Method for calculating wave overtopping of double straight-wall seawall

Abstract

The application discloses a kind of double straight wall type sea embankment single width overtopping quantity calculation method, suitable for the single width overtopping quantity calculation method of double straight wall type sea embankment under irregular wave action is proposed, both facilitate the overtopping design of double straight wall type sea embankment, and can optimize the section size and crest elevation of double straight wall type sea embankment, under the premise of meeting safety conditions, effectively solve the problem that the section size and crest elevation are too large in the application of the single width overtopping quantity formula in existing regulations and specifications in double straight wall type sea embankment, with good economic benefits and high popularization and application value.

Description

Technical Field

[0001] This invention relates to the field of coastal engineering technology, and in particular to a method for calculating the wave overtopping per unit width of a double-straight-wall seawall under irregular wave action. Background Technology

[0002] In recent years, my country's ports, shipping, and coastal protection have flourished, resulting in the construction and renovation of numerous seawall projects. If seawalls are designed to not allow overtopping during the design phase, the seawall crest elevation would inevitably be very high, leading to substantial investment and significantly impacting the views and water activities of residents near the coast. Therefore, seawalls are often designed to allow overtopping, with allowable overtopping values ​​limited based on the seawall grade, crest, and backslope protection type. Existing Chinese regulations and standards, such as the "Code for Design of Seawall Engineering" and the "Guangdong Provincial Guidelines for Seawall Engineering Design," use formulas for calculating overtopping values ​​specifically for sloping (without breast wall), sloping (with breast wall), and composite sloping seawall types. These formulas are not applicable to calculating overtopping values ​​for double-straight-wall seawalls.

[0003] This is because the wave reflection effect in front of a straight-wall seawall is significantly greater than that of a sloping seawall, resulting in a significantly larger overtopping volume for a double-straight-wall seawall compared to sloping (without breast wall), sloping (with breast wall), and composite sloping seawall types. Existing regulations and standards for calculating overtopping volume do not consider the wave reflection effect in front of a straight-wall seawall, nor do they account for the wave reduction effect of the roughness of the intermediate platform of a straight-wall seawall, or the wave breaking effect under wind conditions in front of the straight wall. Therefore, the calculated overtopping volume is significantly lower than expected. Designing a double-straight-wall seawall based on the overtopping volume calculated in existing regulations and standards would increase design redundancy, significantly increasing the workload and investment. Currently, many engineering designers can only roughly determine the overtopping volume of a double-straight-wall seawall based on their own experience and the operation of other projects in the project area, or analyze and determine the overtopping volume using numerical models.

[0004] However, in recent years, with the increasing demand for improved cultural landscapes, various seawall cross-sectional designs have emerged, and the use of the double-straight-wall seawall cross-section, which offers better water access and scenic advantages, has become increasingly widespread. Therefore, developing and researching a formula for calculating the wave volume per unit width applicable to the double-straight-wall seawall cross-section is of great significance. This will not only fill gaps in existing standards and enable more rational structural design of double-straight-wall seawalls, but also serve the planning and construction of coastal engineering projects in my country. Summary of the Invention

[0005] The purpose of this invention is to provide a method for calculating the wave overtopping per unit width of a double-straight-wall seawall, in order to solve the problem of the lack of a systematic evaluation and calculation method for the wave overtopping per unit width of a double-straight-wall seawall.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The method for calculating the wave overtopping per unit width of a double-straight-wall seawall as described in this invention includes the following steps: S1, Determine the effective wave height H of the wave. m0 Spectral peak period T p and the super-high H of the embankment top c Platform width B, water depth on the platform d w Platform surface roughness n, platform surface roughness height K s Wind speed V; S2, calculate parameters f1, f2, f3, f4, and f5 according to formulas (1), (2), (3), (4), and (5); Formula (1) Formula (2) Formula (3) Formula (4) Formula (5) Where L0 is the deep-water wavelength, K s The surface roughness height of the platform is calculated according to formula (6); Formula (6) S3, calculate the wave overpass amount q1 before correction according to formula (7); Formula (7) S4, refer to Table 1 to obtain the correction factor f for wind speed V. v ; Table 1. Wind Speed ​​Correction Factor Comparison Table S5, according to formula (8), the corrected single-width wave overtopping amount q2 is obtained; Formula (8).

