粉砂淤泥质海岸人造沙滩效果——以上海金山城市沙滩为例

AN EFFECTIVE ARTIFICIAL BEACH ON MUDDY COAST: THE CASE OF JINSHAN CITY BEACH OF SHANGHAI

上海市金山区位于杭州湾北岸,发育典型的粉砂淤泥质海岸,潮滩低平、颗粒极细,下陷0.1~0.2 m,且风暴潮期间海水泥沙含量极高,泥层易滑塌。2005年,在金山潮滩构筑3.3 km封闭式围堰围海成湖1.72 km^2,近岸抛沙15.6万m^3并设防泥网建成长度1.4 km的人造沙滩进行跳相养滩,后经多次补沙和围堰加固,将"黄水黑滩"变为"碧海金沙",成为金山城市沙滩。该人造沙滩是中国首个泥岸养滩成功案例,后有天津东疆浴场、潍坊央子人造沙滩、南通启东碧海银滩等10余个人造沙滩建成。金山城市沙滩封闭式围堰消浪护沙、稳定沙滩,结合"沉泥碧水"技术维持海水清洁且防止新滩泥化;固定式防泥网较为坚固,保证游人安全。其围海成湖、沉泥碧水、抛沙建滩及泥沙界网等工程技术为中国粉砂淤泥质海岸人造沙滩建设提供了实践经验。

The Jinshan District of Shanghai,located on the north bank of Hangzhou Bay,has a well developed silty and muddy coast with a low and smooth tidal flat covered by fine sediment in shape of a sink 0.1~0.2 m in depth.The content of sea water in the sediment is extremely high during storm surge so that the mud layers are easy to slide.In 2005,a 3.3 km closed cofferdam was constructed on the Jinshan tidal flat and a lake of 1.72 km^2 was formed.A sediment net was setting up and an 1.4 km long artificial beach was constructed by throwing 156000 m^3 of sand from offshore.After many times of sand replenishment and cofferdam reinforcement,the"Yellow Water covered Black Beach"finally turned into a beach of"Blue Water with Golden Sand",which is called Jinshan City Beach since then.The artificial beach is the first successful case in China to turn a muddy flat into a sand beach.After it,more than ten artificial beaches,such as the Tianjin Dongjiang Beach,Weifang Yangzi Artificial Beach,and Nantong Qidong Beach were built up successively.In the case of the Jinshan City Beach,closed cofferdam is used to eliminate wave and protect sand from erosion,make the beach more stable,keep sea water clean and prevent the deposition of beach mud with the technology of sinking sediment and clean water.The fixed mud net is strong enough to ensure the safety of visitors.Its engineering techniques,such as encircling the sea into a lake,sinking mud to clean water,sand nourishment,beach construction and keeping the mud boundary stable,etc.,have provided useful samples for construction of artificial sand beaches in China.