Gravity dam damage prediction method under underwater explosion load
By simulating the damage to concrete gravity dams by different explosion parameters, measuring the cracking depth ratio and cracking angle, and establishing a fitting curve, the problem that the existing technology is difficult to comprehensively evaluate the damage to concrete gravity dams under underwater explosion loads is solved, and a rapid assessment and prediction of the degree of damage to the dam body is achieved.
Patent Information
- Application Number
- CN202411899630.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2025-04-15
AI Technical Summary
Existing numerical simulations or single-factor simulation tests are difficult to comprehensively evaluate the damage of concrete gravity dams under underwater explosion loads, and there is a lack of effective damage prediction methods.
The ALE algorithm is used to simulate the damage of concrete gravity dams with different explosion parameters, and the cracking depth ratio and cracking angle of concrete gravity dams under different explosion parameters are measured, and a nonlinear fitting curve between the cracking depth ratio and cracking angle is established, and the damage degree prediction is completed based on the cracking angle data of the dam body.
The effective judgment and evaluation of the damage degree of concrete gravity dam under underwater near-field explosion loads is achieved, and the damage degree of concrete gravity dam can be quickly predicted and divided into mild, moderate and severe damage levels.
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Figure CN119830567A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of damage assessment, and in particular relates to a method for predicting damage of a gravity dam under underwater explosion load. Background Art
[0002] As a large public facility, reservoir dams are at high risk of being damaged by explosive loads, and the collapse of the dam will cause tragedy in the downstream area of the dam, as well as property losses and ecological damage. In view of this, it is urgent to study the explosion resistance of dams. However, there is a lack of experimental research on the destruction of concrete gravity dams under underwater explosive loads.
[0003] At present, most scholars use centrifuge model test methods and numerical simulation methods to explore the failure characteristics of concrete gravity dams under explosion. For example, Huang Xieping, Kong Xiangzhen, Hu Jing, et al. Failure modes of concrete gravity dam subjected to near-field underwater explosion: Centrifuge test and numerical simulation [J] used small centrifuge test and numerical simulation methods to compare and analyze the failure modes of dams under underwater near-field explosions; Pan Xinhao, Wang Gaohui, Lu Wenbo, et al. Blast Performance and Damage Evaluation of High Arch Dams Subjected to Far-Field Underwater Explosions: Consideration of Joints [J] conducted underwater far-field explosion tests on scaled models of arch dams to analyze the nonlinear dynamic response and failure process of high arch dams; Wang Gaohui, Liu Aobo, Lu Wenbo, et al. Failure modes and dynamic responses of roller compacted concrete gravity dams subjected to underwater contact explosion based on the cohesive model[J] explored the failure mode and dynamic response of concrete gravity dam under underwater contact explosion load; Xiong Junwei, Lu Wenbo, Wang Gaohui, et al. Vertical crack identification of archdam under underwater explosion based on mode transition[J] explored the identification of arch dam cracks caused by underwater explosion; Khati Tanuja, Kaloni Smita. Comparative Study of CDP and JH2Damage Model of Koyna Dam Under Blast Loading by CEL Technique[M]. ABAQUS was used to analyze the dynamic response of the interaction between dam and reservoir water under underwater explosion.
[0004] At present, some scholars have evaluated the degree of damage to the dam body, such as Wang Xiao-hua, Zhang She-rong, Wang Chao, et al. Blast-induced damage and evaluation method of concrete gravity dam subjected to near-field underwater explosion[J]. The damage mechanism of the dam under the action of underwater explosion was studied, and a recommended formula for predicting the dam blasting vibration was proposed, and an optimization criterion for evaluating the dam blasting damage was proposed; Zhao Xiaohua, Wang Gaohui, Lu Wenbo, et al. Effects of close proximity underwater explosion on the nonlinear dynamic response of concrete gravity dams with orifices[J]. A damage index for evaluating the degree of local damage of an arch dam after an underwater explosion was proposed, and the damage index was used to evaluate the local damage of the middle part of the dam body, the loading hole and the dam shoulder.
