为研究海底隧道初期支护中工字钢在氯离子渗透下严重锈蚀时对结构耐久性的影响，采用室内试验研究工字钢在不同混凝土保护层厚度下锈胀力与锈蚀率的关系以及锈胀的发展过程，再通过数值模拟研究锈胀力作用下的混凝土裂缝、混凝土应力、应变分布规律及胀裂应力变化情况。研究结果表明： 1）相同保护层厚度下，锈胀力随着锈蚀率的增加而增大；锈蚀率相同时，锈胀力随着保护层厚度的增加而增大； 2）工字钢混凝土构件锈胀开裂，裂缝集中于翼缘中部和2个角点区域，翼缘中部的裂缝由外向内发展，2角点区域的裂缝由内向外发展； 3）数值计算得出的混凝土胀裂应力大于试验得到的混凝土胀裂应力。

To study the influence of the serious corrosion of I-shaped steel in the primary support of an undersea tunnel on the durability of the structure, relationship between corrosion rate and corrosion expansion force, and development process of corrosion expansion force under different concrete protective layer thicknesses are studied via laboratory tests. Thereafter, the simulation is used to study the concrete cracks, stress, strain, and cracking corrosion expansion force under different concrete protection layer thicknesses. The results show the following: (1) The corrosion expansion force increases with an increase in corrosion rate under the same protective layer thickness, and the corrosion expansion force increases with an increase in the thickness of the protective layer under the same corrosion rate. (2) The corrosion expansion cracking of the I-shaped concrete members is concentrated in the middle and two corner points of the flange. The concrete crack in the middle of the flange develops from the outside to the inside, whereas the concrete crack in the area of the two corner points develops from the inside to the outside. (3) The concrete crack stress obtained by numerical calculation is larger than that in the test.