6 人 民 长 江 2015篮
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Recent evolution and self—adjustment processes of south branch of Yangtze River estuary
ZHANG Xiaohe,LI Jiufa,YAO Hongyi,ZHU Wenwu
(State Key Laboratory of Estuarine and Costal Research,East China Normal University,Shanghai 200062,China)
Abstract: Based on the digital topographic map and hydrological sediment data since 1997 and the recent hydrologic field ob-
servations,the self—adjustment process of south branch in Yangtze estuary under the influence of Xinliuhe shoal protection works
and Three Gorges Project are analyzed.The results indicate that the water fluvial regime is stable and the riverbed is in eontinu-
OUS erosion state under the condition of sharp sediment decrease and unchanged discharge since the completion of Three Gorge
Project:the river bed is continuously scoured but the intensity has become smaller and has a new balance tendency since 2006; in the same period,the cross sections are narrower and deeper,the changes of Baimao and Xinliuhe shoals exert significant influ—
ence on the stability of the channel;the erosion and deposition of south and north passage bifurcations changes frequently;the
constructed Xinliuhe shoal protection works and Nanshatou channel submerged dike projects play a great role in shoal fixing and
flow limiting,but can not prevent the trend of intense erosion at the front areas of Xinliuhe shoal and Nanshatou channe1.Some
effeetive measures should be taken to the tail of Biandan shoa1.
Key words: river channel evolution;human activities;self—adjustment process;south branch of Yangtze River estuary
・简讯・
长江设计院设计的国内首条高水压大坡度长距离纵向曲线顶管贯通
近日,由长江设计院市政交通院承担设计的国内首条高水
压大坡度长距离纵向曲线顶管工程成功穿越杭州富春江,成为
国内顶管穿江工程的新典范。
该工程为杭州市天然气利用工程的顶管穿越富春江段,拟
穿越的管线为一根DN600天然气高压管线,穿越段位于富春江
窄溪大桥上游约32 m处。隧道穿越方式采用顶管法,顶管水
平长度为646.0 m,实际长度为648.6 m,内径为2 400 mm。顶
管平面轨迹为直线,竖向轨迹为两端采用斜坡,中部采用组合
的圆弧形曲线,始发段斜坡角度为6。,接收端斜坡角度为
8.27。,圆弧段曲率半径为4 300 m和1 200 m。隧道覆土埋深
为5.0~25.3 m,最大水头39.1m。
富春江顶管穿越工程有多项关键性技术挑战。顶管全长
达648.6 m,纵坡呈大坡度的“V”字形,且连接端采用了复曲
线,国内尚无此类工程的成功案例,对设计方及施工方来说是 一个严峻挑战;顶管覆土厚且穿越地层的复杂,既有软可塑的
黏土,也有坚硬的中风化石英砂岩,施工过程非常曲折与复杂,
多次换刀后才确保了顶管设备的顺利掘进;顶管承压水头大,
达到了39.1 m,超过国内市政工程常用的顶管承压水头近20
m,对顶管管节之间的止水设计是一次质的跨越。长江设计院
技术人员经过查阅国内外大量工程案例,并与专家反复讨论,
创新性地采用双道止水的设计方案,确保了此次穿江工程成功
贯通。 该项目是继黄石、武汉、南京等盾构穿江项目之后,长江设
计院设计的第一条顶管穿江隧道工程。富春江穿江工程的顺
利贯通,标志着该项目关键性的土建工程取得圆满成功,为长
江设计院承担顶管穿江工程积累了宝贵经验。
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