本文選題：長江河口　切入點：潮動力　出處：《華東師范大學》2015年碩士論文

【摘要】：近年來隨著水土保持工程、三峽工程和南水北調(diào)工程等長江流域大型工程的建設,將會使流域來水來沙及其季節(jié)分配發(fā)生明顯變化；而長江口大規(guī)模促淤圍墾、深水航道、南匯人半工島、大型水庫、跨江和跨海大橋等河口工程的興建又將改變河槽的邊界條件,從而使各漢道的分流比發(fā)生改變,進而會改變潮流流速的大小和方向、懸沙的時空分布、沉降及輸運,繼而導致河槽地貌發(fā)生變化,河槽地貌的改變又會影響潮動力和懸沙濃度的變化。而當潮動力、懸沙濃度及地貌發(fā)生變化后,將會對河槽邊界的穩(wěn)定性及河口大型工程的安全性產(chǎn)生較大影響,因而是一個直接涉及到河口工程、航道運輸以及沿岸人民生命財產(chǎn)的安全問題�；谝陨弦蛩�,本文在前人的研究基礎(chǔ)之上,以長江河口北港上段、北槽中上段,南匯南灘水域為研究對象,利用近年來在長江河口現(xiàn)場實測潮流、懸沙、地貌資料以及相關(guān)潮位站的潮位資料,研究近期長江河口河槽動力沉積地貌變化過程和水沙輸運機制,并探討動力沉積地貌變化過程對大型工程的響應機制。這將有助于深入了解近期河口河槽的動力沉積地貌過程,為合理開發(fā)利用河口和近海資源提供理論基礎(chǔ),并為河口工程維護、航道疏浚及河槽治理提供參考依據(jù)。因此,本文的研究具有重要的理論和實踐意義。主要研究結(jié)果如下：1.潮汐變化過程。近期研究區(qū)域內(nèi)潮汐性質(zhì)均為非正規(guī)半日淺海分潮,潮動力的非線性特征更加明顯；北港上段、北槽上段河槽淺水分潮性質(zhì)加強,北槽中段、南匯南灘水域淺水分潮性質(zhì)變化不明顯。2.潮流變化過程。北港上段河槽2003-2007年流速減小0.19-0.28 m/s,落潮優(yōu)勢洪季減弱、枯季增強；2007-2012年流速洪季增大、枯季減小,落潮優(yōu)勢洪季增強、枯季減弱。深水航道三期工程后,北槽中段河槽南側(cè)流速略減,落潮優(yōu)勢稍減弱。2003-2012年南匯南灘水域流速洪季增大、枯季減小,落潮優(yōu)勢洪季增強、枯季減弱。3.懸沙濃度變化過程。北港上段2003-2007年懸沙濃度約減少0.10 kg/m3,優(yōu)勢沙洪季減小、枯季增大：2007-2012年懸沙濃度洪季減少、枯季增多,優(yōu)勢沙洪季增大、枯季減小。深水航道三期工程后,北槽中段河槽南側(cè)懸沙濃度增多0.31-0.48 kg/m3,洪季優(yōu)勢沙增大。2003-2012年南匯南灘水域懸沙濃度減少0.19-1.11kg/m3,優(yōu)勢沙洪季增大、枯季減少。4.洪、枯季床面微地貌特征。北港上段洪(2014年7、10月)、枯(2015年2月)季微地貌形態(tài)變化明顯,洪季比枯季沙波發(fā)育范圍廣。新橋通道內(nèi)洪季多為復合沙波,枯季變成單一沙波。橫沙通道北口水域洪季發(fā)育有彎曲型和順直型兩種類型的沙波；枯季彎曲型沙波發(fā)育區(qū)沙波消失且發(fā)育著許多橢圓形的麻坑,順直型沙波波長變大。洪、枯季河床微地貌的異同主要與洪、枯季期間水動力條件以及沉積物的粒徑和分選性有關(guān)。5.近期淺層沉積結(jié)構(gòu)變化過程。2010年1月至2014年10月北港上段新橋通道內(nèi)淺地層剖面表層形態(tài)及分層結(jié)構(gòu)變化不明顯,且均為單層分層、厚度約2m。在北港上段橫斷面最窄附近,2014年10月斷面開始大幅度沖刷并向下游持續(xù)的距離較長,最大刷深約為7 m。2010年1月至2014年10月北港上段長江大橋以西剖面結(jié)構(gòu)變化顯著,上游分層由雙層變?yōu)閱螌?中間分層消失,下游部分分層變厚、部分分層由雙層變?yōu)閱螌印?.水沙輸運機制。懸沙縱向輸運的主要驅(qū)動力包括歐拉余流(向海)、潮泵效應、垂向環(huán)流(向陸)和斯托克斯余流(向陸),歐拉余流在平流輸沙中占主導地位,潮泵效應在潮流輸沙中占主導地位,潮泵效應除北港、南槽口外隨季節(jié)變化外其余河槽均指向海。徐六涇懸沙主要由歐拉余流向海輸運,南支北側(cè)主要由歐拉余流和潮泵效應均向海輸運,北港上段、南港中段主要由歐拉余流、潮泵效應向海和垂向環(huán)流向陸輸運,北支中上段、北港中下段、北槽中段、南槽南邊灘主要由歐拉余流、潮泵效應向海和斯托克斯余流、垂向環(huán)流向陸輸運,口外主要由歐拉余流向海和垂向環(huán)流向陸輸運。7.近期動力沉積地貌過程對大型工程的響應機制。青草沙水庫建成后使北港上段河槽縮窄、斷面束水、水動力增強,再加上流域來沙減少致使懸沙濃度減少,水流會帶起河槽底部泥沙,從而導致北港上段河槽發(fā)生沖刷。深水航道三期工程南導堤加高的阻流作用、泥沙再懸浮和上游來水來沙使中段懸沙濃度增大以及上段潮動力的非線性特征增加強于中段是致使北槽中段河槽淤積的主要原因。上游來沙量的減少、南匯邊灘附近促淤圍墾工程的建設以及沙體的遷移使得該水域懸沙濃度減少,促淤圍墾工程和東海大橋的建設使得該水域洪季潮流流速增大、枯季漲潮流優(yōu)勢加強；潮動力增強和懸沙濃度減少進而導致南匯南灘水域河床沖刷明顯�？梢�,河口河槽動力沉積地貌過程不但與流域來沙有關(guān),還與河口局部工程建造存在著直接聯(lián)系。
[Abstract]:In recent years, along with the soil and water conservation project, the construction of the Three Gorges Project and the South North diversion project and other large projects in Yangtze River Basin, will make the runoff from the basin and its seasonal distribution changed significantly; and the mouth of the Yangtze River siltation reclamation large-scale, deepwater channel, Nanhui half Island, large water pool, cross river bridge and other estuarine engineering the building will change the channel boundary conditions, so that the Chinese road diversion ratio changed, thus changing the magnitude and direction of flow velocity, the temporal and spatial distribution of suspended sediment, sedimentation and transport, and then lead to the change of channel geomorphology, channel changing landscape will affect tidal power and suspended sediment concentration change. When the concentration of suspended sediment in tidal power, and topography changes, have a greater impact on the stability and security will channel boundary and large-scale estuarine engineering, which is a directly related to estuarine engineering, waterway transport The security