Distributed detection of upheaval buckling for buried pipelines with Brillouin fiber optic sensors

During servicing of subsurface transportation pipelines, axial pressure generated by high-temperature and high-pressure working conditions is released through upheaval buckling deformation. When the overall deformation of the pipeline exceeds limits, the weakest part of the pipeline will suddenly break and fail, causing serious economic losses and social problems. To ensure safe pipeline operations, it is necessary to monitor the upheaval buckling mechanism of pipelines with a new type of monitoring technology to realize structural reliability assessment under complex loads. Based on Brillouin optical time-domain analysis (BOTDA) distributed optical fiber sensing technology, this study proposes a method to identify buried pipelines’ structural state to solve the problem of detecting upheaval buckling with initial defects under unknown loads. Based on the BOTDA principle, the proposed method comprises a distributed structural response monitoring approach for pipelines. The Euler-Bernoulli beam deflection curve calculation method is used to establish a pipeline buckling displacement reconstruction algorithm to quantitatively identify the occurrence and development of pipeline upheaval buckling. The initial-defect buried pipeline model test is used to verify the feasibility of the proposed method. The results show that the proposed method for identifying the upheaval buckling of buried pipelines can realize quantitative identification of front and back buckling behavior of submarine pipelines under unknown loads, which has important practical significance and application value.