[0005] However, due to the complex damage mechanism of the dam structure under underwater explosion, and the local damage of the dam body and the instability of the overall vibration under the explosion impact, the existing numerical simulation or single factor simulation test is difficult to comprehensively evaluate the damage of the dam. Therefore, it is necessary to deeply explore the damage characteristics of concrete gravity dams under multi-factor underwater explosion loads and provide a more comprehensive damage prediction method. Summary of the invention
[0006] In view of the defects and problems existing in the current prediction of explosion damage of concrete gravity dams, the present invention provides a method for predicting gravity dam damage under underwater explosion loads.
[0007] The solution adopted by the present invention to solve the technical problem is: a method for predicting gravity dam damage under underwater explosion load, comprising the following steps:
[0008] S1. Select a typical dam section of a concrete gravity dam to determine the influencing factors of damage to the concrete gravity dam under underwater explosion load, wherein the influencing factors include explosion parameters, explosive material parameters, water material parameters, air material parameters, and concrete material parameters; use the ALE algorithm to simulate the damage of the concrete gravity dam under different explosion parameters, and determine the distance h from the lowest crack in the vertical direction of the concrete gravity dam to the explosion center and the horizontal projection l0 of the deepest crack that penetrates the dam body along the river direction under different explosion parameters;
[0009] S2. Calculate the cracking depth ratio and cracking angle of the gravity dam under different blast loads.
[0010]
[0011] Where: D is the crack depth ratio, l0 is the horizontal projection of the crack, l is the cross-sectional height of the dam in the horizontal direction; R is the detonation distance;
[0012] S3. With the cracking angle of the dam body as the horizontal coordinate and the cracking depth ratio of the dam body as the vertical coordinate, a nonlinear fitting curve of the cracking depth ratio and the cracking angle under different explosion loads is established.
[0013] D=m×θ n
[0014] S4. According to the gravity dam damage level classification standard, the cracking angles corresponding to mild damage, moderate damage and severe damage are found on the fitting curve, and the damage level of the dam body is predicted based on the dam body cracking angle data.
[0015] The damage prediction method for gravity dams under underwater explosion loads mentioned above, the damage degree classification standard is:
[0016] Slight damage: There are certain damage areas on the concrete gravity dam, and there are fewer cracks in the dam body, and the maximum cracking depth of the cracks does not exceed 1 / 3 of the thickness of the dam body at the same elevation;
[0017] Moderate damage: The damaged area of the concrete gravity dam is further expanded, and the maximum crack depth is greater than 1 / 3 of the thickness of the dam body at the same elevation but not more than 2 / 3 of the thickness of the dam body at the same elevation;
[0018] Severe damage: The damage area of the concrete gravity dam is very large, and the maximum cracking depth is greater than 2 / 3 of the thickness of the dam body at the same elevation.
[0019] In the above-mentioned gravity dam damage prediction method under underwater explosion load, the explosion parameters in step S1 include explosive equivalent ω, detonation distance R, and detonation depth H; the explosive material parameters include explosive density ρ1, unit volume internal energy E d , explosion velocity v, explosion product expansion coefficient γ; the water material parameters include water density ρ2; the air material parameters include air density ρ3 and sound speed C3; the concrete material parameters include concrete density ρ4, compressive strength σ, and Poisson's ratio δ.
[0020] The above-mentioned gravity dam damage prediction method under underwater explosion load also includes constructing a damage characterization function expression based on dimensional analysis, taking the distance h of the lowest crack in the vertical direction of the concrete gravity dam from the explosion center as the dependent variable and the influencing factors as the independent variables:
[0021] {h}=f(ω,R,H,ρ1,Ed , v, γ, ρ2, ρ3, C3, ρ4, σ, δ).
