Concrete gravity dam dynamic failure model test material and design method

Abstract

The invention discloses a concrete gravity dam dynamic failure model test material and a design method, and relates to the field of concrete model materials, the concrete gravity dam dynamic failure model test material is prepared by mixing cement, gypsum, sand, mineral oil and water according to a weight ratio of 1: 0.2-0.4: 4-5: 0.6-1: 1-1.5. The peak compressive strain value and the tensile strain value of the model test material prepared by the invention are very close to those of prototype dam concrete, and meet the requirements that the strain scale and the acceleration scale of the prototype concrete are 1, and the elastic modulus and the strain scale meet the similarity rate. Mechanical property test results show that main physical properties such as tensile strength, compressive strength, elastic modulus, Poisson's ratio, stress-strain constitutive relationship and the like of a dam model concrete material keep good similar relationship with dam concrete.

Description

Technical Field

[0001] The invention relates to the field of concrete model materials, and in particular to a concrete gravity dam dynamic failure model test material and a design method. Background Art

[0002] As the primary key material condition for conducting dam model shaking table tests, model materials must meet many requirements. For example, in order to make the first few frequencies of the model dam within the vibration frequency range of the shaking table, the model material is required to have a smaller elastic modulus, so that the dynamic test of the dam model can be achieved with higher accuracy within the excitation force range of the shaking table.

[0003] Most existing technologies use a mixed raw material mainly composed of barium sulfate, lead oxide and talcum powder, and a natural drying and pressure molding method to prepare the model dam body material. The model material is similar to the prototype dam in elastic modulus, density, tensile stress, etc., but during the destruction test, it is difficult to satisfy the constitutive relationship between stress and strain and the whole process of the prototype dam concrete. It can only reveal the complete similarity of the quasi-elastic stage when the model dam begins to crack under the action of tensile stress, and cannot fully reflect the similarity between the dam destruction process and the prototype.

[0004] The prior art also uses rubber as a concrete dam model material. For example, the structural test group of Dalian Institute of Technology used rubber to make a dam model with a geometric scale of 1:200 on the Liuxi River arch dam and conducted an elastic vibration test. However, the elastic modulus of rubber materials varies in a relatively large range and is more suitable for similar models with large geometric scales. Since the weighted vulcanized rubber material has a large destructive strength, it is suitable for studying the self-vibration characteristics and dynamic response of the dam in the elastic stage, but is not suitable for dynamic destructive testing.

[0005] The existing technology cannot meet the requirements that the strain ratio of the prototype concrete is 1, the acceleration ratio is 1, and the elastic modulus and the strain ratio meet the similarity requirements. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a concrete gravity dam dynamic failure model test material and a design method.

[0007] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0008] Provided is a concrete gravity dam dynamic destruction model test material, which is obtained by mixing cement, gypsum, sand, mineral oil and water, and the weight ratio thereof is 1:0.2-0.4:4-5:0.6-1:1-1.5.

[0009] Furthermore, the weight ratio of cement, gypsum, sand, mineral oil and water is 1:0.4:4.5:0.8:1.3.

[0010] Furthermore, the D90 particle size of the sand and gravel is 1 mm.

[0011] The present invention also provides a method for designing a concrete gravity dam dynamic failure model test material, comprising the following specific steps:

[0012] S1: Randomly formulate the mix ratio of cement, gypsum, sand, mineral oil and water to prepare concrete samples, conduct uniaxial compressive strength test and tensile strength test on the concrete samples to obtain the compressive strength and tensile strength corresponding to each mix ratio; integrate the mix ratio and the corresponding compressive strength and tensile strength as elements to obtain the sample set;

[0013] S2: Establish a ratio prediction model based on multi-classification logistic regression, and use the sample set to train the ratio prediction model;

[0014] S3: Establish the uniaxial pressure damage factor equation and the uniaxial tension damage factor equation;

[0015] S4: Preset the pressure strain data and tension strain data of the gravity dam to be studied, and obtain the compressive strength f of the concrete of the gravity dam to be studied according to the uniaxial pressure damage factor equation and the uniaxial tension damage factor equation. c and tensile strength f t ;

[0016] S5: input the compressive strength and tensile strength of the gravity dam concrete to be studied into the trained mix ratio prediction model to obtain the corresponding model material prediction formula;

[0017] S6: Expand the predicted formula of the model material to obtain a predicted formula set, and determine the corresponding compressive strength f of any formula in the predicted formula set according to the ratio prediction model c ′ and tensile strength f t ′, and the predicted formula set is cleaned to obtain the material formula range for the concrete gravity dam dynamic failure model test.

[0018] Furthermore, the uniaxial pressure damage factor equation is:

[0019]

[0020] The uniaxial pressure damage factor equation is:

[0021]

[0022] And the middle

[0023] Among them, α c is the parameter of the descending section of the gravity dam pressure curve, α t is the descending section parameter of the gravity dam tension curve, ε cFor and f c The corresponding peak compressive strain of concrete, ε t For and f t The corresponding peak tensile strain of concrete, E 0 is the initial elastic modulus.

