【摘要】：畸形波是海洋中一類(lèi)特殊的災(zāi)害性波浪,隨著人類(lèi)海上活動(dòng)的增加,畸形波對(duì)船舶以及海洋平臺(tái)等結(jié)構(gòu)物的破壞越來(lái)越多,逐漸引起了人們的重視,但由于畸形波本身的復(fù)雜性,并且真正完整的觀測(cè)記錄也相對(duì)較少,至今畸形波的生成機(jī)理和基本特性等,尤其是關(guān)于畸形波的發(fā)生概率仍然不是十分明確,雖然很多學(xué)者也進(jìn)行了大量的研究,并取得了相應(yīng)的成果,但大部分都是基于二維波浪,而實(shí)際的海浪是三維的,不僅有不同頻率的組成波,還有不同方向的組成波。因此,本文對(duì)多向不規(guī)則隨機(jī)波列中畸形波的發(fā)生概率及影響因素等開(kāi)展了研究。 本文考慮了不同方向分布和相對(duì)水深的影響,對(duì)多向不規(guī)則波列進(jìn)行了長(zhǎng)時(shí)間的物理模擬。對(duì)多向不規(guī)則波列的統(tǒng)計(jì)參數(shù)(如有效波高、偏度、峰度和頻譜)以及波高、波峰和波谷的概率分布進(jìn)行了分析,并研究了波陡、方向分布和相對(duì)水深等參數(shù)對(duì)波列統(tǒng)計(jì)參數(shù)和概率分布的影響。研究結(jié)果表明：1.波浪的方向分布和相對(duì)水深對(duì)波列的統(tǒng)計(jì)參數(shù)有明顯的影響,當(dāng)相對(duì)水深較大,方向分布較窄時(shí),由于波浪的非線性不穩(wěn)定性,峰度值隨著波浪的傳播,有逐漸增大的趨勢(shì),波列的頻譜出現(xiàn)主頻下移,高頻能量減小等現(xiàn)象；當(dāng)相對(duì)水深較淺時(shí),波浪的不穩(wěn)定性受到抑制,峰度值隨波浪的傳播變化不大,頻譜的主頻甚至出現(xiàn)上移。2.波浪的方向分布和水深也會(huì)影響到波高、波峰和波谷的概率分布,當(dāng)相對(duì)水深較大,方向分布較窄時(shí),由于波浪的非線性不穩(wěn)定性,波高、波峰和波谷的概率分布末端越增大,并隨著波浪的傳播而明顯增大；對(duì)于淺水情況,不穩(wěn)定性受到抑制,二階非線性起到主要作用,方向分布的變化對(duì)波高、波峰和波谷的概率分布影響不如深水時(shí)明顯。3.從不同的方向分布生成的畸形波的實(shí)驗(yàn)過(guò)程中可以看出,當(dāng)波浪越趨于單向的時(shí)候,則畸形波的生成更多的是基于波浪自身的不穩(wěn)定性自聚焦而成,而當(dāng)波浪的方向分布較大,特別是趨于均勻分布的時(shí)候,畸形波的生成則更多的是基于波浪之間的匯聚而成。 本文通過(guò)對(duì)多向不規(guī)則波列中統(tǒng)計(jì)參數(shù)和概率分布的分析,可以得出,當(dāng)相對(duì)水深較深,方向分布較窄時(shí),由于波浪的不穩(wěn)定性,大波高的出現(xiàn)概率增大,因此,畸形波更容易出現(xiàn)在這種海況下,海上結(jié)構(gòu)物設(shè)計(jì)時(shí),應(yīng)充分考慮到海況對(duì)波高分布的影響。
[Abstract]:Deformed waves are a special kind of disastrous waves in the ocean. With the increase of human activities at sea, the damage of deformities to ships and structures such as offshore platforms is becoming more and more serious, and people pay more and more attention to them. However, due to the complexity of the deformity wave itself and the relatively few truly complete observation records, so far the formation mechanism and basic characteristics of the deformity wave, especially about the occurrence probability of the deformed wave, are still not very clear. Although many scholars have done a lot of research and obtained corresponding results, most of them are based on two-dimensional waves, but the actual waves are three-dimensional, not only have different frequencies of the component waves, but also in different directions. Therefore, in this paper, the occurrence probability and influencing factors of abnormal waves in multidirectional irregular random wave trains are studied. In this paper, the effects of different direction distribution and relative water depth are considered, and a long time physical simulation of multidirectional irregular wave train is carried out. The statistical parameters (such as effective wave height, deviation, kurtosis and spectrum) and the probability distribution of wave height, peak and trough of multidirectional irregular wave train are analyzed, and the wave steepness is studied. The influence of direction distribution and relative water depth on the statistical parameters and probability distribution of wave train. The results of the study show that 1: 1. The directional distribution of wave and the relative water depth have obvious influence on the statistical parameters of wave train. When the relative water depth is larger and the direction distribution is narrower, because of the nonlinear instability of the wave, the kurtosis value increases gradually with the wave propagation. When the relative water depth is shallow, the wave instability is restrained, the kurtosis value changes little with the wave propagation, and the main frequency of the frequency spectrum even moves up. 2. The directional distribution and water depth of wave also affect the probability distribution of wave height, wave peak and trough. When the relative water depth is larger and the direction distribution is narrower, the higher the wave height, the more the probability distribution end of wave peak and trough is due to the nonlinear instability of wave. For shallow water, the instability is restrained, the second order nonlinearity plays a major role, and the variation of directional distribution has less effect on the wave height, the probability distribution of wave peaks and troughs than that of deep water. It can be seen from the experimental process that the abnormal waves generated in different directions tend to be generated on the basis of the instability of the wave itself when the wave tends to be unidirectional, but when the direction distribution of the wave is larger, the formation of the deformable wave is mainly based on the instability of the wave itself. Especially when it tends to uniform distribution, the formation of abnormal waves is more based on the convergence of waves. Through the analysis of the statistical parameters and probability distribution in multidirectional irregular wave trains, it can be concluded that when the relative water depth is deeper and the direction distribution is narrower, the occurrence probability of large wave height increases due to wave instability. Deformed waves are more likely to occur in such sea conditions, and the influence of sea conditions on wave height distribution should be fully taken into account in the design of offshore structures.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：P731.2

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