142] The first processing unit is configured to:

[0143] Used to obtain axial strain by triaxial shear test based on the obtained graded gravel specimens , volumetric strain and deviatoric stress ;

[0144] Specifically, the raw materials of the covering layer foundation sand and gravel are obtained, the gradation of the raw materials of the covering layer foundation sand and gravel is analyzed, the gradation of the raw materials of the covering layer foundation sand and gravel is scaled, and the scaled gradation of the raw materials of the covering layer foundation sand and gravel used in the test is obtained; the scaled gradation of the raw materials of the covering layer foundation sand and gravel is screened to determine the reasonable gradation used in the triaxial shear test to obtain the graded molded sand and gravel raw materials; the gradation data, volume data and dry density data of the graded molded sand and gravel raw materials are obtained to determine the total mass of the covering layer sand and gravel materials; the graded molded sand and gravel raw materials are grouped and the mass of the graded molded sand and gravel raw materials in each test group is determined; the silt content is set based on each test group to obtain multiple test comparison groups, and samples are prepared for the multiple test comparison groups to obtain graded molded sand and gravel samples, and the graded molded sand and gravel samples are subjected to consolidation and drainage triaxial shear tests based on preset shear conditions to obtain test data; based on the test data, the results of the tests under different silt content conditions and different confining pressures are obtained. Axial strain during action , volumetric strain and deviatoric stress .

[0145] The second processing unit is configured to:

[0146] For the deviatoric stress based on and the axial strain The tangent elastic modulus relationship is obtained by constructing the strain softening of the material;

[0147] Specifically, based on standard atmospheric pressure With different confining pressure , determine the peak deviatoric stress and the initial modulus of the overburden gravel material ; Based on the deviatoric stress peak , axial strain and initial modulus Determine the test constants and determine the axial strain based on the test constants and deviatoric stress The axial-deviatoric stress relationship is obtained; based on the axial-deviatoric stress relationship and the test constant, the tangent elastic modulus of the material strain softening is determined relation.

[0148] The third processing unit is configured to:

[0149] For the axial strain based on and volumetric strain Calculated lateral strain , based on the lateral strain With the axial strain Establish the Poisson's ratio relationship of the material's dilatancy properties;

[0150] Specifically, based on different silt content conditions and different confining pressures Axial strain during action and volumetric strain Calculated lateral strain , based on lateral strain With the axial strain Establish the Poisson's ratio relationship of the material's dilatancy characteristics; based on standard atmospheric pressure With different confining pressure Determine the fifth experimental constant ; Based on the fifth experimental constant , standard atmospheric pressure With different confining pressure Determine the fourth experimental constant ; Based on volumetric strain and axial strain Calculated lateral strain ; Based on the fourth experimental constant , the fifth experimental constant , axial strain and lateral strain Determine the relationship between lateral strain and axial strain, and obtain the lateral strain-axial strain relationship; based on the lateral strain-axial strain relationship, establish the Poisson's ratio of the material's shear dilatancy characteristics relation.

[0151] The fourth processing unit is configured to:

[0152] Used to construct a constitutive model based on the tangent elastic modulus relationship and the Poisson's ratio relationship;

[0153] The prediction unit is configured as follows:

[0154] Predicting the simulated data of the overburden foundation gravel material using the constitutive model, predicting the changes of the deviatoric stress and the volumetric strain with the axial strain during the loading process, and obtaining a prediction result;

[0155] Output unit, configured as:

[0156] Used to output prediction results.

[0157] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0158] In addition, it should be understood that although this specification describes the embodiments, not every embodiment contains only one independent technical solution. This description is for clarity only. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for the purpose of illustrating the technical concept of the present invention and cannot be used to limit the scope of protection of the present invention. Any changes made based on the technical solution in accordance with the technical concept proposed by the present invention fall within the scope of protection of the claims of the present invention.

