Method for predicting wave slamming pressure distribution on shallowly submerged circular arc bottom section of marine structure

Abstract

The present application relates to the technical field of research on the interaction between ocean engineering structure and wave, in particular to a method for predicting wave slamming pressure distribution of shallow-submerged circular-arc bottom section ocean engineering component, comprising: obtaining wave slamming pressure data of the circular-arc bottom section ocean engineering component and extracting pressure envelope, establishing spatial coordinates along the direction of the structure bottom plate, adopting double Gaussian function and linear function superposition to construct component pressure distribution model, determining model parameters through nonlinear fitting, and predicting wave slamming pressure spatial distribution according to the fitting result. μ 1, μ 2The present application can effectively reflect two main pressure peak values existing in the actual wave slamming process through the superposition form of double Gaussian function, can clearly locate the potential slamming hotspot area of the structure bottom, and can be applicable to different wave periods and structure clearance conditions through parameter calibration, and can provide more reliable wave load prediction basis for ocean structure design.

Description

Technical Field

[0001] This invention relates to the field of marine engineering structure and wave action research technology, specifically a method that can clearly show the spatial distribution of wave impact pressure on a circular arc bottom section under different wavelengths of waves in a submerged state. This method can be applied to the structural safety assessment and design of offshore bridges, near-shore platform structures, and cross-sea transportation projects to predict the wave impact pressure distribution of shallowly submerged circular arc bottom section marine engineering components. Background Technology

[0002] In nearshore engineering structures, curved cross-section beam-slab structures are widely used due to their high overall stiffness and good load-bearing performance. When the structure is located in shallow nearshore waters or the intertidal zone, the clearance between the structural base and the water surface is small, making it susceptible to wave slamming under strong wave action. Existing research shows that when waves interact strongly with the bottom of the structure, the water accelerates dramatically in a short period, generating transient slamming pressure on the structural base. These wave slamming loads are typically characterized by short duration, high peak value, and strong randomness, significantly impacting structural safety. Under extreme wave conditions, wave slamming can become one of the key loads controlling structural design.

[0003] Existing research on wave slamming primarily utilizes physical model experiments, field monitoring, and numerical simulations to study wave slamming pressure, yielding substantial results regarding its time-history characteristics and peak patterns. However, due to the significant nonlinearity and randomness of the wave slamming process, its spatial distribution remains complex, especially under shallow submerged or low-clearance conditions, where pressure along the structural base often exhibits a markedly non-uniform distribution. Some experimental studies have revealed multiple local peak regions along the structural base of the wave slamming pressure, with significant differences in spatial distribution patterns under different wave periods and structural clearance conditions. However, existing engineering calculation methods often employ simplified distribution assumptions or empirical formulas, resulting in a coarse description of the spatial distribution characteristics of pressure and failing to accurately reflect the multi-peak distribution features observed during actual wave slamming. Therefore, it is necessary to establish a predictive method capable of describing the spatial distribution of wave slamming pressure in circular-bottom cross-section members under shallow-buried conditions. This would improve the accuracy of wave slamming load estimation and provide a more reliable theoretical basis for marine engineering structural design. Summary of the Invention

[0004] The purpose of this invention is to provide a method for predicting the wave impact pressure distribution of shallow submerged circular bottom section marine engineering components by establishing a bimodal nonlinear fitting model to accurately describe the spatial distribution law of wave impact pressure and to identify potential high-risk areas at the bottom of the structure.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for predicting wave slamming pressure distribution on shallowly submerged marine structural members with circular bottom sections includes the following steps:

[0007] Step 1: Obtain wave impact pressure data for marine structural members with a circular arc bottom section and extract the pressure envelope. Perform dimensionless processing on the impact pressure to obtain the normalized pressure value. P * The dimensionless formula is as follows:

[0008] (1), where P To measure the pressure, r The density of seawater, A Amplitude;

[0009] Step 2: Establish spatial coordinates along the direction of the structural base plate, using the leading edge of the structural base plate as the reference origin. Furthermore, a nonlinear fitting model of the spatial distribution of wave impact pressure was constructed, which consists of the superposition of two Gaussian distribution functions and a linear term:

[0010] (2), where, P(x) The normalized slam pressure at position x; A 1, A 2 represents the amplitude of the two pressure peak points; m 1, m 2 represents the location of the two pressure peaks; s 1, s 2 represents the width parameter of the spatial distribution of the pressure peak; K This represents the overall pressure gradient; B Represents the reference value for pressure;

[0011] Step 3: Employ a pressure distribution model for the component by superimposing a double Gaussian function and a linear function;

[0012] Step 4: Determine model parameters through nonlinear fitting. Use the nonlinear least squares method to fit the experimental data to obtain the model parameters: A 1, A 2; m 1, m 2; s 1, s 2; K , B ;

[0013] Step 5: Predict the spatial distribution of wave impact pressure based on the fitting results.

