【摘要】：南海北部外陸架地質(zhì)構(gòu)造、地貌類型和海底水動(dòng)力條件均比較復(fù)雜，發(fā)育有大量海底沙波地貌，，是威脅海底工程設(shè)施安全的重要因素之一。多數(shù)情況下，沙波是一種具有活動(dòng)性的海底地貌，在潮流、暴風(fēng)浪流或內(nèi)波等的作用下會(huì)產(chǎn)生快速遷移，沙波的遷移可能造成海底管道的懸空或掩埋，嚴(yán)重的可能會(huì)造成海底輸油管道的斷裂、鉆井平臺(tái)的傾斜垮塌、航道淤積、海底光纜的斷裂等重大危害。雖然前人曾在該區(qū)域?qū)５咨巢ㄗ鲞^一些工作，但仍有許多科學(xué)問題有待深入研究。 本文在南海北部海底沙波已有研究的基礎(chǔ)上，選取重點(diǎn)研究區(qū)對海底沙波的演化特征進(jìn)行運(yùn)算分析�？偨Y(jié)分析了研究區(qū)表層沉積物以及沙波的特征；利用ROMS模型模擬了研究區(qū)2010年至2011年的底部流場數(shù)據(jù)；計(jì)算了研究區(qū)特定站位的泥沙起動(dòng)流速；利用Rubin公式和筱原-椿東一郎公式模擬計(jì)算了沙波的遷移規(guī)律，并與搜集所得資料進(jìn)行對比分析；結(jié)合臺(tái)風(fēng)資料以及底流數(shù)據(jù)，分析臺(tái)風(fēng)對海底沙波運(yùn)移的影響。獲得的主要認(rèn)識如下： 南海北部沙波區(qū)Ⅰ和Ⅱ的表層沉積物可分為砂質(zhì)礫、礫質(zhì)砂、礫質(zhì)泥質(zhì)砂、含礫砂共4種類型，該區(qū)域表層沉積物中值粒徑在0.233-2.234mm之間，均值為1.414mm；發(fā)育有脊線走向?yàn)镹E-SW的直線型沙波，陡坡傾向主要為NW和SE，波高0.5m以下的沙波分布廣泛，最大為5.67m。研究區(qū)沙波在2010年至2011年間有向南向東方向移動(dòng)的趨勢。 結(jié)合底流資料，使用Rubin公式對研究區(qū)內(nèi)海底沙波運(yùn)移方向的計(jì)算結(jié)果和搜集所得資料比較吻合，均為向東向南方向；不同站點(diǎn)的遷移距離在0-21.8m之間。應(yīng)用筱原-椿東一郎公式對某站位運(yùn)移距離的數(shù)值計(jì)算結(jié)果為0.25m，計(jì)算結(jié)果較Rubin公式的1.9m明顯偏小。 “凡亞比”超強(qiáng)臺(tái)風(fēng)顯著增強(qiáng)了研究區(qū)內(nèi)的底流流速，增幅可達(dá)25-35cm/s。研究區(qū)內(nèi)兩個(gè)點(diǎn)位在“凡亞比”臺(tái)風(fēng)影響期間的遷移距離計(jì)算結(jié)果為2.0m、2.9m，分別占其年運(yùn)移量的9.17%和26.36%，說明臺(tái)風(fēng)過境對海底沙波產(chǎn)生重大的影響。
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圖片說明：水下沙波形成機(jī)理示意圖
[Abstract]:The geological structure, geomorphological types and hydrodynamic conditions of the outer shelf in the northern South China Sea are complex, and a large number of seafloor sand wave landforms are developed, which is one of the important factors threatening the safety of seafloor engineering facilities. In most cases, sand wave is a kind of active seafloor geomorphology, which will migrate rapidly under the action of tidal current, storm wave current or internal wave. The migration of sand wave may cause the suspension or burying of submarine pipeline, which may cause the fracture of submarine oil pipeline, the tilt collapse of drilling platform, the siltation of waterway, the fracture of submarine optical cable and so on. Although some work has been done on seafloor sand waves in this area, there are still many scientific problems to be studied in depth. Based on the existing research of seafloor sand waves in the northern South China Sea, this paper selects the key study areas to analyze the evolution characteristics of seafloor sand waves. The characteristics of surface sediments and sand waves in the study area are summarized and analyzed, the bottom flow field data of the study area from 2010 to 2011 are simulated by ROMS model, the sediment starting velocity at specific stations in the study area is calculated, and the migration law of sand waves is simulated and calculated by using Rubin formula and Xiaoyuan-Chundong Ichiro formula, and the results are compared with the collected data. Based on typhoon data and bottom current data, the influence of typhoon on seafloor sand wave migration is analyzed. The main understandings obtained are as follows: the surface sediments of sand wave area 鈪

本文編號：2509963