摘要
海堤设计中,为了降低堤顶高程,以减小工程造价,通常按允许越浪量标准设计。但越浪会给堤后附近地区的车辆运输和人的活动的安全和效率带来很大的威胁和影响,并且在一定程度上影响着结构物自身的安全。因此,控制越浪量的大小是海堤、护岸工程设计中需要考虑的重要内容。过去的研究多数为单向波正向击堤的情况,对斜向不规则波特别是多向不规则波作用于直立堤的越浪量研究特别少。然而自然界中的波浪是多向不规则的,而且常斜向击堤,斜向波还可能发生大于正向波时的越浪量。为了使工程设计更为经济合理,填补直立堤越浪量在我国规范中的空白,深入研究斜向和多向不规则波作用于直立堤上的越浪量成为当务之急。本文在物理模型试验的基础上,系统研究了研究斜向和多向不规则波浪作用于直立堤上的越浪量。
本文物理模型试验在大连理工大学海岸与近海工程国家重点实验室的多功能水池进行。试验采用Goda建议的JONSWAP谱来模拟不规则波浪。方向分布函数采用光易型分布。波浪入射方向或主波向的范围为θ=0°~45°,方向分布宽度分别采用δ=0°,13°,25°,采用三种深水波陡和五个波高。
通过试验结果分析,讨论了堤顶高度、波浪方向、波浪多向性、堤前水深和波陡等因素对单位堤长平均越浪量和单波最大越浪量的影响。综合各因素的影响,应用最小二乘法进行曲线拟合,得到了斜向波和多向波作用于直立堤上的平均越浪量的计算公式、单波最大越浪量的计算公式、单波最大越浪量和平均越浪量的关系式、越波率计算公式以及单波越浪量的统计分布形式,并通过与按照我国规范中斜坡堤越浪量计算公式形式拟合得到的直立堤越浪量公式和俞聿修,魏德彬的试验结果、Franco C,Franco L试验结果的比较来验证本文所采用的分析方法的合理性、试验结果的可靠性,以便于理论研究和工程设计参考应用。
In the sea dike designs, usually base on admissible overtopping measure standard for reducing the crest free board and the price of the construction, but wave overtopping significantly affects its functional efficiency, the safety of transit and mooring on the rear side, wave transmission in the sheltered area, and to some extent, the structural safety itself. Therefore, The overtopping discharge is in fact the main parameter for the design of sea dike and retaining wall. A series of hydraulic model tests has been carried out in a wave basin with the aim of studying the effect of oblique wave perpendicular attack on the wave overtopping of vertical breakwater, little research work of oblique irregular waves, especially multidirectional irregular waves attack on the wave overtopping of vertical breakwater. However, real sea waves are multidirectional and irregular, and usually attack a breakwater obliquely. It has been found that oblique waves may standing waves, and under oblique and multidirectional waves attack exert larger overtopping,. For making engineering design more economic and reasonable, besides filling up to the content of vertical breakwater in our country criterion of blank, it is necessary of the overtopping study of oblique and multidirectional irregular wave action on vertical breakwater. In this paper, the overtopping discharge of obliquity and multi-directionality action on vertical breakwater is studied systemically by a 3-D hydraulic model test.The physical model test was carried out in the multidirectional basin at the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. The JONSWAP spectrum suggested by Goda was used to simulate irregular waves, and directional spreading function of Guangyi-type was used in the test. Angles of incidence varied from 0° to 45°, and three spreading extent, σ=0° , 13° , 25°, three kinds of wave steepnesses and five kinds of wave heights were tested.The effects of crest, angle, multi-directionality, depth and wave steepness on average overtopping discharge maximum overtopping per wave is presented. By use of the Ordinary Least Square Estimation (OLSE), the empirical formulate of average overtopping discharge and maximum overtopping per wave, the relation formulate of average overtopping and maximum overtopping per wave, the formulate of percentage of overtopping waves, percentage of overtopping probability distribution of overtopping per wave. The analytical method used in this paper is justified by comparing with country norm form formula results , the result of Franco et al and the result of Yuxiu Wei et al.