problem and lose the people's life and property along. Based on the above factors, on the basis of previous research, in the Yangtze River Estuary in the upper, upper North trough and South Beach Nanhui waters as the research object, in recent years the use of suspended sediment in the Changjiang Estuary, tidal field, landform data and tidal data related to tidal station. A recent study in the Yangtze Estuary Channel sedimentary geomorphic processes and sediment transport mechanism, and explore the response mechanism of sedimentary geomorphic processes of large power engineering. It will have dynamic sedimentary processes helps to further understand the recent estuarine channel, to provide a theoretical basis for the rational development and utilization of estuarine and coastal resources, and estuarine engineering maintenance and to provide reference for dredging and channel management. Therefore, it has important theoretical and practical significance of the research in this paper. The main results are as follows: 1. tidal changes Cheng. Recent tidal characteristics in the study area are non regular semidiurnal tidal shallow, nonlinear characteristics of tidal power is more obvious; the upper North, North trough of upper channel shallow water tide properties strengthened, middle section of the north passage, Nanhui south beach waters, shallow water tide properties change process is not obvious. The upper channel North.2. trend 2003-2007 years the velocity 0.19-0.28 m/s, ebb flood season weakened, dry season flow enhancement; 2007-2012 years flood season increased, dry season reduced ebb flood season increased, dry season decreased. The deepwater channel project phase three, speed slightly reduced North trough of middle south part of the river channel flow, ebb weakened slightly.2003-2012 Nanhui south beach waters flow the flood season increased, dry season reduced ebb flood season increased, dry season decreased.3. suspended sediment concentration change process. In upper 2003-2007 years suspended sediment concentration decreased about 0.10 kg/m3, the advantage of the flood season sediment decreases, dry season increase: 2007-2012 The concentration of suspended sediment in the flood season year reduced dry season increased, dominant sediment in flood season increased, dry season decreased. The deepwater channel project phase three, middle section of the north passage channel on the south side of the suspended sediment concentration increased 0.31-0.48 kg/m3, flood season increased.2003-2012 dominant sediment of Nanhui south beach waters, suspended sediment concentration reduced 0.19-1.11kg/ m3, dominant sediment in flood season increased dry season, dry season reduced.4. flood bed surface micro landform. On the north section of the flood (2014 7,10 months), dry season (February 2015) micro topography changes obviously, the flood season than in dry season. The dune development range of Xinqiao channel flood season for composite sand, dry season has become a single sand. Bending straight type and two types of sand North waters of Hengsha passage in flood season development; dry season bend dune development sand waves disappeared and many developed oval pits, straight Sandwaves wavelength becomes larger. The dry season river flood, similarities and differences between the micro topography and the main flood during the dry season. Hydrodynamic conditions and sediment particle size of about.5. and the sorting of the