[0022] The above-mentioned gravity dam damage prediction method under underwater explosion load analyzes the damage mode of the dam body with MLT dimension for the explosion factor parameters, obtains the dimensional power coefficient of each physical quantity, selects the explosive equivalent ω, explosive density ρ1 and detonation velocity v as the basic reference physical quantities, obtains dimensionless independent variables according to П theory and dimensional analysis, uses dimensionless independent variables to express the characterization function as a dimensionless relationship, and expresses the unchanged parameters as constants to simplify the dimensionless relationship;
[0023] Based on the damage simulation of concrete gravity dams under different explosion conditions, a three-dimensional nonlinear surface fitting is performed on the distance h between the projection point of the lowest crack in the vertical direction of the dam body and the center line of the explosive in the dam height direction, and a fitting formula with a specific relationship between h and ω, R, ρ1, and H is obtained.
[0024] Based on the obtained explosive equivalent ω, explosive density ρ1, detonation distance R and detonation depth H, they are substituted into the fitting formula to calculate h.
[0025] In the above-mentioned gravity dam damage prediction method under underwater explosion load, the dimensional power coefficients of various physical quantities are:
[0026]
[0027] Selecting explosive equivalent ω, explosive density ρ1 and detonation velocity v as basic reference physical quantities, 10 dimensionless independent variables are obtained according to П theory and dimensional analysis, which are: π4=γ, π 10 =δ;
[0028] The characterization function relationship is expressed as a dimensionless relationship:
[0029]
[0030] Since only the explosive equivalent ω, detonation distance R and detonation depth H change, the parameters of explosives, water, air and concrete materials do not change. The density ρ1 of the explosive, the internal energy per unit volume E d , explosion velocity v, explosion product expansion coefficient γ, water density ρ2, air density ρ3, sound speed C3, concrete density ρ4, compressive strength σ, Poisson's ratio δ are all constants, and the formula is simplified to:
[0031]
[0032] It can be expressed in the form of exponential product:
[0033]
[0034] Compared with the prior art, the present invention has the following beneficial effects:
[0035] 1. The present invention takes the cracking depth ratio of the concrete gravity dam as a benchmark and the cracking angle as an evaluation index to fit a prediction formula for the damage degree of the gravity dam, which can effectively determine and evaluate the damage degree of the concrete gravity dam under underwater near-field explosion loads.
[0036] 2. The present invention analyzes the various material parameters and factors that affect the damage mode of the concrete gravity dam, uses the dimensional analysis method to analyze the key factors affecting the damage effect of the concrete gravity dam and the dimensionless formula for characterizing h, and performs nonlinear surface fitting on the basis of the numerical results to obtain a specific fitting formula for calculating the cracking angle, which can quickly predict the degree of damage to the concrete gravity dam. BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Figure 1 Schematic diagram of calculation of dam cracking depth ratio.
[0038] Figure 2 Schematic diagram of dam cracking angle calculation.
[0039] Figure 3 is the cracking depth ratio and cracking angle under different explosive equivalents.
[0040] Figure 4 is the cracking depth ratio and cracking angle at different detonation distances.
[0041] Figure 5 is the cracking depth ratio and cracking angle at different initiation depths.
[0042] Figure 6 It is the fitting relationship curve between crack depth ratio and crack angle. DETAILED DESCRIPTION
[0043] The present invention explores the damage modes of gravity dams under different factors and proposes a method for evaluating and predicting gravity dam damage under underwater explosion loads. The present invention is further described below in conjunction with the accompanying drawings and embodiments.
[0044] Example 1: This example provides a method for predicting damage to a gravity dam under underwater explosion loads. The method uses crack depth ratio and crack angle as indicators to evaluate the damage degree of a concrete gravity dam. Figure 1 As shown in the figure, the deepest crack running through the dam body along the river direction is selected, and the ratio of the horizontal projection length l0 of the crack to the cross-sectional width l of the dam body in the horizontal direction is taken as the crack depth ratio D.
[0045]
[0046] like Figure 2 As shown in the figure, the inverse tangent of the ratio of the distance h between the projection point of the lowest crack in the vertical direction of the dam body and the center line of the explosive and the detonation distance R is the cracking angle θ.
