Reliability-based life prediction method for concrete sewage pipelines under microbial attack

Abstract

The durability of concrete sewage pipelines decreased for microbial attack. In this study, a method for life prediction of concrete sewage pipes under microbial-induced attack was developed by combining numerical simulation with theoretical analysis. A mathematical model of the corrosion depth of microbial erosion of concrete was constructed based on the cumulative model of sulfate concentration on the surface of sewage pipes and verified the applicability by comparing it with the experimental results. The Monte Carlo (MC) life prediction method and Fuzzy- Monte Carlo (F-MC) life prediction method for concrete sewage pipes was established based on the reliability theory and fuzzy methodology. Several factors are considered as random variables and analyzed parametrically, including hydrogen sulfide concentration (SH2S), diffusion coefficient (D), and thickness of the concrete cover (CC). In addition failure event was consider as a fuzzey event. It was found that: The increasing SH2S and D result in higher failure rates and lower service life, however as the increase of the thickness of CC, there is the opposite effect. The results of the numerical simulations revealed a NR between the three kinds of parameters and the probability of failure of sewer pipes. Compared with the MC model, the F-Mc model produces more conservative but not minimal different results, which confirms the applicability of the F-MC model.