Dynamic performance of submerged floating tunnel with different mooring styles subjected to anchor cable failure

Submerged floating tunnels(SFTs)are novel structures for transportation across long-and deep-strait regions.Owing to severe wave and current excitation as well as the effects of underwater structures and corrosion,the risk of local anchor cable failure is high,which can result in the progressive failure of the entire structure.In this study,experimental and numerical investigations are conducted to analyze the dynamic behavior of an SFT with different mooring styles under local cable failure.A custom-designed cable failure device and the birth-and-death element method are used to simulate cable failure(i.e.,progressive failure)via experiments and numerical simulation,respectively.A physical-scale segmental model of an SFT with different mooring styles under anchor cable failure is developed in this study.A segmental and entire-length mathematical model is developed using the ANSYS program to perform the numerical simulation.The results of the segmental numerical and experimental models indicate good agreement.The dynamic response of an SFT with different mooring styles under cable failure is comprehensively investigated by investigating the effects of key parameters(wave period,buoyant weight ratio,and cable failure mechanism).Moreover,the progressive failure of the SFT under cable failure is investigated via a segment model test and a numerical simulation of its entire length.The present study can serve as a reference for the safer designs of the SFT mooring style.

Microbiologically influenced corrosion of cable bolts in underground coal mines:The effect of Acidithiobacillus ferrooxidans

Reports on corrosion failure of cable bolts,used in mining and civil industries,have been increasing in the past two decades.The previous studies found that pitting corrosion on the surface of a cable bolt can initiate premature failure of the bolt.In this study,the role of Acidithiobacillus ferrooxidans(A.ferrooxidans)bacterium in the occurrence of pitting corrosion in cable bolts was studied.Stressed coupons,made from the wires of cable bolts,were immersed in testing bottles containing groundwater collected from an underground coal mine and a mixture of A.ferrooxidans and geomaterials.It was observed that A.ferrooxidans caused pitting corrosion on the surface of cable bolts in the near-neutral environment.The presence of geomaterials slightly affected the p H of the environment;however,it did not have any significant influence on the corrosion activity of A.ferrooxidans.This study suggests that the common bacterium A.ferrooxidans found in many underground environments can be a threat to cable bolts'integrity by creating initiation points for other catastrophic failures such as stress corrosion cracking.