摘要：港珠澳大橋沉管隧道位于亞熱帶海域，具有氣溫高、濕度大、海水含鹽度高的特點，受海水、海風、鹽霧、潮汐、干濕循環等眾多因素影響。根據相似環境下的暴露試驗和工程調查研究結果，鋼筋混凝土結構在該腐蝕環境中腐蝕嚴重，耐久性問題突出[1, 2]。港珠澳大橋沉管隧道處于水下或泥下，一旦發生腐蝕（特別是沉管外壁），無法進行維修。因此，保證沉管隧道120年免維修設計使用壽命對整個工程達到120年的設計使用壽命至關重要。

       鋼筋銹蝕是導致港珠澳大橋沉管隧道耐久性下降的主要原因，本文通過從設計、混凝土的原材料、混凝土和施工等方面對港珠澳大橋沉管隧道混凝土結構的耐久指數（Tp）進行分析計算，并結合隧道所處的腐蝕環境的環境指數（Sp）對港珠澳大橋沉管隧道混凝土結構的腐蝕風險進行評估，結果表明：無論是沉管內壁還是外壁，耐久指數（Tp）均大于環境指數（Sp）。表明：只要從設計、混凝土的原材料、混凝土和施工等方面嚴格控制，從理論上即可避免沉管隧道中的鋼筋發生銹蝕，確保沉管隧道120年免維修的耐久性設計使用壽命。

關鍵詞：沉管隧道，腐蝕風險評估，環境指數，耐久指數

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