[0007] Furthermore, the modified wave overtopping capacity q2 is used to assess whether the double straight-wall seawall meets the code requirements and to guide the optimization of the structural design parameters of the double straight-wall seawall.

[0008] Furthermore, in step S4, when the wind speed V is between two wind speed values ​​in Table 1, the wind speed correction factor is obtained using linear interpolation.

[0009] The advantage of this invention lies in proposing a method for calculating the wave overtopping volume per unit width of a double-straight-wall seawall applicable to irregular wave action. This method not only facilitates the wave overtopping design of double-straight-wall seawalls but also optimizes the cross-sectional dimensions and crest elevation of the seawall. Under the premise of meeting safety requirements, it effectively solves the problem of excessively large cross-sectional dimensions and crest elevation caused by the application of the wave overtopping volume per unit width formula in existing regulations and standards to double-straight-wall seawalls. This invention has good economic benefits and high value for widespread application. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of a double-straight-wall seawall.

[0011] Figure 2 The dimensionless factor H in the method described in this invention m0 / H c Relationship between wave volume per unit width and wave volume of double straight-wall seawall.

[0012] Figure 3 The dimensionless factor H in the method described in this invention m0 Relationship between / L0 and wave overtopping per unit width of double straight-wall seawall.

[0013] Figure 4 This is a graph showing the relationship between the dimensionless factor B / L0 of the method described in this invention and the wave overtopping per unit width of a double-straight-wall seawall.

[0014] Figure 5 The dimensionless factor d in the method described in this invention w / H m0 Relationship between wave volume per unit width and wave volume of double straight-wall seawall.

[0015] Figure 6 The dimensionless factor K in the method described in this invention s / H m0 Relationship between wave volume per unit width and wave volume of double straight-wall seawall. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figure 1 This is a schematic diagram of a double-straight-wall seawall, where number 1 represents the back slope of the double-straight-wall seawall; number 2 represents the upper straight wall; number 3 represents the lower straight wall; and number 4 represents the platform, where B is the platform width; d w The platform water depth is the difference between the still water level and the platform elevation. When the still water level is lower than the platform elevation, the platform water depth is d.w A negative value indicates the platform water depth d when the still water level is higher than the platform elevation. w H is a positive value. c The superelevation of the levee crest is the difference between the levee crest elevation 4 and the still water level.

[0018] Example 1: Detailed Explanation of the Method for Calculating the Wave Volume per Unit Width of the Double Straight-Wall Seawall of the Present Invention The inventors of this application collected dozens of sets of wave overtopping data per unit width for double-straight-wall seawalls, simulated and calculated them using a numerical model, and then performed correlation analysis on the calculation results. This yielded five dimensionless factors significantly correlated with the wave overtopping per unit width of double-straight-wall seawalls, namely H... m0 / H c H m0 / L0、B / L0、d w / H m0 K s / H m0 The inventors of this application have identified the relationship between five dimensionless factors and the wave overtopping capacity per unit width of double-straight-wall seawalls through dozens of sets of wave overtopping data per unit width.

[0019] like Figure 2 The figure shows the dimensionless factor H. m0 / H c A graph showing the relationship between wave volume per unit width and the wave volume of a double-straight-wall seawall. The horizontal axis in the graph is H. m0 / H c The vertical axis represents the wave height per unit width. From the graph, we can see that H... m0 / H c It has an exponential relationship with the wave volume per unit width of a double straight-wall seawall.

[0020] like Figure 3 The figure shows the dimensionless factor H. m0 The graph shows the relationship between / L0 and the wave overtopping per unit width of a double-straight-wall seawall. The horizontal axis in the graph is H. m0 / L0 value, the vertical axis represents the wave overtopping value per unit width. From the graph, we can see H m0 / L0 has a polynomial relationship with the wave overtopping per unit width of the double straight-wall seawall.