[0047]
[0048] This embodiment takes the typical dam section in the Koyna gravity dam in India as the research object. Considering the symmetry of the numerical model and to improve the calculation efficiency, only a 1 / 2 model is established. In this model, Euler grids are used for air, water and explosives, and Lagrange grids are used for concrete. The two are coupled through *CONSTRAINED_LAGRANGE_IN_SOILD. The explosives and the surrounding media are progressively extended to the top and bottom of the dam with 200mm, 300mm and 400mm grid units respectively. The grid in the width direction of the dam body is 100mm, with a total of 1546524 units. Transmission boundaries are set for both reservoir water and air to simulate infinite areas of reservoir water and air.
[0049] In addition, the explosive in this model adopts the *MAT_HIGH_EXPLOSIVE_BURN model and the *EOS_JWL state equation, which is expressed as
[0050]
[0051] Where: p is the detonation pressure; a and B are material pressure parameters, whose values are 373.77MPa and 3.75MPa respectively; R1, R2, ω are the dimension coefficients of the state equation, whose values are 4.15, 0.9, and 0.35 respectively; E0 is the internal energy of the unit volume, whose value is 8.9GJ / m 3 .
[0052] Concrete adopts the *MAT_CONCRETE_DAMAGE_REL3 model, and defines the failure criterion through the *MAT_ADD_EROSRION keyword, and the maximum principal strain is taken as 0.01. This model can automatically generate parameters. Just input the density, Poisson's ratio, uniaxial compressive strength and pressure-strain rate improvement coefficient relationship curve to automatically generate other parameters of the material model and the parameters of the state equation *EOS_TABULAIED_COMPACTION. The automatically generated parameters will be in the message file of LS-DYNA. The unconfined compressive strength, density ρ and Poisson's ratio γ are 30MPa and 2.4g / cm respectively. 3 and 0.19.
[0053] Air is considered as an ideal gas, using the *MAT_NULL model and
[0054] *EOS_LINEAR_POLYNOMIAL keyword is defined, the specific formula is as follows:
[0055] p=C0+C1μ+C2μ 2 +C3μ 3 +E(C4+C5μ+C6μ 2 )
[0056]
[0057] Where p is the gas pressure, E is the initial internal energy, V is the relative volume, C0 = 0, C1 = 0, C2 = 0, C3 = 0, C4 = 0.4, C5 = 0.4, C6 = 0, E0 = 2.5 × 10 -4 J, V=1.
[0058] Firstly, the damage to the concrete gravity dam under different explosive equivalents (200kg, 400kg, 600kg, 800kg, 1000kg), different detonation distances (4m, 8m, 12m, 16m) and different detonation depths (10m, 20m, 30m, 40m) was simulated, and the crack depth ratio and crack angle of the concrete gravity dam were calculated. The results are shown in Fig. Figure 3-5 .
[0059] Depend on Figure 3 It can be seen that the cracking depth ratio and cracking angle of the dam body increase with the increase of explosive equivalent. When the amount of explosives is 1000kg, the dam body is about to reach the dam-break state. Figure 4 and Figure 5 It can be seen that the cracking depth ratio and cracking angle of the dam body decrease with the increase of detonation distance and detonation depth.
[0060] Then the relationship between the crack depth ratio and crack angle of the dam body is established and nonlinear fitting analysis is performed to obtain the damage degree prediction formula of concrete gravity dam D = m × θ n ;
[0061] Substituting the cracking depth ratio and cracking angle data under different explosion conditions into the gravity dam damage prediction formula, a specific fitting formula is obtained.
[0062] D = 4.33 × 10 -6 θ 3.78 .
[0063] The fitting curve of cracking depth ratio and cracking angle was constructed by the fitting formula. Taking the cracking depth ratio of the dam body as the benchmark and combining the cracking angle evaluation index, the evaluation index of the damage state of the concrete gravity dam under the underwater near-field explosion load was determined. The damage degree of the concrete gravity dam can be roughly divided into the following three damage levels.
[0064] (1) Mild damage: There are certain damage areas on the concrete gravity dam, and there are fewer cracks in the dam body. The maximum crack depth does not exceed 1 / 3 of the thickness of the dam body at the same elevation.