[0014] In step 2 of this invention, the first Gaussian term in the double Gaussian function characterizes the peak value of the primary impact pressure formed when the wave first strikes the bottom plate of the structure. It has a large amplitude and a small distribution width. The second Gaussian term characterizes the peak value of the secondary impact pressure formed during the wave's receding or reflection process. It has a smaller amplitude, and the peak position lags as the degree of submersion increases. Meanwhile, the width parameter... s Used to reflect the degree of pressure concentration in space. s The smaller the value, the more concentrated and intense the impact.

[0015] Step 5 of this invention involves statistically analyzing the parameters and establishing a parameter database based on different structural clearance C and wave period conditions for structural design calculations. In this embodiment, the structural clearance range is -0.04 m ≤ C ≤ 0.00 m.

[0016] This invention is applicable to different wave conditions under shallow submerged conditions, where short-period waves correspond to higher and more concentrated peak pressure of the main slamming, while long-period waves form a relatively stable or slowly decaying pressure distribution after the main slamming. The prediction results are used to determine the pressure distribution range and extreme value location in the slamming resistance design of marine engineering components.

[0017] Compared with existing technologies, this invention, through the superposition of two Gaussian functions, can effectively reflect the two main pressure peaks present in the actual wave impact process; through m 1, m 2. It can clearly locate potential slamming hotspots at the bottom of the structure; through parameter calibration, it can be applied to different wave cycles and structural clearance conditions; this method can provide a more reliable basis for wave load prediction in marine structure design. Attached Figure Description

[0018] Appendix Figure 1 This is a schematic diagram of the wave action of a marine component with a circular arc bottom cross section in an embodiment of the present invention.

[0019] Appendix Figure 2 These are the pressure envelope curves under different clearance conditions in the embodiments of the present invention, wherein... Figure 2 In case (a), the conditions are T=1.5s, A=0.05m and T=3.0s, A=0.06m. Figure 2 In case (b), the conditions are T=1.5s, A=0.075m and T=3.0s, A=0.085m. Figure 2 In case (c), the time intervals are T=1.5s, A=0.1m and T=3.0s, A=0.11m. Figure 2 In the case of (d), the conditions are T=1.5s, A=0.12m and T=3.0s, A=0.135m.

[0020] Appendix Figure 3 This is a wave impact pressure fitting curve obtained based on the method of the present invention in an embodiment of the present invention, wherein... Figure 3 (a) corresponds to the wave impact pressure fitting curve under the first clearance condition. Figure 3 (b) corresponds to the wave impact pressure fitting curve under the second clearance condition. Figure 3 (c) corresponds to the wave impact pressure fitting curve under the third type of clearance condition. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] This invention addresses the shortcomings and deficiencies of existing technologies by proposing a method for predicting wave impact pressure distribution on shallowly submerged marine structural members with circular slab bottoms, comprising the following steps:

[0023] Step 1: Obtain wave impact pressure data for marine structural members with a circular arc bottom section and extract the pressure envelope. Perform dimensionless processing on the impact pressure to obtain the normalized pressure value. P * The dimensionless formula is as follows:

[0024] (1), where P To measure the pressure, r The density of seawater, A Amplitude;

[0025] Step 2: Establish spatial coordinates along the direction of the structural base plate, using the leading edge of the structural base plate as the reference origin. Furthermore, a nonlinear fitting model of the spatial distribution of wave impact pressure was constructed, which consists of the superposition of two Gaussian distribution functions and a linear term:

[0026] (2), where, P(x) The normalized slam pressure at position x; A 1, A 2 represents the amplitude of the two pressure peak points; m 1, m 2 represents the location of the two pressure peaks; s 1, s 2 represents the width parameter of the spatial distribution of the pressure peak; K This represents the overall pressure gradient; BRepresenting the pressure reference value, the first Gaussian term in the double Gaussian function characterizes the peak value of the primary impact pressure formed when the wave first strikes the bottom plate of the structure. It has a large amplitude and a small distribution width. The second Gaussian term characterizes the peak value of the secondary impact pressure formed during the wave's receding or reflection process. It has a smaller amplitude, and the peak position lags as the degree of submersion increases. Meanwhile, the width parameter... s Used to reflect the degree of pressure concentration in space. s The smaller the value, the more concentrated and intense the impact.

[0027] Step 3: Employ a pressure distribution model for the component by superimposing a double Gaussian function and a linear function;

[0028] Step 4: Determine model parameters through nonlinear fitting. Use the nonlinear least squares method to fit the experimental data to obtain the model parameters: A 1, A 2; m 1, m 2; s 1, s 2; K , B ;

[0029] Step 5: Predict the spatial distribution of wave impact pressure based on the fitting results.

[0030] In wave flue tests, wave loading tests were conducted on a circular arc-bottom cross-section member under different wave periods and amplitudes. Transient pressure data was acquired using an array of pressure sensors placed at the bottom of the member, and the pressure envelope value within each wave period was extracted. The structural clearances were as follows: C =0.00m; C =-0.02m; C When the pressure is -0.04m, the pressure data under different amplitude conditions are statistically processed, and the average value is taken as the representative pressure distribution.