Claims

1. A method for predicting the loading deformation of gravel materials in overburden foundation, characterized in that: The following steps are involved: The axial strain was obtained by triaxial shear test based on the obtained graded gravel samples. , volumetric strain and deviatoric stress ; Based on the deviatoric stress and the axial strain Establish the tangent elastic modulus relationship of material strain softening; Based on the axial strain and volumetric strain Calculated lateral strain , based on the lateral strain With the axial strain Establish the Poisson's ratio relationship of the material's dilatancy properties; A constitutive model is constructed based on the tangent elastic modulus relationship and the Poisson's ratio relationship; wherein the constitutive model is: in, is the axial strain corresponding to the shear strength, is the initial modulus of the overburden gravel material, is the tangent elastic modulus of the overburden gravel material, is the peak deviatoric stress, ,and is the experimental constant, is the Poisson's ratio of the overburden gravel material, is the deviatoric stress; The constitutive model is used to predict the simulation data of the overburden foundation gravel material, and the changes of the deviatoric stress and the volumetric strain with the axial strain during the loading process are predicted to obtain a prediction result.

2. The method for predicting the loading deformation of overburden foundation gravel material according to claim 1, characterized in that: The acquisition of the graded formed sand and gravel sample includes: Obtain the gradation of the raw materials of sand and gravel for the overburden foundation; Scaling the gradation of the overburden foundation sand and gravel raw materials by a mixing method to obtain the scaled gradation of the overburden foundation sand and gravel raw materials; Screening the scaled gradation of the overburden foundation sand and gravel raw materials to determine a reasonable gradation used in a triaxial shear test, thereby obtaining graded shaped sand and gravel raw materials; Obtaining gradation data, volume data, and dry density data of the graded and formed sand and gravel raw materials to determine the total mass of the covering layer sand and gravel materials; Grouping the graded formed sand and gravel raw materials to obtain multiple test groups, and determining the quality of the graded formed sand and gravel raw materials in each test group; Based on the different sludge contents preset in each test group, a plurality of test comparison groups are obtained; Samples were prepared for a plurality of the test comparison groups to obtain graded formed sand and gravel samples, the sample size of which was Ø300×600 mm.

3. The method for predicting the loading deformation of overburden foundation gravel material according to claim 2, characterized in that: Samples are prepared for a plurality of the test comparison groups, including: Arrange the latex film in a triaxial shear tester and load the PVC plate, fix the sample preparation cylinder, and place a filter screen on the base of the triaxial shear tester; The test and comparison group is placed in the sample preparation cylinder of the triaxial shear testing machine, and the graded and formed sand and gravel raw materials in the test and comparison group are loaded in multiple layers. The graded and formed sand and gravel raw materials in each layer are vibrated to a preset height. After the loading is completed, a filter screen and a permeable plate are placed on top, and then vacuuming and negative pressure are applied in sequence to obtain an initial sample; placing the initial sample into a pressure chamber, injecting water into the pressure chamber, saturating the initial sample to obtain a saturated sample; Different confining pressures were applied to the saturated samples. , reaching the specified confining pressure After that, the sample is consolidated and the volume strain reading is observed. When the volume strain reading is stable, the consolidation is considered to be complete, and the graded formed gravel sample is obtained. The graded formed gravel sample is subjected to a triaxial shear test to obtain different confining pressures. The axial strain under the condition , volumetric strain and the deviatoric stress .

4. The method for predicting loading deformation of overburden foundation gravel material according to claim 3, characterized in that: The triaxial shear test was carried out on the graded gravel samples to obtain the different confining pressures. The axial strain under the condition , volumetric strain and the deviatoric stress ,include: Based on the preset shear conditions, the graded gravel samples were subjected to a consolidation and drainage triaxial shear test, and the confining pressures were recorded. Axial load and axial strain curves, volumetric strain and axial strain curves under different conditions; Observe different confining pressures The axial load and axial strain curve, the volumetric strain and axial strain curve under the conditions; If there is a peak in the axial load and axial strain curve and the volumetric strain and axial strain curve, the test is terminated when the axial strain reaches 4% after the peak value appears, and the test data is obtained; If there is no peak in the axial load and axial strain curve and the volumetric strain and axial strain curve, the test is terminated when the shearing is continued until the axial strain reaches 15%, and the test data is obtained; Based on the test data, different confining pressures are obtained. The axial strain under the condition , volumetric strain and the deviatoric stress .