[0065] (2) Moderate damage: The damage area of the concrete gravity dam is further expanded, and the maximum crack depth is greater than 1 / 3 of the thickness of the dam body at the same elevation but not more than 2 / 3 of the thickness of the dam body at the same elevation;
[0066] (3) Severe damage: The damage area of the concrete gravity dam is very large, and the maximum crack depth is greater than 2 / 3 of the thickness of the dam body at the same elevation.
[0067] The fitting relationship curve is as follows Figure 6 As shown in the figure, the damage degree corresponding to different cracking angles can be judged from the fitting curve.
[0068] Depend on Figure 6 It can be seen from the fitting formula that when the cracking angle of the dam body does not exceed 66.1°, the damage degree of the gravity dam is slight damage; when the cracking angle of the dam body is greater than 66.1° but does not exceed 79.5°, the damage degree of the gravity dam is moderate damage; when the cracking angle of the dam body exceeds 79.5°, the damage degree of the gravity dam is severe damage. This method can directly determine the damage degree of the gravity dam based on the cracking angle results.
[0069] Example 2: Based on Example 1, this example characterizes the distance h between the projection point of the lowest crack in the vertical direction of the dam body and the center line of the explosive in the dam height direction under different factors through dimensional analysis. By analyzing various material parameters, the parameters that need to be considered for dimensional analysis are finally determined as follows:
[0070] (1) Factor parameters: explosive equivalent ω, detonation distance R, detonation depth H;
[0071] (2) Explosive material parameters: explosive density ρ1, internal energy per unit volume E d , detonation velocity v, explosion product expansion coefficient γ;
[0072] (3) Water material parameters: water density ρ2;
[0073] (4) Air material parameters include air density ρ3 and sound speed C3;
[0074] (5) Concrete material parameters include concrete density ρ4, compressive strength σ, and Poisson’s ratio δ.
[0075] Taking the distance h from the projection point of the lowest crack in the vertical direction of the dam body to the center line of the explosive in the dam height direction as the dependent variable and other parameters as independent variables, the relevant function expression is obtained:
[0076] {h}=f(ω,R,H,ρ1,Ed , v, γ, ρ2, ρ3, C3, ρ4, σ, δ)
[0077] According to the explosion factor parameters, the damage mode of the dam body is analyzed with the MLT dimension, and the dimensional power coefficients of each physical quantity are obtained, as shown in Table 1 below.
[0078] Table 1 Dimensional power coefficients of basic physical quantities
[0079]
[0080] Selecting explosive equivalent ω, explosive density ρ1 and detonation velocity v as basic reference physical quantities, 10 dimensionless independent variables are obtained according to П theory and dimensional analysis, which are: π4=γ, π 10 =δ;
[0081] Express the functional relationship as a dimensionless relationship:
[0082]
[0083] Since only the explosive equivalent ω, detonation distance R and detonation depth H change, the parameters of explosives, water, air and concrete materials do not change. The density ρ1 of the explosive, the internal energy per unit volume E d , explosion velocity v, explosion product expansion coefficient γ, water density ρ2, air density ρ3, sound speed C3, concrete density ρ4, compressive strength σ, Poisson's ratio δ are all constants, and the formula is simplified to:
[0084]
[0085] It can be expressed in the form of exponential product:
[0086]
[0087] In practical application, based on the damage of concrete gravity dams under different explosion conditions, a three-dimensional nonlinear surface fitting is performed on the distance h from the projection point of the lowest crack in the vertical direction of the dam body in the direction of the dam height to the center line of the explosive, and a fitting formula with a specific relationship between h and ω, R, ρ1 and H is obtained.
[0088] According to the given explosive equivalent, detonation distance and detonation depth, the distance h from the projection point of the lowest crack in the vertical direction of the concrete gravity dam to the center line of the explosive in the dam height direction is substituted into the fitting formula and used to calculate the cracking angle, thereby quickly predicting the damage degree of the concrete gravity dam.