[0024] Furthermore, in step S6, the predicted recipe set is cleaned as follows: c ' <f c or t ' <f t When the formula is found, delete the formula, otherwise, keep the formula; after integrating all the retained formulas, determine the maximum weight ratio and minimum weight ratio of each ingredient, and obtain the formula range of the concrete gravity dam dynamic failure model test material.

[0025] The beneficial effects of the present invention are:

[0026] The peak compressive strain and tensile strain values ​​of the model test material obtained by the configuration of the present invention are very close to those of the prototype dam concrete, and meet the requirements of the strain ratio of the prototype concrete being 1, the acceleration ratio being 1, and the elastic modulus and strain ratio meeting the similarity ratio. The mechanical property test results show that the main physical properties of the dam model concrete material, such as tensile strength, compressive strength, elastic modulus, Poisson's ratio, and stress-strain constitutive relationship, maintain a good similarity relationship with the dam concrete. Therefore, the dam dynamic destruction model test can better simulate the damage process of the prototype dam under the action of a strong earthquake, such as the location, direction, and expansion range of the cracks, and can reveal the law of dam earthquake damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a comparison curve diagram of the uniaxial tensile stress-strain relationship of the present invention;

[0028] Figure 2 It is a comparison curve diagram of the uniaxial compressive stress-strain relationship of the present invention. DETAILED DESCRIPTION

[0029] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0030] Example 1

[0031] A design method for a concrete gravity dam dynamic failure model test material comprises the following specific steps:

[0032] S1: Randomly formulate the mix ratio of cement, gypsum, sand, mineral oil and water to prepare concrete samples, conduct uniaxial compressive strength test and tensile strength test on the concrete samples to obtain the compressive strength and tensile strength corresponding to each mix ratio; integrate the mix ratio and the corresponding compressive strength and tensile strength as elements to obtain the sample set;

[0033] S2: A ratio prediction model is established based on multi-classification logistic regression, and the ratio prediction model is trained using a sample set; the loss function of the ratio prediction model uses a mean square error function; the training process uses conventional gradient descent method for optimization training;

[0034] S3: Establish the uniaxial pressure damage factor equation and the uniaxial tension damage factor equation;

[0035] The uniaxial pressure damage factor equation is:

[0036]

[0037] The uniaxial pressure damage factor equation is:

[0038]

[0039] And the middle

[0040] Among them, α c is the parameter of the descending section of the gravity dam pressure curve, α t is the descending section parameter of the gravity dam tension curve, ε c For and f c The corresponding peak compressive strain of concrete, ε t For and f t The corresponding peak tensile strain of concrete, E 0 is the initial elastic modulus.

[0041] S4: Preset the pressure strain data and tension strain data of the gravity dam to be studied, and obtain the compressive strength f of the concrete of the gravity dam to be studied according to the uniaxial pressure damage factor equation and the uniaxial tension damage factor equation. c and tensile strength f t ;

[0042] S5: input the compressive strength and tensile strength of the gravity dam concrete to be studied into the trained mix ratio prediction model to obtain the corresponding model material prediction formula;

[0043] S6: Expand the predicted formula of the model material to obtain a predicted formula set, and determine the corresponding compressive strength f of any formula in the predicted formula set according to the ratio prediction model c ′ and tensile strength f t′, and the predicted formula set is cleaned to obtain the material formula range for the concrete gravity dam dynamic failure model test.

[0044] In the specific implementation, the specific method of formula expansion is: transform the model material prediction formula obtained in step S5, set the cement weight ratio to 1, and obtain the prediction formula before expansion 1:k 石膏 :k 砂 :k 矿物油 :k 水 ; The weight ratios of gypsum, sand, mineral oil and water are expanded respectively; among them, the weight ratio of gypsum is expanded to [k 石膏 -0.1, k 石膏 -0.05, k 石膏 , k 石膏 +0.05, k 石膏 +0.1, k 石膏 +0.15]; the weight ratio of sand is extended to [k 砂 -2, k 砂 -1, k 砂 , k 砂 +1, k 砂 +2]; the weight ratio of mineral oil is expanded to [k 矿物油 -0.4, k 矿物油 , k 矿物油 +0.4, k 矿物油 +0.8, k 矿物油 +1.2, k 矿物油 +1.6]; the weight ratio of water is expanded to [k 水 -0.6, k 水 -0.4, k 水 -0.2, k 水 , k 水 +0.2, k 水 +0.4, k 水 +0.6];

[0045] The ratios of the components are randomly combined to obtain 6*5*6*7 non-repetitive formulas, which are integrated to obtain the predicted formula set.

[0046] The specific cleaning of the prediction formula set is as follows: when f c ' <f c or t ' <f t When the formula is found, delete the formula, otherwise, keep the formula; after integrating all the retained formulas, determine the maximum weight ratio and minimum weight ratio of each ingredient, and obtain the formula range of the concrete gravity dam dynamic failure model test material.

