| With the increasing of construction of underground structures, people attach importance to the durability problems of underground structures more and more. Durability of underground structures is different from that of ground concrete structures. Due to special environment and characteristics, a large amount of underground structures suffer early damage and need maintaining. In order to maintain the stability of underground structures and to predict their remaining life, it is urgent to extend and deepen the field of underground structures durability research.Firstly, it analyzes the major factors that affect underground structures' durability and also the durability deterioration law controlled by multi-factors in this thesis. Around carbonization corrosion of underground structures under stress state, we make reference to the related experimental data and consider comprehensively stress level, material intensity, environmental temperature, humidity, CO2 thickness and etc. to fit data of influence of carbonization corrosion of concrete structure. By studying the relationship between the various factors and carbonation rate of concrete, a empirical formula of carbonization model influenced by multi-factors is establishedSecondly, it introduces the formula of carbonization remains and considers the relationship between carbonization remains and steel corrosion, a time prediction mode of the initial corrosion of reinforced concrete is thus established. Meanwhile, a prediction model of steel corrosion penetration which takes many integrated factors into account, such as oxygen diffusion, temperature, relative humidity, covering concrete thickness, rebar diameter and concrete strength.Finally, based on the two lifetime-assessment rules prediction modes of concrete carbonization and steel rust expansion are established separately, at the same time, some suggestive measures have been provided to improve the durability of underground structures.
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