本文關(guān)鍵詞：自升式平臺(tái)圓柱樁腿局部沖刷的數(shù)值模擬研究　出處：《西南石油大學(xué)》2015年碩士論文　論文類(lèi)型：學(xué)位論文

  更多相關(guān)文章： 自升式平臺(tái) 局部沖刷 波流聯(lián)合作用 孔隙結(jié)構(gòu)消波 數(shù)值模擬

【摘要】：隨著我國(guó)快速發(fā)展對(duì)油氣能源的需求逐漸增大,陸上油氣資源隨著長(zhǎng)期開(kāi)采日漸匱乏,油氣資源開(kāi)采逐漸向海洋傾斜,目前對(duì)海洋油氣資源開(kāi)采主要集中在近海,而自升式海洋平臺(tái)是近海油氣開(kāi)采的重要工具。處于海洋水流環(huán)境中的自升式海洋平臺(tái)圓柱型樁腿周?chē)ǔ６紩?huì)產(chǎn)生局部沖刷,當(dāng)沖刷嚴(yán)重時(shí)更會(huì)影響平臺(tái)樁基的穩(wěn)定性,導(dǎo)致平臺(tái)事故的發(fā)生。 目前國(guó)內(nèi)外學(xué)者對(duì)于此類(lèi)問(wèn)題的研究主要集中在橋梁圓柱橋墩的局部沖刷和比例模型實(shí)驗(yàn),而針對(duì)實(shí)際尺寸的海洋平臺(tái)圓柱樁腿在不同水流條件下的局部沖刷的研究較少。為此,本文構(gòu)建了單向水流條件下的局部沖刷模型、波浪模型、波流模型及其沖刷模型等一系列數(shù)值模型,采用國(guó)內(nèi)外具有一定較高水平和知名度的模型實(shí)驗(yàn)結(jié)果進(jìn)行對(duì)比驗(yàn)證數(shù)值模型的合理性和準(zhǔn)確性,并模擬分析不同影響因子對(duì)實(shí)際尺寸平臺(tái)樁腿局部沖刷的影響規(guī)律、局部沖刷的形成過(guò)程、局部沖刷的作用機(jī)理和沖刷坑的形態(tài),獲得的研究成果能對(duì)海洋平臺(tái)圓柱樁腿局部沖刷的防護(hù)措施、結(jié)構(gòu)優(yōu)化和安全評(píng)估提供重要參考。 本文完成的研究工作主要分為以下幾個(gè)部分： (1)文獻(xiàn)調(diào)研與分析。對(duì)單向水流條件下局部沖刷的作用機(jī)理和前人的研究成果進(jìn)行調(diào)研和綜述,并對(duì)目前研究較多的橋梁局部沖刷進(jìn)行概述,討論了前人對(duì)不同條件下的圓柱局部沖刷的研究成果；對(duì)運(yùn)動(dòng)中的泥沙分類(lèi)、受力和波流聯(lián)合條件下的泥沙運(yùn)動(dòng)特征進(jìn)行了概述。 (2)概述模擬中使用的數(shù)學(xué)模型和數(shù)值計(jì)算方法。對(duì)研究中用到的模擬軟件、控制方程和泥沙運(yùn)輸模型等數(shù)學(xué)模型進(jìn)行概述,使用Roulund的實(shí)驗(yàn)結(jié)果與模擬結(jié)果進(jìn)行對(duì)比,對(duì)兩種湍流模型進(jìn)行優(yōu)選。 (3)單向水流條件下局部沖刷模型的構(gòu)建及驗(yàn)證。構(gòu)建了單向水流條件下的圓柱局部沖刷模型,將圓柱周?chē)鲌?chǎng)特征及局部沖刷的模擬結(jié)果與Melville的實(shí)驗(yàn)結(jié)果進(jìn)行對(duì)比,驗(yàn)證泥沙運(yùn)輸模型的可靠性。 (4)波浪模型的構(gòu)建以及孔隙結(jié)構(gòu)消波研究。構(gòu)建了一系列三維波浪模型,對(duì)模型中孔隙結(jié)構(gòu)的消波效果進(jìn)行研究,對(duì)孔隙結(jié)構(gòu)消波效果影響較大的孔隙率、材料粒徑和結(jié)構(gòu)斜坡坡度進(jìn)行分析研究,獲得最優(yōu)的孔隙結(jié)構(gòu)消波參數(shù)組合。 (5)波流聯(lián)合模型及其局部沖刷模型的構(gòu)建及驗(yàn)證。先后構(gòu)建了波流聯(lián)合作用模型及其沖刷模型,針對(duì)波流聯(lián)合模型的流體體積不守恒問(wèn)題,設(shè)置出口邊界為壓力出流邊界；選用Van Rijn的實(shí)驗(yàn)結(jié)果對(duì)比驗(yàn)證模型垂直水流流速的合理性；對(duì)波流聯(lián)合條件下的圓柱局部沖刷進(jìn)行模擬,并與Qi的實(shí)驗(yàn)結(jié)果進(jìn)行對(duì)比驗(yàn)證,驗(yàn)證數(shù)值模型在波流條件下局部沖刷模擬結(jié)果的可靠性。 (6)研究不同條件下海洋平臺(tái)圓柱樁腿局部沖刷的變化規(guī)律。調(diào)研勝利作業(yè)三號(hào)平臺(tái)的事故,分析事故原因,指出平臺(tái)樁腿局部沖刷與事故發(fā)生的聯(lián)系；對(duì)樁腿局部沖刷影響較大因子如：流速、水深、樁腿直徑和波流作用下不同波高進(jìn)行模擬分析,研究影響因子變化對(duì)樁腿局部沖刷的影響及其作用機(jī)理。 總之,本文結(jié)合自升式平臺(tái)圓柱樁腿局部沖刷的研究現(xiàn)狀,運(yùn)用計(jì)算流體力學(xué)、泥沙運(yùn)動(dòng)力學(xué)、波浪理論等學(xué)科知識(shí)構(gòu)建了一系列數(shù)值模型進(jìn)行模擬研究,實(shí)現(xiàn)了樁腿的局部沖刷的模擬,并獲得了不同環(huán)境條件下的局部沖刷變化規(guī)律。研究成果能夠?yàn)樽陨胶Ｑ笃脚_(tái)的安全評(píng)估、防護(hù)措施和結(jié)構(gòu)優(yōu)化提供重要參考,具有較高的理論意義和工程實(shí)用價(jià)值。
[Abstract]:With the rapid development of our country , the demand of oil and gas energy gradually increases , and the oil and gas resources are gradually inclined to the sea as the long - term exploitation becomes scarce . At present , the exploitation of offshore oil and gas resources is mainly concentrated in the offshore , and the self - elevating offshore platform is an important tool for offshore oil and gas exploitation . In this paper , a series of numerical models , such as local scour model , wave