引文
[1] 中华人民共和国交通部.海港水文规范(JTJ213—98).北京:人民交通出版社.2000
[2] Takada A. On relations among wave run-up ,overtopping and reflection. Proc. JSCE, Vol. 182, 1970.
[3] Takada A. Wave overtopping quantities correlated to the surface elevation of finite amplitude clapotis. Proc. JSCE,Vol. 201, 1972.
[4] Goda Y. Expected rate of irregular wave overtopping of seawalls. Coastal Engineering. in Japan, 1971, 17:117-128.
[5] Owen M W. Design of seawalls allowing for wave overtopping. Hydraulics Research, Wallingford., HR Report EX 924 June 1980.
[6] Owen M W. Overtopping of sea defences international conf. on the hydraulic Modelling of civil Eng. Structures, 1982.
[7] Goda Y. Random seas and design of maritime structures. University of Tokyo Press, 1985.
[8] Juhl J, Sloth P. Wave overtopping of breakwaters under oblique waves. Proc. 24~(th) Int. Conf. On Coastal Eng. ASCE 1, Kobe, Japan, 1994:1182—1196.
[9] Moriya Y, Mizuguchi M. Wave overtopping rate and reflection coefficient for obliquely incident waves. Proc. 24th Int. Conf. On Coastal Eng. ASCE 1, Kobe, Japan, 1996: 2598-2610.
[10] Franco L, de Gerloni M, van der Meer J W. Wave overtopping on vertical and composite breakwaters. Proceedings 24~(th) Int. Conf Coastal Eng., ACSE, 1994.
[11] Franco C, Franco L, Restano C, Van der Meer J W. The effect of wave obliquity and short crestedness on the overtopping rate and volume distribution on caisson breakwaters. Final Proc., MASTII-MCS Proj., Paper r. 9, University of Hanover, Germany, 1995.
[12] Allsop N W H, Besley P, Madurini L. Overtopping performance of vertical and composite breakwaters, seawalls and low reflection alternatives, Final proc., MAST Ⅱ-MCSProj., Paper 4.6,1995 University of Hanover, Germany.
[13] De Waal J P, Tonjef P, Van Der Meer J W. Wave overtopping of vertical structures including wind effect, 1995.
[14] Napp N, Bruce T, Pearson J. Violent overtopping of vertical seawalls under oblique wave conditions. Proc. 29th. Int. Conf. Coastal Engineering, Lisbon 2004:4482-4493
[15] Mendez L, van der Meer J W, Hawkes P J. Effects of bi-moda waves on overtopping: application of UK and Dutch prediction methods, proc. 27th int. conf. on coastal eng. ASCE, 2000:2114-2129.
[16] 俞聿修.随机波浪及其工程应用(第三版).大连:大连理工大学出版社,2003.
[17] Franco C, Franco L. Overtopping formulas for caisson breakwaters with nonbreaking 3D waves. Journal of Waterway, Port, Coastal, and Ocean Engineering, 1999, Vol.125, No. 2.
[18] Napp N, Pearson J, Richardson S, Bruce T, Allsop W, Pullen T. Overtopping of Seawalls under Oblique and 3-D Wave Conditions. Coastal Engineering, 2000:2178-2190.
[19] Shore Protection Mannal. 1984.
[20] 俞聿修,魏德彬.不规则波越浪量的试验研究.海岸工程,1992,11(1):1-12.
[21] 中华人民共和国交通部,《波浪模型试验规程》.北京:人民交通出版社,2002.
[22] 柳淑学.多向不规则波有效试验区的扩展法.海洋工程,1995,13(4).
[23] Lin P, Li C W. A σ-coordinate three-dimensional numerical model for surface wave propagation. International Journal for Numerical Methods in Fluids, 2002,38:1045-1068
[24] Sekimoto T, Kunisu H, Yamagaki T. 1994. Short term wave overtopping rate of block armored seawall. Proc. 24~(th) Coastal Eng, Conf.,1568-1579