公路跨越大江大河时 ,是采用隧道还是大跨径桥梁 ,两种方案需经技术经济比较 ,若建桥会受到各种因素的制约 ,尤其是当通航要求桥下净空超过 5 0 m时 ,采用桥梁方案已不合理 ,沉管隧道方案则是较优的选择。结合珠江三角洲经济区环行高速公路东环段珠江沉管隧道方案设计 ,介绍沉管隧道的特点 When a highway crosses a large river, it is a tunnel or a long-span bridge. The two schemes need to be technically and economically compared. If the bridge is subject to various factors, especially when the navigation requires that the under-bridge clearance exceed 50 m, Bridge program has been unreasonable, immersed tunnel program is a better choice. Combined with the design of Zhujiang River immersed tunnel in Donghuan section of Central-Loop Expressway in Pearl River Delta Economic Zone, the characteristics of immersed tunnel are introduced