[0047] Example 2

[0048] Using the method of Example 1, step S5 obtains a predicted formula of model materials: the weight ratio of cement, gypsum, sand, mineral oil and water is 1:0.4:4.5:0.8:1.3;

[0049] Step S6 obtains that the material formula range of the concrete gravity dam dynamic failure model test is 1:0.2-0.4:4-5:0.6-1:1-1.5.

[0050] The prototype dam concrete model was established using ANSYS software. The geometric scale of the dynamic failure model of the concrete gravity dam was considered to be 100, and the elastic modulus scale was considered to be 100 considering the use of natural water as reservoir water.

[0051] A simulated concrete sample model was prepared using the predicted formula of model materials: a weight ratio of 1:0.4:4.5:0.8:1.3;

[0052] The vibration table destructive test was carried out on the simulated concrete sample model to obtain the sample performance, and the following statistics were obtained: Figure 1 The uniaxial tensile stress-strain relationship comparison curve shown and Figure 2 The uniaxial compressive stress-strain relationship comparison curve shown; Figure 1 In the figure, the red line is the tensile stress-strain curve of the simulated concrete sample, and the blue line is the tensile stress-strain curve of the control sample; Figure 2 In the figure, the red line is the compressive stress-strain curve of the simulated concrete sample, and the blue line is the compressive stress-strain curve of the control sample.

[0053] Depend on Figure 1 and Figure 2 It can be seen that the peak compressive strain and tensile strain of the simulated concrete sample model prepared using the predicted formula of the model material are very close to those of the prototype dam concrete, meeting the requirements of the similarity rate of the strain ratio of the prototype concrete to 1, the acceleration ratio to 1, and the elastic modulus and strain ratio. According to the dynamic equation and the dimensional relationship, the main physical properties of the simulated concrete sample model, such as tensile strength, compressive strength, elastic modulus, Poisson's ratio, and stress-strain constitutive relationship, maintain a good similarity relationship with the prototype dam concrete model.

Claims

1. A concrete gravity dam dynamic failure model test material, characterized in that: The cement, gypsum, sand, mineral oil and water are mixed in a weight ratio of 1:0.2-0.4:4-5:0.6-1:1-1.

5.

2. The concrete gravity dam dynamic failure model test material according to claim 1, characterized in that: The weight ratio of cement, gypsum, sand, mineral oil and water is 1:0.4:4.5:0.8:1.

3.

3. The concrete gravity dam dynamic failure model test material according to claim 1, characterized in that: The D90 particle size of the sand and gravel is 1 mm.

4. A design method for concrete gravity dam dynamic failure model test material, characterized in that: The specific steps include: S1: Randomly formulate the mix ratio of cement, gypsum, sand, mineral oil and water to prepare concrete samples, conduct uniaxial compressive strength test and tensile strength test on the concrete samples to obtain the compressive strength and tensile strength corresponding to each mix ratio; integrate the mix ratio and the corresponding compressive strength and tensile strength as elements to obtain the sample set; S2: Establish a ratio prediction model based on multi-classification logistic regression, and use the sample set to train the ratio prediction model; S3: Establish the uniaxial pressure damage factor equation and the uniaxial tension damage factor equation; S4: Preset the pressure strain data and tension strain data of the gravity dam to be studied, and obtain the compressive strength f of the concrete of the gravity dam to be studied according to the uniaxial pressure damage factor equation and the uniaxial tension damage factor equation. c and tensile strength f t ; S5: input the compressive strength and tensile strength of the gravity dam concrete to be studied into the trained mix ratio prediction model to obtain the corresponding model material prediction formula; S6: Expand the predicted formula of the model material to obtain a predicted formula set, and determine the corresponding compressive strength f of any formula in the predicted formula set according to the ratio prediction model c ′ and tensile strength f t ′, and the predicted formula set is cleaned to obtain the material formula range for the concrete gravity dam dynamic failure model test.

5. The concrete gravity dam dynamic failure model test material and design method according to claim 4, characterized in that: The uniaxial pressure damage factor equation is: The uniaxial pressure damage factor equation is: And the middle Among them, α c is the parameter of the descending section of the gravity dam pressure curve, α t is the descending section parameter of the gravity dam tension curve, ε c For and f c The corresponding peak compressive strain of concrete, ε t For and f t The corresponding peak tensile strain of concrete, E0 is the initial elastic modulus.

6. The concrete gravity dam dynamic failure model test material and design method according to claim 4, characterized in that: In step S6, the predicted recipe set is cleaned as follows: c ' <f c or t ' <f t If yes, delete the formula, otherwise, keep the formula; After integrating all the retained formulas, the maximum and minimum weight ratios of each ingredient were determined, and the material formula range for the concrete gravity dam dynamic failure model test was obtained.

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