recent changes in the shallow sedimentary structure of.2010 from January to October 2014 in the upper bridge channel change profile of the surface morphology and hierarchical structure of shallow strata is not obvious, and is the single layered, the thickness is about 2M. in the north near the upper cross section of the narrow section, October 2014 began to greatly scour and downstream continuous long distance, the maximum scour depth is about 7 m.2010 from January to October 2014 in the upper Yangtze River bridge west section structure changed significantly, stratified by double into upstream monolayer, the middle layer disappeared, the downstream part of layered thick, partially layered by double into water and sediment transport mechanism of.6. single main driving. The force of suspended sediment transport including longitudinal Eulerian flow (Xiang Hai), tidal pumping effect, vertical circulation (landward) and Stokes (Xiang Lu), the residual current flowing in the Eulerian advection for sand The dominant position, the tidal pumping effect in tidal sand dominated tidal pumping effect in North, south of the groove opening varies with the season the river channel are pointing to the sea. Xu Jing six suspended sediment is mainly composed of Euler residual flow to sea transport, on the north side of South Branch is mainly composed of Euler residual current and tidal pumping effect to the sea transport, north south middle upper, mainly by the Euler residual current and tidal pumping effect to vertical circulation to the sea and land transport, upper North Branch, north middle section, middle section of the north passage, South South Beach trough is mainly composed of Euler residual current and tidal pumping effect to the sea and the Stokes residual current, the vertical circulation to land transport, mainly by extraoral Euler residual flow to the sea to the land circulation and vertical transport of.7. recently sedimentary geomorphic process response mechanism of the large-scale project. Built in Qingcaosha Reservoir after the upper north channel narrow beam section water, water power increased, coupled with the decrease in riverine sediment in suspended sediment concentration reduce water. Bring up the channel flow of sediment at the bottom, resulting in north channel erosion. The upper stage three deep waterway project south dike heightening the flow resistance, sediment resuspension and sediment from the upstream to the middle of suspended sediment concentration increased and the nonlinear characteristics of upper tidal power increased in the middle is the main reason causing strong middle section of the north passage and the siltation.. reducing the upstream sediment, Nanhui beach near and promoting the construction of the reclaiming project and migration of sand makes the waters of the suspended sediment concentration is reduced, the construction of siltation reclamation project and the East China Sea Bridge makes the waters of the flood season tide velocity increases, the dry season tide advantage strengthened; tidal power enhancement and suspended sediment concentration to reduce the resulting Nanhui south beach waters scour significantly. Therefore, channel power estuary sedimentary processes not only with sediment, and local estuary construction there is a direct relationship.

【學位授予單位】：華東師范大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TV148

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