[0021] like Figure 4 The figure shows the relationship between the dimensionless factor B / L0 and the wave overtopping per unit width of a double-straight-wall seawall. The horizontal axis represents the B / L0 value, and the vertical axis represents the wave overtopping per unit width. The figure shows a polynomial relationship between B / L0 and the wave overtopping per unit width of the double-straight-wall seawall.

[0022] like Figure 5 The figure shows the dimensionless factor d. w / H m0 A graph showing the relationship between wave volume per unit width and the wave volume of a double-straight-wall seawall. The horizontal axis in the graph is d. w / H m0 The vertical axis represents the wave height per unit width. From the graph, we can see that d... w / H m0 The wave overtopping per unit width of the double straight-wall seawall exhibits a polynomial relationship.

[0023] like Figure 6 The figure shows the dimensionless factor K. s / H m0 A graph showing the relationship between wave volume per unit width and the wave volume of a double-straight-wall seawall. The horizontal axis in the graph is K. s / H m0 The vertical axis represents the wave height per unit width. From the graph, we can see that K... s / H m0 It has an exponential relationship with the wave volume per unit width of a double straight-wall seawall.

[0024] When calculating the wave overtopping per unit width of a double-straight-wall seawall, the influence or contribution of these five dimensionless factors on the wave overtopping per unit width of the double-straight-wall seawall should be considered comprehensively. Therefore, based on the relationship between each dimensionless factor and the wave overtopping per unit width of the double-straight-wall seawall, the applicant of this invention has established a multiple regression analysis equation for the wave overtopping per unit width and the five dimensionless factors, namely, formula (9). Formula (9) Linear regression analysis yielded the following values ​​for parameters A, B, C, D, E, F, G, H, I, J, K, L, and M: 0.21602, 4.29117, 0.61373, -0.59665, 0.3071, -0.95139, 1.49957, 0.15492, 0.03231, 0.12727, 0.03375, 0.21602, and -0.79084, respectively. The correlation coefficient of the linear regression analysis reached 0.97, indicating a good fit. Based on these results, the applicant of this invention established a method for calculating the wave overtopping volume per unit width of the double-straight-wall seawall, specifically including the following steps: S1, Determine the effective wave height H of the wave. m0 Spectral peak period T p and the super-high H of the embankment top c Platform width B, water depth on the platform d w Platform surface roughness n, platform surface roughness height K s Wind speed V; where, levee crest elevation H c The height exceeding the still water level. The water depth d on the platform. w The value is positive when the still water level exceeds the platform elevation, and negative when it falls below the platform elevation.

[0025] S2, calculate parameters f1, f2, f3, f4, and f5 according to formulas (1), (2), (3), (4), and (5); Formula (1) Formula (2) Formula (3) Formula (4) Formula (5) Where L0 is the deep-water wavelength, which can be obtained according to the calculation formula for deep-water wavelength. The specific calculation formula is formula (10).

[0026] Formula (10) K s The surface roughness height of the platform is calculated according to formula (6); Formula (6) Formula (6) is derived from Manning's formula, which transforms the surface roughness n of the platform into the surface roughness height K of the platform. s .

[0027] Formulas (1) to (5) are regression equations of the five dimensionless factors constructed on the right side of the equation in formula (9) and the wave overtopping volume per unit width of the double-straight-wall seawall. Substituting the values ​​of parameters A, B, C, D, E, F, G, H, I, J, K, L, and M obtained after linear regression analysis into the regression equations, we can obtain the expressions for formulas (1) to (5).

[0028] S3, calculate the wave overpass amount q1 before correction according to formula (7); Formula (7) S4, refer to Table 1 to obtain the correction factor f for wind speed V. v ; Table 1. Wind Speed ​​Correction Factor Comparison Table If the wind speed V is between two wind speed values ​​in Table 1, the wind speed correction factor f is obtained using linear interpolation. v .

[0029] S5, according to formula (8), the corrected single-width wave overtopping amount q2 is obtained; Formula (8).

[0030] The modified wave overtopping q2 is used to assess whether the double straight-wall seawall meets the code requirements and to guide the optimization of the structural design parameters of the double straight-wall seawall.