5. The method for predicting loading deformation of overburden foundation gravel material according to claim 4, characterized in that: The shearing condition is a shear rate of 1.0-2.0 mm / min.

6. The method for predicting loading deformation of overburden foundation gravel material according to claim 1, characterized in that: Based on the axial strain and the deviatoric stress Determine the tangent elastic modulus relationship for strain softening of materials, including: Based on standard atmospheric pressure With different confining pressure Determine the peak deviatoric stress and the initial modulus of the overburden gravel material ; Based on the deviatoric stress peak , the axial strain and the initial modulus Determine the test constant; The axial strain is determined based on the test constants and the deviatoric stress Relationship, the axial-deviatoric stress relationship is obtained; The tangent elastic modulus of the material strain softening is determined based on the axial-deviatoric stress relationship and the test constants. relation; in, is the axial strain corresponding to the shear strength, is the initial modulus of the overburden gravel material, is the axial strain, is the peak deviatoric stress.

7. The method for predicting loading deformation of overburden foundation gravel material according to claim 6, characterized in that: The axial-deviatoric stress relationship is: in, is the deviatoric stress; is the axial strain; is the first experimental constant, is the second experimental constant, is the third experimental constant; The first test constant , the second experimental constant , the third test constant The determination process is: in, is the axial strain corresponding to the shear strength, is the peak deviatoric stress, is the initial modulus of the overburden gravel material.

8. The method for predicting loading deformation of overburden foundation gravel material according to claim 1, characterized in that: Based on the axial strain and volumetric strain Calculated lateral strain , based on the lateral strain With the axial strain Establish the Poisson's ratio relationship for the dilatancy of materials, including: Based on standard atmospheric pressure With different confining pressure Determine the fifth experimental constant ; Based on the fifth experimental constant , the standard atmospheric pressure With different confining pressure Determine the fourth experimental constant ; Based on the volume strain and the axial strain Calculated lateral strain ; Based on the fourth experimental constant , the fifth test constant , the axial strain and the lateral strain The relationship between the lateral strain and the axial strain is determined, and the lateral strain-axial strain relationship is obtained; The Poisson's ratio of the material dilatancy characteristic is established based on the lateral strain-axial strain relationship. relation; in, is the fourth experimental constant, is the fifth experimental constant, is the axial strain.

9. A system for constructing a constitutive model of loading and deformation of gravel materials in overburden foundation, characterized by comprising: The first processing unit is configured to: Used to obtain axial strain by triaxial shear test based on the obtained graded gravel specimens , volumetric strain and deviatoric stress ; The second processing unit is configured to: For the deviatoric stress based on and the axial strain The tangent elastic modulus relationship is obtained by constructing the strain softening of the material; The third processing unit is configured to: For the axial strain based on and volumetric strain Calculated lateral strain , based on the lateral strain With the axial strain Establish the Poisson's ratio relationship of the material's dilatancy properties; The fourth processing unit is configured to: Used to construct a constitutive model based on the tangent elastic modulus relationship and the Poisson's ratio relationship; wherein the constitutive model is: in, is the axial strain corresponding to the shear strength, is the initial modulus of the overburden gravel material, is the tangent elastic modulus of the overburden gravel material, is the peak deviatoric stress, ,and is the experimental constant, is the Poisson's ratio of the overburden gravel material, is the deviatoric stress; The prediction unit is configured as follows: Predicting the simulated data of the overburden foundation gravel material using the constitutive model, predicting the changes of the deviatoric stress and the volumetric strain with the axial strain during the loading process, and obtaining a prediction result; Output unit, configured as: Used to output prediction results.

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