胶州湾海底隧道衬砌混凝土服役寿命预测

胶州湾海底隧道是中国自行建造的第2条海底隧道，其设计服役寿命为100a。分析了海底隧道衬砌混凝土的服役环境，建立了综合考虑氯离子扩散、碳化和弯曲荷载影响的服役寿命预测模型。调查了海底隧道现行施工里程的混凝土耐久性关键参数，建立了海底隧道混凝土氯离子扩散系数与回弹强度间的函数关系，通过预测模型计算了混凝土中氯离子随时间的演化规律及衬砌混凝土服役寿命。结果表明：隧道衬砌混凝土的保护层厚度波动值-4（-6）～＋15mm，标准养护衬砌混凝土氯离子扩散系数均值为2．1（2．7）×10^-12m2／S，混凝土中初始氯离子浓度小于0．35kg／m3。隧道衬砌混凝土氯离子扩散系数与回弹强度呈线性函数关系，施工里程内氯离子扩散系数波动为1．5～3．5×10^-12m2／S。基于模型计算，胶州湾海底隧道左右线衬砌混凝土的服役寿命均超过100a。

Service Life Prediction of Lining Concrete for Jiaozhou Bay Subsea Tunnel

Jiaozhou Bay subsea tunnel is the second self-built tunnel in China with the designed service life over 100 years. On the basis of service environment of subsea tunnel concrete and the durability experiments of concretes, the service life prediction model considering chloride diffusion, carbonation and bending loading was proposed. The key durability coefficient of lining concrete in subsea tunnel was investigated. And the function of chloride diffusion coefficient and rebound strength of concrete was proposed. Moreover, the chloride content in concrete varied with service time and the service life of lining concrete for subsea tunnel was predicted with the proposed service life prediction model. It was found that the value of varied cover thickness was from-4 (6) to 15 mm. The chloride diffusion coefficient mean value of lining concrete in standard curing was 2.1(2.7)×10~(-12)m~2/s. And the initial chloride content in concrete was less than 0.35kg/m~3. The relationship between chloride diffusion coefficient and rebound strength could be regressed to linear relationship, and the calculated chloride diffusion coefficient of lining concrete was varied from 1.5×10~(-12)m~2/s to 3.5×10~(-12)m~2/s. The predicted service life of lining concrete for Jiaozhou bay subsea tunnel was more than 100 years according to proposed model.