[0031] Subsequently, a nonlinear fitting method was used to fit the pressure envelope data to obtain the values ​​of each parameter. The results show that under all wave conditions, the pressure distribution exhibits a bimodal characteristic, with the first peak being significantly larger than the second peak. The difference lies in the trend: under long waves, the overall slamming pressure trend is stable, while under short waves, the slamming pressure shows a decreasing trend.

[0032] Taking a circular arc-shaped bottom beam as an example, with a radius of 3.8m, and using the midpoint of the arc bottom as the coordinate point, upwards is taken as positive. Experiments were conducted with clearance heights of 0.00m, -0.02m, and -0.04m, and the incident wave period was... T =3.0s and T =1.5s, long wave ( T =3.0s) The amplitude used isA =0.06m, 0.085m, 0.11m, 0.135m; shortwave ( T =1.5s) The amplitude used is A =0.05m, 0.075m, 0.10m, 0.12m.

[0033] The experiment was conducted under the above working conditions. The experimental data was recorded using a pressure sensor. The frequency range of wave impact was determined based on wavelet changes. The impact pressure time history curve was obtained by filtering and separation. The average value of the impact pressure peak of six cycles was taken as the standard value.

[0034] Substituting the above pressure values ​​into formula (1-1) yields the dimensionless slamming pressure, where the water density is taken as... p= 1000 kg / m³, gravitational acceleration g =9.81m / s²; This example compares the slamming pressure envelope curves of two different period wavelengths under the same headroom and approximate amplitude. The comparison results are as follows: Figure 2 As shown, it can be seen that after the first significant slam, the attenuation of shortwave is more significant than that of longwave.

[0035] Envelope points under the same clearance but different amplitude conditions were statistically recorded, and the data were fitted. The results are as follows: Figure 3 As shown, further research revealed that as the degree of submersion of the structure increases, the peak value of the first slamming pressure gradually increases; the second peak value gradually decreases and there is a shift in the peak value; the pressure peak value generated by short-period waves is sharper and the slamming characteristics are relatively stronger.

[0036] This method can effectively predict the slamming pressure distribution of a circular arc-shaped bottom section under shallow submerged conditions, providing a basis for engineering design.

[0037] The present invention has the following advantages: (1) It can accurately describe the characteristics of double-peak slamming; (2) Each parameter has a clear engineering interpretation; (3) It can identify the dangerous areas of the structure; (4) It is applicable to different wave conditions; (5) It can be used for extreme value risk assessment and directly used for structural anti-slamming design to improve the safety of structural design.

Claims

1. A method for predicting wave slamming pressure distribution on shallowly submerged marine structural members with circular arc bottom sections, characterized in that, Includes the following steps: Step 1: Obtain wave impact pressure data for marine structural members with a circular arc bottom section and extract the pressure envelope. Perform dimensionless processing on the impact pressure to obtain the normalized pressure value. P * The dimensionless formula is as follows: (1), where P To measure the pressure, ρ The density of seawater, A Amplitude; Step 2: Establish spatial coordinates along the direction of the structural base plate, using the leading edge of the structural base plate as the reference origin. Furthermore, a nonlinear fitting model of the spatial distribution of wave impact pressure was constructed, which consists of the superposition of two Gaussian distribution functions and a linear term: (2), where, P(x) The normalized slam pressure at position x; A 1, A 2 represents the amplitude of the two pressure peak points; μ 1, μ 2 represents the location of the two pressure peaks; σ 1, σ 2 represents the width parameter of the spatial distribution of the pressure peak; K This represents the overall pressure gradient; B Represents the reference value for pressure; Step 3: Employ a pressure distribution model for the component by superimposing a double Gaussian function and a linear function; Step 4: Determine model parameters through nonlinear fitting. Use the nonlinear least squares method to fit the experimental data to obtain the model parameters: A 1, A 2; μ 1, μ 2; σ 1, σ 2; K , B ; Step 5: Predict the spatial distribution of wave impact pressure based on the fitting results.

2. The method for predicting wave impact pressure distribution of shallowly submerged circular arc bottom section marine engineering components according to claim 1, characterized in that, In step 2, the first Gaussian term in the double Gaussian function characterizes the peak value of the primary impact pressure formed when the wave first strikes the bottom plate of the structure. It has a large amplitude and a small distribution width. The second Gaussian term characterizes the peak value of the secondary impact pressure formed during the wave's receding or reflection process. It has a small amplitude, and the peak position lags as the degree of submersion increases. Meanwhile, the width parameter... σ Used to reflect the degree of pressure concentration in space. σ The smaller the value, the more concentrated and intense the impact.

3. The method for predicting wave impact pressure distribution of shallowly submerged circular arc bottom section marine engineering components according to claim 1, characterized in that, Step 5: Based on different structural clearance C and wave period conditions, perform statistical analysis on the parameters and establish a parameter database for structural design calculations. The structural clearance range is: -0.04 m ≤ C ≤ 0.00 m.

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