Service life prediction of lining concrete of subsea tunnel under combined compressive load and carbonation

Qingdao Jiaozhou Bay subsea tunnel is the second self-built tunnel in China with the designed service life over 100 years. The durability of lining concrete are one of an important factors to determinate the service life of tunnel. Considering the main environmental loads and mechanical loads of subsea tunnel, the durability properties of lining concrete under combined action of compressive load and carbonation has been studied through the critical compressive load test, accelerated carbonation test, natural carbonation test and capillary suction test. The tests results show that critical compressive load apparently accelerates the carbonation and deteriorates the anti-permeability of concrete. Under the combined action of critical compressive load and carbonation, the durability of lining concrete decreases. Based on the carbonization life criteria and research results, for the high-performance concrete with proposed mix ratio, the predicted service life of lining concrete for Jiaozhou bay subsea tunnel is about 80 years which fails to reach the required service life. It is necessary to adopt other measurements simultaneously to improve the durability of lining concrete.