model , wave - flow model and scour model , are studied in this paper . The work done in this paper is mainly divided into the following parts : ( 1 ) Literature investigation and analysis . The mechanism of local scour under the condition of one - way water flow and the research results of the former are summarized , and the results of local scour of the cylinder under different conditions are discussed . ( 2 ) The mathematical model and numerical calculation method used in the simulation are summarized . The mathematical models of simulation software , control equation and sediment transport model used in the study are summarized , and the experimental results of Roulund are compared with the simulation results , and the two turbulence models are preferred . ( 3 ) constructing and verifying the local scour model under the condition of one - way water flow , and constructing a cylindrical local scour model under the condition of one - way water flow , comparing the characteristics of the flow field around the cylinder and the simulated results of local scour with the experimental results of Melville , and verifying the reliability of the sediment transport model . ( 4 ) Construction of wave model and wave elimination research of pore structure . A series of three - dimensional wave model is constructed to study the wave - eliminating effect of pore structure in the model . ( 5 ) The combination model of wave current and its local scour model are constructed and verified . The joint action model of wave current and its scouring model are constructed . For the problem of non - conservation of fluid volume in the joint model of the wave flow , the outlet boundary is set as the pressure outlet boundary ; the experimental results of Van Rijn are used to compare the rationality of the vertical water flow velocity of the model , and compared with the experimental results of Qi , the reliability of the numerical model is verified under the condition of wave flow . ( 6 ) To study the regularity of local scour of the cylindrical pile legs of offshore platform under different conditions , and investigate the cause of accident , point out the connection between the local scour and accident of the platform pile legs , and analyze the influence factors on the local scour of the pile legs . In conclusion , this paper constructs a series of numerical models by means of computational fluid mechanics , mud - sand movement mechanics and wave theory to simulate the local scour of the self - elevating platform cylindrical pile leg , and realizes the local scour rule under different environmental conditions . The research results can provide important reference for the safety assessment , protection measures and structural optimization of the self - elevating offshore platform , and has higher theoretical significance and practical value .

【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TE951

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