[0089] The above description is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for predicting gravity dam damage under underwater explosion load, characterized in that: The following steps are involved: S1. Select a typical dam section of a concrete gravity dam to determine the influencing factors of damage to the concrete gravity dam under underwater explosion load, wherein the influencing factors include explosion parameters, explosive material parameters, water material parameters, air material parameters, and concrete material parameters; use the ALE algorithm to simulate the damage of the concrete gravity dam under different explosion parameters, and determine the distance h from the lowest crack in the vertical direction of the concrete gravity dam to the explosion center and the horizontal projection l0 of the deepest crack that penetrates the dam body along the river direction under different explosion parameters; S2. Calculate the cracking depth ratio and cracking angle of the gravity dam under different blast loads. Where: D is the crack depth ratio, l0 is the horizontal projection of the crack, l is the cross-sectional height of the dam in the horizontal direction; R is the detonation distance; S3. With the cracking angle of the dam body as the horizontal coordinate and the cracking depth ratio of the dam body as the vertical coordinate, a nonlinear fitting curve of the cracking depth ratio and the cracking angle under different explosion loads is established. D=m×θ n S4. According to the gravity dam damage level classification standard, the cracking angles corresponding to mild damage, moderate damage and severe damage are found on the fitting curve, and the damage level of the dam body is predicted based on the dam body cracking angle data.
2. The method for predicting gravity dam damage under underwater explosion load according to claim 1, characterized in that: The injury severity classification standards are as follows: Slight damage: There are certain damage areas on the concrete gravity dam, and there are fewer cracks in the dam body, and the maximum cracking depth of the cracks does not exceed 1 / 3 of the thickness of the dam body at the same elevation; Moderate damage: The damaged area of the concrete gravity dam is further expanded, and the maximum crack depth is greater than 1 / 3 of the thickness of the dam body at the same elevation but not more than 2 / 3 of the thickness of the dam body at the same elevation; Severe damage: The damage area of the concrete gravity dam is very large, and the maximum cracking depth is greater than 2 / 3 of the thickness of the dam body at the same elevation.
3. The method for predicting gravity dam damage under underwater explosion load according to claim 1, characterized in that: The explosion parameters in step S1 include explosive equivalent ω, detonation distance R, and detonation depth H; the explosive material parameters include explosive density ρ1, unit volume internal energy E d , explosion velocity v, explosion product expansion coefficient γ; the water material parameters include water density ρ2; the air material parameters include air density ρ3 and sound speed C3; the concrete material parameters include concrete density ρ4, compressive strength σ, and Poisson's ratio δ.
4. The method for predicting gravity dam damage under underwater explosion load according to claim 3 is characterized in that: It also includes constructing the damage characterization function expression based on dimensional analysis, taking the distance h from the lowest crack in the vertical direction of the concrete gravity dam to the explosion center as the dependent variable and the influencing factors as the independent variables. {h}=f(ω,R,H,ρ1,E d , v, γ, p2, p3, C3, p4, σ, δ).
5. The method for predicting gravity dam damage under underwater explosion load according to claim 4, characterized in that: According to the explosion factor parameters, the damage mode of the dam body is analyzed with the MLT dimension to obtain the dimensional power coefficients of each physical quantity. The explosive equivalent ω, explosive density ρ1 and detonation velocity v are selected as the basic reference physical quantities. According to the П theory and dimensional analysis, the dimensionless independent variables are obtained, and the characterization function is expressed as a dimensionless relationship using the dimensionless independent variables. The unchanged parameters are expressed as constants to simplify the dimensionless relationship. Based on the damage simulation of the concrete gravity dam under different explosion conditions, the distance h from the projection point of the lowest crack in the vertical direction of the dam body in the dam height direction to the center line of the explosive is fitted with a three-dimensional nonlinear surface, and the fitting formula with a specific relationship between h and ω, R, ρ1 and H is obtained. Based on the obtained explosive equivalent ω, explosive density ρ1, detonation distance R and detonation depth H, they are substituted into the fitting formula to calculate h.