摘要：港珠澳大桥沉管隧道位于亚热带海域，具有气温高、湿度大、海水含盐度高的特点，受海水、海风、盐雾、潮汐、干湿循环等众多因素影响。根据相似环境下的暴露试验和工程调查研究结果，钢筋混凝土结构在该腐蚀环境中腐蚀严重，耐久性问题突出[1, 2]。港珠澳大桥沉管隧道处于水下或泥下，一旦发生腐蚀（特别是沉管外壁），无法进行维修。因此，保证沉管隧道120年免维修设计使用寿命对整个工程达到120年的设计使用寿命至关重要。

钢筋锈蚀是导致港珠澳大桥沉管隧道耐久性下降的主要原因，本文通过从设计、混凝土的原材料、混凝土和施工等方面对港珠澳大桥沉管隧道混凝土结构的耐久指数（Tp）进行分析计算，并结合隧道所处的腐蚀环境的环境指数（Sp）对港珠澳大桥沉管隧道混凝土结构的腐蚀风险进行评估，结果表明：无论是沉管内壁还是外壁，耐久指数（Tp）均大于环境指数（Sp）。表明：只要从设计、混凝土的原材料、混凝土和施工等方面严格控制，从理论上即可避免沉管隧道中的钢筋发生锈蚀，确保沉管隧道120年免维修的耐久性设计使用寿命。

关键词：沉管隧道，腐蚀风险评估，环境指数，耐久指数

Evaluation study on corrosion risk of immersed tube tunnel of the Hongkong-Zhuhai-Macao Bridge
Tang Yanbing ^{1, 2}, Chen Long ^{1, 2}, Wang Shengnian ^{1, 2}, Fan Zhihong ^{1, 2
1}（CCCC Fourth Harbor Engineering Institute Co., Ltd., Guangzhou, 510230）
²（Key Laboratory of Durability Technology for Harbor and Marine Structure Ministry of Communications, Guangzhou, 510230）

Abstruct: The Hongkong-Zhuhai-Macao Bridge locates at semi-tropical ocean，witch has high temperature, high humidity, and high salinity. It is often suffered seawater, sea breeze, salt fog, tide, dry-wet cycle and so on. The results of exposure experiments and project surveys that the corrosion environment is similar with the Hongkong-Zhuhai-Macao Bridge imply that the corrosion of rebar in concrete is very serious. The reinforced concrete bridge piers are the main reinforced concrete members for the Hongkong-Zhuhai-Macao Bridge. It is very difficult to repair or replace when the rebar is subject to corrosion. Therefore, it is very important to make sure that the rebar in the reinforced concrete bridge piers is not subject to corrosion for 120 years.

The corrosion risk of the immersed tube tunnel of the Hongkong-Zhuhai-Macao Bridge was investigated by comparing the environment index with the durability index. The durability index was analyzed according to design, raw materials of concrete, concrete and construction. The results showed that the durability index is larger than the environmental index. Therefore, if we could control strictly from design, raw materials of concrete, concrete quality and construction, it could avoid the immersed tunnel to suffer corrosion, and ensure to satisfy 120 years maintenance free design life-span.

Keywords: immersed tube tunnel, corrosion risk evaluation, durability index, environment index