[0031] Generally, the calculated corrected unit width overtopping value of a double-straight-wall seawall should not exceed the allowable unit width overtopping value for the corresponding level of seawall specified in the "Code for Design of Seawall Engineering". If the calculated corrected unit width overtopping value of a double-straight-wall seawall exceeds the allowable unit width overtopping value for the corresponding level of seawall specified in the "Code for Design of Seawall Engineering", the structural parameters of the double-straight-wall seawall need to be modified and optimized, such as lengthening the intermediate platform, increasing the platform roughness, and raising the seawall crest elevation. After optimization, the corrected unit width overtopping value of the double-straight-wall seawall can be recalculated until it does not exceed the allowable unit width overtopping value for the corresponding level of seawall specified in the "Code for Design of Seawall Engineering". This effectively solves the problem of excessively large cross-sectional dimensions and seawall crest elevation caused by the application of the unit width overtopping formula in existing regulations and standards to double-straight-wall seawalls, while meeting safety requirements. It has good economic benefits and high value for promotion and application.

[0032] Example 2 illustrates the application process of the method for calculating the wave volume per unit width of a double-straight-wall seawall described in this application. Given that the top of a double-walled seawall is a concrete road surface, and the road surface behind the seawall is a secondary road surface, according to Table 6.6.1 of the "Code for Design of Seawall Engineering", the allowable wave overtoll per unit width is 0.02 (m). 3 / (sm))Control. Observations show that the effective wave height H of the irregular waves at this double-straight-wall seawall is... m0 =1.9m, spectral peak period T p =13s, wind speed V=10m / s; the design of this double straight-wall seawall includes a superelevation H at the top of the seawall. c =2.36m, platform width B=15m, water depth on platform d w =0.34m, platform surface roughness n=0.0235. The wave overtopping per unit width of the double straight-wall seawall described in this application is used to evaluate whether the design plan of the double straight-wall seawall meets the specification requirements.

[0033] First, calculate the parameters L0 and K. s .

[0034] According to formula (10) ; According to formula (6) ; Then calculate the five dimensionless factors, H. m0 / H c =0.805, H m0 / L0=0.007, B / L0=0.057, d w / H m0 =0.179, K s / Hm0 =0.026.

[0035] Substituting the above values ​​into formulas (1) to (5) respectively, we can obtain the values ​​of parameters f1, f2, f3, f4, and f5.

[0036] Substitute the values ​​of f1, f2, f3, f4, and f5 into formula (7). Thus, the wave overtopping amount per unit width before correction can be obtained as q1 = 0.0144 ((m3 / s) / m).

[0037] At this time, the wind speed V = 10 m / s. Referring to Table 1, the wind speed correction factor f is... v =0.97, substituting the value into formula (8) yields, Therefore, the proposed seawall dimensions meet the requirements of the regulations.

Claims

1. A method for calculating the wave volume per unit width of a double-straight-wall seawall, characterized in that: Including the following step: S1, Determine the effective wave height H of the wave. m0 Spectral peak period T p and the super-high H of the embankment top c Platform width B, water depth on the platform d w Platform surface roughness n, platform surface roughness height K s Wind speed V; S2, calculate parameters f1, f2, f3, f4, and f5 according to formulas (1), (2), (3), (4), and (5); Official (1) Official (2) Formula (3) Formula (4) Official (5) Where L0 is the deep-water wavelength, which is calculated according to formula (6); Official (6) S3, calculate the wave overpass amount q1 before correction according to formula (7); Official (7) S4, refer to Table 1 to obtain the correction factor f for wind speed V. v ; Table 1. Wind Speed ​​Correction Factor Comparison Table S5, according to formula (8), the corrected single-width wave overtopping amount q2 is obtained; Official (8).

2. The method for calculating the wave overtopping per unit width of a double-straight-wall seawall according to claim 1, characterized in that: The modified wave overtopping q2 is used to assess whether the double straight-wall seawall meets the code requirements and to guide the optimization of the structural design parameters of the double straight-wall seawall.

3. The method for calculating the wave volume per unit width of a double-straight-wall seawall according to claim 1, characterized in that: In step S4, when the wind speed V is between two wind speed values ​​in Table 1, the wind speed correction factor is obtained by linear interpolation.

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