本文選題：海洋環(huán)境 + 沖刷防護��； 參考：《清華大學》2014年博士論文

【摘要】：海洋結構物基礎周圍會在波浪以及海流的作用下會發(fā)生沖刷現(xiàn)象,過深的沖刷坑會使其承載力下降,從而對結構安全造成威脅。臺風災害到來時,在臺風引發(fā)的洪水以及風暴潮的雙重威脅下,結構基礎面臨的安全挑戰(zhàn)更為嚴峻。為此,一方面需要有合適的基礎沖刷預警模型對日常和極端天氣條件下的水動力過程和沖刷過程進行準確可靠的預報,使得可以及時采取防護加固、撤離物資、限制交通等措施減小損失;另一方面需要應對海洋環(huán)境中波流共存的特點,選擇適合海洋環(huán)境的基礎沖刷防護措施,有效削減結構物基礎的沖刷量,保證結構的安全性。本文結合天氣預報模型、風暴潮水動力學模型以及結構基礎局部沖刷模型,首次建立了海洋結構基礎沖刷的預警數(shù)值模型。分析了不同分辨率氣象數(shù)據(jù)對風暴潮模擬的影響。該預警模型所模擬的多場臺風路徑、強度和降水均有較好的精度;兩場臺風作用下預報的潮位變化、增水分布都具有較好精度,模型1-2天的潮位預報誤差在0.2m左右。然后把驗證過的預警模型應用于嘉紹大橋工程中,所預報的潮位、潮流均有較高精度,預報的最大橋墩沖刷深度亦與實測值接近。利用此預警模型可以預報海上結構基礎在未來幾天的最大可能沖刷深度,提前預知風險,及時采取防護措施。為緩解海洋環(huán)境中沖刷對結構的不利效應,本文采用物理模型試驗方法,在波流水槽中研究了在恒定流以及波流聯(lián)合作用下不同沖刷防護措施保護下樁柱周圍基礎沖刷的變化規(guī)律和防護效果。研究的沖刷防護措施包括拋石防護、水平隔板、擴展基礎、減沖樁、攔沙坎、套筒、四面體框架群、柱身開槽、拋石防護與四面體框架群的組合措施共9種。其中對攔沙坎、套筒、四面體框架群、柱身開槽、組合措施等防護措施在波流環(huán)境中的沖刷防護效果研究尚屬首次。各種防護措施均能削減沖刷深度,但效能相差很大。多種防護措施在波流環(huán)境中會導致較恒定流環(huán)境中更深的沖刷坑,其行為與單獨圓柱在不同水流環(huán)境中的沖刷深度變化情況有顯著的區(qū)別。防護措施在波流聯(lián)合作用的環(huán)境下表現(xiàn)出許多新特點,波浪的參與對沖刷深度、沖刷削減能力、達到?jīng)_刷平衡所需時間均有明顯的影響。提出的組合措施融合了四面體框架群和拋石防護措施的優(yōu)點,對海洋環(huán)境有較強的適應性。
[Abstract]:The scour around the foundation of ocean structures will occur under the action of waves and currents, and a deep scour pit will reduce its bearing capacity, which will threaten the safety of the structure. When the typhoon disaster comes, the security challenge of the structure foundation is more severe under the double threat of the flood caused by the typhoon and the storm surge. Therefore, on the one hand, it is necessary to have an appropriate scour warning model for accurate and reliable prediction of hydrodynamic processes and scour processes under daily and extreme weather conditions, so that timely protection and reinforcement can be taken, and materials can be evacuated. On the other hand, it is necessary to deal with the characteristics of the coexistence of waves and currents in the marine environment, to select the appropriate basic scour protection measures, to effectively reduce the scour amount of the structure foundation, and to ensure the safety of the structure. Combined with weather forecast model, storm tide dynamics model and local scour model of structural foundation, the early warning numerical model of ocean structure foundation scour is established for the first time in this paper. The influence of different resolution meteorological data on storm surge simulation is analyzed. Both the intensity and precipitation of typhoon track simulated by the model have good accuracy, and the tidal level variation and water increase distribution predicted under the action of two typhoons have good accuracy, and the prediction error of tidal level in 1-2 days of the model is about 0.2 m. Then, the verified early warning model is applied to Jiashao Bridge project. The predicted tidal level and tidal current have higher accuracy, and the predicted maximum pier scour depth is close to the measured value. By using this early warning model, the maximum possible erosion depth of offshore structural foundation in the next few days can be predicted, the risk can be predicted in advance, and protective measures can be taken in time. In order to mitigate the adverse effects of scour on structures in marine environment, the physical model test method is used in this paper. The variation law and protective effect of foundation scour around pile column under the protection of different scour protection measures under the action of constant current and combined wave and current are studied in the wave-current flume. The scour protection measures studied include: riprap protection, horizontal partition, extended foundation, anti-impact pile, sand bar, sleeve, tetrahedral frame group, slotted column body, and combined measures of riprap protection and tetrahedron frame group. It is the first time to study the scour protection effect of sand bar, sleeve, tetrahedron frame group, column slotted and combined measures in wave and current environment. All kinds of protective measures can reduce the scour depth, but the efficiency is very different. A variety of protective measures can lead to deeper scour pits in the wave-current environment than in the constant flow environment, and their behavior is significantly different from the variation of the scour depth of a single cylinder in different flow environments. The protective measures show many new characteristics under the combined action of wave and current. The participation of wave has obvious influence on the depth of scour, the ability of erosion reduction and the time required to achieve the balance of scour. The proposed combined measures combine the advantages of the tetrahedron frame group and the riprap protection measures, and have a strong adaptability to the marine environment.
【學位授予單位】：清華大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：U447;U442.32

【參考文獻】

相關碩士學位論文 前1條

1 郭洪琳;甌江口風暴潮漫灘數(shù)值預報研究[D];國家海洋環(huán)境預報研究中心;2011年

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本文編號：1921662